Transurethral radio frequency apparatus for ablation of the prostate gland and method

• US 5,957,922 A
• Filed: 09/12/1997
• Issued: 09/28/1999
• Est. Priority Date: 06/10/1993
• Status: Expired due to Term

• Current Assignee: Vidamed, Inc. (Medtronic Plc)
• Original Assignee: Vidamed, Inc. (Medtronic Plc)
• Inventors: Imran, Mir A.
• Primary Examiner(s): PEFFLEY, MICHAEL F
• Application Number:
  US08/933,622
• Time in Patent Office: 746 Days
• Field of Search: 606/29-31, 606/41, 606/42, 606/45-50, 607/100-105, 607/122
• US Class Current: 606/41
• 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 2017/00026 Conductivity or impedance, e.g. of tissue
• CPC Class Codes: A61B 2017/00084 Temperature
• CPC Class Codes: A61B 2017/00274 Prostate operation, e.g. prostatectomy, turp, bhp treatment
• CPC Class Codes: A61B 2017/00292 mounted on or guided by flexible, e.g. catheter-like, means
• CPC Class Codes: A61B 2018/00023 closed, i.e. without wound contact by the fluid
• CPC Class Codes: A61B 2018/00083 low, i.e. electrically insulating
• CPC Class Codes: A61B 2018/00505 Urinary tract
• CPC Class Codes: A61B 2018/00547 Prostate
• CPC Class Codes: A61B 2018/00577 Ablation
• CPC Class Codes: A61B 2018/00642 with feedback, i.e. closed loop control
• CPC Class Codes: A61B 2018/00702 Power or energy
• CPC Class Codes: A61B 2018/00791 Temperature
• CPC Class Codes: A61B 2018/00815 measured by a thermistor
• CPC Class Codes: A61B 2018/00827 Current
• CPC Class Codes: A61B 2018/00875 Resistance or impedance
• CPC Class Codes: A61B 2018/1253 monopolar
• CPC Class Codes: A61B 2018/1273 including multiple generators in one device
• CPC Class Codes: A61B 2018/1497 Electrodes covering only part of the probe circumference

Abstract

A transurethral radio frequency apparatus for ablation of the prostate gland through the urethra formed by a wall, a probe consisting of a flexible elongate tubular member with proximal and distal extremities and sized so as to be adapted to be inserted into the urethra, and an ablation electrode carried by the distal extremity of the flexible elongate member. The flexible elongate tubular member is provided with first and second flow lumens for delivering a cooled fluid to the ablation electrode to cool the same. Means are connected to the probe to supply a coolant solution to the probe, to supply radio frequency energy to the electrode while it is being cooled, and to monitor the temperature of the ablation electrode so that the ablation electrode is maintained at a temperature below a predetermined temperature to spare the urethral wall from irreversible damage from the radio frequency energy delivered to the ablation electrode.

Claims

1. A transurethral radio frequency apparatus for ablation of target tissue beyond a wall by the use of radio frequency energy comprising a probe consisting of an elongate tubular member having proximal and distal extremities, a cylindrical sleeve ablation electrode carried by the distal extremity of the flexible elongate member, the flexible elongate tubular member being provided with a first flow lumen in communication with the ablation electrode, cooling means connected to the probe for supplying a cooling fluid to the first flow lumen, means connected to the probe for supplying radio frequency energy to the ablation electrode while it is being cooled, temperature monitoring means for monitoring the temperature of the ablation electrode and means coupled to the temperature monitoring means and to the cooling means for controlling the supply of cooling fluid so that the ablation electrode is maintained at a temperature below a predetermined temperature to spare the wall from irreversible damage while radio frequency energy is being delivered to the ablation electrode to ablate the target tissue.

2. Apparatus as in claim 1 wherein said temperature monitoring means includes means for controlling the application of radio frequency energy to the ablation electrode so that the ablation electrode does not rise above the predetermined temperature.

3. Apparatus as in claim 2 wherein said temperature monitoring means includes automatic means for controlling the temperature so that the temperature of the wall does not exceed a temperature ranging from 37-40°

C.

4. Apparatus as in claim 1 wherein the impedance of the target tissue differs from the impedance of the surrounding tissue together with impedance measuring means carried by the distal extremity of the elongate tubular member and providing an electrical signal and means coupled to said electrical signal remote from the probe for displaying the impedance being measured whereby the position of the probe with respect to the target tissue can be ascertained.

5. Apparatus as in claim 4 wherein said impedance measuring means includes first and second pairs of spaced-apart impedance sensing electrodes carried by the distal extremity of the elongate tubular member and means for supplying radio frequency constant current energy of less than 10 milliamperes to the impedance sensing electrodes.

6. Apparatus as in claim 5 wherein at least one pair of said first and second pairs of impedance sensing electrodes includes first and second circumferentially spaced-apart impedance sensing electrodes carried by the distal extremity of the flexible elongate tubular member.

7. Apparatus as in claim 6 wherein the first pair of impedance sensing electrodes is spaced-apart by approximately 90°

from the second pair of impedance sensing electrodes.

8. A method for radio frequency ablation of target tissue beyond a wall by the use of a probe having a distal extremity and having a cylindrical sleeve ablation electrode carried by the distal extremity comprising supplying radio frequency energy to the ablation electrode to cause radio frequency energy to be introduced through the wall and into the target tissue and cooling the electrode while radio frequency energy is being applied to the same to maintain the temperature of the electrode at a temperature below 50°

C.

9. A method as in claim 8 wherein the temperature of the electrode is maintained at a temperature of approximately 37-40°

C.

10. A method as in claim 8 further including the step of sensing the impedance of tissue encountered by the cylindrical sleeve ablation electrode and to determine when a predetermined impedance has been reached and positioning the probe in the tissue in accordance with the predetermined impedance sensed.

11. A method as in claim 10 further including the step of controlling the application of radio frequency power to the electrode to cause ablation of the target tissue to a depth of approximately one centimeter.