ELECTROSURIGICAL INSTRUMENT AND METHOD

• US 20090281535A1
• Filed: 03/18/2009
• Published: 11/12/2009
• Est. Priority Date: 10/22/2001
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: VNUS Medical Technologies Incorporated (Medtronic Plc)
• Inventors: Shadduck, John H., Truckai, Csaba
• Granted Patent: US 8,192,428 B2
• Time in Patent Office: Days
• US Class Current: 606/33
• CPC Class Codes: A61B 18/1442 Probes having pivoting end effectors, e.g. forceps
• 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 2018/00077 high, i.e. electrically conducting
• CPC Class Codes: A61B 2018/00083 low, i.e. electrically insulating
• CPC Class Codes: A61B 2018/00148 with metal
• CPC Class Codes: A61B 2018/00404 Blood vessels other than those in or around the heart
• CPC Class Codes: A61B 2018/0063 Sealing
• CPC Class Codes: A61B 2018/00702 Power or energy
• CPC Class Codes: A61B 2018/00809 measured thermochromatically
• CPC Class Codes: A61B 2090/064 for measuring force, pressure or mechanical tension

Abstract

An electrosurgical instrument and method for treating varicose veins. In one embodiment, an elongate catheter has a distal working end that carries an electrosurgical energy delivery surface comprising at least one electrode with a positive temperature coefficient of resistance (PTCR) surface and/or an electrode with a pressure sensitive variable resistance to provide a smart surface for controlling Rf current flow at the interface of electrosurgical surface and the tissue. The electrode surface then can limit or modulate Rf energy delivery through the surface in response to the temperature of the surface or the engagement pressure of the surface against the engaged tissue. In operation, the smart electrosurgical surface prevents arcing at the electrode-tissue interface, and thus controls ohmic heating to prevent tissue desiccation, charring and emboli formation.

Claims

1. A method for delivering energy to endoluminal tissue, comprising the steps of:

providing a catheter configured for endoluminal navigation, a catheter working end having an electrosurgical surface including a positive temperature coefficient of resistance (PTCR) material carried in the surface;

engaging endoluminal tissue with the electro surgical surface; and

delivering Rf current to the endoluminal tissue wherein said Rf current flows are limited by changes in temperature in at least portions of the PTCR material to prevent arcing.

2. The method of claim 1, wherein delivering Rf current shrinks the endoluminal tissue.

3. The method of claim 1, wherein delivering Rf current causes ohmic tissue heating.

4. The method of claim 1, wherein the engaging step includes moving the electro surgical surface from a first shape to a second expanded shape.

5. The method of claim 1, wherein the engaging step includes translating the electro surgical surface axially within the lumen.

6. The method of claim 1, wherein delivering Rf current is carried out in at least one of a bi-polar manner and a mono-polar manner.

7. The method of claim 1, wherein delivering Rf current is carried out between spaced apart opposing polarity electrodes with a predetermined center-to-center dimension for controlling the depth of ohmic heating.

8. The method of claim 1, wherein delivering Rf current is switched between groups of spaced apart electrodes for selecting a depth of ohmic heating.

9. The method of claim 1, wherein delivering Rf current flows substantially closes a lumen.

10. The method of claim 1, wherein engaging endoluminal tissue includes moving the electro surgical surface from a first cross-sectional shape for endoluminal navigation to a second expanded cross-sectional shape.

11. The method of claim 1, wherein delivering Rf current includes translating the electro surgical surface axially within the lumen.

12. The method of claim 1, wherein the Rf current flows are between spaced apart opposing polarity electrodes coupled to the PTCR material.

13. An electrosurgical method for applying energy to endovascular tissue, the method comprising:

engaging tissue with at least one Rf energy delivery surface, the at least one surface including at least one positive temperature coefficient of resistance (PTCR) body having a switching temperature; and

delivering bi-polar or mono-polar Rf current from the at least one energy delivery surface to ohmically heat the tissue, wherein the PTCR body is utilized to i) limit Rf current flow to tissue adjacent regions of the PTCR body that reach the switching temperature and ii) allow Rf current flow within tissue adjacent regions of the PTCR body that thermally relax from said switching temperature.

14. An electro surgical method for applying energy to endovascular tissue, the method comprising:

engaging tissue with at least one Rf energy delivery surface, the at least one surface including pressure sensitive variable resistance; and

delivering bi-polar or mono-polar Rf current from the at least one energy delivery surface to ohmically heat the tissue, wherein the pressure sensitive variable resistance material is utilized to allow Rf current flow only to tissue adjacent regions of said material that is under a selected level of engagement pressure.