Method and apparatus for thwarting thrombosis

• US 5,603,731 A
• Filed: 11/03/1995
• Issued: 02/18/1997
• Est. Priority Date: 11/21/1994
• Status: Expired due to Fees

• Current Assignee: Douglass G. Whitney
• Original Assignee: Douglass G. Whitney
• Inventors: Whitney, Douglass G.
• Primary Examiner(s): Sykes, Angela D.
• Assistant Examiner(s): HUANG, STEPHEN D
• Application Number:
  US08/553,011
• Time in Patent Office: 473 Days
• Field of Search: 607/119-122, 607/126, 606/7, 606/32, 606/33, 606/41, 606/191, 606/195, 606/38, 604/20, 604/21, 604/96-99, 604/103, 604/104, 604/32, 604/33, 604/41, 623/1
• US Class Current: 607/121
• CPC Class Codes: A61F 2/064 with special features to facilitate anastomotic coupling anastomosis of natural blood vessels A61B17/11
• CPC Class Codes: A61F 2/90 characterised by a net-like or mesh-like structure
• CPC Class Codes: A61F 2/958 Inflatable balloons for placing stents or stent-grafts
• CPC Class Codes: A61F 2002/30107 using materials or accessories for preventing galvanic or electrolytic corrosion
• CPC Class Codes: A61F 2210/0009 using materials or accessories for preventing galvanic or electrolytic corrosion
• CPC Class Codes: A61M 2025/109 having balloons for removing solid matters, e.g. by grasping or scraping plaque, thrombus or other matters that obstruct the flow
• CPC Class Codes: A61M 25/104 used for angioplasty

Abstract

Thrombosis in a blood vessel is prevented in a patient'"'"'s body by the steps of positioning an electrically conductive member in an expanded portion of the blood vessel, at a site where the body is exposed to blood platelets, and disposing an electronegative potential generator in or adjacent to the patient'"'"'s body and connected to the conductive member for maintaining a negative bias on the conductive member. One form of generating the negative bias is by passing microwaves through the patient'"'"'s body to contact an embedded diode which generates the negative potential. The current density is maintained at about 50 milliamps per square centimeter.

Claims

1. A method of preventing thrombosis at a site, in a patient'"'"'s body exposed to platelets, on which site the body has imposed an electropositive current of injury charge, said method comprising the steps of:

(a) positioning within said patient'"'"'s body an electrically conductive member having first and second portions insulated from each other, and a remotely actuatable electrical potential generator capable of producing an electropositive potential and an electronegative potential, said potential generator being electrically coupled to said conductive member to induce, when activated, an electronegative potential on said first portion of said conductive member and an electropositive potential on said second portion of said conductive member;

(b) electrically connecting said second portion of said conductive member to said patient'"'"'s body and exposing said first portion of said conductive member to said site and to said platelets;

(c) imposing an actuation signal through said patient'"'"'s body and onto said electrical potential generator for activating said generator to produce an electropositive potential and an electronegative potential, said electronegative potential being sufficient to offset the electropositive current of injury imposed on the site by the patient'"'"'s body;

(d) said activation signal being predetermined to maintain a current density of about 50 milliamps per square centimeter on said first portion of said conductive member.

2. A method of preventing thrombosis in a patient'"'"'s body exposed to blood platelets by expanding the narrowed portion of a blood vessel in the patient, said blood vessel having an interior surface, comprising the steps of:

(a) positioning an electrically conductive member with a microscopic electronegative potential generator connected thereto so that said conductive member substantially covers a portion of said interior surface, said generator being constructed and arranged to cause an electrical potential to be generated thereacross in response to an activation signal generated remotely of but imposed on said electronegative potential generator;

(b) after said conductive member is substantially covering said portion of said interior surface, imposing said activation signal on said electronegative potential generator through the patient'"'"'s body to cause said electronegative generator to maintain an electronegative potential on said conductive member sufficient to thwart blood platelet congregation around said conductive member; and

(c) said conductive member being a stent capable of being nonelastically expanded and wherein step (a) comprises the substeps of;

(a1) locating said stent over a collapsed balloon of a balloon catheter where the stent has an initial diameter smaller than the narrowed portion of the blood vessel;

(a2) inserting the balloon catheter into the narrowed portion of the blood vessel until the collapsed balloon on the catheter is in registration with the narrowed portion of the blood vessel while holding the stent in position over the collapsed balloon of the catheter; and

(a3) inflating the collapsed balloon to forcibly enlarge the narrowed portion of the blood vessel and nonelastically enlarge the stent into contact with the narrowed portion of the blood vessel;

wherein the step (b) further includes;

(b1) imposing said activation signal on said electronegative generator to maintain an electronegative potential on the stent at least to offset the current of injury potential generated as a result of expanding the blood vessel; and

(b2) imposing microwaves on said microwave detector diode so as to maintain a current density of about 50 milliamps per square centimeter on the interior surface of the blood vessel.

3. A system for thwarting blood platelet congregation at an injured site in a patient'"'"'s body wherein said body generates a current of injury charge to electrically attract blood platelets to said site, said system comprising:

(a) an electrically conductive member disposed in said patient'"'"'s body adjacent to said injured site for holding said injured site in a healing position;

(b) a microscopic electronegative potential generator disposed within the body of said patient and electrically connected to said conductive member, said generator being adapted to impose an electronegative potential on said conductive member, said microscopic electronegative potential generator being adapted to receive activation signals while embedded in said patient'"'"'s body, and means for generating an activation signal through said patient'"'"'s body for causing said electronegative potential generator to be actuated to impose a sufficient electronegative potential on said conductive member to thwart blood platelet congregation at said injured site;

(c) said generator also generating an electropositive potential delivered to said body;

(d) said site being a blood vessel having an interior through which blood passes and wherein said electrically conducting member is an expandable stent disposed in expanded condition against the interior of said blood vessel holding said blood vessel in an expanded condition, said stent having portions insulated from each other and to which said electropositive potential and said electronegative potential are respectively fed;

(e) said insulated portions of said stent including a central portion coupled to receive said electronegative potential and end portion coupled to receive said electropositive potential;

(f) said end portion having outwardly protruding electrically conductive prongs.

4. A method of preventing thrombosis at a site in a patient'"'"'s body exposed to platelets, on which site the body has imposed an electropositive current of injury charge, said method comprising the steps of:

(a) positioning within said patient'"'"'s body an electrically conductive member and an electronegative potential generator, electrically connected to said conductive member, said conductive member having a first portion and a second portion insulated from each other;

(b) electrically connecting said positive portion to said patient'"'"'s body and exposing said negative portion to said site and to said platelets;

(c) imposing an actuation signal through said patient'"'"'s body and onto said electronegative potential generator for activating said electronegative generator to produce an electropositive charge and an electronegative charge;

(d) imposing said electropositive charge on said first portion and said electronegative charge on said second portion sufficient that the charge on said second portion sufficiently will offset the electropositive current of injury charge imposed on said site;

(e) said electrically conductive member comprising a tubular stent having a central portion and an end portion and wherein said first portion is said central portion and said second portion is said end portion of said stent; and

(f) prongs protruding outwardly from said conductive member.

5. A thrombosis thwarting stent for buttressing an injured section of an artery of a patient and preventing congregation of blood platelets at the injured section of the artery, the artery having an artery wall, said stent comprising:

a substantially tubular electrically conductive body sized to be received within and bear against the artery for buttressing the artery against collapse;

a remotely actuatable electrical potential generator for generating an electronegative charge and an electropositive charge, said generator being incorporated into said tubular body so as not to restrict flow of blood through the artery when the tubular body is positioned therein;

first coupling means for coupling said generator to said conductive body to impart, upon activation of said generator, an electronegative charge to said conductive body; and

second coupling means for coupling said generator to a selected location of the artery wall to impart, upon activation of said generator, an electropositive charge to the artery wall.

6. A stent as claimed in claim 5 and wherein said second coupling means comprises at least one prong projecting radially from said conductive body and electrically insulated therefrom, said prong being sized to extend into the artery wall when the stent is in place within the artery.

7. A stent as claimed in claim 6 and wherein said conductive body comprises a central portion and an end portion electrically insulated from each other and wherein said at least one prong projects radially from said end portion.

8. A stent as claimed in claim 5 and wherein said electrical potential generator comprises a microwave detector diode that generates an electrical potential thereacross in response to microwaves being imposed thereon.

9. A stent as claimed in claim 8 and further comprising means for limiting the electrical potential generated by said microwave detector diode to a predetermined maximum potential.

10. A stent as claimed in claim 9 and wherein said means for limiting comprises a zener diode array connected in series with said microwave detector diode.

11. A stent as claimed in claim 8 and further comprising means outside the patient'"'"'s body for generating microwaves and imposing the microwaves through the patient'"'"'s body and on said microwave detector diode to activate said diode to produce an electrical potential.