Selectable Eccentric Remodeling and/or Ablation of Atherosclerotic Material

Abstract

A catheter and catheter system for eccentric remodeling and/or removal of atherosclerotic material of a blood vessel of a patient include an elongate flexible catheter body with a radially expandable structure. A plurality of electrodes or other electrosurgical energy delivery surfaces can radially engage atherosclerotic material when the structure expands. An atherosclerotic material detector near the distal end of the catheter body may measure circumferential atherosclerotic material distribution, and a power source selectively energizes the electrodes to eccentrically remodel the measured atherosclerotic material.

1 . A system for remodeling of tissue about a blood vessel of a patient, the system comprising:
 an elongate catheter body having a proximal end and a distal end with an axis therebetween for delivery into the blood vessel;   a radially expandable structure near the distal end of the catheter body;   a plurality of electrodes supported by the expandable structure so as to be urged radially outward and engage a luminal wall of the blood vessel when the expandable structure expands therein; and   a power source electrically coupled to the electrodes, the power source configured for energizing the electrodes so as to remodel the tissue.   
     
     
         2 . The system of  claim 1 , wherein the electrodes comprise circumferentially and axially offset RF bipolar electrode pairs, and the system further comprises:
 a controller coupling the power source to the electrodes so as to deliver RF energy with the circumferentially and axially offset bipolar electrode pairs.   
     
     
         3 . The system of  claim 2 , wherein the controller couples the power source to the electrodes so that each bipolar electrode pair comprises a circumferentially adjacent pair of electrodes. 
     
     
         4 . The system of  claim 2 , wherein the bipolar electrode pairs alternate between axially and circumferentially offset electrodes. 
     
     
         5 . The system of  claim 2 , wherein RF energy delivery is controlled so as to heat the tissue material to a temperature in a range from about 40 to about 90° C. 
     
     
         6 . The system of  claim 2 , wherein heating of the tissue is controlled so as to limit a temperature of a layer of the blood vessel to below about 63° C. 
     
     
         7 . The system of  claim 1 , wherein the radially expandable structure comprises a balloon, the electrodes being mounted on an outer surface of the balloon. 
     
     
         8 . The system of  claim 7 , wherein the power source is configured to selectively energize pairs of the electrodes. 
     
     
         9 . The system of  claim 1 , wherein the electrodes comprise an array of at least three alternatively selectable electrodes distributed circumferentially about the axis. 
     
     
         10 . The system of  claim 1  further comprising:
 a controller coupling the power source to the electrodes, the controller configured to selectively energize a subset of the electrodes. 
 
     
     
         11 . The system of  claim 10  wherein the controller is configured to energize the subset of electrodes in response to impedance measurements. 
     
     
         12 . The system of  claim 10 , wherein the controller is configured so as to direct energy delivery eccentrically without rotating the electrodes about the axis by selectively energizing the electrodes. 
     
     
         13 . The system of  claim 10  further comprising:
 one or more temperature sensors configured to provide temperature measurement for use in control of energy delivery from the electrodes. 
 
     
     
         14 . The system of  claim 13 , wherein the temperature sensors comprise thermocouples configured to provide tissue temperature measurements or treatment temperature measurements. 
     
     
         15 . The system of  claim 14 , wherein the power source comprises an RF energy source coupled to a plurality of bipolar electrode pairs of the electrodes, each of the thermocouples being coupled to the RF energy source. 
     
     
         16 . The system of  claim 13 , wherein the controller is configured so that energy delivery with the electrodes is controlled using temperature feedback. 
     
     
         17 . The system of  claim 1 , wherein the power source is configured so that the RF energy supplied includes bursts of RF energy. 
     
     
         18 . The system of  claim 1 , wherein the controller is configured to direct the RF energy to differing electrodes with differing power or duration. 
     
     
         19 . The system of  claim 1 , wherein the controller is configured to direct RF energy to differing electrodes according to a duty cycle. 
     
     
         20 . The system of  claim 1 , wherein the blood vessel comprises an artery, the system further comprising:
 a material detector disposed for circumferential measurement of the artery wall.   
     
     
         21 . A system as in  claim 1 , further comprising:
 a processor coupling the electrodes to the power supply, the processor being configured to measure a characteristic of the material when the electrodes are in contact with the material.   
     
     
         22 . A system for eccentric remodeling of a tissue material about a body lumen of a patient, the system comprising:
 a catheter having a distal balloon for delivery into a blood vessel;   an array of electrodes mounted on a surface of the balloon and distributed circumferentially about the balloon, wherein the electrodes are configured for use in selected pairs; and   an RF power source supply coupled with the electrodes and configured to deliver controlled remodeling energy to the tissue material by energizing selected pairs of the electrodes with bipolar remodeling energy so as to remodel the tissue material while limiting collateral tissue damage.   
     
     
         23 . The system of  claim 22 , further comprising:
 a controller for implementing selection of the electrode pairs for energizing with the RF power source.   
     
     
         24 . A method for eccentrically remodeling a tissue material about a body lumen, the method comprising:
 positioning a working end of a balloon catheter within the body lumen, the catheter defining an axis;   radially expanding the balloon so as to urge a plurality of electrodes mounted on a surface of the balloon radially outward so as to directly engage a luminal wall; and   delivering controlled remodeling energy to the tissue material from the engaged electrodes by energizing selected pairs of the electrodes to direct RF energy so as to remodel the tissue material while limiting collateral tissue damage.   
     
     
         25 . The method of  claim 24  wherein the body lumen comprises an artery, the method further comprising:
 circumferentially measuring an artery wall with the electrodes to measure a characteristic of the tissue engaged by the electrodes; and 
 directing energy to energize differing pairs of electrodes with the remodeling energy in response to the circumferential measurements. 
 
     
     
         26 . The method of  claim 24  wherein the remodeling energy is delivered so as to heat the tissue material to a temperature in a range from about 40° C. to about 90° C. 
     
     
         27 . The method of  claim 26  wherein delivery of remodeling energy is controlled using tissue temperature or treatment temperature measurements provided by a plurality of temperature sensing structures. 
     
     
         28 . The method of  claim 26 , wherein delivery of remodeling energy is controlled so as to limit a temperature of a layer of the body lumen to below about 63° C.