Apparatus for percutaneously performing myocardial revascularization having means for sensing tissue parameters and method of use

Abstract

Apparatus and methods for percutaneously performing myocardial revascularization are provided using a catheter having an end region that is directable to contact a patient's endocardium at a plurality of positions. A cutting head is disposed within a lumen of the catheter and coupled to a drive tube that rotates and reciprocates the drive shaft. One or more stabilizing elements are disposed on the distal end to retain the catheter in position when the cutting head is actuated. The cutting head and drive tube include a lumen through which severed tissue is aspirated. Mechanisms and methods are provided for providing the operator with information to assess the desirability of treating a proposed site. Mechanisms also are provided for controlling the maximum extension of the cutting head beyond a distal endface of the catheter, independent of the degree of tortuosity imposed on the catheter.

What is claimed is: 
     
       1. Apparatus for percutaneously performing myocardial revascularization comprising.
 a first catheter adapted for insertion into the left ventricle, the first catheter having a lumen and a distal endface movable to a plurality of sites on an endocardial surface;   a stabilizer element disposed on the first catheter, the stabilizer element contacting the endocardial surface to stabilize the first catheter against the endocardial surface;   a cutting head disposed movable from a retracted position within the lumen of the first catheter to an extended position wherein the cutting head extends beyond the distal endface of the first catheter to form a channel in cardiac tissue; and   means for sensing a physiologic state of cardiac tissue in a region adjacent to the distal endface of the first catheter.   
     
     
       2. The apparatus of  claim 1  wherein a distal region of the first catheter further comprises a preformed bend 
     
     
       3. The apparatus of  claim 1  wherein the first catheter further comprises a pull wire for directing the distal endface of the first catheter. 
     
     
       4. The apparatus of  claim 1  further comprising a second catheter adapted for insertion into the left ventricle, the second catheter having a preformed bend and a lumen for accepting the first catheter therethrough. 
     
     
       5. The apparatus of  claim 1  further comprising means for adjusting a maximum cutting depth of the cutting head. 
     
     
       6. The apparatus of  claim 1  wherein the stabilizer element comprises a first retractable needle. 
     
     
       7. The apparatus of  claim 6  wherein the distal end of the first catheter comprises an electrically conductive end cap, the means for sensing comprising circuitry for measuring an electrical impedance of cardiac tissue between the end cap and a reference electrode located at a remote position. 
     
     
       8. The apparatus of  claim 6  wherein the distal end of the first catheter comprises an electrically conductive end cap, and the means for sensing comprises circuitry for measuring an electrical impedance of cardiac tissue disposed between the end cap and the first retractable needle. 
     
     
       9. The apparatus of  claim 6  wherein the stabilizer element further comprises a second retractable needle, the means for sensing comprising circuitry for measuring a physiologic state of cardiac tissue disposed between the first and second retractable needles. 
     
     
       10. The apparatus of  claim 9  wherein the physiologic state comprises one of: a degree of electrical activity within the cardiac tissue or an electrical impedance of the cardiac tissue. 
     
     
       11. The apparatus of  claim 6  wherein the first retractable needle is curved towards or away from a longitudinal axis of the cutting head. 
     
     
       12. The apparatus of  claim 6  wherein the first retractable needle includes a lumen having one or more ports adapted for injecting a therapeutic agent into the cardiac tissue. 
     
     
       13. The apparatus of  claim 1  further comprising means for limiting extension of the cutting head in the extended position. 
     
     
       14. The apparatus of  claim 13  wherein the means for limiting extension comprises an electrical circuit that senses when the cutting head is disposed a predetermined distance from the distal endface of the first catheter. 
     
     
       15. The apparatus of  claim 14  wherein the electrical circuit further comprises one of: a fiber optic element, a resilient contact member, a strain gauge, a Hall effect sensor or an electrically conductive fluid 
     
     
       16. The apparatus of  claim 13  wherein the means for limiting extension further comprises monitoring circuitry for monitoring a motor parameter and generating a signal that causes movement of the cutting head towards the extended position to cease when the motor parameter exceeds a predetermined threshold. 
     
     
       17. The apparatus of  claim 1  wherein the stabilizer element comprises one of: a plurality of stabilizing members adapted to be adjusted between a contracted state and an expanded state, an inflatable member, and a plurality of sections of the first catheter that fold back on themselves when the distal endface is urged against an endocardial surface. 
     
     
       18. The apparatus of  claim 1  further comprising drive means for rotating the cutting head and a linear actuator that translates the cutting head from the retracted position to the extended position. 
     
     
       19. The apparatus of  claim 1  wherein the cutting head comprises a tubular member having a lumen through which cardiac tissue severed by the cutting head is aspirated, the cutting head further comprising one of: a stepped portion disposed between the lumen and a distal endface of the cutting head, a plurality of flutes or grooves disposed along an interior surface of the lumen, a member that projects within the lumen, and a sharpened element extending from a distal endface of the cutting element. 
     
     
       20. Apparatus for percutaneously performing myocardial revascularization comprising.
 a first catheter adapted for insertion into the left ventricle, the first catheter having a cutting head lumen, a needle lumen, and a distal endface movable to a plurality of sites on an endocardial surface;   a first needle disposed on the first catheter movable from a retracted position within the needle lumen to an extended position extending beyond a distal endface of the first catheter, the first needle contacting and penetrating the endocardial surface to stabilize the first catheter against the endocardial surface; and   a cutting head disposed movable from a retracted position within the lumen of the first catheter to an extended position wherein the cutting head extends beyond the distal endface of the first catheter to form a channel in cardiac tissue.   
     
     
       21. The apparatus of  claim 20  wherein the first needle includes a lumen having one or more ports adapted for injecting a therapeutic agent into the cardiac tissue. 
     
     
       22. The apparatus of  claim 20  wherein the distal end of the first catheter comprises an electrically conductive end cap, the apparatus further comprising sensing circuitry for measuring an electrical impedance of cardiac tissue between the end cap and a reference electrode at a remote location. 
     
     
       23. The apparatus of  claim 20  wherein the distal end of the first catheter comprises an electrically conductive end cap, the apparatus further comprising sensing circuitry for measuring an electrical impedance of cardiac tissue disposed between the end cap and the first needle. 
     
     
       24. The apparatus of  claim 20  wherein further comprising a second needle mounted for extension and retraction from the distal endface of the first catheter, the apparatus further comprising sensing circuitry for measuring a physiologic state of cardiac tissue disposed between the first and second needles. 
     
     
       25. The apparatus of  claim 24  wherein the physiologic state comprises one of: a degree of electrical activity within the cardiac tissue or an electrical impedance of the cardiac tissue. 
     
     
       26. The apparatus of  claim 20  wherein a distal region of the first catheter further comprises a preformed bend, the apparatus of further comprising a second catheter adapted for insertion into the left ventricle, the second catheter having a preformed bend and a lumen for accepting the first catheter therethrough. 
     
     
       27. The apparatus of  claim 20  further comprising means for adjusting a maximum cutting depth of the cutting head 
     
     
       28. The apparatus of  claim 20  further comprising means for limiting extension of the cutting head in the extended position. 
     
     
       29. The apparatus of  claim 20  wherein the cutting head comprises a tubular member having a lumen through which cardiac tissue severed by the cutting head is aspirated, the cutting head further comprising one of. a stepped portion disposed between the lumen and a distal endface of the cutting head, a plurality of flutes or grooves disposed along an interior surface of the lumen, a plurality of pins projecting within the lumen, a sharpened band disposed within and spanning the lumen, and a sharpened element extending from a distal endface of the cutting element. 
     
     
       30. A method of percutaneously performing revascularization of a patient's cardiac tissue, the method comprising:
 providing a first catheter adapted for insertion into the left ventricle comprising a stabilizer element and a cutting head movable from a retracted position to an extended position;   advancing a distal region of the first catheter transluminally to a position within a patient's left ventricle;   deploying the stabilizer element to stabilize the distal region of the first catheter in contact with an endocardial surface;   sensing a physiologic state of cardiac tissue in a portion of the cardiac tissue adjacent to the distal endface of the first catheter; and   if it is determined that myocardial revascularization in the portion of cardiac tissue adjacent to the distal endface would have a beneficial effect, advancing the cutting head from the retracted to the extended position to bore a channel into the patient's cardiac tissue.   
     
     
       31. The method of  claim 30  wherein the stabilizer element comprises a first retractable needle and deploying the stabilizer element comprises advancing the first retractable needle to penetrate into the patient's cardiac tissue. 
     
     
       32. The method of  claim 31  wherein the distal end of the first catheter comprises an electrically conductive end cap, and sensing a physiologic state further comprises measuring an electrical impedance of cardiac tissue between the end cap and a reference electrode located at a remote location. 
     
     
       33. The method of  claim 32  wherein the distal end of the first catheter comprises an electrically conductive end cap, and sensing a physiologic state further comprises measuring an electrical impedance of cardiac tissue disposed between the end cap and the first retractable needle. 
     
     
       34. The method of  claim 33  further comprising comparing a measured value of electrical impedance of the cardiac tissue to a predetermined threshold to decide whether to advance the cutting head or re-position the first catheter. 
     
     
       35. The method of  claim 31  wherein the stabilizer element further comprises a second retractable needle, and sensing a physiologic state further comprises measuring a physiologic state of cardiac tissue disposed between the first and second retractable needles. 
     
     
       36. The method of  claim 35  wherein measuring a physiologic state comprises measuring one of: a degree of electrical activity within the cardiac tissue or an electrical impedance of the cardiac tissue. 
     
     
       37. The method of  claim 36  further comprising determining a degree of infarction based on the measured value of the physiologic state of the cardiac tissue. 
     
     
       38. The method of  claim 31  wherein the first retractable needle includes a lumen having one or more ports, the method further comprising injecting a therapeutic agent into the cardiac tissue through the lumen via the one or more ports. 
     
     
       39. The method of  claim 31  further comprising aspirating cardiac tissue severed by the cutting head. 
     
     
       40. A method of percutaneously performing revascularization of a patient's cardiac tissue, the method comprising:
 providing a first catheter adapted for insertion into the left ventricle comprising a first needle movable from a retracted position to an extended position and a cutting head movable from a retracted position to an extended position;   advancing a distal region of the first catheter transluminally to a position within a patient's left ventricle;   advancing the first needle to the extended position to penetrate and stabilize the distal region of the first catheter in contact with an endocardial surface;   rotating the cutting head; and   advancing the cutting head from the retracted to the extended position to bore a channel into the patient's cardiac tissue.   
     
     
       41. The method of  claim 40  wherein the first needle includes a lumen having one or more ports, the method further comprising injecting a therapeutic agent into the cardiac tissue through the lumen via the one or more ports. 
     
     
       42. The method of  claim 40  wherein the first catheter further comprises a second needle movable from a retracted position to an extended position, the method further comprising measuring a physiologic state of cardiac tissue disposed between the first and second needles. 
     
     
       43. The method of  claim 42  wherein measuring a physiologic state comprises measuring one of: a degree of electrical activity within the cardiac tissue or an electrical impedance of the cardiac tissue. 
     
     
       44. The method of  claim 42  further comprising determining a degree of infarction based on the measured value of the physiologic state of the cardiac tissue. 
     
     
       45. The method of  claim 40  further comprising aspirating cardiac tissue severed by the cutting head. 
     
     
       46. An apparatus comprising:
 a first catheter adapted for percutaneous insertion into a cardiac tissue, the first catheter having a needle lumen with a longitudinal axis, a stabilizer lumen radially offset from the needle lumen, and a distal endface steerable to a plurality of sites on the cardiac tissue relative to another portion of the first catheter proximal to the distal endface;   a needle disposed within the needle lumen while in a retracted position, the needle moveable from the retracted position, through the distal endface, to an external position beyond the distal endface in which the needle extends in alignment with the longitudinal axis of the needle lumen from the distal endface to a distal tip of the needle, the needle having at least one lumen to inject a therapeutic agent into the cardiac tissue;   a stabilizer element to stabilize the first catheter against the cardiac tissue, the stabilizer element moveable through the stabilizer lumen from an unextended position to an extended position, wherein the stabilizer element is disposed within the stabilizer lumen while in the unextended position, and wherein the stabilizer element angles in a distal direction while in the extended position; and   a second catheter adapted for insertion into a left ventricle, the second catheter having a preformed bend and an inner lumen for receiving movement of the first catheter therethrough.    
     
     
       47. The apparatus of claim 46, wherein the stabilizer element comprises at least one wire.  
     
     
       48. The apparatus of claim 47 wherein the at least one wire is responsible for stabilizing the distal endface against the cardiac tissue.  
     
     
       49. The apparatus of claim 46, wherein the cardiac tissue is an intraventricular wall.  
     
     
       50. The apparatus of claim 46, wherein a distal region of the first catheter further comprises a preformed bend.  
     
     
       51. The apparatus of claim 46, wherein the stabilizer element is configured to retain the distal endface of the first catheter against a surface of the cardiac tissue and includes a surface parallel to the first catheter.  
     
     
       52. The apparatus of claim 46 wherein the stabilizer element is configured to retain the distal endface of the first catheter against a surface of the cardiac tissue to ensure that the needle is stable relative to the cardiac tissue when injecting a therapeutic agent into the cardiac tissue.  
     
     
       53. The apparatus of claim 46 wherein the needle can advance to different depths into the cardiac tissue.  
     
     
       54. An apparatus comprising:
 a first catheter adapted for percutaneous insertion into a cardiac tissue, the first catheter having a preformed bend, a needle lumen with a longitudinal axis, a stabilizer lumen radially offset from the needle lumen, and a distal endface steerable to a plurality of sites on the cardiac tissue relative to another portion of the first catheter proximal to the distal endface;   a needle disposed within the needle lumen while in a retracted position, the needle moveable from the retracted position, through the distal endface, to an external position beyond the distal endface in which the needle extends in alignment with the longitudinal axis of the needle lumen from the distal endface to a distal tip of the needle, the needle having at least one lumen to inject a therapeutic agent into the cardiac tissue;   a stabilizer element to stabilize the first catheter against the cardiac tissue, the stabilizer element moveable through the stabilizer lumen from an unextended position to an extended position, wherein the stabilizer element is disposed within the stabilizer lumen while in the unextended position, and wherein the stabilizer element angles in a distal direction while in the extended position; and   a second catheter adapted for insertion into a left ventricle, the second catheter having a preformed bend and an inner lumen for receiving movement of the first catheter therethrough.    
     
     
       55. The apparatus of claim 54 wherein the stabilizer element is configured to retain the distal endface of the first catheter against a surface of the cardiac tissue and includes a surface parallel to the first catheter.  
     
     
       56. An apparatus comprising:
 a first catheter adapted for percutaneous insertion into a cardiac tissue, the first catheter having a needle lumen with a longitudinal axis, a stabilizer lumen radially offset from the needle lumen, and a distal endface steerable to a plurality of sites on the cardiac tissue relative to another portion of the first catheter proximal to the distal endface;   a needle disposed within the needle lumen while in a retracted position, the needle moveable from the retracted position, through the distal endface, to an external position beyond the distal endface in which the needle extends in alignment with the longitudinal axis of the needle lumen from the distal endface to a distal tip of the needle, the needle having at least one lumen to inject a therapeutic agent into the cardiac tissue; and   a stabilizer element to stabilize the first catheter against the cardiac tissue, the stabilizer element moveable through the stabilizer lumen from an unextended position to an extended position, wherein the stabilizer element is disposed within the stabilizer lumen while in the unextended position, and wherein the stabilizer element angles in a distal direction while in the extended position.    
     
     
       57. The apparatus of claim 56 wherein the stabilizer element is configured to retain the distal endface of the first catheter against a surface of the cardiac tissue and includes a surface parallel to the first catheter.