CA2262623A1 - Method and apparatus for performing coronary artery bypass surgery - Google Patents

Abstract

A method and apparatus for performing coronary artery bypass surgery establishes a channel leading directly from a chamber of a heart into a coronary artery with said channel retained open during both diastole and systole. The coronary artery bypass procedure may be performed with or without cardiopulmonary bypass.

Description

W O 98/06356 1 PCTrUS97/13980 M ~,T H O n ~r~D A PP A R ~ T U S F O R P ~,R ~ O R~IIN G
CORONARY ~TFRY Ryp~.~S SURG~Y

BACKGROUND OF THE INVENTION
5 1. Field of the Tnvention.
The present invention relates generally to a method and apparatus for performing a coronary artery bypass procedure. More particularly, the present invention performs a coronary artery bypass by providing a direct flow path from a heart chamber to the coronary artery. The present invention is suitable for a number of approaches including an open-chest approach (with and without cardiopulmonarybypass), a closed-chest approach under direct viewing and/or indirect thoracoscopic viewing (with and without cardiopulmonary bypass), and an intçrn~l approach through catheterization of the heart and a coronary arterial vasculature without direct or indirect viewing (with and without cardiopulmonary bypass).

2. Description of the Prior Art.
A. Coronary Artery Disease Coronary artery disease is the leading cause of premature death in industrialized societies. The mortality statistics tell only a portion of the story.
Many who survive face prolonged suffering and disability.
Arteriosclerosis is "a group of diseases characterized by thickening and loss of elasticity of arterial walls. DORLAND s ILLUSTRATED MEDICAL DICTIONARY 13 7 (27th ed. 1988). Arteriosclerosis "comprises three distinct forms: atherosclerosis, Monckeberg's arteriosclerosis, and arteriolosclerosis." Id Coronary artery disease has been treated by a number of means. Early in this century, the treatment for arteriosclerotic heart disease was largely limited tomedical measures of symptomatic control. Evolving methods of diagnosis, coupled with improving techniques of post-operative support, now allow the precise ,.
Iocalization of the blocked site or sites and either their surgical re-opening or bypass.
B. An~ioplasty The re-opening of the stenosed or occluded site can be accomplished by several techniques. Angioplasty, the expansion of areas of narrowing of a blood Wo 98l06356 2 PCT/US97/13980 vessel, is most often accomplished by the intravascular introduction of a balloon-equipped c~theter. Inflation ofthe balloon causes mechanical con~lession ofthe arteriosclerotic plaque against the vessel wall.
Alternative intravascular procedures to relieve vessel occlusion include 5 atherectomy, which results in the physical desolution of plaque by a catheter equipped with a removal tool (ç~, a cutting blade or high-speed rotating tip). Any of these techniques may or may not be followed by the placement of a mechanical support (i.e., a stent) which physically holds open the artery.
Angioplasty, and the other above-described techniques (although less 10 invasive than coronary artery bypass grafting) are fraught with a correspondingly greater failure rate due to intimal proliferation. Contemporary reports suggest re-stenosis is realized in as many as 25 to 55 percent of cases within 6 months of successful angioplasty. See Bojan Cercek et al., 68 AM. J. CARDIOL. 24C-33C (Nov.
4, 1991). It is presently believed stenting can reduce the re-stenosis rate.
A variety of approaches to delay or prevent re-blockage have evolved. One is to stent the site at the time of balloon angioplasty. Another is pyroplasty, where the balloon itself is heated during inflation. As these alternative techniques are relatively recent innovations, it is too early to tell just how successful they will be in the long term. However, because re-blockage necessitates the performance of another procedure, there has been renewed interest in the clearly longer-lastingbypass operations.
C. Coronary Artery Bypass Grafting i. Qutline of Procedure The traditional open-chest procedure for coronary artery bypass grafting requires an incision of the skin anteriorly from nearly the neck to the navel, the sawing of the sternum in half longitudinally, and the spreading of the ribcage with a mechanical device to afford prolonged exposure of the heart cavity. If the heartchamber or a vessel is opened, a heart-lung, or cardiopulmonary bypass, procedure is usually necessary.
Depending upon the degree and number of coronary vessel occlusions, a single, double, triple, or even greater number of bypass procedures may be W O 98/06356 3 PC~rAUS97tl3980 neces.s~ry. Often each bypass is accomplished by the surgical formation of a separate conduit from the aorta to the stenosed or obstructed coronary artery at a location distal to the diseased site.

ii. Limited N~lmber of Available Grafts The major obstacles to cololl~r artery bypass grafting include both the limited number of vessels that are available to serve as conduits and the skill required to effect complicated multiple vessel repair. Potential conduits include the two saphenous veins of the lower extremities, the two internal thoracic (ms~mms~ry) arteries under the sternum, and the single gastroepiploic artery in the upper abdomen.
Newer procedures using a single vessel to bypass multiple sites have evolved. This technique has its own inherent hazards. When a single vessel is used to p~lrO~ multiple bypasses, physical stress(~, torsion) on the conduit vessel can result. Such torsion is particularly detrimental when this vessel is an artery.
Unfortunately, attempts at using artificial vessels or vessels from other species (xenografts), or other non-related humans (homografts) have been largely unsuccessful. See LUDWIG K. VON SEGESSER, ARTERIAL GRAFTING FOR
MYOCARDIAL REVASCULARIZATION: INDICATIONS, SURGICAL TEcHNIQuEs AND
RESULTS 38-39 (1990).
While experimental procedures transplanting alternative vessels continue to be performed, in general clinical practice, there are five vessels available to use in this procedure over the life of a particular patient. Once these vessels have been sacrificed or affected by disease, there is little or nothing that modern medicine can offer. It is unquestionable that new methods, not limited by the availability of such conduit vessels, are neede~l iii. Trauma of Open Chest Sur~ery ~ In the past, the normal contractions of the heart have usually been stopped during suturing of the bypass vasculature. This can be accomplished by either electrical stimulation which induces ventricular fibrillation, or through the use of Wo 98/063s6 4 PCT/US97/13980 certain solutions, called cardioplegia, which chemically alter the electrolyte milieu surrounding cardiac muscles and arrest heart activity.
Stoppage of the heart enhances visualization of the coronary vessels and elimin~tes movement of the heart while removing the need for blood flow through the coronary arteries during the procedure. This provides the surgeon with a "dry field" in which to operate and create a functional anastomosis.
After the coronary artery bypass procedure is completed, cardioplegia is reversed, and the heart electrically stimulated if necessary. As the heart resumes the systemic pumping of blood, the cardiopulmonary bypass is gradually withdrawn.
The separated sternal sections are then rejoined, and the overlying skin and saphenous donor site or sites (if opened) are sutured closed.
The above-described procedure is highly traumatic. Immediate post-operative complications include infection, bleeding, renal failure, pulmonary edema and cardiac failure. The patient must remain intubated and under intensive post-operative care. Narcotic analgesia is n~cess~ry to alleviate the pain and discomfort.
iv. Post-OperativeCon~licatio~
Once the immediate post-surgical period has passed, the most troubling complication is bypass vessel re-occlusion. This has been a particular problem with bypass grafting of the left anterior descending coronary artery when the saphenous vein is employed.
Grafting with the internal thoracic (internal m~mm~ry) artery results in a long-term patency rate superior to saphenous vein grafts. This is particularly the case when the left anterior descentling coronary artery is bypassed. Despite this finrling, some cardiothoracic surgeons continue to utilize the saphenous vein because the internal thoracic artery is smaller in diameter and more fragile to manipulation.
This makes the bypass more complex, time-consuming, and technically difficult.
Additionally, there are physiological characteristics of an artery (such as a tendency to constrict) which increase the risk of irreversible damage to the heart during the immediate period of post-surgical recovery.
Once the patient leaves the hospital, it may take an additional five to ten weeks to recover completely. There is a prolonged period during which trauma to the sternum (such as that caused by an automobile accident) can be especially dangerous. The risk becomes even greater when the internal thoracic artery or arteries, which are principle suppliers of blood to the st~rnnm~ have been ligated and employed as bypass vessels.
v. T ess InvasiveProcedures Due to the invasive nature of the above technique, methods have been devised which employ contemporary thoracoscopic devices and specially-designed surgical tools to allow coronary artery bypass grafting by closed-chest techniques.
While less invasive, all but the most recent closed-chest techniques still require cardiopulmonary bypass, and rely on direct viewing by the surgeon during vascular anastomoses.
These methods require a very high level of surgical skill together with extensive training. In such situations, the suturing of the bypassing vessel to the coronary artery is performed through a space created in the low anterior chest wall by excising the cartilaginous portion of the left fourth rib. Also, as they continue to rely on the use of the patient' s vessels as bypass conduits, the procedures remain limited as to the number of bypasses which can be performed. Because of these issues, these methods are not yet widely available.
vi. Objectives for In~roved Bypass Procedures In view of the above, it is desirable to provide other methods by which adequate blood flow to the heart can be re-established and which do not rely on the transposition of a patient' s own arteries or veins. Preferably, such methods will result in minim~l tissue injury.
While the ;~ ....e~t ofthe foregoing objectives through an open chest 25 procedure would, by themselves, be a significant advance, it is also desirable if such methods would also be susceptible to surgical procedures which do not require opening of the chest by surgical incision of the overlying skin and the division of the sternum. Such methods would not require surgical removal of cartilage associatedwith the left fourth rib, would not require the surgical transection of one or both 30 internal thoracic arteries, would not require the surgical incision of the skin overlying one or both lower extremities, and would not require the surgical . ., W O 98/063S6 6 PCTnUS97/13980 transection and removal of one or both saphenous veins. In both an open and closed chest approach, it is also be desirable if such methods could be p~,lr~ led without stoppage of the heart and without cardiopulmonary bypass. However, attainment ofthe foregoing objectives in a procedure requiring cardiopulmonary bypass would still be a significant advance in the art.
vii. References for Prior Art Techniques The conventional surgical procedures (such as those described above) for col~oll~y artery bypass grafting using saphenous vein or internal thoracic artery via an open-chest approach have been described and illustrated in detail. See generally Stuart W. Jamieson, Aortocoronary Saphenous Yein Bypass Grafting, in ROB &
SMITH S OPERATIVE SURGERY: ~ARDIAC SURGERY, 454-470 (Stuart W. Jamieson &
Norman E. Shumway eds., 4th ed. 1986); LUDWIG K. VON SEGESSER, ARTERIAL
GRAFTING FOR MYOCARDIAL REVASCULARIZAT~ON: IN~ICATIONS, SURGICAL
TECHNIQUES AND RESULTS 48-80 (1990). Conventional cardiopulmonary bypass techniques are outlined in Mark W. Connolly & Robert A. Guyton, Cardiopulmonary Bypass Techniques, in HURST'S THE HEART 2443-450 (Robert C.
Schlant & R. Wayne Alexander eds., 8th ed. 1994). Coronary artery bypass grafting utili7.ing open-chest techniques but without cardiopulmonary bypass is described in Enio Buffolo et al., Coronary Artery Bypass Grafting Without Cardiopulmonary Bypass, 61 ANN. THORAC. SURG. 63-66 (1996).
Some less conventional techniques (such as those described above) are performed by only a limited number of appropriately skilled practitioners. Recently developed techniques by which to perform a coronary artery bypass graft lltili7ing thoracoscopy and minim~lly-invasive surgery, but with cardiopulmonary bypass, are described and illustrated in Sterman et al., U.S. Patent No. 5,45 ,733 (1995). An even more recent coronary artery bypass procedure employing thoracoscopy and minim~lly-invasive surgery, but without cardiopulmonary bypass, is described andillustrated by Tea E. Acuff et al., Minimally Invasive Coronary Artery Bypass Grafting, 61 ANN. THORAC. SURG. 135-37 (1996).

WO ~8/0~56 7 PCT/US97/l3g80 D . l~yp~ With Direct Flow Fron~ r.eft V~ntricle 1. S~ r of Proc~ res Certain methods have been proposed to provide a direct blood flow path ~ from the left ventricle directly through the heart wall to the coronary artery. These are described in U.S. Patent Nos. 5,429,144 dated July 4, 1995, 5,287,861 dated February 22, 1994; and 5,409,019 dated April 25, 1995 (all to Wilk). All ofthesetechniques include providing a stent in the heart wall to define a direct flow path from the left ventricle of the heart to the coronary artery.
As taught in each of the above-referenced patents, the stent is closed during either systole or diastole to block return flow of blood from the coronary artery during the heart's cycle. For example, the '861 patent teaches a stent which collapses to a closed state in response to heart muscle contraction during systole. The '019 patent (particularly Figs. 7A and 7B) teaches a rigid stent (i.e., open during systole) with a one-way valve which closes during diastole to block return flow of blood from the coronary artery.
ii. Problems The interruption of blood flow during either diastole or systole is undesirable since such inte~ lion can result in areas of stagnant or turbulent blood flow. Such areas of stagnation can result in clot formation which can result in occlusion or thrombi breaking lose. Such thrombi can be carried to the coronary arteries causing one or more areas of cardiac muscle ischemia (myocardial infarction) which can be fatal. Further, the te~chings of the aforementioned patents direct blood flow with a substantial velocity vector orthogonal to the axis of the coronary artery. Such flow can damage the wall of the coronary artery.
Providing direct blood flow from the left ventricle of the coronary artery has been criticized. For example, Munro et al., The Possibility of Myocardial Revascularization By Creation of a Left Ventriculocoronary Artery Fistula, 5~ Jour.
Thoracic and Cardiovascular Surgery, 25-32 (1969) shows such a flow path in Fig.1. Noting a fall in coronary artery flow and other adverse consequences, the authors concluded "that operations designed to revascularize the myocardium direct from the W O9~/Q~356 8 PCT~us97/13980cavity of the left ventricle make the myoc~diu"l i~r.l~mic and are unlikely to s~lcceecl " L at 31.
Notwith~t~n-ling the foregoing problems and scholarly criticism, and as will be more fully described, the present invention is directed to an ~p~lus and method for providing a direct blood flow path from a heart chamber to a coronary arterydownstream of an obstruction. Counter to the te~rhing~ of the prior art, the present invention provides substantial net blood flow to the coronary artery.
E. Addition~l Techniques Methods of c~th~tçn7~tion of the coronary vasculature, techniques utilized in the performance of angioplasty and atherectomy, and the variety of stents in current clinical use have been summarized. See generally Bruce F. Waller & Cass A.
Pinkerton, The Pathology of Interventional Coronary Artery Techniques and Devices, in 1 TOPOL S TEXTBOOK OF INTERVENTIONAL CARDIOLOGY 449-476 (Eric J. Topol ed., 2nd ed. 1994); see also David W. M. Muller & Eric J. Topol, Overview of CoronaryAthrectomy, in 1 TOPOL S TEXTBOOK OF INTERVENTIONAL
CARDIOLOGY at 678-684; see also Ulrich Sigwart, An Overview of Intravascular Stents: Old & New, in 2 TOPOL S TEXTBOOK OF INTERVENTIONAL CARDIOLOGY at 803-815.
Direct laser c~nS~li7~tion of cardiac musculature (as opposed to c~n~li7~tion of coronary artery feeding the cardiac musculature) is described in Peter Whittaker et al., Transmural Channels Can Protect Ischemic Tissue: Assessment of Long-term Myocardial Response to Laser- and Needle-~lade Channels, 94(1) CIRCULATION
143- 152 (Jan. 1, 1996). Massimo et al., Myocardial Revascularization By a New Method of Carrying Blood Directly From The Left Ventricular Cavity Into The Coronary Circulation, 34 Jour. Thoracic Surgery 257-264 (1957) describes a T-shaped tube placed within the ventricular wall and protruding into the cavity of the left ventricle. Also, Vineberg et al., Treatment of Acute Myocardial Infarction By Endocardial Resection, 57 Surgery 832-835 (1965) teaches forrning a large opening between the left ventricular lumen and the sponge-like network of vessels lying within the myocardium.

SUMM~Y OF T~F INVFNTION
According to the present invention, a method and a~al~lus for surgically bypassing an obstructed coronary artery establishes a charmel leading directly from a chamber of the heart into the obstructed coronary artery at a site distal to the5 obstruction and holding the channel open during both systole and diastole.
Additionally, the a~ar~lus of the invention avoids impingement of high velocity blood flow directly against the colollal y artery wall.
The present invention is particularly useful for coronary artery bypass procedures in a patient suffering from obstructive coronary artery disease. The 10 present invention permits an array of procedures of varying invasiveness.
The present invention avoids the previous limitations on the number of performable bypass procedures. Due to the limited number of arteries and/or veins available, standard procedures become increasingly risky to repeat. Rather than relying on harvested veins and arteries as bypass conduits, the present invention 15 ~forms a channel (or conduit) which leads directly from a chamber of a patient's heart into a coronary artery at a site distal to the obstruction or narrowing.
In the most plcfellcd embodiment, the left ventricle is the chamber of the heart lltili7t~:~ There are two reasons for this selection. First, the left ventricle normally provides blood to the coronary arteries, because it pumps blood into the 20 aorta from which the coronary arteries branch. Therefore, the magnitude of the blood pressure peak generated by the left ventricle is most similar to the bloodpressure peak the proximal coronary artery would normally experience. Second, the blood which flows into the left ventricle is returning from the lungs. In the lungs, the blood acquires oxygen and loses carbon dioxide. Thus, the blood available by25 shunting from the chambers of the left side of the heart will have a higher oxygen and lower carbon dioxide content then blood within the right-side heart charnbers.

B~TFF DESCRIPTION OF THE DRAWI~GS
FIG. lA is a right, front and top perspective view of an L-shaped conduit for 30 use in the present invention;

.

w o 98~0(-~6 10 PCTnUS97/l3980 FIG. lB is a side elevation view of the a~d~d~lls of FIG.lA shown partially in section to reveal an optional bi-directional flow regulator located in a lumen of an anchor arm of the conduit;
FIG.lC is a side elevation view of a conduit similar to that of FIG.lA
showing the addition of a capacitance pressure reservoir as an alternative embodiment;
FIG. 2A is a right, front and top perspective view of a T-shaped conduit according to the present invention;
FIG. 2B is a side elevation view of the conduit ofFIG. 2A shown partially in section to reveal an optional bi-directional flow regulator located in a lumen of an anchor arm of the conduit;
FIG. 2C is a side elevation view of the conduit of FIG. 2A shown partially in section to reveal one optional bi-directional flow regulator located in the lumen of the anchor arm of the conduit, and another optional bi-directional flow regulator located in an intracoronary arm of the conduit;
FIG. 2D is a side elevation view of a conduit similar to that of FIG.2A
showing the addition of a capacitance pressure reservoir as an alternative embodiment;
FIG. 3A is a partial side elevation view of a conduit similar to that of FIGS.
lA and 2A shown partially in section to reveal a flexible anchor arm with rigid rings ensheathed in a flexible covering as an alternative embodiment;
FIG. 3B is a partial side elevation view of a conduit similar to that of FIG.
3A shown in section in an extended form;
FIG. 3C is a partial side elevation view of a conduit similar to that of FIG.
3A shown in section in a col,lplessed form;
FIG.4is an anterior view of a human chest which is incised longitudinally to reveal a dissected pericardium and mediastinal contents;
FIG.5is a m~gnified view of an area circled 200 in FIG.4 illustrating a longitudinally incised coronary artery;
FIG.6is a partial external perspective view of a transversely sectioned coronary artery and heart wall illustrating a channel leading from a lumen of a wo98/063s6 11 rcTlus97ll398o coronary artery and into a charnber of the heart according to the method of the present invention;
FIG. 7 is a partial externa} perspective view of a transversely sectioned coronary artery and heart wall illustrating the partial placement of one embodiment 5 of the conduit of the present invention into the incised coronary artery and formed channel illustrated in FIG. 6;
FIG. 8 is a partial external perspective view of a transversely sectioned coronary artery and heart wall illustrating the completed pl~ment of one embodiment of the conduit of the present invention into the incised coronary artery 10 and formed channel illustrated in FIG. 6;
FIG. 9 is a partial external perspective view of a sutured coronary artery and phantom view of the conduit of the present invention;
FIG. 10 is a schematic illustration of the use of an endovascular catheter to catheterize the patient's corona~y artery;
FIG. llA is a cutaway side elevation view of the coronary artery of the bypass procedure illustrating an intravascular catheter with distally-located stent prior to inflation of a catheter balloon underlying the stent;
FIG llB is a cutaway side elevation view of the coronary artery of the bypass procedure illustrating the intravascular catheter with distally-located stent 20 following inflation of the catheter balloon underlying the stent;
FIG. llC is a cutaway side elevation view of a coronary artery illustrating the stent seated to the walls of the coronary artery and the catheter partially withdrawn following deflation of the catheter balloon;
FIG. 12 is a sch~m~tic illustration with the heart in partial cutaway of the use25 of an endovascular catheter to catheterize the patient's left ventricle.
FIG. 13A is a cutaway view of the left ventricle and a partial cutaway view of the coronary artery with seated stent illustrating the formation of a channel into the wall of the left ventricle;
FIG. 13B is a cutaway view of the left ventricle and a partial cutaway view 30 of the coronary artery with seated stent illustrating a completed channel through the WO 98/06356 12 PcT/us97/13980 wall of the left ventricle and deep wall of the coronary artery at the chosen bypass site;
FIG.14Ais a cross-sectioned view of the left ventricle and a partial cutaway view of the coronary artery with seated stent illustrating the pl~c~m~nt of the second S intraventricular catheter within the formed channel;
FIG.14Bis a cross-sectioned view of the left ventricle and a partial cutaway view of the coron~u y artery with seated stent illustrating a blockage of the forrned channel by the re-infl~te-l balloon of the intracoronary catheter;
FIG.14Cis a cross-sectioned view of the left ventricle and a partial cutaway 10 view of the coronary artery with seated stent illustrating an inflation of the balloon located on the distal end of the intraventricular catheter and the seating of anoverlying spiral-shaped device against the walls of the formed channel;
FIG.14Dis a cross-sectioned view of the left ventricle and a partial cutaway view of the coronary artery with seated stent illustrating the device in its locked 15 cylindrical shape seated against the channel walls and the partially withdrawn second intraventricular catheter;
FIG.15Ais a right anterior superior perspective view of the device placed within the forrned channel in its spiral shape;
FIG.15Bis a right anterior superior perspective view of the device placed 20 within the formed channel in its cylindrical forrn;
FIG.16is a cross-sectional view of an interlocking mechanism of the device of FIGS.15A and 15B in its locked position;
FIG.17Ais a cross-sectioned view ofthe left venkicle and a partial cutaway view of the coronary artery, with the device shown in FIGS.15A and 15B seated 25 within the formed channel, illustrating the introduction of a third intraventricular catheter into the formed channel;
FIG.17Bis a cross-sectioned view of the left ventricle and a partial cutaway view of the coronary artery, with the device shown in FIGS.15A and lSB seated within the formed channel, illustrating a tongue and groove interlocking of the bi-30 directional flow regulator equipped device to the device seated within the formedchannel;

W O 98/06356 13 PCTrUS97/13980 FIG.18A is a sçhPm~tic longitudinal cross-sectional view of a bi-directional flow regulator shown in a full flow position.
FIG.18B is the view ofFIG.18A with the bi-directional flow regulator shown in a reduced flow position;
S FIG.18C is a transverse cross-sectional view of the bi-directional flow regulator ofFIG.18B;
FIG.19A is a scht-matic cross-section longitudinal view of an alternative embodiment of a bi-directional flow regulator shown in a full flow position;
FIG.19B is the view ofFIG.~9A showing the bi-directional flow regulator in a reduced flow position;
FIG.19C is a transverse cross-sectional view of the bi-directional flow regulator of FIG.19B;
FIG.20is a schematic longitudinal cross-sectional view of a channel defining conduit with an alternative embodiment tapered anchor arm;
FIG.21is a schematic longitudinal cross-sectional view of the conduit of FIG.lA in place in a coronary artery;
FIG.22is a schematic longitudinal cross-sectional view of a test conduit for animal testing of the invention; and Fig.23is a schematic longitudinal cross-sectional view of a conduit in place in a coronary artery illustrating a deflecting shield to protect the coronary artery.

DESCRIPTION OF THE PRF,FERRED EMBODIMENT
With reference now to the various drawing figures in which identical elements are numbered identically throughout, a description of the ~,cr~ d embodiment of the present invention and various alternative embodiments will nowbe provided.

A, Detailed Summary of the Preferred Embo~liment The invention departs from the traditional bypass approach. Rather then providing an alternative pathway for blood to flow from an aorta to a coronary artery, the invention provides a blood flow path leading directly from a chamber of a wo 98/06356 14 PCT/US97/13980 heart to a coronary artery at a site dowllsLI ealll from the stenosis or occlusion.
Unlike U.S. Patent Nos. 5,429,144; 5,287,861 and 5,409,019 and contrary to the te~hing~ of these patents, the ventricular-to-coronary artery blood flow path remains open during both diastole and systole. The surgical placement of the 5 ~ udlus ofthe present invention establishes this alternative pathway. Also, and as will be more fully described, the invention includes means for protecting the coronary artery from direct impingement of high velocity blood flow.
While the invention will be described in multiple embotl;ment~ and with the description of various surgical procedures for practicing the invention, it will be 10 appreciated that the recitation of such multiple embodiments is done for the purpose of illustrating non-limiting examples of multiple forms which the present invention may take.
The presently plefelled embodiment is illustrated in FIG. lA as an L-shaped conduit 10' with an intracoronary arm 14' to reside in the coronary artery (and 15 opening downstream of an occlusion). The conduit 10' has an anchor arm 12' extending through the heart wall with an opening 12a' in communication with the interior of the left ventricle.
While various minim~lly invasive surgical procedures are described with respect to alternative embodiments, the presently preferred embodiment places the 20 conduit 10' into a coronary artery through an open-chest approach to be described in greater detail with reference to FIGS. 4 - 9. While minim~lly invasive procedures are desirable, an open chest procedure is presently preferred due to the already large number of physicians trained and skilled in such procedures thus making the benefits of the present invention more rapidly available to patients who currently lack 25 effective tre~tm~nt.
While the various embodiments (including the presently preferred embodiment of FIG. lA) will be described in greater detail, a preliminary description of the invention and its method of use will now be given with reference to FIG. 21 to facilitate an underst~n-ling of a detailed description of the invention 30 and the alternate embodiments.

WO 98/06356 15 PCT/US97tl3980 FIG. 21 is a sch~ tic cross-sectional view of a conduit 10' of FIG. lA
placed within a coron~ ~y artery 30. Coronary artery 30 has a lower surface 40 residing against an external surface of a heart wall 42 surrounding the left ventricle 44.
The wall 36 of the artery 30 defines an artery lumen 48 through which blood flows in the direction of arrow A. In the view of FIG. 21, an obstruction 34 is shown within the lumen 48. The obstruction 34 acts to reduce the volume of bloodflow along the direction of arrow A.
The conduit 10' is a rigid, L-shaped tube having an anchor arm 12' with a longitudinal axis X-X and an opening 12a' at an axial end. The conduit 10' may be any suitable device (e.g., rigid tube, lattice stent, etc.) for defining and m~ints~ining a fluid pathway during contraction of the heart.
The conduit 10' has an intracoronary arm 14' with a longitudinal axis Y-Y
and an opening 14a' at an axial end. Both of arms 12', 14' are cylindrical in shape and define a continuous blood flow pathway 11' from opening 12a' to opening 14a'.
The axes X-X and Y-Y are perpendicular in a prerelled embodiment.
Alternatively, the axes X-X, Y-Y could define an angle greater than 90~ to provide a less turbulent blood flow from arm 12' to arm 14'.
The conduit 10' is positioned for the anchor arm 12' to pass through a preformed opening 50 in the heart wall 42 and e~tçncling from the lower surface 40 of the coronary artery 30 into the left ventricle 44. The opening 12a' is in blood flow communication with the interior of the left ventricle 44 so that blood may flow from the left ventricle 44 directly into path 11'. The arm 14' is coaxially aligned with the coronary artery 30 and with the opening 14a' facing downstream (i.e., in a direction facing away from obstruction 34).
Blood flow from opening 12a' passes through the pathway 11' and is discharged through opening 14a' into the lumen 48 of the coronary artery 30 downstream of the obstruction 34. The outer diameter of arm 14a' is approximate to or slightly less than the diameter of the lumen 48.
The axial length of the anchor arrn 12' is preferably greater than the thickness of the heart wall 42 such that a length L protrudes beyond the interior WO ~8/OF3C~ 16 PCT/US97/13980 surface of the heart wall 42 into the left ventricle 44. Preferably, the length L of penetration into the left ventricle 44 is about 1-3 millimeters in order to prevent tissue growth and occlusions over the opening 12a'.
In addition to directing blood flow downstream in the direction of arrow A, S the arm 14' holds the conduit 10' within the coron~ y artery 30 to prevent theconduit 10' from otherwise migrating through the pl~fo~ ed opening 50 and into the left ventricle 44. Additionally, an upper wall 14b' of arm 14' defines a region 15' against which blood flow may impinge. Stated differently, in the absence of an arrn 14' or region 15', blood flow would pass through the anchor arm 12' and impinge 10 directly against the upper wall 36 of the coronary artery 30. High velocity blood flow could damage the wall 36, as will be more fully described, resulting in risk to the patient.
The region 15' acts as a shield to protect the coronary artery 30 from such blood flow and to redirect the blood flow axially out of opening 14a' into the 15 coronary artery 30. This is schematically illustrated in Fig. 23. For ease ofillustration, the axis X-X of the anchor arm 12' is shown at a non-orthogonal angle with respect to the direction A of blood flow in the coronary arter~v 30 (axis X-X
may be either orthogonal or non-orthogonal to direction A). The vector B of blood flow from the anchor arm 12' has a vector component B' parallel to blood flow A
20 and a vector component B" perpendicular to direction A. The region 15' is positioned between the wall 36 and anchor arm 12' to prevent the blood flow B with high vector component B" from impinging upon wall 36. The blood flow deflected off region 15' has a reduced vector component perpendicular to flow direction A and reduced likelihood of damage to the coronary artery 30. The region 15' may be a 25 portion of an intracoronary arm 14' or the arm 14' may be elimin~tcd with the region 15' being an axially spaced extension from arm 12' or a separate shield surgically positioned within the coronary artery.
A portion 17' of the anchor arm 12' extends from the lower surface 40 of the coronary artery 30 and through the lumen 48 to the upper surface 36 to block the30 cross-section ofthe coronary artery u~sllealn from opening 14a'. The region 17' acts as a barrier to impede or prevent any dislodged portions of the obstruction 34 from passing the conduit 10' and flowing downstream through the coronary artery 30.
The present invention m~nt~in.~ blood flow through the conduit 10' during - both diastole and systole. Therefore, while the net blood flow is in the direction of arrow A, during diastole, blood will flow in a direction opposite of that of arrow A.
The constantly open pathway 11' results in a net flow in the direction of arrow A which is extraordinarily high and sufficient to reduce or avoid patient symptoms otherwise associated with an obstruction 34. Specifically, certain aspects of the apl)~udlus and method of the present invention have been preliminary tested in animal studies. FIG. 22 schematically illustrates the tests as the placement of a test conduit 10* in the coronary artery 30' of a pig. For purposes of the tests, a stainless steel T-shaped conduit 10* is used having aligned openings 14a*, 16a~ positionedwithin the coronary artery 30' and with a third opening 12a* protruding 90~ out of the coronary artery 30'. The conduit 10* has a uniform interior diameter of 3 millimeters to correspond in sizing with a 3 millimeter lumen of coronary artery 30 The third opening 12a* is connected by a 3 millimeter conduit 13 to a 3 millimeter rigid Teflon (PTFE) sleeve 13a which was passed through the heart wall 42' into the left ventricle 44'. The conduit 13 and sleeve 13a do not pass through the coronary artery 30'.
In the view of FIG. 22, the direction of net blood flow is shown by arrow A.
A first closure device in the form of a suture loop 300 surrounds the artery 30'adjacent the ul~S~Iealll opening 14at~ of the conduit 10*. The loop 300 provides a means for closing the uy~l~ea~ll opening 14a~ by selectively constricting or opening the loop 300 to selectively open or block blood flow through the coronary artery 30'.
The first loop 300 permits the test to simulate blockage of the coronary artery 30' upstream of the conduit 10*.
A flow meter 304 to measure volumetric flow of blood downstream of the conduit 10* is placed adjacent downstream opening 16a*. A second closure device 302 functioning the same as loop 300 is placed on conduit 13 to selectively open or close blood flow through conduit 13.

.

wo 98/063s6 18 PCTIUS97/13980 When the second device 302 is closed and the first device 300 is open, the conduit 10* simulates normal blood flow through a healthy cololl~l y artery 30' and the normal blood flow can be measured by the flow measuring device 304. By opening second device 302 and closing the first device 300, the test conduit 10~ can S simulate the placement of a conduit such as that in FIG. 21 with an obstruction located on the upsl,Galll side of the conduit. The flow meter 304 can then measure flow of blood through the conduit 10~ during both diastole and systole.
The results of the tests indicate there is a substantial net forward blood flow (i.e., volumetric forward flow less volumetric retro-flow) with the second device 302 10 rem~ining open during both diastole and systole and with the first device 300 closed to simulate an obstruction. Specifically, in the tests, net blood flows in excess of 80 percent of normal net forward blood flow were measured. It was also noted that with the second device 302 closed and first device 300 open to simulate normal blood flow, the peak blood flow through the coronary artery 30' occurred during 15 systole. With the first device 300 closed to simulate an obstruction and with the second device 302 open, the peak blood flow occurred at diastole.
The amount of back flow through a conduit can be conkolled without the need for providing a valve within the conduit. Conveniently referred to as flow "bias", a volumetric forward flow greater than a volumetric rearward flow can be20 manipulated through a variety of means including sizing of the interior diameter of the conduit, geometry of the conduit (e.g., taper, cross-sectional geometry and angle) and, as will be more fully discussed, structure to restrict rear flow relevant to forward flow.
The sizing of the interior diameter of the flow pathway 11 ' can be selected to 25 minimi7~ back flow. As will be more further discussed, the net flow increases with a reduction in the diameter as suggested by simulation modeling of flow through a conduit. One method in which shear rate and flow bias can be controlled is by providing a tapered diameter for a narrower diameter at opening 14a' than at opening 12a'. The selection of the conduit geometry (e.g., an angled anchor arm as 30 shown in Fig. 23 or a tapered geometry as will be discussed with reference to Fig.
20) can be selected to modify the degree to which the conduit is biased to net forward flow (i.e., the conduit offers less resistance to foward flow than to retro-flow) without stopping or blocking retro-flow.
The substantial net blood flow measured in animal testing through the invention is extraordinarily high when colllp~d to minimllm acceptable levels ofnet blood flow following traditional bypass techni~ues (i.e., about 25 percent of normal net blood flow). Further, the results are counter-intuitive and contradictory to the prior te~ching~ of the art of U.S. Patent Nos. 5,429,144; 5,287,861 and 5,409,919 and the afore-mentioned Munro et al. article. In addition, the presentinvention provides a conduit with a shielding area to prevent ~l~m~ging impingement of blood flow directly onto the coronary artery wall as well as providing a blocking area to prevent the migration of debris from an obstruction to a location downstream of the conduit.
Having provided a summarized version of the present invention with reference to the sçh~m~tic drawings of FIGS. 21 and 22, a more detailed description of the present invention as well as a detailed description of alternative embodiments and alternative surgical procedures will now be provided.

B. Embo~lim~nt~ with an Open Chest Approach 1. The App~ratus of the Present Invention for Use in the Open Ch~st Approach As will be more fully described, the present invention places an apparatus for defining a blood flow conduit directly from a chamber of a heart to a coronary artery downstream of an occluded site. Before describing the surgical methods for placing such an a~dlus, an a~ualus of the present invention will be described. The appdldl~ls of the present invention can be a variety of shapes or sizes, and is not meant to be limited as to size, shape, construction, material, or in any other way by the following examples in which a ~.e~l,ed embodiment is illustrated.
a. T-Sh~ed Device With initial reference to FIGS. 2A, 2B, 2C, 2D and 2E, related embodiments of an aplpdldlus according to the present invention are shown as a rigid T-shaped conduit 10 (a preferred L-shaped conduit 10' having already been summarized and to be later described in detail). The conduit 10 is hollow and includes two axially-aligned intracoronary arms 14, 16 t~rmin~ting at open ends 14a, 16a. An anchor arm 12 ~having an open end 12a) extends perpendicularly to arms 14, 16. The entire conduit 10 is hollow to define a blood flow conduit 11 providing blood flow communication between open ends 12a, 14a and 16a.
As will be more fully ~ cllc~e~l arms 14 and 16 are adapted to be placed and retained within a lumen of a coronary artery on a downstream side of an occlusion with open ends 14a, 16a in blood flow communication with the lumen. The anchor arm 12 is adapted to extend through and be retained in a heart wall (e.~., a wall of the left ventricle) with the open end 12a in blood flow col,lnlu~lication with blood within the chamber. When so placed, the conduit 10 defines a surgically-placed conduit establishing direct blood flow from the heart chamber to the artery. By "direct" it is meant that the blood flow does not pass through the aorta as occurs in traditional bypass procedures. The conduit 10 is sufficiently rigid such that itdefines an open blood flow path during both diastole and systole.
b. Optional Forward Flow Bias While unobstructed back flow is preferred, partially restricted back flow can be provided. As will be more fully described, back flow can be controlled by thegeometry of the conduit. The following describes a presently less preferred alternative embodiment for controlling back flow.
FIG. 2B illustrates use of an optional bi-directional flow regulator 22 within the conduit 10 and positioned in anchor arrn 12. The bi-directional flow regulator 22 IJC~ iL:~ unimpeded flow in the direction of arrow A (i.e., from open end 12a to open ends 14a, 16a) while permitting a reduced (but not blocked) reverse flow.
FIG. 2C illustrates the use of a first bi-directional flow regulator 22 as well as a second bi-directional flow regulator 26 in arm 16 near the open end 16a of the apparatus. The second bi-directional flow regulator 26 permits unimpeded blood flow in the direction of arrow B. The second bi-directional flow regulator 26 is used to permit a reduced (but not zero) back flow of blood in an upstream direction within the coronary artery. For example, the coronary artery may not be completely obstructed and may have a reduced flow past an obstruction. The use of the T-WO 98/06356 21 PCT/US97tl3980 conduit 10 with axially aligned arms 14, 16 takes advantage of such reduced flowand supplements such flow with blood through anchor arm 12. As will be described, the conduit 10 is placed with the arms 14, 16 in the lumen of the artery with opening 16a positioned on the ul~slle~n side (i.e., nearest to, but still downstream of, the 5 obstruction).
As indicated above, the flow regulator 22 is a bi-directional flow regulator.
By this it is meant that the flow regulator 22 does not block flow of blood in any direction. Instead, the flow regulator 22 permits a first or maximum flow rate in one direction and a second or reduced flow rate in a second direction. The flow regulator 10 is sçllem~tically illustrated in FIGS. 18A through 19C. In each of these embodiments, the arrow A indicates the direction of blood flow from the left ventricle to the coronary artery.
FIGS. 18A through 18C illustrate one embodiment of a bi-directional flow regulator 22. FIGS. 19A through 19C illustrate an alternative embodiment of a bi-directional flow regulator 22. The regulator 22 of FIGS. 18A through 18C shows abutterfly valve 222 mounted in the anchor arm 12 of a rigid conduit 10. Valve 222 may be pivoted (in response to blood flow in the direction of arrow A) between aposition with the plate 222 generally parallel to the walls 12 of the conduit 10 as illustrated in FIG. 18A. The plate 222 can be rotated (in response to blood flowreverse to arrow A) to a position angled relative to the walls 12 of the conduit 10 as illustrated in FIG. 18B. FIG. 18A may be conveniently referred to as a full flowposition. FIG. 18B may be conveniently referred to as a reduced flow position.
FIG. 18C is a cross-section of the conduit 10 when the plate 222 is in the reduced flow position.
The plate 222 is sized relative to the conduit 10 such that the cross-sectional area of the conduit 10 which remains open is sufficient to perrnit about 20% of the blood flow (measured volumetrically) to flow back through the conduit 10 in a direction opposite to that of arrow A during diastole. As a result, during systole, blood flow from the heart to the coronary artery urges the plate 222 to the full flow position of FIG. 18A such blood may flow unobstructed through the device to the coronary artery. During systole, the blood (due to pressure differentials between the Wo 98/063s6 22 PCT/US97/13980 coronary artery and the left ventricle) will flow in a direction opposite of that of arrow A causing the plate 222 to rotate to the position of FIG. 18B and 18C.
However, even in the reduced flow position, the plate 222 is prevented from moving to a full closed position such that flow through the device is never blocked andinstead may proceed with a back flow of about 20% (volumetrically measured) of the normal flow in the direction of A.
FIGS. 19A through 19C show an alternative design of the conduit 10 with the flow regulator 22a in the forrn of three leafs 222a, 222b, 222c which, in response to blood flow from the left ventricle to the coronary artery, open to a full open position shown in FIG. l9B and move to a restricted flow position in FIGS. 19A
and 19C in response to back flow. The leaves 222a, 222b, 222c are provided with openings 223 to permit flow through the leaves 222a, 222b, 222c at all times.
It is believed that providing a back flow of about 20% (20% being a non-limiting exarnple of a presently anticipated desired back flow rate) of the volumetric anterograde flow is necessary. This is essential because it allows the channel of the conduit 10 and the mechanical elements of the flow regulator 22 to be washed by the retrograde flow. This ensures that no areas of stagnant flow occur. Areas of stagnation, if allowed, could result in clot forrnation which could result in thrombi occluding the conduit or breaking loose. Thrombi could be carried downstream into the coronary arteries to cause one or more areas of cardiac muscle i.~hemi~ (i.e., a myocardial infarction) which could be fatal. Back flow necessary to wash the components can be achieved through either a conduit 10 which has a constant opening through both systole and diastole (i.e., conduit 10 of FIG. 2A without the use of a bi-directional flow regulator 22) or with a device coupled with a bi-directional flow regulator 22 (FIGS. 2B-2C) which permits a 2Q% flow rate back flow during diastole.
c. L-Shaped Device Preferrably, an L-shaped conduit 10' (FIGS. lA, lB, lC) is used to completely bypass the coronary obstruction. An L-shaped conduit 10' has an anchor arm 12' with an open end 12a'. Unlike conduit 10, conduit 10' has only one intracoronary arm 14' perpendicular to arm 12'. Arm 14' has an open end 14a' and W O 9~063S6 23 PCTrUS97/13g80 conduit 10' is hollow to define a continuous fluid pathway 11' from end 12a' to end 14a'. In application, arm 14' is placed within the lumen of an artery. End 14a' faces downstream from an obstruction. Arm 12' is placed through the heart wall with end 12a' in fluid communication with blood within the heart chamber. As 5 illustrated in FIG. lB, the anchor arm 12' can include a bi-direction~l flow regulator 22' similar to bi-directional flow regulator 22 of conduit 10.
d. Optional Flexible Anchor Arm Conduit 10, 10' may be rigid, or have varying flexibilities. Regardless of such flexibility, the conduit 10, 10' should be sufficiently rigid for pathway 11, 11' 10 to remain open during both diastole and systole. FIGS. 3A, 3B and 3C demonstrate one embodiment where the anchor arm (i~, elements 12, 12' of FIGS. lA and 2A) is comprised of a number of rings 17 surrounded by a membrane 18. In FIGS. 3A-3C, only anchor arm 12 is shown. It will-be appreciated that anchor arm 12' may be identically constructed.
In the embodiment of FIGS. 3A-3C, the rings 17 can be constructed of Teflon, and the surrounding membrane 18 can be constructed of a double-walled Dacron sheath into which the rigid supporting rings 17 are sewn. In this embodiment, the rings 17 provide structural strength. The structural strength m~int~in~ an open lumen or conduit 11 leading into the coronary artery by 20 preventing the conduit 11 from collapsing by reason of contraction of the heart muscle surrounding the anchor arm 12. The series of rings 17 provide a degree offlexibility which allows a channel formed through the heart chamber muscular wall (receiving anchor arm 12) to be angled or curved. In addition, the flexibility of the surrounding sheath 18 in concert with the rigid rings 17 will allow the anchor arm 12 25 to expand, FIG. 3B, and contract, FIG. 3C, with the contractions and relaxations of the surrounding cardiac musculature.
It should be noted that, because of the semi-rigid nature of the anchor arm 12 constructed in this manner, a method of attaching that end of the anchor arm in contact with the inner surface of a chamber of a heart can be useful. In the example 30 illustrated, this attaching mec.ll~ni~m 19 is a rigid flange 12a. It will be appreciated ... .

W O 98/06356 24 PCTnUS97/13980 that other ",eC~ m~ of iqtt~.~hm~nt, such as suturing, biologically gluing, etc. are alternative options.
e. Option~l Blood Reservoir The a~p~dlus of the present invention (as thus described) provides a path 11 S through which blood flows from a charnber of a heart and into a corol~l y artery.
Additionally, such a device can store blood under pressure for a period of time prior to its introduction into a coroll~ y artery. As depicted in the embo-limPnt~ of FIGS.
lC and 2D, this aspect of the conduit 10, 10' of the present invention is referred to as a capacitance p.es~ule reservoir (CPR) 24, 24'.
Blood flow through the normal coronary artery is cyclical. Blood flow is increased during diastole (when the heart muscle is in a relaxing state), and decreases or reverses during systole (when the heart muscle is in a contracting state).
See, e.g, F. Kajiya et al., Veloci~y Profiles and Phasic Flow Patterns in the Non-Stenotic Human Lefl Anterior Descending Coronary Ar~ery during Cardiac Surgery, 27 CARDIOVASCULAR RES. 845-50 (1993).
The ples~u.e gradient across the lumens 12a, 12a', 14a', 16a of the apparatus 10, 10' of the present invention will vary over the cardiac cycle. For example, during systole, the contraction of the heart muscles will generate high relativepressures within the left ventricle.
The ~res~u es within the coronary arterioles and capillaries distal to the bypass site can also be high during this time, due to the external c~ plession of the contracting cardiac musculature surrounding these vessels. This is particularly true for the vessels of the microcirculation deep within the heart which serve the endoca~diulll.
The optional CPR 24, 24' stores the pressurized blood during systole for delivery to the heart muscles via the coronary circulation during diastole when pressures are reduced. In essence, the CPR 24, 24' serves a function similar to the elastic connective tissue of the thick-walled aorta. The necessary function of the CPR 24, 24' is to store blood under higher pressure, and to later provide that stored blood to the microcirculation when the external pressures on that microcirculation are reduced.

W O 98/06356 25 PCTrUS97/13980 As depicted in FIG. lC and 2D the bi-directional flow regulators 22,22' provide full blood flow in the direction of A, which is from a chamber of a heart into the conduit 10,10' via the lumen 11,11'. The ples~ on the blood within the - chamber of a heart will be greatest when the surrounding cardiac musculature is in the contracting phase of the cardiac cycle. Because it is during this phase of the cardiac cycle that the e~t~ l ples~u~e on the coronary artery microcirculation is also highest, blood flow through the lumen 11,11 ' of the conduit 10,10' could be limited. To counteract this tendency, the conduit 10,10' is equipped with a reservoir 24,24' which stores this pressurized blood flowing from a chamber of the 10 heart during the cardiac contraction.
The reservoir, or CPR 24,24' is schematically illustrated in FIGS 1C,2D. It can be appreciated that the conduit 10,10' is provided with a fluid passage 28,28' in communication with p~lhw~y 11,11'. The passage 28,28' collln~ icates with an exr~n(l~hle volurne (or storage chamber) 27,27' defined by a movable wall 31,31'contained within a fixed housing 33,33'. Springs 29,29' between wall 31,31' and housing 33,33' urge the wall 31,31' to move to reduce the size of volume 27,27'.The springs 29,29' are pre-loaded to exert a force on wall 31,31' less than a force exerted by blood within volume 27,27' during the contraction phase of the cardiac cycle, but greater than the force exerted by blood within volume 27,27' during the relaxation phase of the cardiac cycle.
The conduit 10,10' is constructed in a manner which allows blood to flow into the storage chamber 27,27' of She conduit 10,10' through the lumen 11,11' of arm 28,28' of the conduit when the cardiac musculature is contracting. When blood is flowing into the storage chamber 27,27', the kinetic energy of the flowing blood is converted to potential energy, and stored in 29,29'. During the relaxation phase of the cardiac musculature, the potential energy stored in 29,29' of the CPR 24,24' is then re-converted to kinetic energy in the form of blood flow out of the storage chamber27,27'oftheconduitlO,lO'viathelumenll,ll'ofarm28,28'ofthe conduit.
While the CPR 24,24' is illustrated with a movable wall 31,31' and springs 29,29' to define a variable volume, other designs can be used. For exarnple. the CPR 24, 24' can be a balloon-like structure. As it fills with blood, the plcs~u~e on that blood increases through the stretching of an elastic component of a balloon. In another embodiment, the CPR, 24, 24', can be a hollow bag, made of a material which is elastic, but imp~ kle to liquids, and pliable similar to a plastic bag.When the heart contracts, blood is forced through lumen 11, 11 ' of arm 28, 28' of the ~ pdlal~lS10~10' ofthe invention into the collection bag.
The incorporation of bi-directional flow regulators 22, 22' within the anchoring arm 12, 12' of the conduit 10, 10' provide most (about 80%) of the flow of blood out of the device during diastole to the coronary artery via the lumen 11 ' 11 ' of arms 14a, 14a', 16a of the device, of the conduit 10, 10' . Similarly, the incorporation of the bi-directional flow regulator 26 within the intracoronary arm 16 of the T-shaped conduit 10, when employed with the bi-directional flow regulator 22 within the anchor arm 20 of the conduit 10, would provide most of the flow of blood out of the device during diastole to the portion of the coronary artery distal to the bypass site via the downstream lumen 11 of arm 14a.
f. Si7in~E of the Conduit The inner and outer cross-sectional diameters of a coronary artery decreases with the distance from the arterial origin. Eventually, the artery branches into a number of arterioles, which feed the capillary bed of the coronary arterial microcirculation.
The typical diameter of a lumen of a coronary artery is, in general, species specific; increasing with heart size. In humans, this lumen diameter is dependent upon which artery is being evaluated, but usually ranges from 1.0 to 4 mm in diameter, and decreases with distance from the aortic origin. In the plcrcllcd embodiment, the cross-sectional outer diameter of the intracoronary arms 14, 14', 16 of the device of the present invention should effectively approximate the diameter of the lumen of the coronary artery being bypassed, at the bypass site. This allows the complete re-approximation of the previously opened superficial wall of the coronary artery during surgical closure, without high suture or staple tension resulting. In the most preferred embodiment, the outer diameter of the intracoronary arms 14, 14', 16 of the conduit 10, 10' of the present invention is equal to the diameter of the lumen W O 98/06356 27 PCT~US97/13980 of the COlOllaly artery which is being bypassed, at the bypass location. When a CPR
is placed, the artery wall may need to be exp~nded by the addition of a patch, such as Dacron, well known in the art.
Also, due to smooth muscle relaxation and secondary vascular dilation, the 5 cross-sectional diameter of a lurnen of a coronary artery will increase with the oxygen dem~n-l of cardiac muscle during times of stress. The cross-sectional inner diameter of the intracoronary arms 14, 14', 16 of the conduit 10, 10' of the present invention should effectively approximate that diameter necessary to provide adequate blood flow through the downstream lumen of the conduit to effectively 10 oxygenate the cardiac musculature normally supplied by the microcirculation of the coronary artery. In the ~,ref~llcd embodiment, the cross-sectional inner diameter of the intracoronary arms 14, 14', 16 of the conduit 10, 10' of the present invention should effectively approximate that diarneter necessary to provide adequate blood flow through the lumen of the device to effectively oxygenate the cardiac 15 musculature normally supplied by the microcirculation of the coronary artery during both times of cardiovascular resting and stress.
If necessary, an initial approximation of the required cross-sectional outer diameter of the intracoronary arms 14, 14', 16 of the conduit 10, 10' of the present invention can be gained by standard radiographic techniques. Also, in the 20 alternative embodiment ap~aldLus when a bi-directional flow regulator 22, 22' is desired, the operating pressure of the bi-directional flow regulator 22, 22' (i.e., the pressure at which the flow regulator moves from a reduced back-flow to a full forward flow position) can be determined by the dynamic measurements of coronaryartery pressure, blood flow, and heart charnber pressures through selective 25 catheterization with standard techniques. See Minoru Hongo et al., 127(3) AM. HEARTJ. 545-51 (March 1994).
During the coronary artery bypass procedure, the most ~yplopl;ate sizing of the intracoronary arms 14, 14', 16 of the conduit 10, 10' of the present invention can be re-assessed. This can be accomplished by probing the distal and ,if needed, the 30 proximal aspects of the coronary artery at the chosen bypass site with blunt instrurnents of known outer diameters. Such sizing by probes is well-known in the Wo 98/06356 28 PCTtUSs7/13980 literature. To facilitate the effective m~tching of the ext~rn~l diameter of theintracolon~y arms 14, 14', 16 of the conduit 10, 10' of the present invention to the lumen 34 of the coronary artery to be bypassed, an assortment of conduits of thepresent invention of various diameters can be available for the surgeon to select 5 from.
The anchor arm 12, 12' is sized to maximize net blood flow from the left ventricle to the coronary artery. Through simulation testing, a counter-intuitive indication is that m~ximi7ing the diameter of anchor arm 12, 12' is not desirable.
For example, such simulation assuming diameters of 3.00 mm, 2.25 mm and 1.50 10 mm for an unrestricted fistula (i.e., without a flow regulator 22) suggests that the smaller diameter of 1.50 mm most closely approximates normal coronary blood flowand minimi7es back flow thus maximi7.ing net forward flow.
It is desirable that the anchor arm 12, 12' protrudes into the heart chamber such that end 12a is spaced from the heart wall. This prevents tissue growth over 15 end 12a.
Finally, it will be noted that the anchor arm 12 defines a longitudinal axis (e.g., axis X-X in FIG. 18A). The region 15 of arms 14, 14 intersects axis X-X.
The region 15 acts as a deflection surface to prevent high velocity blood flow from arm 12 impinging directly upon the coronary artery wall. In~tea(l7 the high velocity 20 blood flow impinges upon region 15 and is directed axially into the coronary artery.
As a result, the coronary artery wall covered by region 15 is protected from damage which would otherwise be caused by the high velocity blood flow and the blood components are transitioned to axial flow with a minimum of cell fl~m~ging shear.
FIG. 20 shows a still further embodiment 10" where the anchor arm 12" has 25 a longitudinal axis X'-X' at a non-orthogonal angle relative to the axis Y'-Y' of the coronary arrns 14", 16". Further, the anchor arm 12" has a taper. In other words, the arm 12" is widest at opening 12a". The taper and angle act to reduce blood flow velocity and to restrict back flow (arrows B) while facilit~ting forward flow (arrow A'). Also, the blood in the forward flow A' impacts against the deflection region 30 15" at an angle to reduce impact of blood cells.

., 2. The Method of the Present Invention U~ the Open ChPst Approach a. General The method of the present invention is suitable for perforrning a variety of surgical cardiac procedures. The procedures may be performed l~tili7ing an open-chest approach, or through minim~lly invasive approaches by the creation of access means into the chest, or through pelcul~-eous access lltili7in~ intracoronary and intraventricular catheterization. Dependent on the invasiveness of the approach utilized, the heart can be allowed to pulse normally, be slowed by varying amounts, or stopped completely. A significant period of complete heart stoppage can necessitate the use of supportive cardiopulmonary bypass.
The method of the present invention for performing a coronary artery bypass procedure will now be described in detail. The patient who is to undergo the procedure can be prepared in a conventional manner for cardiac bypass surgery. The patient pl~ lion, anesthesia utili7f~-1, and access route to the coronary circulation, will vary depending upon the invasiveness of the specific procedure chosen.
b. P~)aldlion for the Procedure i. General Plepa,dLions Standard techniques of general preparation for open-chest surgery in which cardiopulmonary bypass is utilized have been widely reported. See, e.g LUDWIG K.VON SEGESSER, ARTERIAL GRAFTING FOR MYOCARDIAL REVASCULARIZATION
(1990). ln one embodiment of the methods of the invention where an open-chest procedure and cardiopulmonary bypass is utilized, the patient can be prepared for surgery as outlined by Von Segesser.
General plepa~dlions for open-chest surgery in which cardiopulmonary bypass is not utilized have been published by Buffolo et al., 61 ANN. THORAC.
SURG. 63-66(1996). In one embodiment of the methods of the invention where an open-chest procedure without cardiopulmonary bypass is lltili7Ptl, the patient can be plel)a~d for surgery as outlined by Buffolo.
General ~lepdldtions for closed-chest surgery, to be performed using thoracoscopy and where cardiopulmonary bypass is lltili7~-l, have been outlined by - w 098/06356 30 PCTrUS97/13980 Sterman et al., U.S. Pat. No. 5,452,733 (1995). In one embodiment of the methodsof the invention where a closed-chest procedure and cardiopulmonary bypass is tili7~cl, the patient can be prepared for surgery as outlined by Sterman.
General plel)a,alions for closed-chest surgery to be performed using 5 thoracoscopy, but where cardiopulmonary bypass is not lltili7~-1, have been published by Acuff et al., 61 ANN. THORAC.SURG.135 37 (1996). In one embodiment of the methods of the invention where a closed-chest procedure without cardiopulmonary bypass is ~ltili7.~-~, the patient can be prepared for surgery as outlined by Acuff.
General prepaldlions for percutaneous coronary artery bypass grafting ntili7ing intracoronary and intraventricular catheterization and without cardiopulmonary bypass have been described by Wilk in his afore-mentioned U. S.
patents. Preparations can include the sterile scrubbing and draping of at least one groin to permit access to a femoral artery for catheterization of the coronary 15 vasculature and the sterile scrubbing and draping of the right superior anterior chest wall to permit access to the innominate artery for catheterization of the left ventricle.
Further suggested preparations can include those outlined by Sterman and Acuff for thoracoscopic surgery with and without cardiopulmonary bypass, respectively.
ii. Anesthesia Prior to and During the Procedure Most often, the patient will be placed under general anesthesia prior to the procedure. In one embodiment, standard cardiac operative anesthetic techniques, such as premedication with diazepam, induction with propofol and sufentanil, andm~int~n~nce with desflurane can be employed. On occasion, less than general anesthesia can be utili7Pcl Less than general anesthesia is well known in the literature. When the invasiveness of the procedure is minim~l, such as when the procedure is to be carried out via intracoronary and intraventricular catheterization, or when the risks of general anesthesia to the individual patient outweighs the risks of less than general anesthesia with regard to the particular procedure planned, less than general anesthesia can be induced. Selective ventilation of the lungs can be achieved through the placement of a double-lumen endobronchial tube which independently provides for the intubation of the left and right main stem bronchi.

3 l PCT/USg7/13980 An intraesophageal probe can be placed to facilitate cardiac monitoring and the synchronization of power to the laser, when deemed useful.
iii. Access to the Heart ~n~l Coronary Vasculature for the Procedure Following p,~aldLion, access to the patient's coronary arterial vasculature can be ~ttslinf~-l through a variety of techniques, dependent upon the route of access chosen.
Von Segesser has reported a method of access to the coronary arterial vasculature when lltili7ing an open-chest approach and cardiopulmonary bypass. In one embodiment, lltili7in~ an open-chest approach with cardiopulmonary bypass, access to the coronary vasculature can be obtained as reported by Von Segesser.
Buffolo et al. has reported an open-chest approach to the coronary arterial vasculature when performed without cardiopulmonary bypass. See Buffolo et al., 61 A~rN. THORAC. SURG. 63-66 (1996). In one embodiment utili7.ing an open-chest approach without cardiopulmonary bypass, access to the coronary vasculature can be obtained as reported by Buffolo.
Sterman et al. has reported a method of access to the coronary arterial vasculature when a closed-chest approach with cardiopulmonary bypass is l~tili7t~cl .See Sterman et al., U.S. Pat. No. 5,452,733 (1995). Sterman positions a plurality of access trocar sheaths along the patient's left and right anterolateral chest wall. These trocar sheaths provide access to the coronary vasculature, and allow the temporary repositioning of the heart to facilitate the performance of the procedure. The repositioning is accomplished utili7ing grasping tools introduced through the ~ op,;ate trocar sheaths. Visualization during this procedure can be either indirectly via thoracoscopy, or directly via a 'window' placed in the left middle anterior chest wall by the surgical removal of the fourth rib. Access to the bypass site can therefore be obtained by following the techniques outlined by Sterman. The instruments to be used in the procedure can also be similar to those described by Sterman.
Acuff et al. has described a method of access to the coronary arterial vasculature when a closed-chest approach without cardiopulmonary bypass is W O 98/06356 32 PCTrUS97t13980 ~Iti~ See Acuff et al., 61 ANN. THORAC.SURG.135 37 (1996). Similar to the techniques of Sterman, Acuff positions a plurality of access trocar sheaths along the patient's left and right anterolateral chest wall. Also similar to Sterman, Acuff surgically establishes an access space, or window in the left anterior chest wall through the removal of the left fourth rib cartilage. The trocar shP~th.~, in concert with this window, allow the temporary repositioning of the heart, and access to the coronary arterial vasculature. Visuali_ation during this procedure can be eitherindirectly via thoracoscopy, or directly via the window. Access to the bypass site can therefore be obtained by following the techniques outlined by Acuff. The 10 instruments to be used in the procedure can also be similar to those described by Acuff.
Access to a chamber of a heart and a coronary artery when the bypass is performed through the pcl~;ul~leous approach of intracoronary and intraventricular catheterization can be obtained as follows. Access to a coronary artery can be obtained by the introduction of a catheter into the left or right femoral artery through an arterial cut down procedure. The catheter can then be fed retrograde past thedescending aorta, through the ascending aorta, and into the coronary artery by standard cathetPri7~tion techniques. In a preferred embodiment, access to a chamber of the left side of a heart can be obtained by the introduction of a catheter into the 20 innominate artery, also through an arterial cut down procedure. In the most preferred embodiment, access to the left ventricle is obtained by the introduction of a catheter into the innominate artery and the advancement of this catheter into the left ventricle. In this embodiment, the catheter is advanced through the ascending aorta, past the aortic valve. and into the left ventricle. Techniques by which the left25 ventricle is catheterized are well known in the literature.
3. Open Chest Approach In the coronary artery bypass graft procedures of the present invention, a chamber of a heart provides blood to a coronary artery. The method of the present invention can accomplish this by establishing one or more channels through the wall 30 of a chamber of a heart which lead directly from a chamber of a heart into a coronary artery at a site distal to the narrowing or blockage. The methods of the invention in W O 98/06356 33 PCTrUS97/13980 various embo~lim~nt~ can achieve the establishment of such a channel or channelsthrough a variety of techniques.
Referring now to FIGS. 4, 5, 6, 7, 8, and 9, an exemplary open-chest procedure, which may or may not include cardiopulmonary bypass, by which a 5 coronary artery bypass procedure may be accomplished will be described. The open-chest approach affords m~im~l access to, and visualization of, the coronaryvasculature; although at the expense of injury to normal tissue.
Through the methods of the present invention, the conduit 10, 10' of the present invention, which provides blood from a charnber of a heart 43 directly into a 10 coronary artery 30, is placed. To illustrate the invention, only placement of conduit 10' is discussed. It will be appreciated that conduit 10 can be similarly placed. In addition, exarnples will be limited to the embodiment of the conduit of the invention as illustrated in FIG. lA.
P.~ ion for the procedure, and anesthesia prior to and during the 15 procedure, is outlined above.
First, the chest cavity is entered, and pericardium 52 incised anteriorly, to expose a coronary artery 30 (having an obstruction 34) to be bypassed. This is illustrated in Fig. 4.
Second, cardiopulmonary bypass may be initiated by a variety of standard 20 techniques as outlined by George Silvay et al., Cardiopulmonary Bypass for Adult patients: A Survey of Equipment and Techniques, 9(4) J. CARDIOTHORAC. VASC.
ANESTH. 420-24 (August 1995).
Third, if bypassed, the heart is slowed and/or stopped by a variety of standard techniques. One standard technique is to electrically induce ventricular 25 fibrillation. Another standard technique is warrn or cold blood cardioplegia,delivered antegrade or retrograde, and interrnittent or continuous, as outlined by Gerald D. Buckberg, Update on Current Techniques of Myocardial Protection, 60 ANN. THORAC. SURG. 805-14 (1995).
Fourth, the heart is inspected and coronary arteries identified. The narrowed 30 or occluded coronary artery 30 can be visually identified, and an apl,lopliate site distal or downstream from the occlusion 34 chosen.

CA 02262623 l999-02-08 W O ~810~356 34 PCTnUS97/13980 Fifth, blood flow through the target coronary artery 30 is halted by standard techniques. For exa~nple, standard techniques include cl~mrin~ the aorta above the coronary ostia with an arterial clamp. Alternatively, in the beating heart procedure, the flow of blood within the coronary artery 30 can be halted by forrning a looparound the artery 30 with suture either proximally, or both proximally and distally, and applying appIo~l;ate tension on the suture or sutures, or tying the suture or sutures.
Sixth, depending on the degree of exposure deemed necess~ry, the epicardium overlying the coronary artery at the selected bypass site is incised. This exposure can facilitate locating the lumen of the coronary artery 30 via palpation.
Seventh, as shown in FIG. 5, the superficial wall 36 of the coronary artery 30 is longitudinally incised by standard techniques, such as incision with a scalpel, electrosurgical cuning device, or similar tool; taking care not to darnage the deep wall of the artery. This initial incision can be lengthened, if neces~ry, to accommodate the intracoronary arms 14' using standard tools such as fine angled scissors.
Eighth, a channel 50 is initi~te-l into the deep coronary arterial wall 40 and through the musculature 42 of a chamber of a heart. In the pIefe,.~d embodiment,the chamber of a heart is the left ventricular chamber of the heart. The channel 50 can be initiated by standard techniques such as awl punching, incising, use of a laser, or the like. The channel 50 is then extended into the chamber of a heart, in this case the left ventricle 44, by standard techniques (such as punching with a trocar 46, incising with a scalpel blade, electrosurgical cuning with an electrosurgical cutting tool, laser or radio frequency ablation, blunt dissection, etc.).
Ninth, once a channel extçn-ling through the entire thickness of a wall 42 of a charnber of a heart is formed, it can be systematically sized by the passage of standard probes.
Tenth, through palpation, inspection, and probing of the distal and proximal coronary arterv lumen 48, a conduit 10' of appropriate dimensions is selected, as outlined above.

Eleventh, as illustrated in FIGS. 7 and 8, the anchor arm 12' is inserted into the formed channel 50. The intracoronary arm 14' is then seated within the lumen48 of the coronary artery 30.
Twelfth, as shown in FIG. 9, the longitudinal incision 38 previously incised 5 in the anterior wall 36 of the coronary artery 30 is surgically re-approxim~t~d The re-ap~,loxil~-ation can be p~lroll..ed by a number of conventional techniques, including suturing 52, laser welding, microstapling, and the like.
Thirteenth, the clamps or sutures closing off blood flow to the coronary artery are released.
Fourteenth, contractions ofthe heart, if previously stopped, are reiniti~ted by standard electrostim~ tion or the reversal of cardioplegia and the patient is slowly weaned from cardiopulmonary bypass by standard techniques.
Fifteenth, the pericardium, sternum, and overlying skin of the chest is re-approximated and surgically closed by standard, conventional techniques.
Sixteenth, ~nesthesi~ is reversed and the patient revived by standard techniques.
D. Fmbodinlent~ for a Closed Chest A~proach 1. The ~pparatus of the Present Invention for Use in the Closed Chest A~roach A closed chest approach according to the method of the present invention may use the conduit 10, 10' as described above. Such a procedure will now be described. I~ollowing this description, a closed chest approach using alternative embodiments of the a~dfdlus of the invention will be described.

2. The Method of the Present Invention U.~i~ the Closed Chest Approach An exemplary closed-chest procedure, without cardiopulmonary bypass, by which a coronary artery bypass may be accomplished will now be described. The closed-chest approach is less invasive than the open-chest approach, although providing the surgeon with somewhat poorer visualization and limited direct access to both the chambers of the heart and coronary artery bypass site.

wo 98/06356 36 PcT/us97/13980 Pl~paldlion for the procedure, and ~n~sth~ prior to and during the procedure, is outlined above.
First, a plurality of access trocar sheaths is positioned anterior and laterallyalong the left and right chest walls as outlined by Acuff et al.
Second, a space in the left low anterior chest wall may be formed by removal of the fourth rib cartilage, as outlined by Acuff et al. In this embodiment, the heart and coronary artery can be both directly viewed via this space or window, as well as indirectly vi~ P-l via a thoracoscope.
Third, a standard pericardiotomy is performed using a scalpel or electrosurgical cutting tool introduced through the left lateral chest trocar sheaths while viewing under thoroacoscopy. The pericardium can be excised and either spread open, or removed from the thoracic cavity as outlined by Acuff et al.
Fourth, if necessary, the heart can be rotated within the mediastinum. Direct access and viS~ i7~tion through the forrned chest wall space can require rotation of the heart. Rotation of the heart can be accomplished by the grasping of the heart by tools inserted through access trocar sheaths located along the left and right chest wall as described by Sterman et al. Alternatively, traction on sutures placed in the pericardium can distract the heart allowing appropliate direct visualization of the area to be bypassed as described by Acuff et al. In another alternative procedure, the heart can be accessed from the patient's back with an endoscope for implantation of the stent in the posterior vascular beds which are not currently accessible by minim~lly invasive techni~ues.
Fifth, once the coronary artery to be bypassed is identified and well-visualized; snare sutures of 5-0 polypropylene are placed at least proximally to the target area as described by Acuff et al.
Sixth, the heart rate can be pharmacologically slowed to approximately 40 beats/minute to minimi7e motion within the operative field as described by Acuff et.
al. Nitroglycerin and heparin can also be ~lmini~tered to reduce cardiac ischemia and prevent clotting respectively as outlined by Acuff et al.
Because cardiopulmonary bypass is omitted in this embodiment, intermittent coronary artery occlusion to induce ischemic preconditioning, as well as r WO 981Q~ 37 PCT/US97/13980 transesophageal echocardiography to review cardiac wall motion changes, can be utilized as described by Acuff et al. The epicardiulll can be incised over the area selected for bypass and the anterior surface of the artery cleared under direct vis~l~li7~tion through the space or window, or via remote instruments inserted 5 through the trocar sheaths under thoracoscopic guidance.
Seventh, in situations where the coronary artery can be directly viewed, the lumen 48 of the coronary artery is identified by palpation. Either under direct visualization, or under thoracoscopic guidance and using instruments manipulatedthrough the trocar sh~th.~, the superficial wall 36 of the coronary artery is then 10 longitudinally opened. As above, care is taken to leave the deep wall 40 of the artery llnd~m~ged. The incision 38 can be enlarged, as nec~c.s~ry, to accommodate the intracoronary arms 14, 14', 16 ofthe conduit 10, 10' using fine angled scissors.
This enlargement can be performed with standard surgical scissors under direct viewing through the window, or via other surgical instruments remotely manipulated 15 following their insertion through the trocar sheaths.
Eighth, a channel 50 through the heart wall is initiated by incising or laser ablating into the deep wall 40 of the coronary artery. This also can be performed by standard surgical tools under direct viewing, or by the remote manipulation of specialized instruments introduced through the trocar sheaths and viewed 20 thoracoscopically. The channel 50 is then extended through the deep coronary arterial wall 40, through underlying cardiac musculature 42, and into the underlying chamber of the heart 44 by incising with a scalpel or electrosurgical cutting blade, laser ablation, blunt dissection, or the like. In the preferred embodiment, a charnber of a heart 44 is one of the two chambers of the left side of the heart. In the most 25 preferred embodiment, a chamber of a heart 44 is the left ventricle.
Ninth, the channel 50 extending through the entire thickness of a muscular wall 42 can be systematically sized by the passage of standard me~llring probes.These standard measuring probes, with fixed and known tip diameters, can be similarly used to size and deterrnine the proximal and distal patency of the coronary 30 artery being bypassed.

WO 98l06356 38 PCT/USg7/13980 Tenth, through direct andlor thoracoscopic inspection of the coronary artery lumen 48, or by probing as outlined above, an apl)lop.;ately ~limen~ioned conduit 10, 10' of the present invention is selected. As in the case of the open-chest approach (outlined above), an array of conduits 10, 10' of various sizes can be 5 available for the operation.
Eleventh, either under direct control and visu~1i7~tion, or by indirect manipulation and thoracoscopic viewing, the anchoring arm 12, 12' of the conduit10, 10' of the invention is inserted into the formed channel 50. By similar techniques the rem~ining intracoronary arm or arrns 14, 14', 16 of the conduit 10, 10' are seated within the lurnen 48 of the coronary artery 30 being bypassed. In one embodiment where the procedure is performed under thoracoscopic viewing, the conduit 10, 10' can be introduced into the cardiac cavity through the space or window previously formed within the anterior inferior aspect of the left chest wall.
In this embodiment, the conduit 10,10' can be grasped, once introduced into the chest cavity, by surgical instruments inserted through the trocar sheaths and remotely manipulated into position. In this manner the anchor arm 12, 12' of theconduit 10, 10' is then inserted into the channel formed 50 via the remote manipulation of these instruments.
Twelfth, the incision present in the superficial wall 38 of the coronary artery 30 is closed by conventional surgical techniques such as suturing, laser welding, microstapling, and the like. When closure is by indirect thoracoscopic versus direct viewing, suturing, laser welding, microstapling and the like can be accomplished by Iltili7.ing surgical instruments remotely manipulated following their introduction through the trocar sheaths.
Thirteenth, upon completion of placement of the conduit 10, 10' of the present invention, the heart, if rotated, can be returned to its normal orientation.
Fourteenth, all heart manipulating devices are removed from the chest cavity.
Fifteenth, contractions of the heart can be allowed to return to their normal resting rate by the discontinuation of intravenous esmolol and diltiazem, if utilized.

. .

W O 98t06356 39 PCTrUS97/13980Sixteenth, the peric~diu~ll 52 is partially or completely re-applo~ ated. An external drain can be placed inside the pericardiu,ll, as needed, as described by Acuff et al.
Sevenleenth, the trocar sheaths are removed, and all thoracic punctures 5 surgically repaired in a conventional manner.
Eighteenth, ~nPsthesi~ is reversed and the patient revived by standard techniques.

E. F.mbodiments with the Catheter-Controlled Approach Referring now to FIGS. 10, 11, 12, 13, 14, 15, and 16, an exemplary coronary artery bypass procedure performed through catheteri_ation will be described. This approach allows no direct visualization of the coronary vasculature, although the chamber of the heart could be indirectly visualized during the procedure by equipping the intraventricular catheter with a standard fiber-optic15 device, if desired. Because the procedure is performed through catheters introduced remotely, normal tissue injury is minimi7P~I
Preparation for the procedure, and anesthesia prior to and during the procedure, is outlined above.
In the embodiment to be described, cardiopulmonary bypass is unnecessary.
20 However, the procedure would be in no way limited if cardiopulmonary bypass were performed.
First, an intracoronary catheter 120 (FIG. 10) is inserted via an incision in the groin 126 and advanced within the femoral artery 124. Through continued advancement within the ~escçn~1ing aorta 128, and the ~cPn~1in~ aorta 122, the 25 coronary artery 30 is entered.
Dependent on the degree of narrowing or occlusion of the coronary artery, standard angioplasty, atherectomy, or some similar procedure can be optionally performed if passage of the catheter tip 136 (FIG. 1 lA) is hindered. Angioplasty.
arthrectomy, and the like could optionally precede the catheter-controlled bypass 30 procedure.

W O 98t06356 40 PCTrUS97/13980 If desired, the heart may be slowed while catheterizing the coronary vasculature, during the construction of a channel or ch~nn~l~ 50 leading from a chamber of a heart 44 into a lumen of a coronary artery 30 itself, or both. Suchslowing can improve visualization of the catheters as facilitated by fluoroscopy or 5 the alternative radiologic techniques by which the procedure can be performed.Standard ph~ cologic methods, as described above, to slow the heart are well known in the lilcl~Lu~c.
Second, the intracoronary catheter 120 is advanced within the coronary arterial vasculature tree to the target location through standard catheter manipulation 10 techniques. The proper location of the intracoronary catheter tip 136 in relation to the targeted bypass site can be det~rrnin~d through standard radiographic techniques.
Third, as shown in FIGS. llA-llC, a balloon 130 located on the distal end of the intracoronary catheter 120 is inflated (FIG. 11B). Inflation of the balloon 130 causes a stent 134 located circumferentially surrounding the balloon 130 to be seated against the coronary arterial walls 36, 40. The stent 134 is a hollow expandablestent having a cut-out area 135 along the cylindrical wall of the stent 134, forreasons that will become app~c~ll. The stent 134 is positioned at placement within the coronary artery in a manner that the cut-out 135 is juxtaposed against the deep wall 40 of the coronary artery 30 upon inflation of the intracoronary catheter balloon 20 130.
Fourth, the balloon 130 is deflated (FIG. llC) and the catheter 120 withdrawn into the ascending aorta 122 leaving the expanded stent 134 in place.
Fifth, an intraventricular catheter 140 is inserted into the innominate artery 144 via an incision in the anterior superior right chest wall 142 as shown in FIG. 12.
25 The intraventricular catheter 140 is advanced in a retrograde fashion through the ascending aorta 22, and into the chambers of the left side of the heart. By continued advancement, the intraventricular catheter 140 is extended past the semilunar valves 148 and into the left ventricle 44. Throughout the procedure, the location of the intraventricular catheter 140 within a chamber of a heart 44 can be ascertained by 30 either indirect vi~ li7~tion employing standard fiber-optic instrumentation inherent to the intraventricular catheter, or and/or by standard radiographic techniques.

W O 98/06356 41 PCTnUS97/13980 Sixth, a channel 50 can be ablated (FIGS. 13A-13B) through both a wall of a chamber of a heart 42 and the deep wall of a coronary artery 40 utili7.ing an ablating tip 132. Such ablating devices are well known in the literature and can include a laser, a radio frequency device, or the like. Power to the ablating tip 132 can be synchronized via the intraesophageal probe such that ablation occurs at a recurring aspect of the cardiac cycle. Such synchronization of devices to physiological function is well-known in the lil~ld~lue. The ablation can be indirectly observed via fiber optics associated with the intraventricular catheter 140. Alternatively, the location of the ablating tip 132 can be determined by standard radiographic techniques.
Seventh, once a channel 50 through the heart chamber wall 42 is formed, the intracoronary catheter 120 is re-advanced into the coronary artery 30.
Eighth, the balloon 130 on the distal end of the intracoronary catheter 120 is re-inflated upon re~clling the target bypass site, as illustrated in FIGS. 14A and 14B.
Inflation of the intracoronary catheter balloon 130 seals the formed channel 50 so that blood is prevented from flowing from the coronary artery lumen 48, through the formed channel 50, and into a chamber of the heart 44. Note, though, that the inflation of the intracoronary catheter balloon 130 still allows blood to perfuse the downstream portion of the coronary artery 30. This is because the intracoronary catheter 120 is equipped with channels 138 which allow blood to pass internally within the intracoronary catheter 120 from the upstream portion of the coronary artery 30, and to exit the catheter into the downstream portion of the coronary artery 30.
Ninth, the ablating catheter 140 is removed from the body completely.
Tenth, a second intraventricular catheter 160 is inserted into the innominate artery 144 at the arterial cut-down site 142, as shown in FIG. 12. The intraventricular catheter 160 is next advanced in a retrograde fashion into the ascending aorta 22. By continued advancement, the intraventricular catheter 160 is finally extended past the semilunar valves 148 and into the left ventricle 44.

- wo 98/06356 42 PcTlUS97/13980 This i~ v~ cular catheter is equipped with a inflatable balloon 60 on the catheter's distal end, and a stent-forming device 61 circumferentially surrounding the balloon 60 on the catheter's distal end (FIGS. 14A-14D).
The stent forming device 61 is a spiral sheet shown separately in FIGS. 15A
5 and 15B. Initially, the device 61 is a sheet formed in a spiral shape as shown in FIG. lSA to present a reduced diameter smaller than the diameter of the formed channel 50. In response to çxp~n~1in~ forces (e.g., expansion of a balloon 60 within device 61), device 61 expands to a cylinder as shown in FIG. l5B. Interlocking tabs 61a and recesses 61b on opposing edges of the device 61 define a locking 10 mechanism 62 to retain the device 61 in a cylindrical shape. The cylindrical shape of device 61 after expansion of the balloon 60, as shown in FIG. 15B,is larger in diameter than the spiral shape of device 61 prior to expansion of the balloon 60, as shown in FIG. 15A. The device 61 as expanded is sized to be retained within the formed channel 50 upon expansion.
Throughout this portion of the procedure, the location of this second intraventricular catheter 160 within a chamber of a heart 44 can be ascertained by either indirect visualization employing standard fiber-optic instrumentation inherent to the second intraventricular catheter, or and/or by standard radiographic techniques.
Eleventh, the tip 180 (FIG. 14A) of the second intraventricular catheter 160 is introduced into and advanced within the formed channel 50.
Twelfth, with the tip 180 of the second intraventricular catheter 160 near or abutting the side of the intracoronary catheter balloon 130, a balloon 60 surrounding circumferentially the tip of the second intraventricular catheter 160, is inflated. As shown in FIGS. 14C and 14D, inflation of the balloon 60 causes the device 61 located circumferentially around the balloon 60 located on the end of the secondintraventricular catheter 160 to become seated against the walls of the formed channel 50.
As shown in FIG. 16, the device 61, is locked into the cylindrical position when the underlying balloon 60 is inflated by an interlocking mechanism 62 constructed as part of the device 61.

.. ...

W O 98/06356 43 PCTnUS97/13980 Thi.leel~ the balloon 60 on the intraventricular c~th~.t~.r tip is deflated, andthe catheter removed from the body, as shown in FIG. 14D.
Fou~ lh, a third intraventricular catheter 70 is inserted at the innominate artery access site 142. This third intraventricular catheter 70 is then advanced in a 5 retrograde fashion into a chamber of the left side of a heart, as outlined above.
This third intraventricular catheter 70 is equipped with a hollow tube 71 on its distal tip which can interlock to the device 61 previously placed within theformed channel 50, as shown in FIGS. 17A and 17B.
Fifteenth, the hollow tube 71 is forwarded within the formed channel 50, and 10 interlocked to the device 61. In one embodiment, the hollow tube 71 can partially insert into the device 61 previously seated within the formed channel 50.
The hollow tube 71 can, but may not necessarily, be equipped with a bi-directional flow regulator 74 to provide full blood flow in the direction of arrow C
with reduced (but not blocked) blood flow opposite the direction of arrow C. An 15 array of such hollow tubes 71 of various dimensions can be available to the surgeon at the operative procedure.
Sixteenth, the balloon 130 on the end of the intracoronary catheter 120 is deflated.
Seventeenth, angiographic dye can be introduced into a chamber of the heart 20 through a port intem:ll to the third intraventricular catheter 71. The introduction of angiographic dye can allow the blood flow to be visualized under fluoroscopy, digital subtraction angiography, or similar standard techniques. By such radiographic e~r~min~tion~ blood flow directly from a chamber of a heart into a coronary artery can be ascertained. In cases where a bi-directional flow regulator 74 25 is ~ltili7f~d~ the bi-directional flow from a chamber of a heart and into a coronary artery and the flow rates can be verified.
Eighteenth, the third intraventricular catheter 70 is withdrawn from the body through the innominate incision site 142.
Nineteenth, the intracoronary catheter 120 is withdrawn from the body 30 through the femoral incision site 126.

W 0 98/06356 44 PCTnUS97/13980 Twentieth, the sites of the innominate incision 142 and femoral incision 126 are surgically re-approximated through standard closure techniques.
Twenty-first, anesthesia is reversed and the patient revived by sta~ndard techniques.
s Chan~es ~ntl Modification~
Although the foregoing invention has been described in detail by way of illustration and example, for purposes of clarity of understan-lin~, it will be obvious that changes and modifications may be practiced within the scope of the appended1 0 claims.

Claims (32)

Claims

1. An apparatus for use in a coronary artery bypass procedure, said apparatus comprising:
(a) a blood flow conduit having a first end which is so dimensioned and configured that it can be inserted into and retained within a wall of a heart chamber containing oxygenated blood with said first end in blood flow communication with blood contained within said chamber;
(b) said conduit having a second end which is so dimensioned and configured that it can be inserted into and retained within said coronary artery with said second end in blood flow communication with a lumen of said coronary artery;
(c) said apparatus further comprising a deflection surface that is so arranged relative to said first end of said conduit that, in use, blood flow in a first flow direction from said first end of said conduit is diverted to a second flow direction; and (d) said conduit being so arranged that, in use, it defines an open blood flow path during both diastole and systole.

2. An apparatus according to claim 1, in which the deflection is so located relative to the first end of the conduit that, in use, it blocks blood flow through said conduit from impinging directly upon said coronary artery.

3. An apparatus according to claim 1 or claim 2, wherein said deflection surface is a portion of a wall of said conduit.

4. An apparatus for use in a coronary artery bypass procedure, said apparatus comprising:

(a) a blood flow conduit having a first end which is so dimensioned and configured that it can be inserted into and retained within a wall of a heart chamber containing oxygenated blood with said first end in blood flow communication with blood contained within said chamber;
(b) said conduit having a second end which is so dimensioned and configured that it can be inserted into and retained within said coronary artery with said second end in blood flow communication with a lumen of said coronary artery;
(c) said second end being so oriented relative to said first end that, in use, when the first end has been inserted into and is retained within said wall of said heart chamber, said second end can be so positioned that blood flow is directed out of said second end in a direction substantially aligned with said lumen; and (d) said conduit being so arranged that it can define an open blood flow path during both diastole and systole.

5. An apparatus according to any one of claims 1 to 4, wherein said conduit has a cross-sectional area sufficient to pass blood at a volumetric flow rate to supply blood to cardiac musculature served by said coronary artery in an amount to reduce signs and symptoms of reduced coronary blood flow.

6. An apparatus according to any one of claims 1 to 5, wherein said conduit has a geometry selected to bias forward flow of blood from said first end toward said second end while not blocking blood flow from a direction from said second end toward said first end.

7. An apparatus according to any one of claims 1 to 6, wherein said second end is sized to be inserted into and retained within said coronary artery on a downstream side of a predetermined obstruction site.

8. An apparatus according to any one of claims 1 to 7, wherein said conduit is sized to extend through said heart chamber wall and a lower wall of said coronary artery.

9. An apparatus according to any one of claims 1 to 8, wherein said conduit is biased for a net volumetric blood flow said first end toward said second end.

10. An apparatus according to any one of claims 1 to 9, in which there is provided in the conduit means for reducing but not blocking blood flow through said blood flow path during diastole.

11. An apparatus according to any one of claims 1 to 10, wherein said second end extends in a direction that is substantially perpendicular to or at an oblique angle relative to the direction in which said first end extends.

12. An apparatus according to any one of claims 1 to 11, wherein said conduit is defined by a continuous wall extending from said first end to said second end, said apparatus being suitable in use for substantially complete replacement of coronary arterial flow in said coronary artery.

13. An apparatus according to any one of claims 1 to 12, wherein said conduit is a hollow, substantially L-shaped rigid tube.

14. An apparatus according to any one of claims 1 to 11, which is so constructed that in use blood flow from a portion of said lumen located upstream of said conduit is confluent with said blood flow path, said apparatus being suitable in use for supplementation of coronary-arterial flow.

15. An apparatus according to claim 11, wherein said conduit is a hollow, substantially T-shaped tube.

16. An apparatus according to any one of claims 1 to 13, in which said first end of said conduit comprises retention means which are so arranged that, in use of the -apparatus, they are able to retain said first end in position in said chamber wall.

17. An apparatus according to any one of claims 1 to 14, wherein said conduit is sized for said first end to penetrate beyond said wall and into said heart chamber.

18. An apparatus according to claim 1 or claim 4, wherein the second portion is expandable, whereby it can be inserted in use into an artery and expanded to the desired size.

19. An apparatus for use in a coronary artery bypass procedure for supplementing a flow of blood to a coronary artery, said apparatus comprising:
(a) a blood flow conduit having a first end adapted to be inserted into and retained within a wall of a heart chamber containing oxygenated blood with said first end in blood flow communication with blood contained within said chamber;
(b) said conduit having a second end adapted to be inserted into and retained within said coronary artery with said second end in blood flow communication with a lumen of said coronary artery;
(c) said first end of said conduit comprising retention means which are so arranged that, in use of the apparatus, they are able to retain said first end in position in said chamber wall; and (d) said conduit adapted to define an open blood flow path during both diastole and systole.

20. An apparatus for use in a coronary artery bypass procedure for supplementing a flow of blood to a coronary artery, said apparatus comprising:
(a) a blood flow conduit having a first end which is so dimensioned and configured that it can be inserted into and retained within a wall of a heart chamber containing oxygenated blood with said first end in blood flow communication with blood contained within said chamber;
(b) said conduit having a second end which is so dimensioned and configured that it can be inserted into and retained within said coronary artery with said second end in blood flow communication with a lumen of said coronary artery;
(c) said conduit being so arranged that, in use, it defines an open blood flow path during both diastole and systole; and (d) said conduit configured to direct blood flow, in use, out of said second end in a direction substantially aligned with said lumen.

21. An apparatus for use in a coronary artery bypass procedure for supplementing a flow of blood to a coronary artery, said apparatus comprising:
(a) a blood flow conduit having a first end which is so dimensioned and configured that it can be inserted into and retained within a wall of a heart chamber containing oxygenated blood with said first end in blood flow communication with blood contained within said chamber;
(b) said conduit having a second end which is so dimensioned and configured that it can be connected to said coronary artery distal to an obstruction with said second end in blood flow communication with a lumen of said coronary artery;
(c) said conduit being so arranged that, in use, it defines an open blood flow path during both diastole and systole; and (d) said conduit is sized for said first end, in use, to penetrate beyond said wall and into said heart chamber.

22. An apparatus for use in the treatment of coronary artery disease, said apparatus comprising:

(a) a blood flow conduit having a first end adapted to be inserted into and retained within a wall of a heart chamber containing oxygenated blood with said first end in blood flow communication with blood contained within said chamber;
(b) said conduit having a second end adapted to be inserted into and retained within said coronary artery with said second end in blood flow communication with a lumen of said coronary artery; and (c) said conduit adapted to define an open blood flow path during both diastole and systole.

23. A kit of parts for assembly to form an apparatus according to any one of claims 1 to 22, said kit comprising a first part comprising a first end adapted to be inserted into and retained within said chamber wall and a second part comprising a deflection surface for blocking blood flow through said first part from impinging directly upon said coronary artery.

24. The use in the preparation of an apparatus for the treatment of coronary artery disease of a device comprising:
(a) a blood flow conduit having a first end adapted to be inserted into and retained within a wall of a heart chamber containing oxygenated blood with said first end in blood flow communication with blood contained within said chamber;
(b) said conduit having a second end adapted to be inserted into and retained within said coronary artery with said second end in blood flow communication with a lumen of said coronary artery; and (c) said conduit adapted to define an open blood flow path during both diastole and systole

25. A method for performing a coronary artery bypass procedure for supplementing a flow of blood to a coronary artery, said method comprising: forming a blood flow path from a heart chamber directly to said coronary artery and maintaining said blood flow path open during both systole and diastole.

26. A method according to claim 25, comprising selecting a blood conduit having a first end and a second end and placing said first end in blood flow communication with said chamber and placing said second end in blood flow communication with said coronary artery.

27. A method according to claim 26, wherein said conduit is selected with a cross-sectional area sufficient for blood to flow through said conduit at a volumetric flow rate to effectively reduce signs and symptoms of reduced coronary blood flow.

28. A method according to claim 25 or claim 26, comprising:
(a) inserting said first end into said chamber through a wall of said chamber and retaining said first in said wall and in blood flow communication with said blood within said chamber; and (b) inserting said second end into said coronary artery and retaining said second end in said coronary artery and in blood flow communication with a lumen of said coronary artery.

29. A method according to any one of claims 25 to 28, wherein said coronary artery is at least partially obstructed at a predetermined site, said method further comprising forming said path directly to said coronary artery downstream of said site.

30. A method according to any one of claims 25 to 29, further comprising reducing but not blocking blood flow through said path during diastole.

31. A method according to any one of claims 25 to 30, comprising directing blood flow through said path to reduce direct impingement of said blood flow upon a wall of the coronary artery.

32. A method according to any one of claims 25 to 31, comprising forming said path through said wall and through a lower wall of said artery.