Lead assembly with masked microdisk tip electrode and monolithic controlled release device

• US 6,405,091 B1
• Filed: 07/20/1999
• Issued: 06/11/2002
• Est. Priority Date: 07/20/1999
• Status: Expired due to Fees

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories)
• Original Assignee: Pacesetter Incorporated (Abbott Laboratories)
• Inventors: Morgan, Kevin L., Bornzin, Gene A., Moaddeb, Shahram, Vachon, David J.
• Primary Examiner(s): LAYNO, CARL HERNANDZ
• Application Number:
  US09/359,327
• Time in Patent Office: 1,057 Days
• Field of Search: 607/120, 607/126, 607/128
• US Class Current: 607/120
• CPC Class Codes: A61N 1/0565 Electrode heads
• CPC Class Codes: A61N 1/057 Anchoring means; Means for fixing the head inside the heart

Abstract

A passive fixation, body implantable lead assembly has a cylindrical tip electrode whose outer side surface is covered with a thin dielectric insulating layer so as to mask an active, disk-shaped electrode surface at the distal extremity of the tip electrode. The active electrode surface preferably has an area less than about 1 mm². An MCRD, in the form of a collar, may be carried by a proximal portion of the tip electrode. Supplementing a set of main tines projecting from the distal end portion of an insulating sheath housing the lead assembly is a set of nubby auxiliary tines extending from the sheath immediately adjacent the distal extremity thereof.

Claims

1. A passive fixation body implantable lead assembly adapted to transmit electrical signals between a proximal end portion of the lead assembly and a distal end portion of the lead assembly and to thereby stimulate selected body tissue and/or sense electrical signals therefrom, the lead assembly having a longitudinal axis and comprising:

an electrical conductor extending between said proximal and distal end portions of the lead assembly for transmitting the electrical signals, the conductor having a distal end;

a sheath of insulative, biocompatible material enclosing the electrical conductor for electrically insulating the conductor from body tissue and body fluids, the insulative sheath having a distal extremity;

a tip electrode electrically connected to the distal end of the electrical conductor, the tip electrode being in the form of a cylinder disposed coaxially of the longitudinal axis of the lead assembly, the tip electrode having a side surface and a distal extremity comprising a generally planar active electrode surface extending substantially perpendicular to the longitudinal axis of the assembly; and

a thin dielectric insulating layer covering substantially the entire side surface of the tip electrode.

2. A lead assembly, as defined in claim 1, in which:

the active electrode surface at the distal extremity of the tip electrode has an area less than about 1 mm².

3. A lead assembly, as defined in claim 1, in which:

the active electrode surface of the tip electrode is coated with a material that reduces polarization.

4. A lead assembly, as defined in claim 1, in which:

the side surface of the tip electrode includes a distal portion and a proximal portion; and

a drug dispensing member is disposed around the proximal portion of the tip electrode for storing a drug to be dispensed to the body tissue.

5. A lead assembly, as defined in claim 4, in which:

the drug dispensing member is in the form of a collar disposed about the tip electrode, and in which a first plurality of tines extends outwardly from said collar; and

a second plurality of tines extends outwardly from said sheath and away from the tip electrode to form an acute angle with the sheath material, said second plurality of tines being disposed proximally of said first plurality of tines along the distal end portion of the lead assembly, the first plurality of tines having a length less than that of the second plurality of tines.

6. A lead assembly, as defined in claim 1, in which:

the tip electrode is fabricated of a porous material adapted to retain and dispense a therapeutic drug.

7. A lead assembly, as defined in claim 6, in which:

the distal extremity of the insulative sheath includes an inwardly directed wall, the wall having a central aperture, the porous tip electrode extending through said aperture.

8. A lead assembly, as defined in claim 7, in which:

the aperture of the inwardly directed wall of the insulative sheath is defined by a surface in contact with the outer side surface of the body of the tip electrode, the porous material of the tip electrode body permitting dispensing of the drug.

9. A lead assembly, as defined in claim 7, in which:

the aperture of the inwardly directed wall of the insulative sheath is defined by a surface, the aperture-defining surface being spaced from the outer side surface of the tip electrode to allow dispensing of the drug through the space defined by the aperture defining surface and the side surface of the tip electrode body.

10. A lead assembly, as defined in claim 1, in which the sheath includes:

a first plurality of tines extending outwardly from said sheath, said first plurality of tines being disposed adjacent the distal extremity of the sheath; and

a second plurality of tines extending outwardly from said sheath and away from the tip electrode to form an acute angle with the sheath material, said second plurality of tines being disposed proximally of said first plurality of tines along the distal end portion of the lead assembly, the first plurality of tines having a length less than that of the second plurality of tines.

11. A passive fixation body implantable lead assembly adapted to transmit electrical signals between a proximal end portion of the lead assembly and a distal end portion of the lead assembly and to thereby stimulate selected body tissue and/or sense electrical signals therefrom, the lead assembly having a longitudinal axis and comprising:

an electrical conductor extending between said proximal and distal end portions of the lead assembly for transmitting the electrical signals, the conductor having a distal end;

a sheath of insulative, biocompatible material enclosing the electrical conductor for electrically insulating the conductor from body tissue and body fluids, the insulative sheath having a distal extremity;

a tip electrode electrically connected to the distal end of the electrical conductor, the tip electrode being coaxial of the longitudinal axis of the lead assembly and having a proximal portion, a distal portion and a distal extremity comprising a generally planar active electrode surface extending substantially perpendicular to the longitudinal axis of the assembly; and

a drug dispensing annular member disposed around the proximal portion of the tip electrode for storing a drug to be dispensed to the body tissue.

12. A lead assembly, as defined in claim 11, in which:

the tip electrode is substantially cylindrical, the planar active electrode surface at the distal extremity of the tip electrode body comprising a disc-shaped area and the drug dispensing member comprising an annular collar.

13. A lead assembly, as defined in claim 12, in which:

the drug dispensing member comprises a material whose swelling is minimal when placed in contact with body fluids.

14. A lead assembly, as defined in claim 12, in which:

the drug dispensing member is bonded to the proximal portion of the tip electrode body.

15. A lead assembly, as defined in claim 11, in which:

the active electrode surface at the distal extremity of the tip electrode has an area less than about 1 mm².

16. A lead assembly, as defined in claim 11, in which:

the active electrode surface of the tip electrode is coated to reduce polarization.

17. A lead assembly, as defined in claim 11, in which:

the tip electrode has an outer, side surface, the side surface being coated with a thin dielectric insulating material.

18. A lead assembly, as defined in claim 11, in which:

the distal portion and at least part of the proximal portion of the tip electrode project from the distal extremity of the insulative sheath.

19. A lead assembly, as defined in claim 18, in which:

the drug dispensing member is disposed distally of the distal extremity of the insulative sheath.

20. A lead assembly, as defined in claim 18, in which:

at least a portion of the drug dispensing member is disposed within the insulative sheath.

21. A lead assembly, as defined in claim 20, in which:

the drug dispensing member is disposed in its entirety within the insulative sheath immediately adjacent the distal extremity thereof.

22. A lead assembly, as defined in claim 21, in which:

the distal extremity of the insulative sheath includes an inwardly directed wall, the wall having a central aperture, the tip electrode extending through said aperture.

23. A lead assembly, as defined in claim 22, in which:

the tip electrode has an outer side surface, the aperture of the inwardly directed wall of the insulative sheath being defined by a surface, the aperture-defining surface being spaced from the outer side surface of the tip electrode body to allow dispensing of the drug through the space defined by the aperture defining surface and the side surface of the tip electrode body.