Retraction stop for helical medical lead electrode

• US 5,837,006 A
• Filed: 09/10/1996
• Issued: 11/17/1998
• Est. Priority Date: 09/10/1996
• Status: Expired due to Term

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Holleman, Timothy W., Ocel, Jon M., Boser, Gregory A.
• Primary Examiner(s): Jastrzab, Jeffrey R.
• Assistant Examiner(s): Ruddy, David M.
• Application Number:
  US08/711,747
• Time in Patent Office: 798 Days
• Field of Search: 607/127, 607/119, 607/122, 607/126-131, 128/642, 128/698, 600/373, 600/374, 600/375, 600/376, 600/377
• US Class Current: 607/127
• CPC Class Codes: A61N 1/0573 chacterised by means penetrating the heart tissue, e.g. helix needle or hook

Abstract

In an endocardial, active fixation, screw-in lead of the type having a fixation helix adapted to be rotated in a first, advancement direction out of an electrode head chamber and into cardiac tissue by rotation of a lead connector end and attached lead conductor with respect to an insulating sheath in the first direction and retracted into the chamber by rotation of the lead connector in the opposite, retraction direction, a retraction stop mechanism for preventing over rotation of the helix in the retraction direction. The rotational motion of the lead conductor is transmitted to the helix by a connecting assembly and is translated into axial advancement and retraction of the helix by a guide cooperating with the helix turns. A retraction stop mechanism stops rotation of the helix in the retraction direction upon full retraction of the helix into the chamber and allows rotation of helix in the advancement direction. The retraction stop mechanism includes a fixed stop formed of a plurality of fixed cam and axial stop surfaces surrounding a proximal end bore of the chamber through which the lead conductor passes and a movable stop formed in the connecting mechanism of a like plurality of rotatable cam and axial stop surfaces aligned to face the fixed cam and axial stop surfaces adapted to engage in a locked relation of the stop surfaces upon full retraction of the fixation device into the chamber.

Claims

1. An implantable lead formed of materials substantially inert to body fluids and tissue comprising:

a length of electrical lead conductor having proximal and distal ends;

sheath means having proximal and distal ends for loosely receiving and insulating said conductor from body tissue;

an electrode connected to the distal end of said lead conductor, said electrode having tissue engaging means adopted for securely engaging said electrode in contact with body tissue;

electrode head means attached to the distal end of said sheath means for supporting said electrode and for receiving and isolating said tissue engaging means from body fluids and tissue;

a lead connector coupled to the proximal end of said lead conductor and adapted to be rotated with respect to said sheath means for imparting rotation to said conductor with respect to said sheath means and said tissue engaging means with respect to said electrode head means;

guide means for translating rotation of said lead conductor in a first direction into axial advancement of said tissue engaging means for a predetermined distance from said electrode head means and for translating rotation of said lead conductor in a second direction into axial retraction of said tissue engaging means into said electrode head means; and

retraction stop means for stopping rotation of said tissue engaging means in said second direction upon full retraction of said tissue engaging means into said electrode head means, wherein said tissue engaging means further comprises a helix having a tissue piercing point and a number of tissue engaging turns, said helix being mechanically connected to the distal end of said lead conductor and adapted to be advanced from said electrode head means and screwed into body tissue, to firmly lodge in and permanently secure said electrode to the body tissue, upon rotation in of said lead conductor in said first direction and wherein said guide means contacts at least one turn of said helix for allowing axial advancement and retraction of said helix with respect to said electrode head means only by rotation of said lead conductor with respect to said sheath means and wherein said guide means contacts said at least one turn of said helix when said helix is fully retracted into said electrode head.

2. An implantable lead formed of materials substantially inert to body fluids and tissue comprising:

a length of electrical lead conductor having proximal and distal ends;

sheath means having proximal and distal ends for loosely receiving and insulating said conductor from body tissue;

an electrode connected to the distal end of said lead conductor, said electrode having tissue engaging means adapted for securely engaging said electrode in contact with body tissue;

electrode head means attached to the distal end of said sheath means for supporting said electrode and for receiving and isolating said tissue engaging means from body fluids and tissue;

a lead connector coupled to the proximal end of said lead conductor and adapted to be rotated with respect to said sheath means for imparting rotation to said conductor with respect to said sheath means and said tissue engaging means with respect to said electrode head means;

guide means for translating rotation of said lead conductor in a first direction into axial advancement of said tissue engaging means for a predetermined distance from said electrode head means and for translating rotation of said lead conductor in a second direction into axial retraction of said tissue engaging means into said electrode head means; and

retraction stop means for stopping rotation of said tissue engaging means in said second direction upon full retraction of said tissue engaging means into said electrode head means, wherein said tissue engaging means further comprises a helix having a tissue piercing point and a number of tissue engaging turns, said helix being mechanically connected to the distal end of said lead conductor and adapted to be advanced from said electrode head means and screwed into body tissue, to firmly lodge in and permanently secure said electrode to the body tissue, upon rotation in of said lead conductor in said first direction and wherein said guide means contacts at least one turn of said helix for allowing axial advancement and retraction of said helix with respect to said electrode head means only by rotation of said lead conductor with respect to said sheath means and wherein

said electrode head means further comprises a housing providing a cylindrical chamber of a length sufficient to enclose said helix retracted therein extending between proximal and distal chamber ends and supporting said guide means for cooperation with a turn of said helix at said distal chamber end;

said distal end of said lead conductor and said helix are connected together by a connecting assembly fitted within said cylindrical chamber for axial and rotational movement therein; and

said retraction stop means further comprises;

a fixed stop formed in the proximal end of said chamber having a plurality of fixed cam and axial stop surfaces; and

a movable stop formed in the connecting assembly having a like plurality of rotatable cam and axial stop surfaces aligned to face the fixed cam and axial stop surfaces in a locked relation of said stop surfaces upon full retraction of said helix into said chamber to prevent rotation of said helix in said second direction and to allow rotation of said helix in said first direction.

3. The implantable lead of claim 2 wherein:

said fixed stop is formed in said proximal chamber end surrounding an axial bore aligned with said distal sheath end and sheath lumen for passing said distal end of said lead conductor into said chamber whereby said fixed cam and axial stop surfaces face toward said chamber distal end;

said connecting assembly axially receives said distal end of said lead conductor and said proximal end of said helix; and

said movable stop is formed on said connecting assembly facing toward said chamber proximal end and surrounding said distal end of said lead conductor.

4. An implantable lead comprising:

a lead conductor having a proximal end and a distal end;

an insulating sheath having a sheath lumen for receiving said lead conductor and a proximal end and a distal end;

an electrode head having a chamber attached to said distal end of said insulating sheath having a proximal end bore for receiving said distal end of said lead conductor and a chamber distal aperture;

a fixation device rotatably fitted within said chamber whereby rotation of said fixation device in a first direction causes said fixation device to move distal relative to said chamber distal aperture and rotation of said fixation device in a second direction causes said fixation device to move proximal relative to said chamber distal aperture;

connecting means for connecting said distal end of said lead conductor with said fixation device within said chamber; and

retraction stop means for allowing rotation of said fixation device in said first direction and said second direction to advance and retract said fixation device through said chamber distal aperture and for stopping rotation of said fixation device in said second direction upon a predetermined retraction position of said fixation device into said chamber wherein said tissue fixation device comprises a helix having a tissue piercing distal point and a number of tissue engaging turns and a proximal end mechanically connected to the distal end of said lead conductor through said connecting means and adapted to be advanced from said chamber distal aperture and screwed into body tissue, to firmly lodge in and permanently secure said electrode to the body tissue, upon rotation in of said lead conductor in said first direction and wherein said lead further comprises guide means contacting at least one turn of said helix for allowing axial advancement and retraction of said helix with respect to said electrode head means only by rotation of said lead conductor with respect to said sheath and wherein said guide means contacts said at least one turn of said helix when said helix is fully retracted into said electrode head.

5. The implantable lead of claim 4 wherein said retraction stop means further comprises:

fixed stop means formed surrounding said proximal end bore for surrounding said lead conductor passing therethrough; and

movable stop means formed on said connecting means aligned toward said fixed stop means for making locking engagement therewith upon rotation of said fixation device in said second direction to said predetermined retracted position.

8. The implantable lead of claim 4 wherein said retraction stop means further comprises:

fixed stop means formed surrounding said chamber proximal bore for surrounding said lead conductor passing therethrough; and

movable stop means formed on said connecting means aligned toward said fixed stop means for making locking engagement therewith upon rotation of said helix in said second direction to said predetermined retracted position.

9. The implantable lead of claim 4 wherein said retraction stop means further comprises:

a fixed stop formed adjacent said proximal end bore of said chamber having a plurality of fixed cam and axial stop surfaces; and

a movable stop formed in the connecting assembly having a like plurality of rotatable cam and axial stop surfaces aligned to face the fixed cam and axial stop surfaces in a locked relation of said stop surfaces upon full retraction of said helix into said chamber to prevent rotation of said helix in said second direction and to allow rotation of said helix in said first direction.

10. The implantable lead of claim 9 wherein:

said fixed stop is formed surrounding said proximal end bore aligned with said distal sheath end and sheath lumen for passing said distal end of said lead conductor into said chamber whereby said fixed cam and axial stop surfaces face toward said chamber distal end;

said connecting means axially receives said distal end of said lead conductor and said proximal end of said helix; and

said movable stop is formed on said connecting means facing toward said chamber proximal end and surrounding said distal end of said lead conductor.

6. An implantable lead comprising:

a lead conductor having a proximal end and a distal end;

an insulating sheath having a sheath lumen for receiving said lead conductor and a proximal end and a distal end;

an electrode head having a chamber attached to said distal end of said insulating sheath having a proximal end bore for receiving said distal end of said lead conductor and a chamber distal aperture;

a fixation device rotatable fitted within said chamber whereby rotation of said fixation device in a first direction causes said fixation device to move distal relative to said chamber distal aperture and rotation of said fixation device in a second direction causes said fixation device to move proximal relative to said chamber distal aperture;

connecting means for connecting said distal end of said lead conductor with said fixation device within said chamber; and

retraction stop means for allowing rotation of said fixation device in said first direction and said second direction to advance and retract said fixation device through said chamber distal aperture and for stopping rotation of said fixation device in said second direction upon a predetermined retraction position of said fixation device into said chamber, wherein said tissue fixation device comprises a helix having a tissue piercing distal point and a number of tissue engaging turns and a proximal end mechanically connected to the distal end of said lead conductor through said connecting means and adapted to be advanced from said chamber distal aperture and screwed into body tissue, to firmly lodge in and permanently secure said electrode to the body tissue, upon rotation in of said lead conductor in said first direction and wherein said lead further comprises guide means contacting at least one turn of said helix for allowing axial advancement and retraction of said helix with respect to said electrode head means only by rotation of said lead conductor with respect to said sheath, said retraction stop means comprising

a fixed stop formed surrounding said proximal end bore of said chamber having a plurality of fixed cam and axial stop surfaces; and

a movable stop formed in the connecting means having a like plurality of rotatable cam and axial stop surfaces aligned to face the fixed cam and axial stop surfaces in a locked relation of said stop surfaces upon full retraction of said fixation device into said chamber to prevent rotation of said fixation device in said second direction and to allow rotation of said fixation device in said first direction.

7. The implantable lead of claim 6 wherein:

said fixed cam and axial stop surfaces face toward said chamber distal aperture;

said connecting means axially receives said distal end of said lead conductor and a proximal end of said fixation device; and

said movable stop is formed on said connecting assembly facing toward said chamber proximal end and surrounding said distal end of said lead conductor.