Catheter for RF ablation with cooled electrode and method

• US 5,658,278 A
• Filed: 01/31/1995
• Issued: 08/19/1997
• Est. Priority Date: 12/01/1992
• Status: Expired due to Term

• Current Assignee: Boston Scientific Scimed, Inc. (Boston Scientific Corporation)
• Original Assignee: Cardiac Pathways Corp. (Boston Scientific Corporation)
• Inventors: Imran, Mir A., Pomeranz, Mark L.
• Primary Examiner(s): Cohen, Lee S.
• Application Number:
  US08/381,198
• Time in Patent Office: 931 Days
• Field of Search: 607/98, 607/99, 607/101, 607/102, 607/104, 607/105, 607/113, 607/116, 607/122, 606/41, 606/45, 606/49
• US Class Current: 606/41
• CPC Class Codes: A61B 18/1402 Probes for open surgery
• CPC Class Codes: A61B 18/1492 having a flexible, catheter-like structure, e.g. for heart ablation A61B18/1477 takes precedence
• CPC Class Codes: A61B 2017/00084 Temperature
• CPC Class Codes: A61B 2017/003 Steerable
• CPC Class Codes: A61B 2018/00023 closed, i.e. without wound contact by the fluid
• CPC Class Codes: A61B 2018/00029 open
• CPC Class Codes: A61B 2018/00035 with return means
• CPC Class Codes: A61B 2018/00166 Multiple lumina
• CPC Class Codes: A61B 2018/00351 Heart
• CPC Class Codes: A61B 2018/00577 Ablation
• CPC Class Codes: A61B 2018/00821 measured by a thermocouple

Abstract

A catheter for radio frequency ablation with a cooled electrode for use in tissue having a surface comprising an elongate member having proximal and distal extremities. A metal conducting electrode secured to the distal extremity of the elongate member and having a chamber therein. A conductor extends through the elongate member from the proximal to the distal extremity for supplying radio frequency energy to the electrode. The elongate member has a lumen in the distal extremity which is in communication with the chamber. A coolant is disposed in the chamber and in contact with the electrode for dissipating heat created in the electrode by the application of radio frequency energy thereto.

Claims

1. A method for creating a lesion in tissue having blood therein and having a surface by the use of an impervious metal conducting electrode having a chamber therein comprising bringing the electrode into contact with the surface of the tissue to form an electrode-surface interface, supplying radio frequency energy at a predetermined power level in excess of 10 watts to the inpervious metal conducting electrode to cause heating of the tissue in the vicinity of the surface contacted by the impervious metal conducting electrode, cooling the impervious metal conducting electrode with a cooling liquid delivered into the chamber so that the temperature in the tissue does not reach a temperature in excess of approximately 95°

C. and thereby inhibiting coagulation of blood on the impervious metal conducting electrode and making possible the formation of a wide and deep lesion in the tissue.

2. A method for controlling the temperature of an energy delivering electrode disposed on an ablation catheter for forming a lesion in tissue in an internal organ having blood therein comprising providing an ablation catheter in the form of a thin, flexible elongate member having disposed at a distal portion thereof at least one imprevious energy delivering electrode having a chamber therein, the catheter having a liquid delivering lumen associated therewith in communication with the chamber and being adapted for intravascular delivery to an internal organ and being in electrical communication with a radio frequency power supply, intravascularly delivering the catheter to an internal organ, delivering radio frequency energy in excess of 10 watts of power from the power supply through the catheter to the impervious energy delivering electrode and into the tissue, selectively delivering a cooling liquid through the lumen of the cathether into the chamber at a desired flow rate and adjusting the flow rate of the cooling liquid through the lumen of the catheter so that a wide and deep lesion is formed in the tissue while inhibiting the coagulation of blood on the electrode.

3. A method as in claim 2 wherein the step of selectively delivering cooling liquid further comprises the step of allowing the cooling liquid to exit the catheter at a distal portion thereof.

4. A method as in claim 3 wherein [the flow rate is adjusted by a ]pump means is provided for supplying the cooling liquid and further comprising the step of controlling the pump means to adjust the flow rate of the cooling liquid.

5. A method for performing an ablation in the myocardium of a heart by utilizing a catheter having a distal extremity with an impervious conductive electrode having a chamber therein mounted thereon comprising introducing the catheter into the heart so that the electrode is in contact with the myocardium, supplying radio frequency energy to the electrode at a power level in excess of 10 watts and supplying a cooling liquid to the chamber of the electrode for cooling the electrode during the time that the radio frequency energy is being supplied to the electrode and withdrawing the cooling liquid after it has cooled the electrode to make possible the formation of a wide and deep lesion in the myocardium while inhibiting the coagulation of blood on the conductive electrode.

6. A method as in claim 5 further comprising adjusting the power level so that it is between 10 and 50 watts.

7. A method as in claim 6 further comprising sensing the temperature of the tissue of the myocardium and adjusting the power level in accordance with the sensed temperature.