ROTATING BURR PMR DEVICE AND METHOD

Abstract: A catheter (10) including an elongate drive shaft (11) having a proximal end and a distal end. An abrasive burr (12) disposed at a distal end of the drive shaft. A stop (22) for limiting the depth of penetration of the burr disposed proximate to and proximal of the abrasive burr.

Description: ROTATING BURR PMR DEVICE AND METHOD Related Applications The present application is related to U.S. Provisional Patent Application No. 60/064,210, filed November 4, 1997, and entitled TRANSMYOCARDIAL REVASCULARIZATION GROWTH FACTOR MEDIUMS AND METHOD. The present application is also related to U.S. Patent Application Serial No. 08/812,425, filed on March 6, 1997, entitled TRANSMYOCARDIAL REVASCULARIZATION CATHETER AND METHOD. Field of the Invention The present invention relates generally to medical devices for forming holes in heart chamber interior walls in percutaneous myocardial revascularization (PMR) procedures. More specifically, the present invention relates to intravascular PMR devices having rotating burrs. Background of the Invention A number of techniques are available for treating cardiovascular disease such as cardiovascular by-pass surgery, coronary angioplasty, laser angioplasty and atherectomy. These techniques are generally applied to by-pass or open lesions in coronary vessels to restore and increase blood flow to the heart muscle. In some patients, the number of lesions are so great, or the location so remote in the patient vasculature that restoring blood flow to the heart muscle is difficult. Percutaneous myocardial revascularization (PMR) has been developed as an alternative to these techniques which are directed at by-passing or removing lesions. Heart muscle may be classified as healthy, hibernating and "dead". Dead tissue is not dead but is scarred, not contracting, and no longer capable of contracting even if it were supplied adequately with blood. Hibernating tissue is not contracting muscle tissue but is capable of contracting, should it be adequately re-supplied with blood. PMR is performed by boring channels directly into the myocardium of the heart. PMR was inspired in part by observations that reptilian hearts muscle is supplied primarily by blood perfusing directly from within heart chambers to the heart muscle. This contrasts with the human heart, which is supplied by coronary vessels receiving blood from the aorta. Positive results have been demonstrated in some human patients receiving PMR treatments. These results are believed to be caused in part by blood flowing from within a heart chamber through patent channels formed by PMR to the myocardial tissue. Suitable PMR holes have been burned by laser, cut by mechanical means, and burned by radio frequency current devices. Increased blood flow to the myocardium is also believed to be caused in part by the healing response to wound formation. Specifically, the formation of new blood vessels is believed to occur in response to the newly created wound. What would be desirable is a device capable of forming holes in the wall and reliably limiting the depth of those holes. Summary of the Invention The present invention pertains to a catheter assembly for performing percutaneous myocardial revascularization (PMR). The catheter of the present invention can be used to abrasively form holes in the myocardium of a patient's heart. The depth of the hole is controlled to a predetermined dimension. The control is provided by a stop disposed proximate to and proximally of the abrasive burr. In one embodiment of the catheter in accordance with the present invention, the catheter includes an elongate drive shaft having a proximal end and a distal end. An abrasive burr is disposed at the distal end of the drive shaft. A stop for limiting the depth of penetration of the burr is disposed proximate to and proximal of the abrasive burr. The burr can be used to form holes in the heart wall which are volumetric removals of material from the wall. The holes can be in the shape of channels which are deeper than they are wide. Alternately, the holes can be in the shape of craters which are wider than they are deep. The distance between the distal end of the burr and the stop will determine the depth of the hole whereas the diameter of the burr will determine the width of the hole. The catheter of the present invention can include an outer elongate shaft disposed around the drive shaft. The outer shaft and the drive shaft can define an annular lumen for infusion of contrast medium, growth factor or other drugs to the myocardium. In one embodiment, the drive shaft can define an elongate infusion lumen. The burr preferably includes an abrasive surface disposed distally and transversely on the burr. The burr can include a generally conical tip. In one embodiment, the abrasive burr includes a transversely extending stop disposed proximally of the tip of the burr. The stop can have a generally annular shape. In a method in accordance with the present invention, percutaneous myocardial revascularization is performed by providing a catheter having an elongate drive shaft. The drive shaft has a proximal end and a distal end. An abrasive burr is disposed at the distal end. The abrasive burr has a distal tip. The catheter includes a stop disposed proximate to and proximally of the tip. The tip is advanced to proximate the myocardium. The burr is rotated and advanced into the myocardium. Brief Description of the Drawings Figure 1 is a view of the catheter in accordance with the present invention advanced into the myocardium of the patient's heart; Figure 2 shows an embodiment of the catheter in accordance with the present invention wherein drugs are being infused therethrough; and Figure 3 shows an embodiment of the catheter in accordance with the present invention where drugs are being infused therethrough. Detailed Description of the Invention Referring now to the drawings wherein like reference numerals refer to like elements throughout the several views, Figure 1 is a view of a catheter 10 in accordance with the present invention. Catheter 10 includes an elongate drive shaft 11 having a proximal end and a distal end. An abrasive burr 12 is disposed at the distal end of the drive shaft 11. An outer sheath 13 is preferably disposed around drive shaft 11. As shown in Figure 1, burr 12 has been advanced into a heart wall 14 of a chamber 16, for example, the left ventricle. By rotation and advancement of burr 12 into wall 14, a hole 15 has been formed. It can be appreciated by those skilled in the art of catheter construction that at the proximal end of catheter 10, an appropriate manifold and motor can be provided for the rotation of drive shaft 11 and to facilitate the other uses of catheter 10 described in more detail below. Various biocompatible materials are available to construct catheter 10. One skilled in the art will be aware of various of these materials and how they could advantageously be applied to construct a catheter as described in accordance with the present invention. Tip 15, for example, may be made abrasive by applying a coating of micro fine diamond abrasive to ablate tissue such that the resultant particles are absorbed in the bloodstream to avoid forming emboli. Figure 2 is an embodiment of catheter 10 of Figure 1 in which drive shaft 11 and burr 12 define a longitudinally extending lumen 18. Lumen 18 extends from the proximal end of catheter 10 to a tip 20 of burr 12. As shown by the arrows, contrast media, growth factors or other drugs may be infused through lumen 18. Tip 20, as shown, preferably has a generally conical shape. At the opposite end of burr 12 is a stop 22. Stop 22 preferably does not include an abrasive coating. Stop 22 limits the penetration of burr 12 to form a hole 15 of a predetermined depth. Figure 3 is yet another embodiment of catheter 10 of Figure 1 in accordance with the present invention. In Figure 3, an infusion lumen 19 is defined between drive shaft 11 and outer shaft 13. As shown by the arrows, contrast media, growth factors or other drugs may be infused through lumen 19. In use, catheter 10 is advanced to a chamber of the patient's heart. Usually this will be the left ventricle. A percutaneous route to the left ventricle can be, for example, the aorta. Once catheter 10 has been advanced to the left ventricle, tip 12 is rotated and plunged into the myocardium of the patient's heart to form a plurality of holes 15. Contrast media may be infused through catheter 10 to monitor the progress of the PMR procedure. Growth factors or other drugs may also be infused during the procedure. Numerous advantages of the invention covered by this document have been set forth in the foregoing description. It will be understood, however, that this disclosure is, in many respects, only illustrative. Changes may be made in details, particularly in matters of shape, size, and arrangement of parts without exceeding the scope of the invention. The inventions's scope is, of course, defined in the language in which the appended claims are expressed.

Claims: What is claimed is: 1. A catheter, comprising: an elongate drive shaft having a proximal end and a distal end; an abrasive burr disposed at the distal end of the drive shaft; and means for limiting the depth of penetration of the burr disposed proximate to and proximal of the abrasive burr. 2. A catheter in accordance with claim 1, further comprising an outer elongate shaft disposed around the drive shaft, and defining an annular drug infusion lumen between the drive shaft and the outer shaft. 3. A catheter in accordance with claim 1, wherein the drive shaft defines an elongate drug infusion lumen. 4. A catheter in accordance with claim 1, wherein the burr includes an abrasive surface disposed distally. 5. A catheter in accordance with claim 4, wherein the burr includes an abrasive surface disposed transversely. 6. A catheter in accordance with claim 1, wherein the abrasive bun- includes a generally conical tip. 7. A PMR catheter, comprising: an elongate drive shaft having a proximal end and a distal end; an abrasive burr disposed at the distal end of the drive shaft, the burr including a distal tip and a transversely extending stop disposed proximally of the distal tip. 8. A catheter in accordance with claim 7, further comprising an outer elongate shaft disposed around the drive shaft, and defining an annular drug infusion lumen between the drive shaft and the outer shaft. 9. A catheter in accordance with claim 7, wherein the drive shaft defines an elongate drug infusion lumen. 10. A catheter in accordance with claim 7, wherein the burr includes an abrasive surface disposed distally. 11. A catheter in accordance with claim 10, wherein the burr includes an abrasive surface disposed transversely. 12. A catheter in accordance with claim 7, wherein the abrasive burr includes a generally conical tip. 13. A PMR catheter in accordance with claim 7, wherein the stop has an annular shape. 14. A method of percutaneous myocardial revascularization, comprising the steps of: providing a catheter having an elongate drive shaft, having a proximal end and a distal end, an abrasive burr disposed at the distal end, the abrasive burr having a distal tip, and the catheter including a stop disposed proximate and proximally of the tip; advancing the tip to proximate the myocardium; rotating the burr; and advancing the rotating burr into the myocardium. 15. The method in accordance with claim 14, wherein the rotating bun- is advanced repeatedly into the myocardium. 16. The method in accordance with claim 14, further comprising the step of providing the catheter with an elongate lumen. 17. The method in accordance with claim 16, further comprising the step of perfusing the drug through the lumen.

Inventors: DEVORE LAURI, DEVORE, LAURI
Applicants: BSC NORTHWEST TECHNOLOGY CENTE, BSC NORTHWEST TECHNOLOGY CENTER, INC.
Application year: 1999
Main classification: A61B17
IPC codes: A61B17, A61B19