WO2001091830A1

WO2001091830A1 - Implantable fluid delivery system

Info

Publication number: WO2001091830A1
Application number: PCT/US2000/014872
Authority: WO
Inventors: Lide Fang; Yong H. Zhu; Wolff M. Kirsch
Original assignee: Loma Linda University Medical Center
Priority date: 2000-05-25
Filing date: 2000-05-30
Publication date: 2001-12-06
Also published as: AU2000253054A1

Abstract

An implantable fluid delivery catheter (10) comprises an elongated cannula (14) having a proximal end, a distal end opposite the proximal end, at least one internal lumen (18) extending axially therethrough, a distal tip (20) that axially occludes the internal lumen, at least one infusion port (22) located near the distal end, and extending transverse to the lumen. The infusion port has an internal opening (22b) at its intersection with the lumen, and an external opening (22a) opposite the internal opening. The external opening is located so that it is downstream of the internal opening when the catheter is positioned in a blood vessel of a patient. A method of delivering fluid to a blood vessel of a patient comprises creating an insertion channel extending from an insertion site to the blood vessel, inserting a fluid delivery catheter having at least one infusion port that is angled with respect to a lumen of the catheter at least partway through the insertion channel to the blood vessel, and positioning the catheter in the blood vessel such that an external opening of the infusion port is located downstream of an internal opening of the infusion port.

Description

IMPLANT ABLE FLUID DELIVERY SYSTEM

Background of the Invention Field of the Invention

The present invention relates generally to an improved implantable fluid delivery system, and more particularly to a fluid delivery catheter having a tip configuration that yields improved performance in comparison to prior art systems. Description of the Related Art

In the care and treatment of certain patients, catheters of various types are used to carry out necessary treatments, by injecting or infusing medication or other fluids into the patient's bloodstream. For example, catheters are used for infusion of intervention chemotherapy drugs into blood vessels. Standard implantable catheters for drug or fluid delivery are typically flexible, tubular structures having one or more distal openings to permit the delivered fluid to flow from the catheter into the patient. These catheters may incorporate a unidirectional or bidirectional check valve to prevent undesired flow through the catheter when appropriate.

Fluid-delivery catheters may be used for either short-term or prolonged treatment, depending on the particular therapy being administered to the patient. Once the catheter is positioned in the patient, it may be used repeatedly for an extended time, commonly more than several months, and often for 1-2 years or more. It is desirable to maintain the catheter in place throughout this period, to minimize patient trauma and reduce the threat of infection from repeated punctures.

However, when catheters are used for drug or fluid delivery over an extended period of time, difficulties may arise. Quite frequently, blood will clot near the distal end of the catheter and impede the flow of fluid therethrough. It is believed that blockage rates by clotting for prior art fluid-delivery catheters can be as high as 8% after one year, 12.9% after two years, and 18.8% after three years of catheterization. When blood clots the catheter, the catheter must be removed, cleaned, and reinserted. Since clotting is unpredictable, patients must therefore be closely monitored for signs of blocked catheters. Once a clot has impeded drug delivery, the patient must suffer repeated trauma, as the catheter is withdrawn and subsequently reinserted after each incidence of clotting. Summary of the Invention In accordance with one preferred embodiment an implantable fluid delivery catheter comprises an elongated cannula having a proximal end and a distal end opposite the proximal end, and at least one internal lumen extending axially therethrough, a distal tip that axially occludes the internal lumen, and at least one infusion port located near the distal end and extending transverse to the lumen. The infusion port is angled with respect to the lumen so that the infusion port extends downstream when the catheter is positioned in a blood vessel of a patient.

In accordance with another preferred embodiment an implantable fluid delivery catheter comprises an elongated cannula having a proximal end and a distal end opposite the proximal end, and at least one internal lumen extending axially therethrough, a distal tip that axially occludes the internal lumen, and at least one infusion port located near the distal end and extending transverse to the lumen. The infusion port has an internal opening at its intersection with the lumen and an external opening opposite the internal opening. The external opening is located so that it is downstream of the internal opening when the catheter is positioned in a blood vessel of a patient.

In accordance with yet another preferred embodiment an implantable fluid delivery system comprises a catheter, the catheter having an elongated cannula with a proximal end and a distal end opposite the proximal end, and at least one internal lumen extending axially therethrough, a distal tip that axially occludes the internal lumen, and at least one infusion port located near the distal end and extending transverse to the lumen. The infusion port has an internal opening at its intersection with the lumen and an external opening opposite the internal opening, and the external opening is located so that it is downstream of the internal opening when the catheter is positioned in a blood vessel of a patient. The implantable fluid delivery system also comprises a fluid source connected to the proximal end of the catheter.

In accordance with still another preferred embodiment a method of delivering fluid to a blood vessel of a patient comprises creating an insertion channel extending from an insertion site to the blood vessel, inserting a fluid delivery catheter having at least one infusion port that is angled with respect to a lumen of the catheter at least partway through the insertion channel to the blood vessel, and positioning the catheter in the blood vessel such that an external opening of the at least one infusion port is located downstream of an internal opening of the infusion port.

For purposes of summarizing the invention and the advantages achieved over the prior art, certain objects and advantages of the invention have been described herein above. Of course, it is to be understood that not necessarily all such objects or advantages may be achieved in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein.

All of these embodiments are intended to be within the scope of the invention herein disclosed. These and other embodiments of the present invention will become readily apparent to those skilled in the art from the following detailed description of the preferred embodiments having reference to the attached figures, the invention not being limited to any particular preferred embodiment(s) disclosed.

Brief Description of the Drawings Having thus summarized the general nature of the invention and its essential features and advantages, certain preferred embodiments and modifications thereof will become apparent to those skilled in the art from the detailed description herein having reference to the figures that follow, of which:

Figure 1 is a sectional view of a fluid delivery catheter having features in accordance with one preferred embodiment of the present invention, positioned within a blood vessel of a patient; and

Figure 2 is a sectional view of a fluid delivery catheter having features in accordance with another preferred embodiment of the present invention, positioned within a blood vessel of a patient.

Detailed Description of the Preferred Embodiment

FIG.l shows in section a catheter 10 having features in accordance with one preferred embodiment of the present invention. The catheter 10 is shown positioned in the lumen of a blood vessel 12, and generally comprises an elongated cannula 14 with a wall

16 that defines and encloses an internal, axial lumen 18. The catheter 10 also comprises a distal tip 20 and (preferably two) infusion ports 22, each having an external opening 22a and an internal opening 22b. Although two is the preferred number of infusion ports 22, in alternative embodiments the catheter may have one, three, four, five, six, or any suitable number of ports.

Advantageously, the distal tip 20 axially occludes the lumen 18 of the cannula 14; that is, the distal tip 20 prevents fluid from flowing in or out of the cannula 14 along the longitudinal axis A- A of the catheter 10 or blood vessel 12. Thus the fluid delivered through the catheter 10 to its distal end may exit the cannula 14 only though the infusion ports 22. In the embodiment shown in FIG. 1, the infusion ports 22 are angled proximally with respect to the longitudinal axis A-A of the catheter 10 by an angle that is advantageously between about 10° and about 80°, preferably between about 20° and about 70°, and most preferably between about 30° and about 60°. Accordingly, in this embodiment the external openings 22a of the infusion ports 22 are located proximal of the internal openings 22b thereof.

The distal tip 20 may advantageously have a highly tapered shape along its external surface 24. Specifically, the preferred distal tip 20 has an external surface 24 that is curved, but more sharply so than a blunt or hemispherical tip. Thus in any cross section the external surface 24 is defined by a curve of decreasing radius as it extends from the distal end to the proximal end of the distal tip 20.

When positioned in a patient, a portion of the cannula 14 extends from the insertion site and may connect to a fluid or drug source (not shown) such as, but not limited to, an IN bag, pump, etc. Thus there is facilitated a fluid delivery system that may be used to deliver a selected fluid through the catheter 10, into the blood vessel 12 and subsequently to the rest of the patient's vascular system.

The embodiment of FIG. 1 is intended for "retrograde" insertion into a blood vessel. In other words, the catheter 10 is positioned in the blood vessel 12 by advancing the catheter against the direction of blood flow (as indicated in FIG. 1) until the desired position is reached, and the distal tip 20 is located upstream of the insertion site. Thus in the retrograde embodiment the external openings 22a of the infusion ports 22 may be defined as being located downstream of, or antegrade of, the internal openings 22b thereof. With the catheter of FIG. 1 so positioned, the configuration of the distal tip 20 and infusion ports 22 prevents blood from flowing into (and clotting in) the lumen 18 of the cannula 14. As can be readily observed in FIG. 1, the angled orientation of the infusion ports 22 greatly reduces the tendency of the blood to enter the catheter 10, as the blood flow would be required to turn through significantly more than 90° to work its way through the infusion ports and into the catheter. This effect is augmented by the orientation of the external openings of the infusion ports 22, which are preferably substantially parallel to the overall direction of blood flow, and thus tend not to "catch" blood flowing along the exterior of the catheter. In addition, due to the Bernoulli effect, the lower fluid pressure of the blood flowing past the external openings 22a tends to draw fluid out of the infusion ports 22 and into the blood flow, creating a counterflow that prevents undesired flow of blood into the ports 22. The configuration of the distal tip 20 and the infusion ports 22 yields other desirable performance aspects of the catheter 10. Specifically, because of the reduced tendency of the blood to flow into the infusion ports 22 (i.e., the reduced/negative "back pressure" experienced at the infusion ports 22) less pressure is needed to infuse a selected fluid through the catheter 10 and into the patient's vasculature. This is particularly advantageous when relying on a "gravity-driven" fluid-flow apparatus, such as a simple IN bag system. Furthermore, because of the reduced back pressure the catheter 10 can be constructed and used without a check valve, if desired, to prevent backflow into the cannula 14. Without a check valve, a clinician can withdraw blood into the cannula 14 as a visual means of determining whether the catheter has been properly inserted into the vessel. Finally, the distal tip 20 not only prevents direct, axial blood flow into the cannula 14 but also has a shape, detailed above, that promotes easier insertion and advancement of the catheter 10 into the patient and the blood vessel 12, as compared to a blunt or hemispherical tip.

It is contemplated that the catheter 10 can be constructed from conventional materials known in the art to be suitable for similar applications, including but not limited to polyethylene, polytetrafluoroethylene, polyvinyl chloride, and thermoplastic polyether- based polyamides such as PEBAX®. Similarly, the catheter 10 can be made by employing conventional techniques of, for example, extrusion (to form the cannula 14), molding (to form the distal tip 20 and/or infusion ports 22), and/or drilling (to form the infusion ports 22). In one preferred embodiment, the catheter 10 has an inner diameter of about 0.5-1 mm and the walls 16 are about 0.5 mm thick. However, it must be noted that these dimensions are merely exemplary and can vary widely within the scope of the present invention, as the catheter 10 may be employed in blood vessels of varying size throughout the body. For instance, the inner and outer diameters of the catheter 10 may be selected to provide the desired flow rate of fluid and/or allow the catheter 10 to fit into a certain size of blood vessel. Advantageously, the walls 16 may be made relatively thick for a given application

(i.e., within the thicker range of acceptable dimensions for specific use of the catheter 10) to better define and support the preferred angled orientation of the infusion ports 22. It has been found that thinner walls 16 tend to degrade the performance of the ports, as they lose their shape and orientation. In addition, thicker walls facilitate the use of more steeply angled infusion ports (with a smaller angle α) and prevent the catheter 10 from twisting about the longitudinal axis A-A.

In light of the factors detailed above the infusion ports 22, in one preferred embodiment, abut the distal tip 20 so that the proximal end of the tip 20 forms their distal walls. Thus the distal tip 20, which is preferably a large and/or solid mass of the material used to form the catheter 10, may provide sturdiness to the distal walls of the infusion ports 22, regardless of the thickness of the catheter walls 16. It will be noted, however, that in other embodiments the infusion ports may be located in the catheter walls 16 remote from (i.e., not adjacent to) the distal tip 20.

As mentioned above, the catheter 10 is intended for percutaneous insertion into a blood vessel and advancement therein to achieve the required positioning. As the catheter 10 is desirably flexible along its length, a conventional insertion needle, insertion-site implant or other known devices may be used to pierce the skin and create an insertion channel to the blood vessel 12, through which the catheter 10 is inserted until it reaches the vessel lumen. Once positioned properly with the infusion ports 22 well inside the vessel 12, the catheter 10 is ready to deliver fluid to the patient's bloodstream from the fluid source (pump, IN bag, etc. as detailed above).

FIG. 2 depicts another embodiment of the catheter 10, intended for antegrade insertion to the blood vessel 12, that is, insertion and advancement in the vessel 12 in the same direction as the blood flow. The antegrade embodiment of FIG. 2 is preferably similar in all respects to the retrograde embodiment of FIG. 1, and has all the same features and advantages, except that the infusion ports 22 are angled distally rather than proximally. In other words, in the embodiment of FIG. 2 the external openings 22a of the infusion ports 22 are located distal of the internal openings 22b thereof. Thus in the antegrade embodiment the infusion ports 22 are properly oriented to impart the same performance characteristics (inter alia, prevention of blood flow into the catheter 10) as are observed in the retrograde embodiment detailed above.

In one clinical study, reduced rates of blockage/clotting were observed when using a fluid delivery system like the embodiments of FIGS. 1-2 described above, specifically a closed-end catheter with side infusion ports tilted toward the direction of blood flow, and a tapered distal tip. This type of catheter was tested against a conventional open-ended fluid- delivery catheter with over 500 patients treated by Dr. Lide Fang at Shanghai 9th Peoples' Hospital. For each group of patients, blockage rates were recorded at 3 months, 6 months, and one, two, and three years. The results, in terms of clotting/blockage rates, are summarized in the following table:

Thus it may be seen that superior results, reflected in reduced instance of clotting/blockage, may be obtained by using fluid delivery catheters having features and advantages in accordance with the present invention. The improved design shows uniformly better performance over the conventional catheters, by a factor of two or more at each measurement interval. Accordingly, the test results underscore the superior performance aspects of catheters made in accordance with the present invention.

Various alternative embodiments of the present invention may incorporate additional features without departing from the scope of the invention. For example, while the infusion ports 22 are depicted in the embodiments of FIGS. 1 and 2 as being angled only in the longitudinal plane, in other embodiments the infusion ports 22 may also be angled in a plane transverse to the longitudinal plane (or even curved) so long as the external openings 22a of the infusion ports 22 are located proximal (in the case of the retrograde catheter of FIG. 1) or distal (in the case of the antegrade catheter of FIG. 2) of the internal openings 22b thereof. In addition, the embodiments of FIGS. 1-2 have been depicted and described as having a single lumen 18; however other embodiments of the present invention may incorporate multiple lumens 18 in the same cannula 14. In these alternative embodiments some or all of the lumens may have infusion ports and thus have an infusion function, or some of the lumens may be dedicated to other desired functions. Although the present invention has been described with reference to specific exemplary embodiments, it will be apparent to those of ordinary skill in the art that various modifications and augmentations may be made to these embodiments without departing from the broader spirit of the scope of the present invention as set forth in the following claims.

Claims

WHAT IS CLAIMED IS:

1. An implantable fluid delivery catheter, comprising: an elongated cannula having a proximal end and a distal end opposite the proximal end, and at least one internal lumen extending axially therethrough; a distal tip that axially occludes said internal lumen; and at least one infusion port located near said distal end and extending transverse to said lumen, said infusion port being angled with respect to said lumen so that said infusion port extends downstream when said catheter is positioned in a blood vessel of a patient.

2. An implantable fluid delivery catheter, comprising: an elongated cannula having a proximal end and a distal end opposite the proximal end, and at least one internal lumen extending axially therethrough; a distal tip that axially occludes said internal lumen; and at least one infusion port located near said distal end and extending transverse to said lumen, said infusion port having an internal opening at its intersection with said lumen and an external opening opposite said internal opening; wherein said external opening is located so that it is downstream of said internal opening when said catheter is positioned in a blood vessel of a patient.

3. The fluid delivery catheter of Claim 2, wherein said at least one infusion port extends through a sidewall of said cannula.

4. The fluid delivery catheter of Claim 2, wherein said external opening is located proximal of said internal opening.

5. The fluid delivery catheter of Claim 2, wherein said external opening is located distal of said internal opening.

6. The fluid delivery catheter of Claim 2, wherein said at least one infusion port extends proximally from said internal opening to said external opening.

7. The fluid delivery catheter of Claim 2, wherein said at least one infusion port extends distally from said internal opening to said external opening.

8. The fluid delivery catheter of Claim 2, wherein said at least one infusion port is angled proximally.

9. The fluid delivery catheter of Claim 8, wherein said at least one infusion port is angled with respect to said lumen by about 10°-80°.

10. The fluid delivery catheter of Claim 2, wherein said at least one infusion port is angled distally.

11. The fluid delivery catheter of Claim 10, wherein said at least one infusion port is angled with respect to said lumen by about 10°-80°.

12. The fluid delivery catheter of Claim 2, wherein said distal tip has an external surface that defines a curve of decreasing radius as it extends from a distal end to a proximal end of said distal tip.

13. An implantable fluid delivery system, comprising: a catheter, said catheter comprising: an elongated cannula having a proximal end and a distal end opposite the proximal end, and at least one internal lumen extending axially therethrough; a distal tip that axially occludes said internal lumen; and at least one infusion port located near said distal end and extending transverse to said lumen, said infusion port having an internal opening at its intersection with said lumen and an external opening opposite said internal opening; wherein said external opening is located so that it is downstream of said internal opening when said catheter is positioned in a blood vessel of a patient; and a fluid source connected to the proximal end of said catheter.

14. A method of delivering fluid to a blood vessel of a patient, the method comprising: creating an insertion channel extending from an insertion site to said blood vessel; inserting a fluid delivery catheter having at least one infusion port that is angled with respect to a lumen of said catheter at least partway through said insertion channel to said blood vessel; and positioning said catheter in said blood vessel such that an external opening of said at least one infusion port is located downstream of an internal opening of said infusion port.