Removable endocardial lead

• US 5,231,996 A
• Filed: 01/28/1992
• Issued: 08/03/1993
• Est. Priority Date: 01/28/1992
• Status: Expired due to Fees

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Williams, Terrell W., Bardy, Gust H., Thornton, Arnold W., Cannon, Norbert H.
• Primary Examiner(s): Howell, Kyle L.
• Assistant Examiner(s): SCHAETZLE, KENNEDY
• Application Number:
  US07/827,121
• Time in Patent Office: 553 Days
• Field of Search: 128/783, 128/784, 128/785, 128/786, 128/642, 128/419 P, 606/1, 606/106, 606/108
• US Class Current: 607/126
• CPC Class Codes: A61N 1/056 Transvascular endocardial electrode systems

Abstract

In a coiled wire medical lead structure, such as a transvenous, endocardial cardiac pacemaker and/or cardioverter/defibrillator lead, an improved mechanical structure for strengthening the lead to enable its intact removal by traction after a period of chronic implant, one or more normally relaxed, nonextensible filaments loosely contained within the insulating sheath and having proximal and distal ends mechanically coupled to the connector and electrode shank, respectively, of the lead operate as means for restraining the stretching of the lead body to a stretched length exceeding the relaxed, predetermined length by an amount sufficient to allow the lead to be stretched without breaking in its normal usage and during removal by traction. In certain embodiments, the filament may take the form of a loosely woven fabric sheath formed in a tubular shape and fitted in the space between the lead body outer sheath and one or more coiled wire conductors. The filament(s) or woven sheath may be embedded within or on the interior surface of the outer insulating sheath or an inner insulating sheath of a bipolar or multipolar lead.

Claims

1. In an elongated electrical medical lead for use with a pulse generator to be implanted within a human body,

(a) said lead having a proximal and distal lead end and further comprising:

(1) an outer insulating sheath having a relaxed predetermined sheath length between a proximal and distal sheath end thereof, said sheath being capable of lengthening under tension;

(2) at least one conductor positioned within said outer insulating sheath and extending between said proximal and distal sheath ends thereof, each of said at least one conductor having a relaxed predetermined conductor length between a proximal and distal conductor end thereof, and each of said at least one conductor being capable of lengthening under tension;

(3) a connector interconnecting said proximal sheath end with said proximal conductor end of each of said at least one conductor therein, said connector for providing an electrical connection to said implanted pulse generator;

(4) at least one tip electrode disposed adjacent said distal sheath end of said lead, each of said at least one electrode having a normally electrically insulated shank portion and an exposed electrode surface; and

(5) means for electrically and mechanically connecting said distal conductor end of each of said at least one conductor to said electrically insulated shank portion of said electrode;

(b) wherein the improvement in said lead body construction comprises;

lead body strengthening means permanently attached at said proximal and distal lead ends and extending therebetween for allowing said lead body insulating sheath and each of said at least one conductor to be stretched only to an extended predetermined length exceeding said relaxed predetermined length as long as applied tension does not exceed the tensile strength of said lead body strengthening means.

2. The elongated electrical medical lead of claim 1, wherein:

said lead body strengthening means does not restrain the stretching and lengthening of said lead body insulating sheath and conductor between said relaxed and extended predetermined lengths.

3. The elongated electrical medical lead of claim 1, wherein:

said lead body strengthening means further comprises one or more normally relaxed, nonextensible filaments loosely contained within said insulating sheath and having proximal and distal filament ends mechanically coupled to said connector and said normally insulated shank portion of said electrode, respectively, said filaments for restraining the stretching of said lead body to a stretched length exceeding said relaxed predetermined length by an amount sufficient to allow said lead to be stretched without breaking in its normal usage and during removal by traction.

4. The elongated electrical medical lead of claim 3, wherein:

(a) each of said at least one conductor comprises a coiled wire conductor; and

(b) said one or more filaments comprise a polyester yarn loosely wound around the outer diameter of said coiled wire conductor, said yarn being mechanically attached to said connector and said normally insulated shank portion of said electrode.

5. The elongated electrical medical lead of claim 3, wherein:

(a) said conductor comprises a coiled wire conductor;

(b) said one or more filaments comprise a loosely woven fabric sheath formed in a tubular shape and fitted loosely around said coiled wire conductor in its relaxed condition; and

(c) said lead body construction further comprises means for mechanically connecting said loosely woven fabric sheath to said connector and said normally insulated shank portion of said electrode.

8. The elongated electrical medical lead of claim 1, wherein:

said lead body strengthening means further comprises one or more normally relaxed, nonextensible filaments loosely contained within said insulating sheath and having proximal and distal filament ends mechanically coupled to said connector and said normally insulated shank portion of said electrode, respectively, said filaments for restraining the stretching of said lead body to a stretched length exceeding said relaxed predetermined length by an amount sufficient to allow said lead to be stretched without breaking in its normal usage and during removal by traction.

9. The elongated electrical medical lead of claim 8, wherein:

(a) each of said at least one conductor comprises a coiled wire conductor; and

(b) said one or more filaments comprise a polyester yarn loosely wound around the outer diameter of said coiled wire conductor, said yarn being mechanically attached to said connector and said normally insulated shank portion of said electrode.

10. The elongated electrical medical lead of claim 8, wherein:

(a) said conductor comprises a coiled wire conductor;

(b) said one or more filaments comprise a loosely woven fabric sheath formed in a tubular shape and fitted loosely around said coiled wire conductor in its relaxed condition; and

(c) said lead body construction further comprises means for mechanically connecting said loosely woven fabric sheath to said connector and said normally insulated shank portion of said electrode.

6. In a transvenous, electrical medical lead for use with a pulse generator to be implanted within the human body,

(a) said lead having a proximal and distal lead end and further comprising:

(1) an outer insulating sheath having a relaxed predetermined sheath length between a proximal and distal sheath end thereof, said sheath being capable of lengthening under tension;

(2) at least one conductor positioned within said outer insulating sheath and extending between said proximal and distal sheath ends thereof, each of said at least one conductor having a relaxed predetermined conductor length between a proximal and distal conductor end thereof, and each of said at least one conductor being capable of lengthening under tension;

(3) a connector interconnecting said proximal sheath end with said proximal conductor end of each of said at least one conductor therein, said connector for providing an electrical connection to said implanted pulse generator;

(4) at least one tip electrode disposed adjacent said distal sheath end of said lead, each of said at least one electrode having a normally electrically insulated shank portion and an exposed electrode surface; and

(5) means for electrically and mechanically connecting said distal conductor end of each of said at least one conductor to said electrically insulated shank portion of said electrode;

(b) wherein the improvement comprises;

means connected to said connector and said distal tip electrode for allowing said lead body extending therebetween to be stretched to a stretched length exceeding its normal relaxed length and for preventing the extension of said lead body beyond said stretched length during the application of traction forces thereto until a predetermined traction force is exceeded.

7. The lead of claim 6, wherein:

said lead body strengthening means does not restrain the stretching and lengthening of said lead body insulating sheath and conductor between said relaxed and extended predetermined lengths.