Electrosurgical catheter and method for vascular applications

Claims

I claim:

1. An electrosurgical plaque-resolving or tissue-eroding device having a distal end which is insertable within and along the lumen of a blood vessel and manipulated therethrough to a desired position without causing undue trauma where the device is operated to thermally resolve atherosclerotic plaque buildup or erode tissue in the blood vessel to re-establish desired blood flow through the blood vessel or to remove tissue therefrom, said device comprising: an elongate flexible hollow tubular body having a distal end, a proximal end, and a diameter smaller than the diameter of the vessel into which said device is inserted; first passage means within said tubular body for supplying a flushing fluid to the site where plaque or tissue is resolved or eroded; second passage means within said tubular body for evacuating, such as by suction, debris at the site of resolving plaque or eroding tissue from the site; a hollow tip member mounted at said distal end of said flexible hollow tubular body; an electrode adjacent to and in operative association with said hollow tip member for resolving plaque or eroding tissue, said tip member being beveled or rounded at the distal end of said device; means for supplying a high-frequency electrical current to said electrode for cutting tissue or coagulating body fluid; and means for sensing, from time to time, the amount of plaque or tissue at the site in the blood vessel.

2. The device of claim 1 wherein said hollow tip member is said electrode.

3. The device of claim 2 wherein said hollow tip member is made of stainless steel.

4. The device of claim 2 wherein said electrode has the shape of a stove pipe hat having its top removed, with the brim shaped portion of said electrode being at the distal end of said device.

5. The device of claim 2 wherein said electrode is an unobstructed ring electrode positioned within said first passage means of the hollow tip member, a distal end of said ring electrode being flush with the end of said tip member.

6. The device of claim 2 wherein said electrode has the shape of a hollow mushroom including a head which is situated at the distal end of the device.

7. The device of claim 2 including an electrical insulator which has a high temperature melting point and which connects said tip member electrode to said tubular body.

8. The device of claim 7 including a ring electrode between said electrical insulator and said tubular body to form said device as a bipolar device.

9. The device of claim 7 wherein said insulator is made of a material selected from the group consisting of glass, ceramic, fluorocarbon polymers, polyimide polymers, and polyphenylene sulfide.

10. The device of claim 7 wherein said insulator has an inwardly stepped formation and said electrode is cup shaped, with a portion of its bottom removed, and is attached to a distal end of said electrical insulator with the cup walls surrounding said stepped formation.

11. The device of claim 1 wherein said electrode is covered with an ultra thin layer of insulation on the surface thereof which contacts the plaque or tissue buildup.

12. The device of claim 1 wherein said hollow tubular body is made of silicone rubber.

13. The device of claim 1 wherein said hollow tubular body is made of polyurethane.

14. The device of claim 1 wherein said hollow tubular body is made of polytetrafluoroethylene.

15. The device of claim 1 wherein said hollow tubular body is made of a polymeric substance capable of resisting softening during resolving.

16. The device of claim 1 wherein said hollow tip member is made of aluminum.

17. The device of claim 1 wherein said hollow tip member is made of tantalum.

18. The device of claim 1 wherein said hollow tip member is made of platinum.

19. The device of claim 1 wherein said high-voltage, high-frequency current supply means is capable of generating a pulsed current waveform having an intermittent group of pulses separated by periods of no current and being adapted for use in a coagulation mode of operation of said device.

20. The device of claim 19 wherein said pulsed current waveform has high voltage peaks and a low duty cycle.

21. The device of claim 1 wherein said high-voltage, high-frequency, current supply means is capable of generating a current waveform having a pure sine waveform.

22. The device of claim 1 wherein said high-voltage is several hundred volts.

23. The device of claim 1 wherein said high frequency is between 0.5 and 20 megahertz.

24. The device of claim 1 wherein said sensing means further includes radio-opaque dye and X-ray viewing means, said radio-opaque dye being injected into the blood vessel at the site and the X-ray image showing the amount of plaque remaining being displayed on said viewing means.

25. The device of claim 1 further including a third passage means for carrying at least one conductor.

26. The device of claim 25 wherein said passage means are arranged with their axes contained within the diameter of said tubular body.

27. The device of claim 21 wherein said passage means are arranged with their axes eccentric of the axis of said tubular body.

28. The device of claim 25 wherein said first passage means opens onto a cylindrical side wall surface of said tubular body at a location adjacent said tip member.

29. The device of claim 25 wherein said first passage means extends through said tip memeber and opens onto a front end surface of said tip member.

30. The device of claim 25 including a second electrode at the distal end of said tubular body.

31. The device of claim 30 wherein said tip member is made of a relatively high temperature resistance insulative material, said first electrode is mounted in said tip member and has an electrode surface on the distal end thereof, and said second electrode is a ring or sleeve electrode on said tubular body and located adjacent but rearwardly of said tip member.

32. The device of claim 30 wherein said tip member is made of a relatively high temperature resistance insulative material, and said first and second electrodes are semi-cylindrical in shape and are positioned with said tip member facing each other across the axis of said tip member.

33. The device of claim 30 including a fourth passage means for carrying a second wire conductor therein for connection to said second electrode.

34. The device of claim 25 including a trident structure at the proximal end of said tubular body, said trident structure having three legs each of which has a passageway communicating individually with a respective one of said passage means in said tubular body.

35. The device of claim 25 including a stiffening wire which extends through said first passageway for stiffening said tubular body.

36. The device of claim 1 including a collar at said distal end of said device, said collar having a bore therein and a countersunk formation in said bore, a front flat surface and an outer generally cylindrical surface said electrode being fully received within said countersunk formation having a bore therethrough which mates with and is flush with said bore of said collar, and having an annular front surface which is flush with said front surface of said collar, and said collar being beveled or rounded between the front surface and the outer surface.

37. The device of claim 1 wherein said sensing means includes means coupled to said electrode for measuring the impedance between said electrode through the plaque or tissue buildup and a current return path, the impedance measured being directly related to the amount of plaque or tissue buildup at the site.

38. The device of claim 37 wherein said impedance measuring means include means for supplying a low voltage DC current to said electrode for making the impedance measurement.

39. A cardiovascular thermal ablation device having a distal portion which is insertable into and along a lumen of a blood vessel to a desired position against an area of atherosclerotic plaque buildup or like obstruction within the lumen of the vessel without undue trauma, said device having means for thermally resolving the area of obstruction within the vessel and having means for removing resolved tissue from the area of thermal ablation, said device further comprising an elongate flexible hollow tubular body having a distal end and a proximal end; a hollow tip member mounted at said distal end of said flexible hollow tubular body; at least one electrode adjacent to and in operative association with said hollow tip member for resolving plaque or eroding tissue; said tip member being beveled or rounded at said distal end of said device; means for supplying electrical current to said electrode; means for sensing, between periods of application of electrical current to said electrode, the amount of plaque or tissue remaining to obstruct the site in the blood vessel by measuring the impedance of the plaque of tissue; means for supplying fluid to, or for supplying suction from, the site including at least one channel extending through said flexible hollow tubular body and tip member, and said device having at least one further channel, at least one wire conductor in said further channel extending proximally from said at least one electrode to said proximal end of said device and means for connecting said conductor to a source of electrical current.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a device and method for resolving or removing atherosclerotic plaque buildup or tissue in a blood vessel in order to restore necessary blood flow. The device includes a hollow catheter with a hollow tip member having an electrode for actively eroding, by means of high frequency high voltage electric current, atherosclerotic plaque areas or unwanted tissue within a blood vessel. The current generated at the electrode through the fatty material resolves the fatty material of the plaque and the residue of same may be removed through the hollow catheter.

2. Description of the Prior Art

Heretofore, various body insertable devices, such as catheters, having means for delivering impulses of electric current have been proposed for delivering electric current to internal organs, cavities or orifices of a body.

Such devices have generally been used with one electrode external of the body, and with means for delivery of irrigant fluid to or from the body.

Examples of some of the previously proposed devices are disclosed in the following patents:

______________________________________ U.S. PAT. NO. PATENTEE Re. 27,569 Ackerman 452,220 Gunning 552,832 Fort 623,022 Johnson 4,060,086 Storz 4,429,694 McGreevy ______________________________________

The McGreevy U.S. Pat. No. 4,429,694 discloses an electrosurgical generator for generating waveforms for electrosurgical fulguration.

The Ackerman U.S. Pat. No. Re. 27,569 discloses a catheter which is designed for insertion through the chest and into the heart specifically for the purpose of introduction of electrical stimulation during cardiac arrest. When the heart has ceased to beat, a generated impulse is provided which is capable of delivering electric current approximating in strength, frequency and distribution the normal current of the heart. No reference is made to a hollow catheter or to a tip thereof which can be supplied with sufficient power for removal of plaque or tissue from a blood vessel.

The Gunning U.S. Pat. No. 452,220 discloses a surgical electrode device in the form of a solid catheter composed of electrically discrete coaxially movable electrodes. The electrodes of Gunning are connected to a battery so that direct current may be introduced to an organ or part of the body after the device is inserted through a body orifice. The Gunning catheter is not hollow, does not use high frequency current and is used in a different manner and for a different purpose than the device of the present invention.

The Fort U.S. Pat. No. 552,832 discloses a catheter for treatment of strictures in body orifices, e.g. urethra, esophagus, uterus or rectum. The catheter includes one electrode in the middle of the catheter which is defined by a bowed platinum plate or wire which projects to one side of the catheter. Another electrode is applied externally to the body, for example, on the abdomen whereby current is passed through the stricture and acts "electrolytically or electrochemically thereupon". Fort does not teach a hollow electrode tip catheter which can be used for eroding tissue in vessels.

The Johnson U.S. Pat. No. 623,022 discloses a catheter which is adapted for insertion into a body cavity and which is allegedly capable of delivering an electric current to the body. The electric current was believed to have some curative powers and no reference is made in this patent to erosion of plaque or tissue in a vessel. The catheter can be used for delivering fluid into the body and the electric current allegedly flows from the catheter through the fluid into the body.

No metallic surface comes into contact with the mucous surface, and hence, the current is not concentrated at any point of contact, but is diffused by the liquid so that comparatively heavy current may be used without harm to the body parts. There is no teaching of high frequency current, bipolarity, or electro-surgery in the Johnson patent and this catheter is clearly used in an electrochemical manner and not for electrical erosion of plaque or tissue.

The Storz U.S. Pat. No. 4,060,086 discloses an endoscope which is an instrument for visually examining the inside of a hollow organ. This particular endoscope includes a loop-like electrode and has a body which is inflexible and which is not designed for use in cleaning blood vessels but which is arranged for transurethral operations. Cutting action is carried on by an inner cutting edge of the endoscope in combination with an electrically charged loop of wire which sparks. The exact mechanism and its operation are unclear. A washing agent is supplied and discharged through the endoscope.

As will be described in greater detail hereinafter, the device and method of the present invention for resolving atherosclerotic plaques and unwanted tissue differ from the devices and methods previously proposed by providing a catheter which is sized to be received in a blood vessel and which has an erosion electrode localized near a hollow tip member mounted at the distal end of the catheter. The catheter is flexible and therefore manipulatable into and through the lumen of a blood vessel and can be positioned therein proximate atherosclerotic plaque or unwanted tissue in the blood vessel. High frequency high voltage electric current is generated and supplied to the atherosclerotic plaques or tissue for a predetermined period of time to resolve the plaque or tissue. In particular, the erosion resulting from high frequency high voltage current about the electrode positioned proximate the tip of the device member actively resolves plaque or erodes tissue.

In one preferred embodiment of the device of the present invention, there is provided a tubular hollow tip member open at the distal end thereof and communicating with a flexible and elongated hollow catheter body. The eroded debris resulting from the intermittent application of high frequency high voltage current about the electrode is conveniently carried out of the catheter by a trident connection at the proximal end. In between applications of the current, a low voltage direct current is passed through the plaque or tissue for making an impedance measurement to determine if a sufficient amount of plaque has been resolved or tissue eroded.

The electrosurgical device of the present invention employs the application of electric current directly to an area of plaque or tissue buildup for resolving, ablating or removing the buildup and differs from copending U.S. application Ser. No. 536,852 filed Sept. 28, 1983 by Harold Herschenson for: PLAQUE RESOLVING DEVICE AND METHOD, which resolves plaque by heating plaque with a heat conductive member at the tip of a catheter heated by an electric coil.

SUMMARY OF THE INVENTION

According to the invention, there is provided a method for resolving atherosclerotic plaque buildup and/or eroding unwanted tissue in a blood vessel including the steps of: inserting an electrode in and along the lumen of a blood vessel; manually manipulating said electrode through the blood vessel; positioning said electrode proximate to atherosclerotic plaque buildup site or unwanted tissue site in the blood vessel; supplying a predetermined high frequency high voltage electrical current to said electrode; maintaining said predetermined current for a predetermined time period; and sensing from time to time the amount of plaque or unwanted tissue at the site.

Further, according to the invention, there is provided an electrosurgical plaque resolving or tissue eroding device adapted to be inserted within and along the lumen of a blood vessel and manipulated therethrough to a desired position where the device is operated to resolve atherosclerotic plaque buildup or erode tissue in the blood vessel to re-establish desired blood flow through the blood vessel or to remove tissue therefrom, said device comprising: an elongate flexible hollow tubular body having a distal end and a proximal end; a hollow tip member mounted at said distal end of said flexible hollow tubular body; an electrode associated with said hollow tip member for resolving plaque or eroding tissue; means for supplying a high frequency high voltage electrical current to said electrode; and means for sensing from time to time the amount of plaque or