WO2001024851A1

WO2001024851A1 - Drug delivery catheter

Info

Publication number: WO2001024851A1
Application number: PCT/US1999/022676
Authority: WO
Inventors: Russell W. Bowden
Original assignee: Cormedica Corporation
Priority date: 1999-09-30
Filing date: 1999-09-30
Publication date: 2001-04-12
Also published as: AU6503399A

Abstract

A medical system and method provides delivery of angiogenic drugs within a patient's heart. The system has an inner or drug delivery catheter (14) with a needle (26) extendable between retracted and extended positions. The catheter has a distal end that is positioned using a tracking system of transducers (16) (18) in the catheter and transducers (24) external to the patient. A spring (22) in an outer catheter (12) stabilizes the drug delivery catheter (10) within the patient's heart and the drug delivery catheter (10) can slide relative to the outer catheter (12). The needle (26) is extended out of the housing to precisely target angiogenic drugs at ischemic tissue.

Description

DRUG DELIVERY CATHETER Background of the Invention The present invention relates to a catheter for treatment of a patient and a related process. More specifically, the catheter is used to supply angiogenic substances to revascularize ischemic areas of a patients' heart.

Various techniques are used to deliver substances such as medical drugs to a patient. A common technique is for the patient to orally ingest the medicinal substance. Sometimes medicine is supplied to the patient intravenously by having a needle injecting medicine into the patient's bloodstream.

Oral ingestion or supplying medicine into the patient's bloodstream work well for various kinds of medication and various kinds of ailments. However, other situations require that medication be targeted to a particular body location (i.e., organ, part of organ, etc. of the patient) . This may be necessary or advisable if the medicinal effect is dissipated by general dispersal of the medicine throughout the patient. Medicinal drugs may require concentrating doses in particular parts of the body for maximum medicinal effects. Some drugs require targeting or concentrating doses at desired locations because the drug is so expensive that it is not practical to apply it to regions of the body except those that need it. Drugs may require targeting particular parts of the body to reduce side effects or effects on portions of the body not in need of the medication. The targeting of drugs to specific locations may be accomplished in various ways. Sometimes medicines are supplied to the patient by indirect targeting so that they are concentrated in the targeted part of the body. Such concentration at a desired site may arise from natural properties of the medicine or from chemical agents added to the medicine for the purpose of directing concentration towards a particular location. Other times the medicine is directly applied to the targeted part of the body. An example of such direct targeting is where a medication for a sore muscle may be injected directly into a muscle of the patient using a needle. (As used herein, direct targeting shall mean application of drugs physically at the target site, instead of using indirect targeting which uses insertion of the drugs at one or more body locations and bodily processes such as blood flow to carry the drugs to a desired location different from the sites of application of the drugs.)

Although the direct targeting of drugs to specific body locations such as a muscle is well known, circumstances or treatments may call for the targeting of drugs to very specific body locations. The indirect targeting rarely is practical when precise targeting is needed. Direct targeting likewise is often unable to supply a drug to a precise location. The drug delivery with direct targeting may be imprecise. The medical device used for drug application may be unable to localize the applied drug sufficiently. Alternately, or additionally, even when a medical drug applicator device can localize the application of a drug, getting the applicator device to a precise location may be difficult. That is, if a medical treatment requires application of a drug to a given small surface area of an internal organ and the drug applicator can localize the drug application to a surface area of the required size, there may still be a problem- if the applicator applies the drug with an offset from the specific small surface area that is the target. Such an offset is common if the technique used for locating and positioning the applicator is imprecise. If the applicator can be located reliably within 20 mm, but a given situation calls for drug application in a radius of 10 mm about a point, the applicator may apply all of the drug outside the target area.

There have been recent news reports and journal articles about the application of angiogenic substances to revascularize ischemic areas of patients' heart in combination with traditional coronary artery bypass graft (CABG) . The results have been encouraging, as new vessels have been found permeating the heart at the site of injection. However, any practical medical treatment using such an injection requires more precise positioning of the tip of a drug applying catheter than prior devices usually provide.

Objects and Summary of the Invention Accordingly, it is a primary object of the present invention to provide a new and improved drug applicator device.

A more specific object of the present invention is to provide a catheter with highly localized direct targeting of a drug. A further object of the present invention is to provide a catheter allowing quite precise direct targeting of a drug.

Yet another object of the present invention is to provide a catheter allowing precise and localized delivery of angiogenic substances to within a patient's heart.

A further object of the present invention is to provide a drug applying catheter providing a high level of stability when set in a position. Yet another object of the present invention is to provide a drug applying catheter which is easy to position and to move between desired positions. The above and other features of the present invention which will be more readily understood when the following detailed description is considered in conjunction with the accompanying drawings are realized by a medical system for treating a patient including: a drug delivery device for percutaneous application of an angiogenic drug by direct targeting injection into heart tissue of a patient by at least part of the drug delivery device extending into the heart tissue, the drug delivery device having a proximal end and a distal end; and a tracking system operable to track the location of the • distal end within the patient and having one or more device transducers at the distal end of the drug delivery device and one or more external transducers. The location of the distal end is sensed by electromagnetic interactions of the device transducer (s) and the external transducer(s) . The drug delivery device is preferably a catheter. The catheter includes a housing and a needle at least partly within the housing. The needle is slidable relative to the housing such that it is movable between a retracted position completely within the housing and an extended position at least partly out of the housing. An outer catheter is optionally used with the inner or drug delivery catheter slidable within the outer catheter. The outer catheter includes a spring for steering the outer catheter position in a patient's heart.

The invention may alternately be described as a medical system for treating a patient including: a drug delivery device for percutaneous application of drug by direct targeting injection into interior tissue of a patient by at least part of the drug delivery device extending into the tissue, the drug delivery device having a proximal end and a distal end; and a spring disposable within a patient for steering the position of the drug delivery device inside of a patient. A tracking system is operable to track the location of the distal end within the patient and has one or more device transducers at the distal end of the drug delivery device and one or more external transducers.

The invention may alternately be described as a method of applying angiogenic drugs percutaneously to heart wall tissue of a patient, the steps including: percutaneously inserting a drug delivery device into the patient, the drug delivery device having distal and proximal ends; positioning the distal end within the heart of a patient and at a target location as determined by using a tracking system to track the location of the distal end within the patient, the tracking system having one or more device transducers at the distal end of the drug delivery device and one or more external transducers, the location of the distal end being sensed by electromagnetic interactions of the device transducer(s) and the external transducer(s) ; and injecting by direct targeting injection an angiogenic drug into heart tissue of a patient by having at least part of the drug delivery device extending into the heart tissue. The drug delivery device is a catheter, the catheter has a needle and the injecting step is performed by moving the needle from a retracted position within a housing of the catheter and an extended position with at least part of the needle extending into heart tissue. The catheter is within an outer catheter and the positioning step includes sliding the catheter relative to the outer catheter. The positioning step includes use of a spring within the patient in order to steer the catheter such that a distal tip of the catheter is in a proper position (i.e., proper site for injection) relative to the heart wall prior to injection. Brief Description of the Drawings The above and other features of the present invention will be more readily understood when the following detailed description is considered in conjunction with the accompanying drawings wherein like characters represent like parts throughout the several views and in which: FIG. 1 is a side cross section view of the distal end of a catheter with a needle retracted according to the present invention combined with an external transducer system;

FIG. 2 is a side cross section view of the distal end of the catheter of FIG. 1 with a needle extended and combined with a pressure source;

FIG. 3 is a side view wherein the catheter of FIG. 1 is an inner catheter within an outer catheter; and

FIG. 4 is a side view of the catheter as used to insert a stent; and

FIG. 5 is a simplified side view of an alternate embodiment where an insertable member is a stent or plug having a needle built into it by virtue of the shape of the stent or plug.

Detailed Description

Turning now to FIG. 1, a drug applicator 10, which is more specifically a catheter, includes a tubular outer housing 12 of flexible material as commonly used for catheters and a tubular inner housing 14 of the same material. As shown, the inner housing 14 does not extend as far in the distal (rightmost in the FIG.) distance as the outer housing 12.

A tip electrode 16 is disposed at the distal tip and may be made of platinum or gold. A sensor coil 18 is disposed in the outer housing 12. The electrode wires and sensor wires are not shown for ease of illustration, but such wires would extend to a proximal end (not shown) of the catheter. The catheter 10 will have the anchoring arrangement disclosed in Abela, Bowden et al. U. S. Patent 5,782,824 issued July 21, 1998. That patent, which is incorporated by reference, discloses a laser catheter having a spring in an outer catheter and an inner catheter which is movable relative to the outer catheter. The spring in the outer catheter is used for anchoring the outer catheter in a stable position and for steering the outer catheter(the inner catheter being steered in turn by the steering of the outer catheter) , but the catheter provides for sliding movement of the inner catheter relative to the outer catheter and a windshield wiper movement back and forth as an anchoring point of the outer catheter remains stable. The construction of the present catheter is like that of the '824 patent except where noted. One difference is that the present invention does not need the windshield wiper type movement. Another difference is that spring as used in the present invention provides the steering functions of the spring of the '824 patent, but usually would not need provide the anchoring and biasing (i.e., pressing the distal tip of the catheter into the wall) functions of the spring in that patent.

As shown in FIG. 3, the catheter 10 is the inner catheter in such a construction, whereas an outer catheter 20 having spring 22 for steering is used like the outer catheter of the '824 patent. The inner catheter 10 (also referred to as a drug delivery catheter) of the present invention has a needle, instead of the optical fiber arrangement of the '824 patent. Although not shown, the spring 22 could alternately be directly in the drug delivery catheter 10 without the use of any outer catheter like 20.

Turning back to FIG. 1, the catheter 10 cooperates with an external transducer system 24 which may have one or more coils or other transducers (not shown) .

Specifically, the external transducer system 24 and the catheter sensing coil 18 (more generally this is a transducer) are part of a navigation system (not shown) allowing one to use interaction between transducers such as coil 18 on the catheter and external transducers to precisely calculate the position of the catheter 10. Although only the one sensing coil 18 is shown, there may be a plurality of transducers on the catheter 10. The navigation system is that disclosed in U.S. Patent application serial no. 08/996,125 filed December 22, 1997 in the name of Mark Schneider and assigned to the present assignee. A broader discussion of an earlier version of the navigation system in also disclosed in U.S. Patent 5,769,843 issued June 23, 1998 in the names of Abela and Bowden and assigned to the present assignee. That application and the '843 patent are hereby incorporated by reference. The present invention would use the navigation or position sensing arrangement of the Schneider application such that details need not be discussed.

Continuing to view FIG. 1, but also considering FIG. 2, the catheter 10 has a needle 26 and a tube 28 extending to the proximal end. At the proximal end, the tube 28 is connected to a needle control 30 which is simply a grip or holder allowing one to slide the tube 28 within the catheter 10. The details of the needle control 30 are not shown, but may be like the control used for translating an inner catheter relative to an outer catheter in the '824 patent. Additionally, the tube 28 is connected to a pressure or medicine source 30 such that drugs are supplied to the needle 26 via tube 28.

The delivery of angiogenic drugs to the endocardium, via catheter, will require the same precise positioning of the catheter tip as in percutaneous laser revascularization techniques of the '843 patent and the Schneider application. Of course, the present invention uses an angiogenic drug, instead of a channel creating laser, for revascularization. There is no need to unnecessarily apply a drug or therapy to healthy areas of myocardium. Since the application of a drug may mean its spreading through a area significantly larger than the needle induced hole in the heart wall, the ability to locate the catheter tip becomes more critical than in the laser situation of the Schneider application and the '843 patent. The combination of drug delivery catheter used with the tracking system will allow the precise targeting of ischemic areas.

Drug delivery can take several forms. The most straightforward is the catheter 10 with needle 26. The needle 26 projects either from the end of the catheter or is sheathed in some manner to prevent accidental drug delivery. The catheter tip would be placed against the heart wall (using the positioning and position-sensing or tracking techniques of the incorporated by reference application and patents) . Needle control 30 slides tube 28 and, in turn, moves the needle 26 from its FIG. 1 position to its extended FIG. 2 position. The catheter tip would then be moved to the next location, using the tracking system (i.e., position sensing) for precise positioning, and the process repeated. The drug delivery lumen within tube 28 of the catheter is preferable very small as the cost of any angiogenic drug is likely to be very high. This would reduce the amount of drug needed to fill the lumen prior to injection.

An alternative technique to simple injection of the drug is shown schematically in FIG. 4. A metallic raicro- stent device 34 coated with a drug or drugs could be implanted. The drugs could be antithrombic (something like heparin that is known to aid in endotheliazation and antipoliferation) and an angiogenic drug. This would have the advantage of creating a channel that would stay open due to the antithrombic drug and would spur local vessel growth due to the angiogenic drug. Approximately ten or so of these micro-stents (only 3 shown in FIG. 4, with one already mostly out of needle 26) could be preloaded in the lumen of the catheter. The catheter tip would be placed against the heart wall, a needle or the like would cause a cut in the endocardium and the micro- stent would be ejected into the tissue by pushing on the proximal end of a pusher wire 36. It would expand to form a channel. The expanded dimensions may be on the order of 1.5mm OD, 1mm ID and 4mm length.

Instead of using the sleeve-like stent structure, another option is to implant a biodegradable / bioabsorbable polymer plug like the stent 34 incorporating a angiogenic drug. The same sort of delivery system as above would apply.

Another option could be the combination of the preceding two concepts. This would be a biodegradable micro-stent that stays open long enough to create a channel with endotheliazation. It may also contain antithrombic and angiogenic drug such that endotheliazation takes place as the polymer degrades and new vessels are grown to supplies the region of interest. Turning now to FIG. 5, yet another alternative uses the catheter 10 and pusher wire 36 to insert implants 42 into a patient's heart wall 40. The implants 42 may be stents 34 or biodegradable plugs as discussed above with an additional feature. Specifically, and as shown at the right ends of implants 42 in FIG. 5, the implants have a sharp end such that they have a needle built into them. Although this sharp end or hole creating part (i.e., it creates a hole in the heart wall) of the implant is shown as a needle, it could alternately be a pencil-point-like sharp end, a blade-like sharp end, or other shape.

The catheter for the above applications would have the same operating characteristics as the catheter of the '843 patent. It must be able to reach target areas of the left ventricle. Therefore it would have a deflectable tip (steerable) and may have the tip extension feature of that patent. The catheter tip would contain the tracking system coil so that the tip could be precisely tracked and positioned. It may also contain a electrode on the tip to insure that firm contact is being made with the wall of the ventricle.

Although specific constructions have been presented herein, it is to be understood that these are for illustrative purposes only. Various modifications and adaptations will be apparent to those of skill in the art. In view of possible modifications, it will be appreciated that the scope of the present invention should be determined by reference to the claims appended hereto.

Claims

What is claimed is: 1. A medical system for treating a patient comprising: a drug delivery device for percutaneous application of an angiogenic drug by direct targeting injection into heart tissue of a patient by at least part of the drug delivery device extending into the heart tissue, the drug delivery device having a proximal end and a distal end; and a tracking system operable to track the location of the distal end within the patient and having one or more device transducers at the distal end of the drug delivery device and one or more external transducers, the location of the distal end being sensed by electromagnetic interactions of the device transducer (s) and the external transducer(s) .

2. The medical system of Claim 1 wherein the drug delivery device is a catheter.

3. The medical system of Claim 2 wherein the catheter includes a housing and a needle at least partly within the housing.

4. The medical system of Claim 3 wherein the needle is slidable relative to the housing such that it is movable between a retracted position completely within the housing and an extended position at least partly out of the housing.

5. The medical system of Claim 4 further including an outer catheter and wherein the catheter is slidable within the outer catheter and the outer catheter includes a spring for steering outer catheter position in a patient's heart.

6. The medical system of Claim 3 further including a spring for steering catheter position in a patient's heart.

7. The medical system of Claim 2 wherein the catheter is operable to put an implant into the heart wall, the implant dispensing a drug over time and after the catheter has been removed from the patient.

8. The medical system of Claim 1 wherein the catheter is operable to put an implant into the heart wall, the implant dispensing a drug over time and after the catheter has been removed from the patient.

9. The medical system of Claim 8 wherein the implant is selected from the group consisting of: a stent, and a biodegradable member.

10. A medical system for treating a patient comprising: a drug delivery device for percutaneous application of drug by direct targeting injection into interior tissue of a patient by at least part of the drug delivery device extending into the tissue, the drug delivery device having a proximal end and a distal end; and a spring operably connected with the drug delivery device and disposable within a patient for steering the position of the drug delivery device inside of a patient.

11. The medical system of Claim 10 wherein the drug delivery device is a catheter having a needle for insertion of drugs into a heart wall.

12. The medical system of Claim 11 wherein the catheter includes a housing and wherein the needle is slidable relative to the housing such that it is movable between a retracted position completely within the housing and an extended position at least partly out of the housing.

13. The medical system of Claim 12 wherein the needle is part of an implant, the implant dispensing a drug over time into a heart wall and after the catheter has been removed from the patient.

14. The medical system of Claim 11 further comprising a tracking system operable to track the location of the distal end within the patient and having one or more device transducers at the distal end of the drug delivery device and one or more external transducers, the location of the distal end being sensed by electromagnetic interactions of the device transducer (s) and the external transducer (s) .

15. The medical system of Claim 10 wherein the drug delivery device is a catheter.

16. The medical system of Claim 15 wherein the catheter includes a housing and a needle at least partly within the housing.

17. The medical system of Claim 16 wherein the needle is slidable relative to the housing such that it is movable between a retracted position completely within the housing and an extended position at least partly out of the housing.

18. A method of applying angiogenic drugs percutaneously to heart wall tissue of a patient, the steps comprising: percutaneously inserting a drug delivery device into the patient, the drug delivery device having distal and proximal ends; positioning the distal end within the heart of a patient and at a target location as determined by using a tracking system to track the location of the distal end within the patient, the tracking system having one or more device transducers at the distal end of the drug delivery device and one or more external transducers, the location of the distal end being sensed by electromagnetic interactions of the device transducer (s) and the external transducer(s) ; and injecting by direct targeting injection an angiogenic drug into heart tissue of a patient by having at least part of the drug delivery device extending into the heart tissue.

19. The method of Claim 18 wherein the drug delivery device is a catheter and wherein the catheter has a needle and the injecting step is performed by moving the needle from a retracted position within a housing of the catheter and an extended position with at least part of the needle extending into heart tissue.

20. The method of Claim 19 wherein the catheter is within an outer catheter and the positioning step includes sliding the catheter relative to the outer catheter.

21. The method of Claim 19 wherein the positioning step includes use of a spring within the patient in order to steer a distal tip of the catheter into a proper position relative to the heart wall prior to injection.

22. The method of Claim 19 wherein the needle is part of an implant, the implant dispensing a drug over time into a heart wall and after the catheter has been removed from the patient.

23. A medical system for treating a patient comprising: a drug delivery device for percutaneous application of an angiogenic drug by direct targeting injection into heart tissue of a patient, the drug delivery device including a hole creating part operable to create a hole in a heart wall for drug insertion and an implant for insertion into the hole, the implant operable to dispense a drug over time into a heart wall and after the drug delivery device has been removed from the patient.

24. A medical system of Claim 23 wherein the hole creating part is a part of the implant and remains in a patient after the drug delivery device has been removed from the patient.

25. A medical system of Claim 24 wherein the hole creating part is a sharp part of the implant.

26. A medical system of Claim 24 wherein the hole creating part is a needle part of the implant.

27. The medical system of Claim 26 wherein the implant is selected from the group consisting of: a stent, and a biodegradable member.

28. The medical system of Claim 23 further comprising: a tracking system operable to track the location of the drug delivery device within the patient and having one or more device transducers at the drug delivery device and one or more external transducers, the location of the drug delivery device being sensed by electromagnetic interactions of the device transducer(s) and the external transducer(s) .

29. The medical system of Claim 23 wherein the hole creating part is a needle.

30. The medical system of Claim 23 wherein the drug delivery device has a spring for steering the drug delivery device.