High impedance active fixation electrode of an electrical medical lead
First Claim
1. An electrical medical lead adapted to be implanted within the body at an implantation site to conduct electrical stimulation from an implantable stimulator to the site and to conduct electrical signals of the body from the site to the implantable or external stimulator comprising:
- an elongated lead body extending from a lead body proximal end to a lead body distal end;
a lead connector element at the lead body proximal end;
a lead conductor enclosed within the lead body and electrically coupled to the first lead connector element;
an active fixation helix attached to the lead body distal end electrically coupled to the lead conductor,the fixation helix comprising a plurality of coil turns wound about a helix lumen, the fixation helix extending distally from a helix attachment end to a helix tip shaped to penetrate body tissue when the helix is screwed into body tissue to secure fixation to the implantation site,the plurality of coil turns each having a coil outer diameter defining a helix outer diameter and a coil inner diameter defining a helix lumen diameter;
each coil turn of the fixation helix being formed from a substantially circular wire having a circumferential surface area; and
means for directing stimulation energy outward from the plurality of coil turns of the helix away from the helix lumen and substantially avoiding delivery of stimulation energy to body tissue within the plurality of coil turns forming the helix lumen, the delivery directing and avoiding means includinga continuous layer of insulation extending without interruption from the helix attachment end to the helix tip covering only an inner helical surface of each of the coil turns and disposed to face inward toward the helix lumen, the insulation layer covering a substantial portion of the circumferential surface area of the wire forming each coil turn to define a portion of the circumferential surface area of the wire that is uninsulated,wherein at least a portion of an outer helical surface extending along the helix outer diameter of each coil turn is uninsulated and facing opposite the inner helical surface covered by the layer of insulation, andwherein the uninsulated outer helical surface forms an outer helical electrode disposed toward body tissue and away from the helix lumen.
1 Assignment
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Accused Products
Abstract
Electrical medical leads having active fixation electrodes, particularly helix electrodes intended to be screwed into body tissue, e.g., the heart, are disclosed having selectively applied insulation to optimize exposed electrode surface area and dispose the exposed electrode surface area toward tissue that is less traumatized by injury caused by screwing in the fixation helix. In a preferred fabrication method, an outer helical surface is masked by contact with a masking tube while a dielectric coating is applied to the inner helical surface of the coil turns of the helix, and the masking tube is removed when the dielectric coating has set. In one variation, at least one aperture is formed through the masking tube sidewall exposing an area of the outer helical surface thereby interrupting the uninsulated outer helical electrode.
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Citations
32 Claims
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1. An electrical medical lead adapted to be implanted within the body at an implantation site to conduct electrical stimulation from an implantable stimulator to the site and to conduct electrical signals of the body from the site to the implantable or external stimulator comprising:
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an elongated lead body extending from a lead body proximal end to a lead body distal end; a lead connector element at the lead body proximal end; a lead conductor enclosed within the lead body and electrically coupled to the first lead connector element; an active fixation helix attached to the lead body distal end electrically coupled to the lead conductor, the fixation helix comprising a plurality of coil turns wound about a helix lumen, the fixation helix extending distally from a helix attachment end to a helix tip shaped to penetrate body tissue when the helix is screwed into body tissue to secure fixation to the implantation site, the plurality of coil turns each having a coil outer diameter defining a helix outer diameter and a coil inner diameter defining a helix lumen diameter; each coil turn of the fixation helix being formed from a substantially circular wire having a circumferential surface area; and means for directing stimulation energy outward from the plurality of coil turns of the helix away from the helix lumen and substantially avoiding delivery of stimulation energy to body tissue within the plurality of coil turns forming the helix lumen, the delivery directing and avoiding means including a continuous layer of insulation extending without interruption from the helix attachment end to the helix tip covering only an inner helical surface of each of the coil turns and disposed to face inward toward the helix lumen, the insulation layer covering a substantial portion of the circumferential surface area of the wire forming each coil turn to define a portion of the circumferential surface area of the wire that is uninsulated, wherein at least a portion of an outer helical surface extending along the helix outer diameter of each coil turn is uninsulated and facing opposite the inner helical surface covered by the layer of insulation, and wherein the uninsulated outer helical surface forms an outer helical electrode disposed toward body tissue and away from the helix lumen. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A method of fabricating an electrical medical lead adapted to be implanted within the body at an implantation site to conduct electrical stimulation from an implantable stimulator to the site and to conduct electrical signals of the body from the site to the implantable or external stimulator comprising the steps of:
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forming an elongated lead body extending from a lead body proximal end to a lead body distal end enclosing a lead conductor; forming a lead connector element at the lead body proximal end; electrically coupling the lead conductor to the first lead connector element fabricating an active fixation helix by; forming a conductive wire into a helix comprising a plurality of coil turns wound about a helix lumen, the helix extending from a helix attachment end to a distal end terminating in a helix tip shaped to penetrate body tissue when the helix is screwed into body tissue to secure fixation to the implantation site, each of the plurality of coil turns having a coil outer diameter defining a helix outer diameter and a coil inner diameter defining a helix lumen diameter; applying a layer of insulation extending continuously from the helix attachment end to the helix distal end over an inner helical surface of each of the plurality of coil turns, the layer of insulation facing toward the helix lumen, and wherein at least a portion of an outer helical surface extending along the helix outer diameter of the plurality of coil turns is uninsulated to form an outer helical electrode surface that is disposed toward body tissue away from the helix lumen when implanted; attaching the fixation end of the fixation helix to the lead body distal end; and electrically coupling the fixation helix to the lead conductor, whereby the uninsulated outer helical surface is disposed toward body tissue away from the helix lumen to function as an outer helical electrode. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. An electrical medical lead adapted to be implanted within the body at an implantation site to conduct electrical stimulation from an implantable stimulator to the site and to conduct electrical signals of the body from the site to the implantable or external stimulator comprising:
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an elongated lead body extending from a lead body proximal end to a lead body distal end; a lead connector element at the lead body proximal end; a lead conductor enclosed within the lead body and electrically coupled to the first lead connector element; an active fixation helix attached to the lead body distal end electrically coupled to the lead conductor, the fixation helix comprising a conductive wire formed into a coil comprising a plurality of coil turns wound about a helix lumen, the fixation helix extending distally from a helix attachment end to a helix tip shaped to penetrate body tissue when the helix is screwed into body tissue to secure fixation to the implantation site, the conductive wire having a circumferential surface and each coil turn formed by the conductive wire having a coil outer diameter defining a helix outer diameter and a coil inner diameter defining a helix lumen diameter; means for directing stimulation energy outward from the plurality of coil turns of the helix away from the helix lumen and substantially avoiding delivery of stimulation energy to body tissue within the plurality of coil turns forming the helix lumen, the delivery directing and avoiding means including a layer of insulation applied to the circumferential surface of the conductive wire, the insulating layer extending only part way around the circumferential surface of the conductive wire to cover the coil inner diameter without covering the coil outer diameter directly opposite the covered coil inner diameter of each coil turn, wherein the insulating layer covers an inner helical surface disposed toward the helix lumen of each coil turn and an outer helical surface opposite the insulated inner helical surface extending along the helix outer diameter of each coil turn is uninsulated, and the uninsulated outer helical surface functions as an outer helical electrode disposed toward body tissue away from the helix.
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32. An electrical medical lead adapted to be implanted within the body at an implantation site to conduct electrical stimulation from an implantable stimulator to the site and to conduct electrical signals of the body from the site to the implantable or external stimulator comprising:
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an elongated lead body extending from a lead body proximal end to a lead body distal end; a lead connector element at the lead body proximal end; a lead conductor enclosed within the lead body and electrically coupled to the first lead connector element; an active fixation helix attached to the lead body distal end electrically coupled to the lead conductor, the fixation helix comprising a plurality of coil turns wound about a helix lumen, the fixation helix extending distally from a helix attachment end to a helix tip shaped to penetrate body tissue when the helix is screwed into body tissue to secure fixation to the implantation site, the fixation helix having an outer surface and an inner surface forming a helix lumen; each coil turn of the fixation helix being formed from a substantially circular wire having a circumferential surface area; and means for directing stimulation energy outward from the plurality of coil turns of the helix away from the helix lumen and substantially avoiding delivery of stimulation energy to body tissue within the plurality of coil turns forming the helix lumen, the delivery directing and avoiding means including a layer of insulation extending without interruption from the helix attachment end to the helix tip, the insulation layer covering a substantial portion of the circumferential surface area of the wire forming each coil turn to define a portion of the circumferential surface area of the wire that is uninsulated so as to cover only the helix inner surface and leave an exposed helix outer surface, wherein only the exposed helix outer surface functions as an electrode disposed toward body tissue away from the helix lumen.
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Specification