Helix rotation by traction

• US 20020177888A1
• Filed: 04/30/2002
• Published: 11/28/2002
• Est. Priority Date: 04/26/2000
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Williams, Terrell M., Foerster, Laurie D., Chivers, Bruce E.
• Granted Patent: US 7,092,764 B2
• Time in Patent Office: Days
• US Class Current: 607/122
• CPC Class Codes: A61N 1/056 Transvascular endocardial electrode systems
• CPC Class Codes: A61N 1/0573 chacterised by means penetrating the heart tissue, e.g. helix needle or hook
• CPC Class Codes: A61N 2001/0578 having means for removal or extraction

Abstract

The present invention discloses use of a “Z-shaped” configuration for a pair of internal windings of a fiber core of a medical electrical lead. As illustrated and described, these Z-shaped braids, or windings, are a primary source of counter-rotation for an electrode coupled to cardiac tissue during extraction of the lead with axial tension, or traction. When fully assembled and implanted within a patient, an electrode, such as a helical electrode, is electrically coupled to a coil conductor and mechanically coupled to a loop formed at an end of the Z-shaped braided fiber. To remove the lead, a traction force is applied to the lead and as the Z-shaped braids begin to unwind rotational force is applied to unscrew the helical electrode. A lead constructed according to the present invention is isodiametric, has an outer diameter of less than about 4 French, and rotates counterclockwise in response to tensile force.

Claims

1. A medical electrical lead, comprising:

an elongated insulative sheath having proximal and distal ends;

first and second electrical components, located such that a length of said insulative sheath extends therebetween; and

a coil/core structure mechanically and electrically coupling said first and second electrical components disposed within said insulative sheath, said coil/core structure comprising a fiber core wrapped in a Z-shape braid and having an elongated electrical conductor wound around the fiber core,

wherein the elongated electrical conductor is coupled electrically to the first and second electrical components, and the fiber core is mechanically coupled to the first and second electrical components so that when a tensile force is applied between the first and second electrical components the Z-shape braid of the fiber core unwinds thus imparting counter-rotational motion to the first electrical component.

2. The lead of claim 1, wherein the fiber core comprises two lengths of a single fiber cord, folded back upon itself to define a loop at one end thereof.

3. The lead of claim 1, wherein the elongated electrical conductor applies compressive force to the fiber core.

4. The lead of claim 1, wherein the first electrical component is a helical electrode.

7. The lead of claim 1, wherein the coiled conductor is wound around the first electrical component.

8. The lead of claim 1, wherein the lead has a diameter of about 2.6 French.

9. The lead of claim 1, wherein at least a portion of the lead adjacent the first electrical component is isodiametric.

10. The lead of claim 1, wherein the insulative sheath is formed of a biocompatible polymer.

11. The lead of claim 10, wherein the elongated insulative sheath is an outer sheath and further comprising an inner insulative sheath disposed between the outer sheath and the coil/core structure.

12. The lead of claim 11, wherein the lead has an outer diameter less than about 4 French.

13. The lead of claim 12, further comprising a cylindrical sleeve member disposed around a shaft portion of the first electrical component and at least partially covered by the outer sheath and the inner sheath.

15. The method of claim 14, wherein producing the coil/core structure comprises the steps of:

folding a fiber cord back upon itself to define the two segments of fiber cord and thereby providing a loop of fiber cord at one end thereof.

16. The method of claim 15, wherein electrically coupling the metal conductor to the first electrical component comprises winding the metal conductor around the first electrical component.

17. The method of claim 14, wherein the encasing step is followed by an additional encasing step wherein the encased lead is encased in a second insulative sheath thereby constructing a double-sheathed lead.

19. The medical electrical lead of claim 18, wherein the lead has a lead diameter less than about 4 French.

20. The medical electrical lead of claim 18, further comprising an additional insulative sheath covering a majority of the surface of the insulative sheath.

5. The lead of claim 5, wherein the second electrical component is an electrically conductive pad.

6. The lead of claim 6, wherein the medical electrical lead is a bipolar lead.

14. A method of constructing a medical electrical lead, comprising the steps of:

producing a coil/core structure by twisting two segments of fiber cord around one another to produce a fiber core having a Z-shaped braid and winding an elongated electrical conductor around the fiber core;

electrically coupling opposite ends of the elongate electrical conductor to a first and a second electrical component;

mechanically coupling opposite ends of the fiber core to the first and second electrical components; and

encasing substantially all the coil/core structure with an insulative sheath.

18. A medical electrical lead, comprising:

an elongated non-conductive resilient cord segment, folded over and twisted to form a series of Z-shaped braids and having a loop formed at a distal end;

an elongated electrical conductor helically wrapped around a majority of the elongated resilient cord to thereby constrain the Z-shaped braids and not constrain the loop;

an electrode electrically coupled to the distal end portion of the elongated electrical conductor and mechanically coupled to the loop of the elongated non-conductive resilient cord; and

an insulative sheath surrounding substantially all of the medical electrical lead with the exception of at least a portion of the electrode.