CA2321671C - Tissue ablation system and method for forming long linear lesion - Google Patents

Abstract

The present invention relates to a tissue ablation device assembly which is adapted to form a conduction block along a length of tissue between two predetermined locations along the left atrial wall. The assembly comprises an ablation element on an elongated ablation member which is coupled to each of two delivery members, the delivery members having first and second anchors, respectively, that are adapted to anchor at the two predetermined locations, such that the delivery members are adapted to controllably position and secure the ablation element along the length of tissue between the predetermined locations. A linear lesion in the tissue between the predetermined locations is then formed by actuation of the ablation element. The invention further provides that the ablation member may slideably engage one or two delivery members such that an adjustable length of the ablation element along the ablation member may be extended externally from the engaged delivery member and along a length of tissue.

Description

TISSUE ABLATION SYSTEM AND METHOD FOR
FORMING LONG LINEAR LESION
Background of the lnvention The present invention relates to a surgical device and more specificaby, to a tissue ablation assemldy which is adapted to form a conrhwtion blodc along a langth of tissue between two predetermined locations along a left atrial wall.
Cardiac arrhythmia's, perticularly atrial fibrillation, are a pervasive problem in modern society. Although many individuals lead relatively normal lives despite persistent ataal fibrillation, the concition is associated with an increased risk of myocardial ischemia, especially during strenuous activity.
Furthermore, persistent atrial fibrillation has been linked to congestive heart failure, stroke, and other thromboembolic events.
Thus, etrial fibrillation is a major public health problem.
Nomtial cardiac rhythm is maintained by a duster of pacemaker cdls, known as the sinostrial I"SA") node, located within the wal of the right atrium. The SA node undergoes repetitiva cydes of membrane depolarization and repolarization, thereby generating a continuous stream of electrical impuises, called "action potentials." These action poten6als orchestrate the reguler contraction and relaxation of the card~ac musde cells throughout the heart. Action poten6als spread rapidly from cell to cell through both the right and left stria via gap junctions between the cardiac muscle cells. Atrial arrhythmia's n:sdt when electrical impulses originsting from sites other than the SA node are conducted through the atrial cardiac tissue.
In most cases, atrial fibrigation results from perpetually wandering reentrant wavelets, wlrch exhibit no consistent locdized regionts) of aberrant conduction. Alternatively, atrial fibrMation may be focal in nature, resulting from rapid and repetitive changes in membrane potential odginating from isolated centers, or foci, witlan the atrial cardiac muscle tissue.
These foci exhibit centrifugal patterns of electrical activation, and may act as either a trigger of paroxysmal attial fibrillation or may even sustain the fibriAation. Recent studies have suggested that focal arrhythmia's often originate from a tissue region along the pdmonary veins of the left etrium, and even more pardculady in the superior puimanary veins.
Several surgical approaches have been developed for the treatment of atrial fibrillation. One particular example, known as the "maze" procedure, is disdosed by Cox, JL et al. "The surgical tmstrnent of atdal fibnllation. I. Summary; Thoracic andCarifovascdarSiagery 10113002-405(1991) and also by Cox, JL "The surgicW
treatment of atrial fibrillation. IV. Surgical Techrique", Thaaca and CamliovascdarSwgery 101141:584-592(1991). In general, the maze procedure is designed to relieve atrial arrhythmia by restoring effective SA node control through a pnscribed pattern of incisions about the cardiac tissue.wall.
Although early dinical stu(kes on the maze procedure included surgical incisions in both the oght and left atrial chambers, more recent reports suggest that the maze procedun: may be effective when perfmmed ody in the left atrium (see for example Sueda et al., "Simde Left Atrial Procedure for Chronic Atriat Fibnllation Associated With Mitral Valve Disease" (19961).
The left atrial maze procedure involves forming vertical incisions from the two superior puknonary veins and temiinating in the region of the mitral valve annulus, traversing the inferior pdmonary veins en route. An addtiond horizontal incision connects the superior ends of the two vertical incisions. Thus, the atrial wali region bordered by the pdmonary vein SUBSTITUTE SHEET (RULE 26) WO 99/44519 PCTlUS99/04521 ostie is iadeted from the other atrid tissue. In thia process, the mecherical sectiorirg of atdal tima elbninates the atrid arthydNraa by 6iociung conduction of the abmrent action potemiels.
The moderate auccess observed with the meze procedure and other surgical segmentation procedures have vekdeted the principie that etectricaYy isdating cerdiac tissue may successfuMy prevent atriat arrhythmia's, par6adady atriai fibri9adon, reWting from either patpetuagy wandering reentrant vusvdets or focal mgions of eberrant cmduction. Unfortunateiy, the lwgHy invasive nature of such procedures may be prohibitive in many caaes.
Consequentiy, less invasive cetheter-based approaches to treat atriri fidedon through cardiec tissue adation have been developed.
Thess less invasive catheter-based therepies generally invdve introducing a catheter within a cardiac chamber, mch as in a parcutaneous translumenal procedure, wherein an energy sink on the catheter's distal end pordon is positioned at or adjacent to the abetrant conductive tissue. Upon application of energy, the targeted tissue is ahlated and rendered non-conductive.
The catheter-based methods can be subdivided into two related categories, based on the etidogy of the etriel errhytiutaa. First, focal arrhythmia's have lxoven emena6le to localized abletion techtrques, wtuch target the foci of abwant electdcal activity. Accorringly, devices and techniques hava been disdosed wNch use end-electrode catheter designs for ablating focal arrhythmia's centered in the puknonary veins, uWog a point source of energy to ablate the locus of abnormal electricel activity. Such pracedires typically employ incremental appGcation of electrical energy to the tissue to form focel lesions. The secand category of catheter=based adation methods are designed for treetment of the more common fmms of afisl fibrillation, resulting from perpetueNy wandering reentrant wavelets.
Such arrhydania's are generagy not amenable to localized adetion techniques, bec,ause the excitation weves may circnnavigate a focal lesion. Thus, the second dass of catheter-based approaches have generally attempted to nrimic the eerGer swgical selpnentation techniques, such as the maze procedure, wherein continuous Gnear lesions ara n3quired to completdy segment the atrial tissue so as to blodc conduction of the reentrant wave fronts.
An example of an ablation method taige6ng focal wrhythmia's originating from a pdmonary vein is disclosed by Haissaguarre et aL in "Right end Left Atrtaf RaLlofrequency Catheter Therapy of Paroxysmal Atrial FibriBation" in Joranal of Ca-&~vescdaiElectrophysidogy71121, pp.1132-1144(1996). Heissaguerre et al.
describe radiofrequency catheter ablation of dnig-refractory paroxysmal atrial fibtilation using linear atriel lesions complemented by focal ablation targeted at arrhythmogeric fod in a scwed pafat popdatron. The site of the arrhythmogenic foci were generaUy located just inside the superior puMonary vein, and were aNeted using a standard 4 nan tip single abIation electrode.
Another ablatian method dmcted at paroucysmal arrhythmia's ariaing from a focal source is duxtosed by dais et al. "A
focal source of atriri fibriation treated by discrete radiofrequency a6lation"
Cficdatian 95:572-576 (1997). At the site of arrhyttnnogenic tissue, in both right and left atrie, several pulses of a riscrete source of radiofrequency energy were appiied in order to elnninate the fibn'patory process.
AppGcation of cathatm-based abla6on techniqm for treatment of reentrant wavelet arrhyttmia's demanded development of methods and devices for generating continuous Gnear lesions, Nke those employed in the maze procedure.
Initially, conventional abletion tip electrodes were adoptml for use in "dreg burn" procedun:s to fonn linear iesions. During the .2.

SUBSTITUTE SHEET (RULE 26) WO 99/44519 PCr/US99/04521 "drag" procedure, as energy vnaa beirg eppGed the catheter 6p vres dravun across the tissue dong a predetanrined pethuvay vuithin the heart. Alternatively, ines of ablatian were also mede by sequentiaAy positioning the distal tip electrode, applying a pulse of energy, and then re-poaitiaring the dectrode along a predetemined inear pathway.
S'ubsaquerrtly, conventionel catheters were modified to indude multiple electrode arrxqemts. Such cathetera typically contained a piurality of ring electrodes cinding the catheter at various distances extending proximally from the cistal tip of the catheter.
Whde feasible catheter designs existed for imparting Gnear abledon tracks, as a practical mattet, most of these catheter assernbGes have been dffiadt to position and meintain plar.ement and contact pressree long enough and in a sufficiently precise manner in the beating heart to successfully form aegnmted linear lesions along a chamber vuab. Indeed, many of the aforememioned methods have generally faled to produce dosed msrnural lesions, thus leaving the opporturity for the reentrant circiits to mappear in the gaps remaining betvueen point or dreg ablations. In addition, ninimal meow hava been disclosed in these embodiments for steedng the catheters to anetomic sites of interest such as the ptimonery veins.
Subsequentiy, a number of sohrtions to the problems encountered vuith precise positiorrng, maintenance of contact pressue, and catheter steering have been described These indude primerdy the use of (1) preshaped ablating configurations, (2) deflectable catheter assemblies, and (3) transcatheter ablation assemb6ea.
One approach to improved placement has been to use preAaped configurations which impart vadous predetemined lesion pattems, such as "hairpins" or "J-shapes". Typicagy, these configuretions are situated at the cistal end of various steering catheters. Such catheters gerrerally indude steering vares, extending from a steering mechmism at the proxarnal end of the catheter to an anchor point at the ristal end of the catheter. By applying teraion to the steeting vuires, the tip of the catheter can be drected in a desired direction. Furthennore, some catheters comprise a rotatable steering feature vahich aYows the catheter as a whole to be rotated about its iongitudmai axis, by maripdating the proximal end of the catheter. This exerts a torque vuhich translates to a rotatirig motion at the cistal end vuhich agows a lateraby deflected distal tip to be rotated. Once the catheter is steered and positioned to a desired site within an attid chrenber, ablating elements may be activated to fonn the lesion.
Some preshaped catheter assembGes empioy a flexible outer sheath vuhidt is advenced over the cistal end of the preshaped "gride" catheter. Movement of the gdde catheter vuithin the sheath modifies the predetemined curve of the cistal end of the catheter. By inserting different shaped guide catheters through the outer sheath, dffarent shapes for the distal end of the catheter are created. In one embodiment, the giide catheter position is visua5zed by X-ray fluoroscopy and progressively repodtioned in real time by remote percutaneous maniprdation along a preferred pathway in the moving vuaU of a beating atrium to form conenuouslesions.
Deflectade catheter configurabons adapted to form cirvihnear lesions vuithin an atrial chamber, include devices having a three dimensional basket stnrcttrce that encloses an open interior at the distal end of the device. The deflectable basket elements may carry single or mdtiple electrodes. The baskets may be deployed from the catheter by removd of a shmth, dona by manipulating the steeang assembly located at the proximal end of the catheter. Such deflectable catheter assembGes may fam elorigeted lesions, or simple or complex pattems of cruviiinear lesions, dependng on the pattem of ebia6ng =3-SUBSTITUTE SHEET (RULE 26).

electrodes on the baaket elements. Curviinear elements may be depfoyed 'mdridudly in succession to create the deaired meze pattem. In furft emboddnents, muviineer ekmts may indude a family of flexible, elongated ablating elements which are contrdled by a steering medianisrn thereby peWtting the physicien to create flexea or curvea in the ablating elments. Such curAnear alemeirts mdude a variety of ablating electrode configurations indudng inear dbbons and dose{y wound spirals. A
further variation includes the use of gripping members wHch serve to fix the position of the ablation surface against the atriel wall. The gripping members may include teeth or pins to enhance the ablation of the cwdiec tissue by maintaiiing a substantially constant pnssre ageinst the heart tiaaue to increese the uirfomuty of the ablation.
Tramscetheter-based assembl'res indude systems for creeting both Gnear iesions of varieMe length or complex lesion pettems. Such assendes and methods involve catheter systems which can adapt to the tissue stna:tures and maintain adequate contact and which are easily deployetde and manewerable. One example of a trenscetheter-based essembly and method for creating conplex lesion patterns indudes the use of flexible electrode segments with an edjustable cog length wlMch may form a convoluted lesiai pattem of varying letgth. This device indudes a composite stnMure which may be flexed along its length to form a vaiety of caxvginear shapes from a generally Gnear shape.
Other transcetheter ablatian assemblies indude the use of steerabte vascular catheters which are expended to confotm to the surface of the cardiec chamber. One such expandable system comprises single or mdtiple proximally constreined dcverging spline,s wfich expend upon emergence from the dstal ernl of a catheter sheath, Gke the deflectabe basket assembfy desaibed above. The spines are suffidently dgid to maintain a predisposed shape but are adapted to be defocted by contact with the cardiac chamber wal. This expand" mdti-electrode catheter is adopted to be positioned against the irrw wafl of a catdac chamber to create fmmr continuous lesions.
Another example describes an expendade stnicture and method for ablatirg cardac tissue, indudmg a bendede probe which is deptoyed within the heart. The probe carries at kast one elongated flexible ablation dement, a movable spine leg and further indud'ing a bendable stylet in a single loop support stntcture. The assembly provides for tonsion to bend the stylet which then flexes the eWation element into a curWinear shape or other readly contrdled arcuate catheter shapes to eUow a dose degree of contact between the electrode elements and the target tissue for fonning long, thin lesion pattems in cardec tissue.
An additional example of a bendable transcathetm assembly compeses an outer deivery sheath and an elongated EP
device sGdeably dsposed wrtFrn the axier iumen of the de6very sheath and secured at its distai end wititin the delivery sheath.
The EP device has a piuraity of dectrodes on its distal poraon. Proximal marrpulation of the EP element causes the dstal portion of the EP device to arch, or "bow" outwardly away from the distal section of the deGvery sheath which engages the heart chamber, thereby fomnng a Gnew lesion in atrid well.
None of the present catheter-based devices, howaver, indude a tissue a6lation assembly heving two separate and independent delivery members with an elargated ablation member coupted therebetween. Nor does the peor art disdose an assembty where the abletion member is adapted to vatiably extend from a passegeway through a dstal port in one of the delivery members, thereby provicing en ablation means having an adjustable Isngth, extendmg between the first and second delivery nonbers. Nor does the prior art dsdose a method for securing the a6lation member between a fuM and second SIIBSTTTUTE SHEET (RULE 26) anclmr, thereby maiMaining a deired lum position in contact with the atrial wal end facilitating the forrnation of a linear a6lation track along the length of tissue between the anduors.

Summacy of the Inven6on A tissue ablation device assembly is provided which is adapted to forrn a conduction block along a length of tissue between first and second predetamined bcetions along an atrial weA of an etrium in a petient.
According to one mode of the assembly, a first delivery member has a proximal end portion and a distal end portion with a first anchor, a second delivery member has a proximal end portion and a distal end portion vvith a second anchor, and an ablation member has first and second end portions and an ablation element between those end portions.
The ablation member's end portions are engaged to the distal end portions of the first and second delivery members, respectively. In adkition, the first and second anchors are adapted to secure the ablation eimnent to the first and second predetermined locations in order to secure the ablation element along the length of tissue.
Accordng to another mode of the assembly, first and second deHvery members each have proximal and distal end portions, and an ablation member has first and second and portions with an ablation element between those end portions. The proximal end portions of the first and second delivery members are adapted to sGdeably engage a delivery sheath in a side-by-side arrangement. By manipulating the proximal end portion of the first deGvery member extemalay of the body, the distal end portion of the first delivery member is adapted to contrdlably position the first end portion of the ablation meinber vvithin the atrium and to secure the ablation element to the first predetermined location. Similatly, by manipulating the proximal end poraon of the second deGvery member extemally of the body, the dstal end portion of the second delivery member is adapted to controllably position the second end portion of the ablation member within the atrium and to secure the ablation element to the second predetemiined location.
According to another mode of the assembly, a first delivery member has proximal and distal end portions and a passageway that extends between a distal port located along the distal end portion and a proximai port located proximally of the distal port. A second de6very member is also provided having proximal and dstal end portions. An ablation member has a first end portion that is slideably engaged with an adjusteWe position within the passageway in the first daiivery member, a second end portion that is engaged to the distal end portion of the second delivery member, and an ablation element with an ablation length located between the first and second and portions. Further to this mode, at least a portion of the ablation member which indudes the ablation element is adapted to extend drstally from the passageway through the distal port vuith an adjustable length extending between the first and second delivery members.
According to a further mode of the assembly, a first deGvery member has a proximal and portion, a distal and portion with a first anchor, and a passageway that extends between a distal port located along the distal and portion and a proximal port located proximally of the distal port. An ablation member has a first end portion that is slideably engaged within the passageway with an adjustable position, and dso has a second end portion which indudes the ablation element that is adapted to extend distally from the passageway through the dstal port with an adjustable length. The adjustable length between the dstal port in the first delivery member and the second end portion of the SUBSTITUTE SHEET (RULE 26) wo 99/44319 PCT/US99/04521 ablation member is actdeved by sGdeabiy adjusdng the position of the first end portion of the ablation member within the passageway. Further to this mode, a second anchor is elso located along the second end portion of the ablation member. The first and second anchors of this aaaembly are adapted to secure the abiation element to the first and second predetermined locations, respectively, such that at least a portion of the ablation length is secured to and extends along the length of tissue.
In one further espect of the modes just deacribed, a tracking member for tracldng over a guidewire or other guidernember is included with the first or second delivery member, or the first or second anchor. Alternatively, a giidevuire tracking member may be provided for each of two of these assembly canponents, thereby adapting the assembly to track over two wires in order to string the ablation element between adjacent vessels respectively engaged by those wires. Further to this aspect, one or more guidewire tracking members has a passageway for tracking over=a guidewire and which tenninetes in a distal port. Accorcingly, the ablation member may be engaged to the guidewire tracking member either at or adjacent to the c6stal port or proximally thereof.
In another aspect of the modes just described, first and second actuating members are positioned vuithin the first and second delivery members. Each actuating member terminates proximally at a proximal coupler along the proximal end portion of the respectively engaged delivery member, the proximat couplers being adapted to couple to an ablation actuator. In one variation of this aspect, the ablation element is an electrode element with one or more electrodes and each ablation actuating member is an eiectrical lead wire. In another variation, the ablation element includes an idtrasound transducer and each ablation actuating member is en electrical lead which is coupled to a different surface on that transducer.

Brief Desaiotion of the Drawinas Figures 1A shows en angdor perspective view of a tissue ablation assembly comprising a ribbon shaped ablation member having a first end portion everted and secured to a first delivery member and a second end portion secured to a second delivery member.
Figwe 1 B shows a side perspective view of the tissue ablation assembly shown in Figure 1 A, except that the ablation member is shown extending between the first and second delivery members, in a direction paralld to the defivery members; an alterna6ve bowed shape for the abletion member is shown in shadowed view, wherein the abiation member is adapted to flex.
Figure 2 shows a perspective view of another tissue aSation assem6ly of the present invention.
Figure 3 shows a perspective view of another tissue ablation assembly in accordance vuith the present invention.
Figure 4A shows a perspective view of another tissue ablation assembly of the present imention.
Figure 4B is a perspective view of the same tissue ablation assembly shown in Figure 4A, dlustrating a de6very mode of the assembly.
Figure 5 shows a perspective view of another tissue ablation assem6ly in accordance with the present invention.
Figure 8 shows a perspective view of another embodiment of the tissue ablation assembly of the present inven6ai.
Figure 7A is a perspective view of another tissue a6lation assembly in accordance with the present invention, ibustrating de6very through a transeptel sheath in a transeptal left atdel abletion procedure.
~
SUBSTITUTE SHEET (RULE 26) Fgures 78-C scFmiaticady show two altemative cross-sectional ahapes for the deivery members of the tiasue ablation assembly skwm in Figure 7A.
Figure 70 shows a cross sectional view of a left etriel deGvery catheter having first and second passageways which are separated by a deflectable wali, and shows in shadowed view first and second guidewires respectively engaged vuithin first and second deGvery members of a tissue ablation device, which first and second doivery members are respectively engaged vuithin the first and second passageways and are separated by the wap.
Figure 7E shows a similar cross-aectionai view of a left atrial delivery catheter and tissue ablation device assembly as shown in Figure 70, although shovuing one mode of operation wherein the wall is deflected to one side of the delivery catheter and an ablation member is shown in shadowed view to extend between the first and second delivery members, thereby bridging between the first and second passageweys.
Figure 7F shows a sanilar cross-sectional view es shown in Figure 7E, and shows a different mode for the wall as it deflects wittdn the delivery catheter to allow the ablation member to bridge between the first end second passegeways.
Figure 7G shows a samiar cross-sectional view as shown in Figure 7E-F, and shows still a further mode of construction and operation for the waN as it deflects to allow the ablation munber to bridge between the first and second passageways.
Figure 8A is a perspective view of another tissue ablation assembly of the present inven6on lustrating delivery through a transeptel deNvery sheath.
Figure 88 is a perspective view iqustrating a variation of the tissua abla6on assembly shown in FRgure 8A
Figure 8C shows a prespective view of another vaaation of the dssue ablation assembly shown in Figure 8A.
Figtee 80 is a perspective view of enother variation of the assembly shown in Figure 8C.
Figure 9 shows a perspective view of another tissue ablation essembly of the invention during de6very through a transeptal deGvery sheath.
F'gure 10A is a perspective viaw of another tissue ablation assembly in accordance with the present invention, during delivery through a transeptel defivery sheath.
Figure 108 is a perspective view igustrating a variation of the assembly shown in Figure 10A.
Figwe 10C is a perspective view of anotter vadation of the assembly shown in Figure 10A.
Figure 100 is a perspective view of another vreiation of the assembly shown in Rgure 10C.
Figure 11 A is a perspectiva view of another tissue ablation assembly of the invention.
FiQure 11 B is another perspective view of the tissue ablation assembly shown in Figure 11 A, tliustrating the asmndy during use in forming a lesion from a lower pdtnonary vein to e natral valve anndus.
Figure 12 shows a patapective view of a tissue ebfetion assembly ainaler to that shown in f=igure 10C, except further irdudmg a ckumfemtial sMation mrenber in combination with a inear ablation m"er in an overall catheter assembty.
Figure 13A shows a secfsoned crosa-sectional view of a circumferential ablation member an the distel end portion of the deGvery number, adapted for use in aixordaru:e vHth the tissue aNation assembly shovm in Figure 12.

.7.
SUBSTITUTE SHEET (RULE 26) Figure 13B shows a trmuvarn croas=sectiond view taken along ine 1313-13B
through the elongate body of the delivery mamber shown in Figure 13A.
Figure 13C shows a transverse crosa-sectional view taken elong I'ine 13C-13C
through the arcumferential aldation ekamnt dong the dreimferentid a6lation manber 3hown in Figure 13A.
F'igure 130 shows an angdar perspective view of a cylindricat dtrasound tranaducer which is adopted for use in the dramferential a6ladon elment shown in figures 13A end 13C.
Figure 13E shows an angdor perspective view of another cy6ndrical dtresound transducer which is adapted for use in the an:umferentiel ablation element shown in figurea 13A and 13C.

pet_ailed Descriotion of the Pneferred Embodments Definitions The term "anchor" is herein intended to mean an dement which is at least in part located in an anchoring region of the device and which is adapted to secure that region at a predetermined location along a body space wall. As such, "anchor" is intended to provide fixation as a securing means over and above a mere nornnal force against a single tissua surface wtdch is created by confronting contact between the device and the tissue. Examples of suitabie "anchors" within the intended meaning indude Ibut are not 6mited to): an element that directly engages the tissue of the wall at the predetemrined location such as by clamping, suctioning, or penetrating that tissue; and an element that is adapted to penetrate the plane of the body space wall, such as through an ostium of a vessel extending from the wefl, for example, induding a guidevuire engaging or tracking member which provides a bore or lumen adapted to track a guidewire through an ostium of a lumen extending from the body space wall.
Furthermore, an expandeble element, such as an expendeble balloon or cage, is considered an anchor to the extent that it radially engages at least two opposite body space wall portions to secure the expandable element in place (such as opposite sides of a vessel). To the extent that the disclosure of the invention below is ditected to any one particular anchoring element, it is contemoated that other variations and equivalents such as those described may also be used in addtion or in the altemative to that particular element.
The term "guidewire" as used herein wili be understood by those of skiu in the art to cover any member which serves as a guide, including but not limited to a conventional guidewire, a catheter, a deflectable tip catheter, such as the type with dstal end electrodes for mapong, as well as a hollow guide tube.
The term "ablation" or derivatives thereof is herein intended to mean the substantial altering of the mechanical, electrical, chemical, or other structural nature of the tissue. In tha context of intrecardiac ablation app6cations as shown and described Wth reference to the embodiments below, "ablation" is intended to mean sufficient ahering of the tissue properties to substantially block conduction of eiectricai signds from or through the eblated card=iac tfsaue.

.g.
SUBSTITLITE SHEET (RULE 26) The term "dement" vtithin the context of "ablation element" is herein intended to mean a discrete element, such as an electrode, or a pluraGty of discrete elements, such as a plurality of spaced electrodes, which are positioned so as to collectively abiate an elongated region of tissue upon activation by an actuator.
Therefore, an "ablation eiement" within the intended meening of the current invention may be adepted to ablate tissue in a variety of ways. For example, one suitable "ablation element" may be adapted to emit energy sufficient to ablate tissue when coupled to and energized by an energy source.
Suitable examples of energy enritting "ablation eiements" within this meaning indude without limitation: an electrode element adapted to coupte to a direct current (OC) or alternating current (AC) source, such as a redofrequency (RFl current aoun:e; an antenna element which is energized by a microwave energy source; a heating element, such as a metapic element which is enenozed by heat such as by convection or current flow, or a fiber optic element which is heated by light; a light emitting element, such as a fiber optic element which transmits light sufficient to ablate tissue when coupled to a light soun:e; or an ultrasonic dement such as an ultrasound crystal element which is adapted to emit ultrasonic sound waves sufficient to ablate tissue when couoed to a suitable excitation source.
More detailed descriptions of radiofrequency IRFI ablation electrode designs which may be suitable in whole or in part as the abieting element according to the present invention are disclosed in U.S. Patent No. 5,209,229 to GiNis;
U.S. Patent No. 5,487,385 to Avitall; and WO 98110961 to Fleischman at al.
More detailed descriptions of other energy emitting ablation elements which may be suitable according to the present invention are disdosed in U.S. Patent No.
4,841,649 to Welinsky at al. (microwave ablation); and U.S. Patent No.
5,156,157 to Valenta, Jr. at W. (Iasar ablation).
In adation, other elements for alteting the nature of tissue may be suitable as "ablation elements" within the intended meaning of the current invention. For example, a cryoblation probe dament adapted to sufficiently cool tissue to substantially alter the structure thereof may be suitable. Furthermore, a fluid delivery element, such as a discrete port or a plurality of ports which are fluidly coupled to a fluid delivery source, may be adapted to infuse an ablating fluid, such as a fluid containing alcohol, into the tissue adjacent to the port or ports to substantially alter the nature of that tissue. More detailed examples of cryoblation or fldd delivery elements such as those just described are disdosed in U.S. Patent No. 5,147,355 to Friedman at al. and WO 95119738 to Mdder, respectivefy.
It is also to be further appreciated that the various embociments shown and described in this disclosure collectively provide one beneficial mode of the invention, which mode is specifically adapted for use in the left attium of a mammal. In this mode, the elongate ablation element is adapted to have its ends anchored in adjacent pulmonary vein ostia in the left atrium, with the elongate abfation element in substantial contact vuith the tissue that spans the length between those ostia. By subsequent ablation of the tissue between anchors in the adjacent ostia, a long linear lesion is created and provides a conduction block to electrical flow across the length of the lesion.
As will be appreciated from the more detaded dsclosure of the embodiments below, a pattem of multiple long linear lesions between adjacent pulmonary vein ostia, and also inclucing portions of the mitral valve annulus and septran, may be completed with the present invention. One pattern of such multiple ablation lesions can be considered a "box"
.g.

SUBSTITUTE SHEET (RULE 26) of isdated canduction within the region of the pubnonary veins, and is betieved to provide a less-invasive improvenrent end less traumatic alternative to the invasive "maze" surgical procedure previously described. -Tisaue Abletion Assembiies While a number of embodiments of the present invention are disclosed in deted, reference numerals are used consistently where possible. The first digit of each reference numerel refers to the embodiment of the assembly (e.g. (1) in Figure 1 and (2) in Figure 2), while the foliowing digits refer to the specific component (e.g. 14 for the "ablation member I. Thus, for example, in the first embo(iment of the tissue ablation assembly iilustrated in Figure 1A, the "ablation member" is labeled as 114, whereas a verietion of the "eblation member" shown in Figure 2A is referred to es 214.
With reference to Figure 1A, pmticular designs for first and second delivery members (110,1121 and also for ablation member 1114), are shown. A ribbon shaped member (116) has a first end portion 1118) secured to a first delivery member (1101 and a second and portion (120) secured to a second delivery member (112).
In a preferred aspect of the several embodiments herein described, the ablation member (114) is specificegy provided as an electrode assembly with one or more electrodes 1122) which traverses e length elong the ablation member and which is adapted to engage the targeted length of tissue for ablation. The one or more electrodes are etectrically coupled to at least one coupler along a proximat end portion of a daGvery member via electdcal lead wires extending along the deGvery member. The proximal coupler is further adapted to couple to an ablation actuator, such as en RF current source.
The ablation actuator or actuators are engaged to the electrical coupler or couMers of the ablation device assembly and also to a ground patch (not shown). A circuit is thereby created which includes the ablation actuator, the electrode ablation element, the patient's body (not showni, and the ground patch which provides either earth ground or floating ground to the current source. In this circuit, an elactrical current, such as an RF signal, may be sent through the patient between the electrode element and the ground patch, as would be apparent to one of ordinary skig.
In the specific embodimant shown in Figure 1A, the ablation member (114) is shown to include a pturaiity of electrodes (122) in a spaced arrangement along the longitudinaf axis of ablation member 1114). A central region (124) is further bordered on either side by adjacent insulating regions (126,128).
According to this design, the central region (1241 is adapted to engage a length of tissue to be ablated while the adjecent insuiating regions (126,128) engage adjscent lengths of tissue, thereby isolating the length of tissue from the blood pooi during ablation. Electrodes 1122) may also have an opposing surface (not shown) wtnch is exposed in order to allow blood flow on a side opposite the active ablation surface to cool the electrode during ablation. Furthermore, eiectrode ports (130) are also shown in Figure 1 A on electrodes 1122) and may provide a housing for sensing members (not shown), such as for example thermocouples or thermisters. In addition, or in the atternative, etectrode ports (130) may also provide communication for fluid from an inner passageway to leak through the electrodes during ablation, such as for example to aid in cooling.

SUBSTITUTE SHEET (RULE 26) Figure 1 A further shows first and second de6very members (110,112) as having structmdly different designs, although each design is adepted to engage the ablation element and to controNably position the eMation element by manipulating the proximal end pordon of the respective delivery member.
In more detail to the design for first dewvery member (110), as shown in Figure 1A, a guidewire traching member (134) is tubular and indudes a giadevWre lumen or passageway (136) between a distal guidawire port (1381 and a proximal guidevuire port (not shown) that is slideably engaged over a guidewire (1401. The first end portion (118) of abtation member (1141 is secured to the delivery member 0 10) at a location which is proximal to the dstal guidewire port (138). The ablation member (114) also has a hinge point (144) which is either a preshaped hinge or is flexible to allow a certain degree of rotation and flexibibty between the first delivery member 1110) and the ablation member (1141.
In more detail to the design for a second de6very moinber (112), shown in Figure 1 A, a coupbng or tracking member (146) is tubular and indudes a lumen or passageway (1481 that is slideabiy engaged over a gtide member (150).
The gtide member indudes a proximal gdde portion (152) and a distal guide portion (154) which includes a shaped or shapeable tip (not show in Figure 1A; 156 in Figure 1B). The shapeable tip (156; Figure iB) is torsionally couoed to the proximal guide portion (162) such that the tip is steerable by torqrang or rotating the guide member (150). In a preferred embodment, the dstai tip (156) of the gtide member (150) is radiopaque under X=ray visualization, in order to faciitate its placement in a predetermined location. Also shown in shadow between proximal and distal guide portions is an intermediate coupGng portion (158) which indudes an extension of the guide member (150) and two spaced enlmgements (160,162) over the guide member. The tubdar coupGng member (146) is also shown in Fgure 1A to coaxially house the guide mefnber (150) between the two spaced eniargements (160,162). The guide member (1501 is therefore rotatably engaged through the tubular coupling member (146), although with a limited range of motion relative to the tracking mamber's long axis due to the mechanical barriers at the enlargements (180,162). The ablation member (114) is secured to the tubular coupGng member (146), vath ablation member (114) extending from the engagement in a proximd orientation.
The various feetures of the Figure 1 A embodiment are believed to provide benefidal functionality in ablating a length of tissue between adjacent vessels, such as between pulmonery vein ostia in the left atrium.
In one example of the functional aspects of the design shown in Figwe 1A, both first and second delivery members (110,112) are adapted to controllably position the respectivaly engaged end portions of ablation member (114) within an atrium. More specifically, the first delivery member (110) is adapted to track over gtadev+rire (140) in order to advance or withdraw from a puknonary vein which is engaged by the guidewire.
Consequently, the first depvery member is adapted to contrdlably place and remove the ablation element against a first point along the iength of tissue to be aaated. The second delivery member (112) is also ade to controllably place or remove the second end portion (120) of a6lation member (114) within an adjacent pidmonery vein. However, in contrast to the "guide wire tracking"
mechanism provided by the first delivery member (110), the second deGvery member (112) utilizes a rotatable coupGng design, whereby advancing andlor torquing the proximal guide portion (152) of guide member (150) allows one to SUBSTITUTE SHEET (RULE 26) maneuver the position of the sheped tip (156; Figure 1 B) into the vein. The gmited rarige of longitucinei motion between the guide member 1150) and the coupling member (1481 permits the edvancing or withdrawing of the proximal gude portion (152) to transmit these forces to the second end portion (120) of ablation member (114), thereby achieving controilable positiordng of this member.
Another example of the functionel aspects of the design shown in Figure 1A is provided by the orientation of the abletion member (114) at each end where secured to the first and second delivery members (110,112). This relative orientation between component parts in the cverell assernbty allows the most distal portion of the delivery members to be seated deeply vuithin a pWmonery vein while ellowing each ablation member end to extend proximally out of the respective vein in order to traverse the edjoining region of etrial waA
tissue. Moreover, the hinge point (144) for the ablation member on at least one of the delivery members also allows the assembly to "coliapse" from adepioyed position and to theraby allow the deGvery members to fit in a"side-byside" or relatively pareNel arrangement within a dalivery sheath during delivery into and out of the etrium. For the purpose of further illustrating this arrangement, Figure 1 A depicts the assembly in a configuration which is midway between a deployed configuration and a collapsed configuration for delivery, and further illustrates the motion of the hinge point (1441 by way of an arrow adjacent thereto.
Notvuithstanding the functional benefits just described for the specific embodiment shown in Figure 1 A, Figure 1B shows another tissue atdation assembiy vuith many simiar components as those just described for Figure 1A, although with slight modifications which are aiso believed to be beneficid in some applications.
In one aspect of the emborGment shown in Figure 1 B, the first end porpon (118) of the ablation member (114) is shown secured to the first delivery member 1110) vuith a distal orientation wherein the ablation member (114) extends distafly ftom first delivery member (110). This distal orientation is believed to provide another beneficial design in order to accmnmodate the collapse of the assembly such that the deGvery manbers (110,112) are in a side-by-side and relatively parallel relationship during delivery through adeGvery sheath, as is further illustrated by the relatively collapsed configuration shown in Figure 1B. Further to this orientation, a hinge point, such as shown at hinge point (1441, may stiU provide a benefit at the engagement between ablation member 1114) and first delivery member (110), although having a reverse role to the Figure 1 A embodiment, wherein the hinge point is relatively straight during detivery and is flexed and rotated during deployment of the assembly in the region of the pulmonary veins.
Figure 18 also shows a shadowed view of an alternative shape (164) for ablation member (114) which is believed to provide a benefit in some applications. In perticdar, shape (184) is shown as a sweeping, curve or arc between the first and second end portions (118,120) of abiation member (114).
By advancing guidewire tracking member 0 10) over guidewire (1401 a first pulmonary vein lee(ing from the atriwn, and also advancing guide member (1501 within a second adjacent pulmonary vein, the ebtation mornber (114) is edapted to compress against the region of atriel waU tissue between the veins. It is beiieved that this compression may deflect the curved shape of abtation member (114) against a bias force along that curve and thereby provide a means for transmitting the force at the first ,12-SUBSTITUTE SHEET (RULE 26) and second end portiona (118,120), due to forcing the respactive delivery members distally, along the central regions of the ablation etament to aid engagement to tisaue along that region.
Further to the beneficial embodnumts just shown and desctibed by reference to F'igures 1A=B, the specific arrangement of the overali assenbly may be modified to form other beneficial devices which are further contmnplated within the scope of the present invention. For example, the tissue ableGon essmnbly shown in Figure 2A, indudes two delivery members which independendy control the positioning of each of two ends of an ablation member 1218,2201, as was provided by the embodiment of figures 1A=B. However, Figure 2A shows first and second dewvery mmnbers (210,212) to each include elongete bodes forming respective guidewire tracking members (234,2481 with passageways (238,248; shown in shadow), respectively, extendmg between distal ports (238,239), also respectively, and proximal ports (not shown). First and second delivery members (210,212) are therefore adepted to stideably engage and track over guidewiras (240,250), stmh as in order to position ablation member (214) along a length of tissue between pulmonary veins engaged by the gaidewires. Moreover, it is believed that the inclusion of an elongate guidevuire tracking member also provides a larger cross=sectioned member by wluch to push the respectively engaged end pordon of the ablation member, thereby increasing the overaN efficiency of contact along the ablation element length.
In addtion, Figure 2A shows first end portion (218) of ablation member (214) engaging first delivery member 1210) with a proximal orientation and second end portion (2201 engaging second delivery member (212) with a distai orientation, and is therefore adapted to adjust the configuration between a deployed position (es shown for example in Figure 2A) and a deGvery position in a similar manner as previously shown and described by reference to Figure 1 B. A
hinge point (244) similar to hinge point 1144) in F'igure 1A is also shown at the second end portion-second degvery member engagement, which hinge point is further shown in cross=sectiond detail in one preferred embodiment in Figure 2B which uses a coupiing member (288).
Further to the coupling member 1288), shown in Figure 2B, a"U"=shaped core (288) with a coil (270) provided over its exterior surface engages second delivery member (212) and also engages end portion (220) of ablation member (214) such that ablation member (214) effectively extends with a proximal orientation away from the tip of delivery member. Further to this design, the core 1288) may be a metallic core, such as for example a core made of an alloy of nickel and titarrum, or of stainless steel, and the coil thereover may be of a variety of metals, such as stainless steel, platinum, or the like, whereas use of radiopaque coils such as platinum or tungsten may provide a visible marker at the location where the ablation member extends from the delivery member.
Coup6ng member may be adapted to the relative members by.positiomng the arms of the "U"=shaped member within seats provided by the other respectively coupled members, as is shown in Figure 2B. In one method of making this transition, the waA forming the lumen is coHapsed over the coupling member's errn, such as by heat shrinking the respective tubing over the coupfing member's arm. Alternatively, an outer jacket (not shown) may be placed over the couoing member and also the respectivdy couoed other member and then heat shrunk to capture the engagernent within that jacket. In addition, or in the alternative to both or either of these other methods, an edhesive may be used to pot the coupling member to the delivery and ablation members.

=13-SUBSTITiJTE SHEET (RULE 26) It is also to be further understood that other designs and matedels may be used as a coupling member for the engagement between the ablation member and the deYvery member. In one altemative, a pre-shaped member such as the previously described'U"-sheped core may be made of a heat-set polymer, such as a polyirnide member forrned into a bend shape. In another variation, a composite member may be used, such as for example a coil reinforced pdymetic tubing, at the transition to form the hinge point (244). Moreover, notwithstending the particdar variations just described, other substitutes may also be suitable so long as a flexible hinge is estabfished which allows seated engagement of the tip of the delivery member deep within a vessel such that the ablation member extends proximaUy therefrom so that it may engage the length of atrial wall tissue extending from the vein for aldation.
In one further beneficial aspect of the embod'anent shown for delivery members (210,212) in Figure 2B, an elongate body of the type shown for each delivery member may ellow for additional passageways or lumens besides just the guidewire lumens, which adtitionai passageways may further allow for additional components along the devices which may further facilitate tha ablation process. For example, passageways (236,248) are shown in shadow Wong first and second delivery members (210,2121, respectively, in Figure 2A. In more detail to the variation shown in Figure 2A, multipie a6lation actuating members Inot shown) may extend along these passegeweys which are adapted to couple to eblation element (214) and also to a proximal coupler Inot shown) that is further adapted to couple to an ablation actuator, as is shown schematically at individual ablation actuators (272,274) coupled to each delivery member, although the various actuating members may also couple to a single common abtation actuator.
In adrktion, each of the guidevare tracking members (234,248) shown in Figure 2A, and also shown previmWy (134) for the first delivery member in Figure 1 A and B, is adapted to receive the respective guidewire through its lumen such that the guidewire extends extemslly of the cathetet's elongate body on either side of the region of slideable engegement. This arrangement, however, is merely one exarnple of a broader functional structure of the guidewire tracking variation illustrated by the anchors of Figure 2A. Considering this variation more generally, bores are formed at each of the tkstal and intermediate regions of the elongate body. Each bore is adapted to track over a guidewire separately and independently of the other bore. Each bore generally has two open ends or ports, and the respectively engaged guidewire extends through the bore and externally of the device from each bore end.
Accordng to the general structure just described, the specific guidewire tracking member embodknents of Figure 2A, and othervuise where appropriate to the embodiments, may be modified according to one of ordinary skgl without departing from the scope of the invention. For example, a cuff or looped tether of matetial may be provided at the desired anchoring location along the elongate body and thereby form a bore that is adapted to circumferentia8y engage a guidewire according to the description above. More particularly, a metallic ring, or a polymedc ring such as polyimide, polyethyiene, posyvinyl chloride, fluoroethylpolymer (FEP), or polytetrafluoroethylene (PTFE) may extend from the elongate body in a sufficient varietion. Or, a satable strand of material for forming a looped bore for guidewire engagement may also be constructed out of a filament fiber, such as a Kevlar or nylon fiiament fiber. One more specific example of such an altemative gWdevuire tracking member which may be suitable for use in the current invention, particularly as a distal guidevuire tracking member, is disdosed in U.S.
Patent No. 5,505,702 to Amay.

SUBSTITUTE SHEET (RULE 26) With reference to Figure 3, an embodiment of another overall mode of a tissue ablation assembly is shown, wherein an ablation member (314) has its first end portion (318) coaxieNy and slideebly engaged within a passageway (376) through a first delivery member (310).
In more detail to Figure 3, first delivery member (3101 has an elongate body (309) which forms a guidewire tracking member that includes a gudewire lumen or passageway 1338) extending between a distal guidewire port (338) and a proximal port (not shown). A first guidewire (340) is slideably engaged within the guidewire passageway (338). A
second passageway (376) also extends along the elongate body 13091 between a distal port (378), which is located along (1stal end portion 1380) proximelly of distal guidewire port (338) and a proximal port (not shown) located proximally of the distal port. Central to this embotiment, an adation member (314) is adapted to the first deGvery member 1310) such that its first end portion (318) is slideably engaged within a passageway (376). Accorcing to this reletionship, the ablation member (314) has adjustable positioning within the passageway with remote manipuiation of a region of the first end portion (382) which extends externaUy of the body by a user. As such, the second end portion (320) is adapted to extend an adjustable length extemaliy of the passageway (376) from dstal port (378) and between.
first delivery member (310) and second delivery member 1312). Further to this adjustable positioning, it is further contemplated that the ablation element along the ablation member may also be adjusted to extend entirely out frmn the passagewey, or only a portion may extend externally between the delivery members. It is believed that this arrangement baneficiaily allows for a vatiable cbstance between the anchors formed by guidewire tracking members. In addition, it has been observed that, by puAing on the first end portion of the ablation member once both anchors or guidevuire tracking members are engaged vuittun vessels, a"cinching" action may be echievad which tightens the ablation member and guidewire tracking anchors along the tissue between the anchors.
Aiso shown in the embodiment of Figure 3 is a second gWde tracking member (346) along the second end (320) of ablation member 1314) wldch is slideaWy engaged over a second guidewire or guide member (350). Further to second guide tracking member (348), Figure 3 also shows, in shadow, two eniargmnents 1360,382) on guide member 1350) which border either end of tracking member (346) to form a simiiar type of guide member-coupling member arrangement for a delivery member to that previously shown and described by reference to Fgure 1 A-8.
Moreover, either one of the enlargements 1360,382) may also be provided at the exciusion of the other for the purpose of allowing a stop within a vessel against which the ablation member can abut when advanced, in the case of provi(ing only eWargmnent 1382), or for allowing a stop that can be used to engage and push ablation member (314) distally with the gWde member, in the case of providing only enlargement (3801. Further to the latter purpose, which holds true for the case of providing either both enlargements (360,382) or oniy edargement (380), a further beneficiei varietion not shown provides a robust pushing member for the proximal guide member portion of the guide member (3501. In one such variation not shown, a hypotube of metal such as stairdess steel or nickel titanium alloy is provided proximally of eniargement (380), and may for exemple transition into a core vvire in the distal regions, such as at a location proximally adjacent to enlargement (362). Such transition may be achieved for example by welding, soldering, adhering, or swaging or othervuise securing and affixing a core vuire to andlor within the bore of a hypotube according =15=
SUBSTITUTE SHEET (RULE 26) to that variatien. In another vadation, the core wire may transition from a large diameter pation proximagy of the en(argement (3801, to a tapered tranaition into a amaNer clameter portion such as at or dstally of enlargement (362).
In addition, Figure 3 shows in shadowed view that each of the first delivery member (310) and the guide tracking member (346) formed by the second end of ablation member (314) further indude expandable members (384,386). Each of the expendable members is adapted to adjust from a radially collapsed condition during de6very into an atrium or vessel extending therefrom, and to a radially expanded condtion which is adapted to ciraanferentiagy or othmvvise radiegy engage a vessel wall to secure the respective anchor there.
For further illustration, such expandable members may be inflatab(e balloons, or may be other suiteble substitutes according to the anchoring purpose put forth, such as for exmnple a mechanically expandable cage. Moreover, it is to be further understood by reference to the other embodiments, particulady where a distal end partion extends distaily from a point of engagement with an aWation member, that such expandable members as just described by reference to Figure 3 may be equally suited for use in cmnbination with the specific cariponents of those particular other essemblies and embodiments.
A further tissue eldatian assembly is shown in Figura 4A and includes two elongate delivery members (410,412) with an adation member (4141 extendng therebetween, and essentially combines the side-by-side elongate body dual delivery member design, as previously shown and described by reference to Figure 2A, together with a coaxially housed, slideably engaged ablation member design of Figure 3. Both first and second deGvery members (410,412) have guidevuire tracking passageways (436,448) for s(ideably engaging guidewires (440,450). However, in a further modification, a first end (418) of adetion member (414) is affixed to a (ista( portion (480) of the first delivery mmrrber (410), whereas the second end (420) of abletion mmnber (414) extends from and is slideably engaged within passageway (477) in the second delivery member (412), via a distal port (479) located at the distal tip (490) of the second delivery member (4121.
Accorcing to the particular errangement of the assembly of Figure 4A, the assembly is further shown in the partially segmented view in Figure 4B in a coNapsed condition during delivery within and through a delivery sheath (492).
Further to this delivery made of operation, atdation member (414) is adapted to be substantially housed within passageway (477) through dista( port (479) by either advancing second delivery member (412) or withdrawing ablation member (414) until distal port (479) abuts against the engagement between first end portion (4181 of ablation member and the distal end portion (480) of the first delivery member (410). The second end portion (420) of the ablation member (4141 is withdrewn into the passageway (477) in the second delivery member (4121.
Still a further tissue eblation assembly is shown in Figure 5 and further modtfies the assembly shown in Figures 4A-B to indude a coaxial engagement between ablation member (514) and a first passageway 1576) within a first delivery member (5101, and within a second passageway (577) vWthin a second delivery member (512). More particrdady, Figure 5 shows ablation member (514) to indude an intermediate portion (594) which is located between first and second end portions (518,520) and which includes one or more ablation electrodes 1522). The first end portion (518) of abtation member (514) is slideably engaged with adjustable positioning vuithin passageway (576) along the first delivery member (510) end through the first distal port (578) laceted in the distal tip (589) of first delivery member SUBSTITUTE SHEET (RULE 26) (510). The second end portion (520) is slideably engaged with adjustable positioning within pasaageway (6771 along the second debvery mernber (512) and through a second rGstal port (579) located at the distal tip 1590) of the second ddivery member (512). According to this assembly, the length and positioning of ablation member 1514) between the first and second delivery members (510,512) is adjustable from either side or both sides (either by adjusting the relative poaition of the first end portion along the first deGvery member or of the second end portion along the second deGrery member). In adtktion, passageways and actuating members may extend along each of the first and second end pordons of the ablation member.
Moreover, accorrkng to the assembly shown in Figure 5, one conduit fluid passageway (532) may extend from the first proximal end portion 1582), which extends externally beyond the first delivery member (5101, through ablation member (514), to the second proximal end portion (583), which extends extemagy beyond the second delivery member (512). In this aspect, the passegeway (532) is thermeily coupled to the ablation dectrodels) (522) and is adepted to cool the ablation eiectrode(s) (522) when heated during abtation and when flaid is allowed to flow through the fluid passageway, as is shown by way of example, by arrows pointing into the passageway at the first proximal and portion (582) and out of passageway at the second proximd end portion (583).
Stdl further to the variation shown in Figure 5, (istal ports 1578,579) are shown at the distel tips 1589,590) of first and second delivery members (510,5121, wherein the distal tips (589,5901 are further shown to include radiopaque markers, such as by use of rad'iopaque metel bands or by metal powder loaded polymeric materiei.
The assembly shown in Figure 6 indudes first and second delivery members (810,812) with guidewire tracidng members (634,646) engaged over guidewires (640,650), and further provides dual-coaxial engagement within those delivery members (610,612) with ablation member (614), as shown previously in Figure 5. However, eccording to the variation shown in Figure 6, the distal ports (678,679) to the respective passageways (876,877) through which first and second end portions (618,620) of ablation member (814) are respectively engaged are positioned proxima8y of first and second distai guidewire ports (638,8391, as is identified during use by way of ra(lopaque markers (698,897) thet are further shown on proximd and dstal sides of ports 1878,679), respectively.
Further shown in shadow in Figure 6, the first and second anchors (684,686) provided in part by the two elongate guidewire tracking members (634,8481 of the de6very members (810,612) may further include expandable members, which are beGeved to be particularly well suited to this design by virtue of the extensions of the guidewire tracking members distally beyond the abiation member.
In an altemative veriation not shown, it is further contemplated that the portion of the elongate body which forms the grridevuire tracking member for either delivery member may also temiinate at a distal port that is located proximally of the distal port of the pessageway through which the ablation member is slideably engaged.
The tissue ablation assembly shown in Figure 7A is illustrative of a vatiation which is believed to be readily combinable with the other variations of the embodiments. Figure 7A shows a simdar assembly to that just shown and described previously by reference to Figure 5, except that the (5stal end portions of the respective delivery catheters have curved shapes. These shaped regions (711,713) are adapted to point the first and second delivery members (710,712) toward the posterior wall of an atrium when introduced through a transeptal deGvery sheath seated across =17-SUBSTITUTE SHEET (RULE 26) the fossa ovals (not shown). The first and second delivery members (710, 712) are shown in shadow within delivery sheath (792). Figures 7B-C schematicdly show ahernetive shaft configurations for first and second delivery members 1710,712) shown in Figure 7A, and include, respectively, two round delivery members (710,712) within an ovular delivery sheath (7921, or two ovular delivery members 1710,7121 in a round delivery sheath (792). Conventional round shaft designs vvithin round delivery sheath lumens are also considered acceptade, and in any case, all of these alternstive variations apply equally as suitable substitutes for the other embodiments shown to indude two delivery members with elongate tubder members in aida-by-aide arrangement within a ddivery sheath.
Figures 70-G show various modes for a further defivery sheathltissue a6lation device assembly embodiment, wherein the delivery sheath or catheter (792) indudes a wall (795) that separate first and second delivery passageways (797, 798). Accordng to these modes, first and second delivery passageways (797, 798) are adepted to house first and second guidewires (740, 750) and respectively engaged first and second delivery members (710, 712). Well (795) is constructed to allow relative separation and isolation between these members in their respectively engaged passageways in order to prevent entanglement dudng dekvery. However, the wall (795) is further constructed to be deflectable in order to eUow the ablation mmnber 1714) extending between delivery members (710, 7121 to btidge between the passageways (797, 798) during delivery of the ablation member (714) through the delivery catheter (792) and into the atrium for ablation.
More specifically, the well (795) may be constructed in many alternative modes in order to achieve the feature just described, which is to provide relative isolation of the delivery passageways when only the respective guidewires or elongate bodies of the delivery members are housed within those passageways, but also to ailow such isolation to be selectively broken such that the ablation member can bridge between these same passageways during delivery into the atrium.
For example, Hgure 70 shows wall (795) to be broken at a separation (798).
According to this construction, where only the guidewires (740, 7501 or delivery members (710, 1721 are housed vuithin passageways (797, 798), waA
(795) is constructed to retain its shape to substantially transect the lumen formed by delivery catheter (7921 and maintain the relative isolation and integrity between the two passageways (797, 798). However, where the adation member (7141 is also housed vAthin delivery catheter (7921, the wall (795) is pushed aside within the deGvery catheter lumen, as shown in slightly varied modes in Figures 7E-F. It is contemplated by reference to the Figures 70-G as a whole that the passageways (797, 798) may be common when the wall (7951 is deflected according to the embodiments shown.

Other modes of construction for wall (795) may also be suitable substitutes for that shown and described by reference to Rgures 70-E. In one further ilustrative example, wall (795) may be secured at each of its ends to the tubdar wall of dehvery catheter 1792), with a break or separation along an intermediate region of the waD within the delivery catheter iumen. A further more detniled example of this variation is shown at separation (796) in Figure 70.
=18-SUBSTITUTE SHEET (RULE 26) This embodiment is shown in a further mode of use in Figure 7G, wherein ablation member (714) is shown to bridge between passagaweys 1797, 798) between two separate wall porfions 1795, 7951 that are deflected.
It is also further contemptated that such defiectebdity may be edueved with a waN construction that does not heve literal "separations" to aYow for the bddging of the ablation member between the passageways. For exampie, a frangibte wall construction may be suitab{e, wh"n the wsN hes stnucturel integrity but has a week point that is adapted to break or shear when the ablation member is forced along and within the inner lumen of the deNvery catheter.
Figures 7D-G also Nlustrate one particular construction for deavery catheter (792), wherein an outer tubing (793) is disposed over en inner tubing (794). Accorcing to this construction, outer tubing (793) may have a first construction and material composition which provides the structural integrity necessary for the ddivery catheter 1792) to be delivered into the atrium during use. Inner tubing (794) may be therefore chosen merely as a"liner" in order to provide the wall structure as described, end may be one extrusion or tubing (as shown in the Figures), or may be two separate tubings that are aooined in a menner resulting in the desired passageway and wall construction for the overWi assembly. In any event, the separation or frangibility of the wall may be inherent in the construction of the inner tubing (794), such as by designing a separation into the tubing extrusion or formation itsetf, or may be post-processed, such as by cutting or scoring the desired separation or frangible porbon after formation of the tubing. In one particdar embodiment for inner tubing (794), a thin-walled polymer is used, where may or may not be the same polymer used for outer tubing (793), and in the latter case may be for example a thin-wafied fluoropotymer lining, such as a PTFE ining.
StNt further, one uniform wall construction may also be a sciteble substitute for the outerlinner tubing variation just described by reference to the particular, exemplery embodiment in the Figures.
The modes for the delivery catheter (792) variously shown throughout Figures 7A-G are believed to be highfy desirable for use in combination with the "dual-delivery member" tissue ablation device assemblies herein shown and described. It shodd be apparent to those skilled in the art, however, that the above-described deGvery catheter or sheath construction with a franoble or separated waN can readily be applied in other applications and designed to accommodate other types of dWivery members.
The tissue ablation assamblies shown in Figure 8 exemplify further variations, wherein similar assmrrbGes. to that previously shown and described by reference to F'igure 3 are provided in mo(fified fonn. Accorring to the variation shown in Figure 8A, the intpradon of the ablatioh member and the second detivery member described in Figure 3, is replaced by a separate guidewire tracking member (846), which serves as the second delivery member 1812), wherein the guidewire tracking member is adapted to slideably engage and track over a guidewire 1850) as en anchor for the second end por4on (820) of abletion member (814). This assembly is further mo(ified in Figure 8B wherein the guidewire tracking member (834) of the first delivery member (8101 extends along only a distal portion of this deGvery member (810), such that guidewire (840) is only engaged along a portion of the delivery member's length. Also encompassed witfwn this embodiment, but not shown in Figure 88, is that the guidewire tracking member 1848) of the second deGvery member (812) extends along ordy a r6stal portion of delivery member (812), such that guidevuire (850) is oniy engaged dong e portion of this delivery member's length.

SUBSTITUTE SHEET (RULE 26) The tissue ablation assembiy shown in Figures 8C and 80 further modfy the previous mnbodiments, to include the coaxiel engagement of the guidewire tracking mambers for both first and second delivery members and the aldation member. In this embodment, the first end portion (818) of the a6tation member is coaxially engaged vuithin a first passageway (876) in delivery member (810). The guidewire tracking member (834) along first de!'rvery member (810) includes a second passageway engaged over a vuire (840). The first debvery member (810) indudes still a third passageway (898) with a second delivery member coaxially engaged. The second delivery member elso includes a second 9uidewire tracking member (846) over a second wire (850). In Figure 8C, the gddewires are engaged along substantielly the entire length of the guidewire tracking members. In contrast, in Figure 8D, the gudewires are ody engaged eiong a distal portion of the guidewire tracking members.
The tissue ablation assembly of Figure 9 indudes a first delivery member (910) with two passageways (938,976). Passageway (936) ends in a dstal gddewire port (938) and forms guidewire tracking member (934) over a guidewire (940) as a first anchor. Passageway (976) terminates distaliy in a distai port (978) located proximally of distal guidewire port (938). Ablation member (914) is slideably engaged within passageway (976) as similady described for previous ablation members in Figures 3 and 8, except that the ablation member (914) in Figure 9 further includes a passageway (948) running its length which tracks over a second guidewire (950) thereby providing a second anchor.
In the tissue abletion assembly shown in Figure 10A, effectively one continuous member forms first and second delivery members vWth anchors and an ablation member strung therebetween. An elongate body (1009) has a first end portion (1082) and a second end portion (1083), both extending along a delivery sheath lumen (1092) in e side-by-side artangenrent. A first passageway (1076) extends along the first end portion (1082) and terminates adjacent to an ablation member (1014) in a first rkstal port 11038), which is pictured within the right supetior pulmonary vein ostium (101). The second and portion has a second passageway (1077) terminating rGstally adjacent to the ablation member (1014) in a second distal port (10391, which is pictured in the adjacent left superior pulmonary vein ostium (102). The simplicity of tNs design aNows for two guidewire tracking members over first end second guidewires (1040,1050) and provides anchors for both ends of ablation member (1014) along the length of tissue to be ablated.
It is further contemplated (shown in shadow), that another guidewire (1045) may exit another port (1081) in the elongate member (1009), at or adjacent to the left inferior ptdmonery vein ostium (103), wherain an additionel verdcal ablation element {1015) is provided, such that the abiation element (1015) spans the Gnear distance between the superior and inferior left pulmonary vein ostia. Thus, one of skill in the art will readily recognize that further modfication of the ablation assembly shown in Figure 9A, to include an adcitional guidewire and ad(itional abla6on elements, may facilitate the induction of a four-sided closed abletion lesion connecling the four pulmonary vein ostia;
the right inferior pdmonary vein ostium (104) is also pictured. Referring to Figure 10B, the ablation assembly is modfied such that the guidewires are only engaged along a distat portion of the elongate body (1009).
Figtnes 10C-D, deoct another tissue ablation assembly during deavery through a transeptal delivery sheath (10921, and shows an ablation member (1014) which indudes a proximal portion (1083) that fomns a guidewire tracking member (1046) extending proximally in a side-by-side arrangement in parallel vuith a guidewire tracking member (1034) SUBSTITUTE SHEET (RULE 26) of a del'ivery member (10101 along the defivery sheath. Figure 10C and Q
further show each of the guidewire tracking members (1034,1046) to indude a distal port into a passageway through which a guidewire is slideably enga'ged substentiaily along the end portion's length, and further shows the intermediete portion 11094) to indude shaped regions (1011,1013) located at or adjacent to each of the distal ports 11038,1039) such that each shaped region is adapted to engage a vessel extendng from an atrial wall while the ablation element is engaged along a length of atriai we1l tissue extendirig between the vessels' ostia. Figure 100 is similar to the assembly shown in Figure 10C, except showing the first and second guidewire tracking members (1034,1046) to extend along only a distal region of the respective end portion.
Figure 11 A shows a perspective view of another tissue ablation assembly that indudes an ablation member (1114) with a proximal end portion (1118) that is sideably engaged within a passageway 11178) extending along a first delivery member (1110) that further includes a guidewire tracking member (11341 slideebly engaged over a guidewire (1140), and also shows a predetermined length of the dstai end portion of the ablation member, which includes an ablation element, extending a predetermined distance distally from the passageway through a distal port (1178). The predetermined length of the distal end portion of the ablation member has a predetermined shape which is adapted, as shown in Figure 11 B, to be secured to a length of atrial wall tissue from a pradetermined location when the ablation member (1114) is anchored by the guidewire (1140) at or adjacent to the predetermined location. The anchoring may optionagy be enhanced by operation of an expandable member (1184) on the guidevuire traciting member (1134).
Figures 12 and 13A-E show various specific mnbodments of an abletion assembly which utilizes both a linear ablation member (1214) end a circumferential etdation element (1217). These ablation elements 11214,12171 may comprise any of the ablation devices discussed above. In an exempiary mode, as iUustrated in Figure 12, the ablation member (1214) has a linear configuration and the circumferential ablation element (1217) uti6zes an ecoustic energy sowce that radially emits a coUimated energy bemn in a circumferentiaf pattern. The present linear and circumferential abtation elements (1214,1217) have particWar utility in connection vwth fomiing Gnear and circumferential lesions along a posterior waU of the left atrium and within or about one of the associated pulmonary vein ostia (or within the vein itself) in order to form conductive blocks. This application of the present ablation assembly, however, is merely exemplary, and it is understood that those skiDed in the art can readly adapt the present ablation device assembly for app6cations in other body spaces.
The abiation essembly is principally configured in accordance with the disclosure set forth above in connection with Figure 10C, with the exception of the addtion of the circumferential ablation element (1217). Accordingly, the foregoing description should be understood as applying equally to the present mode, except where noted otherwise.
In the illustrated embod'iment, the circumferential ablation element (1217) indudes a source of acoustic enargy, an ultresound transducer (1223), and an anchoring device 11284) that anchors the transducer (1223) within the targeted body space (e.g., pdrnonary vein ostium). The anchoring device (1284) may also couple the transducer (1223) to the targeted tissue site. Both the anchor (1284) and the transducer 11223) are positioned at a distal end por6on (1280) of ona of the delivery members (1210,1212) of the ablation device assembly.

-21.
SUBSTITUTE SHEET (RULE 26) In one mode, the anchoring device (1284) comprises an expendable member that also positions fi.a., orients) the transducer (1223) witidn the body space; however, other anchoring and positioring devices may elso be used, such as, for exampie, a basket mechanism. In a more specific form, the transducer (1223) is located within the expandable member (1284) and the expandeble member (1284) is adapted to engage a circumferential path of 6ssue either about or along a pdmonrey vein in the region of its ostium or along a left atrial posterior waU. The transducer (12231 in turn is acoustically coupled to the wail of the expendable member (1284), and thus to the circunferential region of tisaue engaged by the expandable member wall, when actuated by an acoustic energy driver (1273) to emit a circumferential end longitudinally coDimated ultrasound signal. The linear ablation member (1214) is operated by an actuator (1272).
The use of acoustic energy, and particularly ultrasonic energy, offers the advantage of simultaneously eppiying a dose of energy sufficient to ablate a relatively large surface area vuithin or near the heart to a desired heating depth without exposing the heart to a large amount of current. For example, a coUimated ultrasonic transducer can.
form a lesion, which has about a 1.5 mm width, about a 2.5 mm chameter lumen, such as a pulmonary vein, end of4a sufficient depth to form en effective conductive block. It is bel'ieved that an effective conductive btodc can be formed by producing a lesion within the tissue that is transmural or substantiaNy transmural. Dependmg upon the patient, as weA as the location within the ptdnonary vein ostium, the lesion may have a depth of 1 mi6meter to 10 mAGmeters. It has been observed that the couimated ultrasonic transducer can be potnaered to provide a tesion Iaving these paremeters so as to form an effective conductive blodr between the puknonary vein and the posterior wal of the left atrium.
With specific referance now to the embodiment iNustrated in Figures 13A
through 13D, the distal end poraon (1380) of one of the delivery mmnbers (1310) includes an elongate body (1309) with proximal and cistal sections (1353,1355), an expandable balloon (13841 located along the d1stel and portion (13801, and a circwnferential dtresound transducer (1323) which forms a circumferential ablation member that is acoustically coupled to the expandable balloon (1384). In more detail, Figures 13A-C variousty show the elongate body section (1309) to include a guidewire lumen (1336), an inflation lumen (1385), and an electrical lead iumen (1375). The ablation device, however, can be of a self steeong type rather than an over-the-wire type device, as noted below.
Each lumen extends between a proximal port (not shown) and a respective distal port, which distal ports are shown as a distal guidewire port 11338) for the gWdewire lumen (1336), a distal inflation part (1387) for the inffation lumen 11385), and the distal lead port (1388) for electtical lead lumen (1375). Although the guidewire, inflation and etectrical lead lumens are generally arranged in a side-by-side relationship, the elongate body section (1309) of the distal end portion (1380) can be constructed with one or more of these lumens arranged in a coaxial relationship, or in any of a wide variety of configurations that will be readily apparent to one of ordinary skitt in the art.
In adtition, the eiongete body (1309) is also shown in Figure 13A and 13C to include an inner member (1308) that extends distally beyond the distai inflation and lead ports (1387,1388), through an interior chamber formed by the expandable balloon (1384), and distally beyond the expandable baitoon where the elongate body (1309) terminates in a distal tip. The inner member (1308) forms the dstal region for the guidewire lumen (1336) beyond the inflation and lead .22-SUBSTITUTE SHEET (RULE 26) ports, and also provides a support member for the cylindricel uftrasound transducer (i 323) and for the distal neck of the expension balloon (13841, as described in more detail bdow.
One more detailed construction for the components of the elongate body section (1309) which is believed to be suitable for use in transeptel left atrial ablation procedures is as follows. The elongate body (1309) itself may have an outer diameter provided within the range of from about 5 French to about 10 French, and more preferaldy frorn about 7 French to about 9 French. The gudewire lumen preferably is adapted to slideably receive guidewires ranging from about 0.010 inch to about 0.038 inch in d'iamater, and preferably is adapted for use with guidewires ranging from about 0.018 inch to about 0.035 inch in d'iameter. Where a 0.035 inch guidevuire is to be used, the guidewire lumen preferaMy has an inner d'iameter of 0.040 inch to about 0.042 inch. In addition, the inflation lumen preferatdy has an inner d=iamater of about 0.020 inch in order to allow for rapid deflation times, although may vary based upon the viscosity of inflation metium used, length of the lumen, and other dynamic factors reletiag to fluid flow and preaaure.
In addition to provirGng the requisite lumens and support members for the ultrasound transducer assembly, the elongate body section (13091 of the dekvery member must also be adapted to be introduced into the left atrium such that the distal end portion with the balioon (1384) and transducer (1323) may be placed within the puknonary vein ostium in a percuteneous transiumenal procedure, and even more preferably in a transeptal procedure es otherwise herein provided. Therefore, the cistal end portion 113801 is preferably flexible and adapted to track over and along a guidevuire seated within the targeted pulmonary vein. In one further more detailed construction which is believed to be srntable, the proximal end portion is adapted to be at least 30% more stiff than the distal end portion. According to ttas relationship, the proximal end portion may be suiteay adapted to provide push transmission Iand possibly torque transnussian) to the distal end portion while the distal end portion is suitably adapted to track through bending aoatomy during in vivo delivery of the distal end portion of the device into the desired aWetion region.
At least a distal portion of the delivery member (1310) tracks over a guide vuire 113401. Notwithstanding the specific device constructions just described, other variations of the delivery member are also contemplated. For example, widle the illustrated mode is shown as an "over=the=wire" catheter construction, other guidevuire tracking designs may be suitable substitutes, such as, for exampie, catheter devices which are known as "rapid exchange" or "monorail" veriations wherein the giiridewire is ody housed coaxielly within a lumen of the catheter in the rkstal regions of the catheter. In another example, a deflectsble tip design may also be a suitable substitute and which is adapted to independentiy select a desired pulmonary vein and direct the transducer assembly into the desired location for ablation. Further to this latter variation, the guidevuire lunren and guidevvire shown in Figure 13A may be replaced with a"puliwire" lumen and associated fixed puAvuire which is adapted to deflect the catheter tip by applying tension along varied stiffness transitians along the catheter's length. S61i further to this pullvuire variation, acceptable pullwires may have a rGameter within the range from about 0.008 inch to about 0.020 inch, and may further include a taper, such as, for example, a tapered outer diameter from about 0.020 inch to about 0.008 inch.
More spacifbcSIly regarding the expendeble baNoon (1384) as shown in varied detail between Figures 13A and 13C, a central region (1381) is generally coaxially (isposed over the inner member (1308) and is bordered at its end neck =23-SUBSTITUTE SHEET (RULE 26) regions by proximal and distal adaptations (1393,1395). The proximel adaptation (13931 is sealed over Wongate body section (13091 proximelly of the d'istal inflation and the electricW lead ports (1387,1388), and the (istal adaptation 113951 is sealed over inner member (13091. According to this arrangement, a fluid tight interior chamber is formed within expandsble balloon (13841. This intedor chamber is fluidly coupled to a pressurizeeble fluid aource Inot shovml via the inflation lumen (1387). in addition to the inflation lumen (1385), the electrical lead Iwnen (1375) also communicates vuith the interior chember of expandalde balloon 11384) so that the ultrasound transducer (1323), which is positioned within that the chamber and over the inner member (1308), may be elactrically coupled to an idtrasound drive source or actuator, as wi0 be provided in more detail below.
The expandable balloon (1384) may be constructed from a variety of known materials, although the baHoon (1384) preferably is adapted to conform to the contour of a pulmonary vein ostium. For this purpose, the balloon materiW can be of the tdghly compfiant vatiety, such that the material elongates upon application of pressure and takes on the shape of the body lumen or space when fully inflated. SWtable balloon materials include elastomers, such as, for exampie, but without limitation, silicone, latex, or low dixometer polyurethane (for example a durorneter of about 80A).
In adtktion or in the aiternative to constructing the balfoon of higNy compGant material, the balloon (1384) can be fonned to have a predefined fuUy inflated shape Ii.e., be preshaped) to generally match the anatomic shape of the body lumen or space in wfdch the balloon is inflated. For instance, as described below in greater detail, the balloon can have acistally tapering shape to generally match the shape of a pulmonary vein ostium, andlor can include a bulbous proximal end to generWly match a transition region of the atrium posterior wap adjacent to the pulmonary vein ostitm.
In this manner, the desired seating wittNn the irregular geometry of a pulmonery vein or vein ostium can be achieved with both canp6ant and non-compGant belloon variations.
Notwithstanding the altematives which may be acceptable as just described, the bailoon 11384) is preferably constructed to exhibit at least 300% expansion at 3 atmospheres of pressure, and more proferably to exhibit at least 400% expansion at that pressure. The term "expansion" is herein intended to mean the badoon outer dameter after pnsseizadon dwided by the baqoon inner clameter before pressurization, wherein the baNoon inner diameter before preasuraatiai is taken after the balloon is substantiaqy fi0ed with fluid in a teught configuration. In other words, "expansion" is herein intended to relete to change in ilameter that is attributable to the material compGance in a stress strain relationship. In one more detailed construction wlrch is believed to be suitsble for use in most conduction block procedures in the region of the pulmonary veins, the balloon is adapted to expand under a normal range of pressure such that its outer diameter may be adjusted from a racially collapsed position of about 5 mii6meters to a rediapy expanded position of about 2.5 centimeters (or approximateiy 500% expansion ratio).
The aSation member (13231, which is illustrated in Figures 13A-D, takes the form of an annular ultrasonic tranaducer applicator. In the iilustrated embodiment, the annular dtrasonic transducer applicator (1323) has a unitary cylindricel shape with a hdlow intetior (i.e., is tubular shaped); however, the transducer applicator can have a generally anndar shape and be fonned of a plurality of segments. For instance, the transducer applicator can be fonned by a plurebty of tube sectors that together form an annular shape. The generally annular shape can also be formed by a SUBSTITUTE SHEET (RULE 26) plurdity of planar transducer segments which are arranged in a polygon shape (e.g., hexagon). In addition, efthough in the dlustrated embodiment the ultrasonic transducer comprises a singie transducer eiement, the transducer appGcstor can be fonned of a multi-element array, as desaibed in greater datdl below.
As is shown in detail in Figuue 130, the cylindrical ultrasound transducer 113231 indudes a tubular wall which includes three concentric tubuler layers. A central layer 11325) has a tubder shaped member of a piezoceramic or piezoelectric crystaUine materiel. This transducer element preferably is made of type PZT-4, PZT-5 or PZT-8, quartz or Lithium-Niobate type pieroceramic material to ensure high power output capabdities. These types of transducer materieis are commerciaqy avalabie from Stavely Sensors, Inc. of East Hartford, Connecticut, or from Valpey-fischer Corp. of Hopkinton, Massachusetts.
The outer and inner tubufar members (1327,1329) enclose the central layer 11325) within their coexial space and are constructed of an electricaliy conductive materiel. In the iiiustrated embodiment, these outer and inner members which form the transducer electrodes (1327,1329) comprise a metallic coating, and more preferably a coating of nickel, copper, silver, gold, platinum, or alloys of these metals.
One more detailed construction for e cylindrical ultrasound transducer 11323) for use in the present appiication is as follows. The length D of the transducer applicator (1323) or trensducer applicator assembly (e.g., multi-element array of transducer elements) desirably is selected for a given dinical application, but is less than a length D of the balloon (1384) that contacts the tissue. In connection with forming circumferential conduction blocks in cardiac. or prdmonary vein wWl tissue, the trensducer length can faA within the range of approximately 2 mm up to greater then 10 mm, and preferably equals about 5 mm to 10 mm. A transducer accordnoy sized is believed to form a lasion of a vuidth sufficient to ensure the integrity of the formed conductive block without undue tisstm ablation. For other applications, however, the length can be sigrrficantly longer.
Likewise, the transducer outer diameter desirably is selected to account for delivery through a particdar access path (e.g., percutaneously and transeptally), for proper placement and location within a particular body space, and for achieving a desired ablation effect. In the given application within or proximate of the pulmonary vein ostium, the transducer preferably has an outer d'imneter within the range of about 1.8 mm to greater than 2.5 mm. It has been observed that a transducer with an outer diameter of about 2 mm generates acoustic power levels approaching 20 Watts per centimeter radiator or greater within myocardial or vasculm tissue, which is believed to be sufficient for ablation of tissue engaged by the outer balloon for up to about a 2 cm outer diameter of the baAoon. For applications in other body spaces, the trensducer epplicator may have an outer diameter vWthin the range of about 1 mm to greater than 34 mm (e.g., as large as 1 to 2 cm for applications in some body spaces).
The central layer 113251 of the transducer applicator (1323) has a thickness selected to produce a desired operating frequency. The operating frequency will vary of course depending upon clinical needs, such as the tolerable outer diameter of the ablation and the depth of heeting, as well as upon the size of the transducer as limited by the delivery path and the size of the target site. As described in greater detail below, the transducer in the illustrated appbcation preferably operates within ihe range of about 5 MHz to about 20 MHz, and more preferably within the range SUBSTITUTE SHEET (RULE 26) of about 7 MHz to about 10 MHz. Thus, for examoe, the transducer can have a thickness of approximately 0.3 mm for an opereting frequency of about 7 MHz (i.e., a thidcness genereRy equal to A
the wavelength associated vuith the desired operating ftequency).
The transducer applicator 11323) is vibrated across the wall thickness to radiate collimated acoustic energy in a ra(IW direction. For this purpose, as best seen in Figures 13A and 13D, the distal ends of electrical leads (1331,1333) are electrically coupled to outer and inner tubuler members or electrodes (1327,1329), respectiveiy, of the transducer (1323), such es, for example, by sddering the leads to the metelbc coatings or by resistance welding. In the iAustrated embodiment, the electrical leads are 4-8 mil (0.004 to 0.008 inch d'iameter) saver wire or the bke.
Importantly, as best understood from Figure 12, the wire leads or lead set, indicated generelly by reference numeral 112351, for the circumferential aaation element (1223) are routed through the lead lumen (1275) of the first delivery member 0 2101, while the wire leads or lead set (1237) for the linear ablation element 112141 are routed through one or more wire lead Iumens that extends through the linear ablation member (12141 and through the second delivery member (1212). The seperetion of these lead sets (1235,1237) reduces any cross-contamination or noise in the signol carried by one of the lead sets due to its proximity of the other lead set.
The proximal ends of the leads of the lead set 112351 for the circumferential ablation element (1223) are adapted to couple to an uitrasonic driver or actuator (1273), which is schematicaliy iAustrated in Figure 12. Figures 13A-C further show leads as separate vuires within electrical lead lumen, in which configuration the leads must be well insulated when in close contact. Other configurations for leads are therefore contempleted. For exampie, a coaxial cable may provide one cable for both leads which is weA insulated as to inductance interference. Or, the leads may be communicated toward the distal end portion of the elongate body through different lumens which are separated by the catheter body.

Still with reference to F'igure 12, the leads of the lead sets (1237) for the Gnear ablation element (1214) are coupled to an ablation actuator 11272), which is configured in accordance with the above description. The ablation actuator (1272) desirably includes a current source for supplying an RF
current, a morbtoring circuit, and a control circuit: -The current source is coupled to the linear abletion element (1214) viathe iead set 11237), and to a ground patch (not shown). The monitor circuit desirably communicates with one or more sensors (e.g., temperature or current sensors) which monitor the operation of the linear aMetion element 11214). The control circtat is connected to the monitoring circWt and to the current source in order to adjust the output ievel of the current dtiving the electrodes of the Gnear ablation element (1214) based upon the sensed condition le.g., upon the relationship between the monitored temperature and a predetemrned temperature set-point-.
The ultrasonic actuator (12731 generates altemating current to power the transducer. The ultrasonic actuator (1273) drives the transducer at frequencies within the range of about 5 to about 20 MHz, and preferably for the dlustrated epoication within the range of about 7 MHz to about 10 MHz. In addition, the ultrasonic driver 11273) can modulate the driving frequencies andlor vary power in order to smooth or unify the produced collimeted ultrasonic .28.

SUBSTITIJTE SHEET (RULE 26) wo 99/44519 PCT/US99/04521 beam. For instance, the function generator of the ultrasonic driver can drive the transducer at frequencies within the range of 6.8 MHz and 7.2 MHz by continuousiy or (iscretWy sweeqng between these frequencies.
The ultrasound transducer (1223) of the present ambodiment sonically couples with the outer skin of the balloon (1284) in e manner which forms a circumferential conduction block in a pWmonery vein as foYows. Initially, the ultrasound transducer (1223) is bebeved to aWt its energy in a circumferential pattern wldch is highly colGmated along the transducer's length relative to its longitudinal axis L (see Figwe 13D).
The circurnferential band therefore mainteins its width and circumferential pattem over en appreciable range of diameters away from the source at the transducer.
Also, the balloon (1284) is preferably inflated with fluid which is relatively ultrasonicagy transparent, such as, for example, degassed water. Therefore, by actuating the transducer while the balloon is inflated, the cin:uunferentia) band of energy is allowed to translate through the inflation fluid and ultimateiy sonicagy couple with a cin:umferential band:of balioon skin which cin:umscribes the belloon. Moreover, the circumferential band of balloon skin materiel may also be fnrther engaged along a circumferential path of tissue which circwnscdbes the balloon, such as, for example, if the balloon is inflated vvithin and engages a ptdmonery vein wall, ostium, or region of atrial wall. Accordingiy, where the balloon is constructed of a relativeiy ultrasonically transparent material, the circumferential band of ultrasound energy is allowed to pass through the belloon skin and into the engaged circumferential path of tissue such that the circumferential path of tissue is ablated.
With reference to Fgure 13E, the transducer (1323) also can be sectored by scodng or notching the outer, transducer electrode and part of the central layer along lines paraUel to the longitudinal axis L of the transducer (1323).
A separate electdcal lead connects to each sector in order to couple the sector to a dedicated power control that ind-ividually excites the corresponding transducer sector. By controlling the driving power and operating frequency to each ind'ividuai sector, the ultrasonic driver can enhance the unifonnity of the ultrasonic beam around the transducer, and vary the degree of heating (i.e., lesion control) in the angular dimension. Again the leads for each sector may be routed through rrifferent lumens of the two delivery members.
The ultrasound trensducer just described is combined vvith the overall device assembly eccording to the present embot6ment as foAows. in assembly, the transducer desirably is "air-backed" to produce more energy and to enhance energy cistribution unifonnity, as known in the art. In other words, the inner member does not contact an appreciable amount of the inner surf ace of transducer inner tubular member.
For this purpose, the transducer seats coaxial about the inner member and is supported about the inner member in a manner provicing a gap between the inner member and the transducer inner tubular member. That is, the inner tubular member forms an interior bore which loosely receives the inner member. Any of a variety of structures can be used to support the transducer about the inner member. For instance, spaces or spGnes can be used to coaxially position the transducer about the inner member while leaving a generagy annalar space between these components. In the Wtemative, other conventional and known approaches to support the transducer can also be used. For instance, 0-rings that circumscribe the inner member and Cie between the inner member and the transducer can support the .27.

SUBSTITUTE SHEET (RULE 26) transducer in a manner similar to that illustrated in U.S. Pat. No. 5,606,974 to Castellano. Another example of alternative transducer support structures is disclosed in U.S. Pat. No.
5,620,479 to Diederich.

In the illustrated embodiment, a stand-off (1341) is provided in order to ensure that the transducer has a radial separation from the inner member to form a gap filled with air and/or other fluid. In one preferred mode shown in Figure. 13C, stand-off (1341) is a tubular member with a plurality of circumferentially spaced outer splines (1343) which hold the majority of the transducer inner surface away from the surface of the stand-off between the splines, thereby minimizing damping affects from the coupling of the transducer to the catheter. The stand-off (1341) is inserted within the inner hollow cavity (1347) of the transducer (1323).

The transducer desirably is electrically and mechanically isolated from the interior of the balloon. Again, any of a variety of coatings, sheaths, sealants, tubings and the like may be suitable for this purpose, such as those described in U.S. Patent Nos. 5,620,479 and 5,606,974. In the illustrated embodiment, as best illustrated in Figure 13C, a conventional sealant, such as, for example, General Electric Silicon II
gasket glue and sealant, desirably is applied at the proximal and distal ends of the transducer around the exposed portions of the inner member, wires and standoff to seal the space between the transducer and the inner member at these locations. In addition, a conventional, flexible, acoustically compatible, and medical grade epoxy can be applied over the transducer, The epoxy may be, for example, EpotekTM' 301, EpotekT"^ 310, which is available commercially from Epoxy Technology, or Tracon FDA-8.
An ultra thin-walled polyester heat shrink tubing or the like then seals the epoxy coated transducer.
Alternatively, the epoxy covered transducer, inner member and standoff can be instead into a tight thin wall rubber or plastic tubing made from a material such as Teflon0, polyethylene, polyurethane, silastic or the like. The tubing desirably has a thickness of 0.0005 to 0.003 inches.

When assembling the ablation device assembly, additional epoxy is injected into the tubing after the tubing is placed over the epoxy coated transducer. As the tube shrinks, excess epoxy flows out and a thin layer of epoxy remains between the transducer and the heat shrink tubing. This layer protects the transducer surface, helps acoustically match the transducer to the load, makes the ablation device more robust, and ensures air-tight integrity of the air backing.

Although not illustrated in figure 13A in order to simplify the drawing, the tubing extends beyond the ends of transducer and surrounds a portion of the inner member on either side of the transducer. A filler (not shown) can also be used to support the ends of the tubing. Suitable fillers include flexible materials such as, for example, but without limitation, epoxy, Teflon tape and the like.

Further to known ablation catheter devices and methods of the type just summarized above, early disclosures of such ablation catheter treatments include emitting direct current (DC) from an electrode on the distal end of a catheter in order to ablate the targeted tissue believed to be the focus of a particular arrhythmia. However, more recently, devices and procedures instead use radio frequency (RF) current as the energy source for tissue ablation, as disclosed in U.S. Pat. Nos. 5,209,229 to Gilli; 5,293,868 to Nardella; 5,228,442 to Imran. Other energy sources which have been used in catheter-based ablation prooedures are disclosed in the foNovNng referencex U.S. Patent No. 5,147,355 to Fdedrnan et el; U.S. Patent No. 5,156,157 to Valenta Jr, et al.; WO 93120767 to Stern et a1; end U.S. Patent No.
5,104,393 to laner et al. -Wh'lee a nunber of preferred embodiments of the invention and variations thereof have been described in detaa, other modifications end methods of use vuiM be readly appaent to those of skal in the art Accordmgiy, it shodd be arxderstood that variais app6cations, mocifxations and substitu6ans may be made of equivalents vuithout departing from the spirit of the invention or the scope of the daims.

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SUBSTITUTE SHEET (RULE 26)

Claims (16)

What is claimed is:

1. A tissue ablation device assembly for ablating a length of tissue between first and second predetermined locations in a patient, comprising: a first delivery member having a distal end portion and defining a first tracking member adapted to slidably engage and track over a first guide member, the first delivery member also defining a passageway terminating in a side port proximal to a distal end; a second delivery member having a distal end portion; and an elongated ablation member having a first end portion slidably engaged in the passageway of the first delivery member and a second end portion coupled to the distal end portion of the second delivery member, the ablation member including an ablation element located at least in part between the first and second end portions of the ablation member; wherein the ablation member is selectively extendable from the passageway and the first and second delivery members are adapted for advancement to the first and second predetermined locations, respectively, such that the ablation element can be positioned along the length of tissue.

2. The tissue ablation device assembly of claim 1, further comprising an expandable member disposed along the distal end portion of the first delivery member distal to the side port, the expandable member being adapted for engagement in a tubular body structure.

3. The tissue ablation device assembly of claim 2, wherein the expandable member is a balloon.

4. The tissue ablation device assembly of claim 1, wherein the first guide member is a first guidewire.

5. The tissue ablation device assembly of claim 1, wherein the second end portion of the ablation member further comprises a second tracking member adapted to slidably engage and track over the second delivery member.

6. The tissue ablation device assembly of claim 5, wherein the second delivery member is a second guidewire.

7. The tissue ablation device assembly of claim 5, further comprising at least one radial enlargement located along the distal end portion of the second delivery member and sized for contacting the second end portion of the ablation member.

8. The tissue ablation device assembly of claim 1, wherein the ablation member is adapted to form a conduction block along a length of tissue between first and second pulmonary vein ostia along an atrial wall and the first delivery member is adapted for advancement into a first pulmonary vein ostium.

9. The tissue ablation device assembly of claim 8, wherein the second delivery member is adapted for advancement into a second pulmonary vein ostium.

10. The tissue ablation device assembly of claim 1, wherein the distal end portion of at least one of the delivery members further comprises a curved shape.

11. The tissue ablation device assembly of claim 1, wherein the ablation element comprises at least one electrode.

12. The tissue ablation device assembly of claim 1, further comprising a delivery sheath and wherein the first and second delivery members are adapted to be slidably engaged within the delivery sheath in a side-by-side arrangement during delivery to a treatment site.

13. The tissue ablation device assembly of claim 1, wherein the ablation element comprises an ablation length with multiple electrodes along the length.

14. The tissue ablation device assembly of claim 1, wherein the ablation element comprises at least one ultrasound transducer.

15. A tissue ablation device assembly adapted to form a linear conduction block along a length of tissue between first and second pulmonary vein ostia along an atrial wall in a patient, comprising: a first guidewire; a first delivery member having a distal end portion and defining a first tracking member adapted to slidably engage and track over the first guidewire, the first delivery member also having a passageway terminating in a side port proximal to a distal end, the distal end portion of the first delivery member being adapted for insertion into the first pulmonary vein ostium; a second delivery member having a distal end portion adapted for insertion into the second pulmonary vein ostium; and an elongated ablation member having a first end portion slidably engaged in the passageway of the first delivery member and a second end portion coupled to the distal end portion of the second delivery member, the ablation member including an ablation element located at least in part between the first and second end portions of the ablation member;
wherein the ablation member is selectively extendable from the passageway of the first delivery member and the first and second delivery members can be manipulated to position the ablation element along the length of tissue between the first and second pulmonary vein ostia.

16. A tissue ablation device assembly adapted to form a linear conduction block along a length of tissue between first and second pulmonary vein ostia along an atrial wall in a patient, comprising: a first guidewire; a delivery member having a distal end portion and a first tracking member adapted to slidably engage and track over the first guidewire, the delivery member also having a passageway terminating in a side port proximal to a distal end, the distal end portion of the first delivery member being adapted for insertion into the first pulmonary vein ostium, the delivery member having a first expandable member disposed along the distal end portion for anchoring in the first pulmonary vein ostium;
a second guidewire having a distal end portion adapted for insertion into the second pulmonary vein ostium, the second guidewire including a radial enlargement;
and a single elongated ablation member having a first end portion slidably engaged in the passageway of the delivery member and a second end portion formed with a second tracking member adapted to slidably engage and track over the second guidewire, the ablation member including an ablation element located at least in part between the first and second end portions of the ablation member, the ablation member also including a second expandable member disposed along the second end portion for anchoring in the second pulmonary vein ostium; wherein the second guidewire is independently advanceable such that the radial enlargement contacts the second end portion of the ablation member to selectively extend the ablation member from the passageway and the first and second guidewires can be manipulated to position the ablation element along the length of tissue located between the first and second pulmonary vein ostia to form a linear conduction block thereon.