Implantable lead affixation structure for nerve stimulation to alleviate bladder dysfunction and other indication
Anchoring devices and methods for affixing an implanted lead of a neurostimulation system at a target location in a patient are provided herein. Such anchoring devices includes a helical body having a plurality of tines extending laterally outward from the lead when deployed that engage tissue to inhibit axial movement of the implanted lead. The plurality of tines are biased towards the laterally extended deployed configuration and fold inward towards the lead to a delivery configuration to facilitate delivery of the lead through a sheath. The tines may be angled in a proximal direction or in both proximal and distal directions and may include various features to assist in visualization and delivery of the lead. The anchor may be formed according to various methods, including laser cutting of a tubular section along with heat or reflow to set the material with the anchor in the deployed configuration and injection molding.
1. A method of forming a neurostimulation lead anchor for anchoring an implanted neurostimulation lead at a target tissue location in a body of a patient, the method comprising:
laser cutting a helical pattern into a single tubular section of a material, the helical pattern corresponding to a neurostimulation lead anchor with a helical body having a plurality of tines in a constrained configuration;
supporting the plurality of tines of the single tubular section in an outwardly protruding position corresponding to a deployed configuration of the neurostimulation lead anchor; and
heat setting the single tubular section while the plurality of tines are supported, thereby setting the material while the neurostimulation lead anchor is in the deployed configuration.
2. The method of claim 1 , wherein the material is a shape-memory metal alloy such that the shape-memory metal alloy resiliently returns to the deployed configuration upon heating in the body after implantation.
3. The method of claim 1 , wherein the material is a polymer-based material that is set by reflow and that remains sufficiently flexible when set so that the plurality of tines can fold inward against a lead when constrained within a sheath to facilitate implantation of the neurostimulation lead anchor when affixed on the lead.
4. The method of claim 1 further comprising:
affixing the neurostimulation lead anchor to an anchoring portion of a neurostimulation lead by wrapping the helical body about the anchoring portion of the neurostimulation lead.
5. The method of claim 1 , wherein the neurostimulation lead anchor is dimensioned such that, when attached to a lead body and in the constrained configuration, the neurostimulation lead anchor has a cross sectional profile sufficiently small to facilitate delivery through a 5 French sheath.
6. The method of claim 1 , wherein the material has sufficient stiffness so that, when attached to an implanted lead and in the deployed configuration, engagement of tissue with the plurality of tines inhibits axial movement of the implanted lead when implanted in the tissue at a target location.
7. The method of claim 6 , wherein the material comprises a polyurethane based material having a shore hardness in a range between 50A and 80D.
8. The method of claim 6 , wherein the material comprises a metal.
9. The method of claim 1 , further comprising:
affixing the neurostimulation lead anchor to an anchoring portion of a neurostimulation lead.
10. The method of claim 9 , wherein the neurostimulation lead has one or more neurostimulation electrodes distal of the anchoring portion.
11. The method of claim 10 , wherein the neurostimulation lead comprises a sacral neuromodulation lead configured for advancing through a sacral foramen until the one or more neurostimulation electrodes are positioned at a sacral nerve.
12. The method of claim 9 , wherein the anchoring portion of the neurostimulation lead has a reduced profile so as to reduce a cross-section thereof along the neurostimulation lead anchor.
13. The method of claim 12 , wherein the reduced profile is about 2 mm or less.
14. The method of claim 9 , wherein the helical body is heat set to a smaller inside diameter than a diameter of the neurostimulation lead so as to provide an interference fit on the neurostimulation lead.
15. A method of forming a neurostimulation lead anchor for anchoring an implanted neurostimulation lead at a target tissue location in a body of a patient, the method comprising:
cutting a pattern into a single tubular portion of a material, the pattern corresponding to a neurostimulation lead anchor comprising a plurality of tines in a constrained configuration, wherein the plurality of tines are distributed along a longitudinal axis of the neurostimulation lead anchor;
supporting the plurality of tines in an outwardly protruding position corresponding to a deployed configuration of the anchor; and
setting the plurality of tines in the outwardly protruding position by heat setting or reflow.
16. The method of claim 15 , wherein the material is a shape-memory metal alloy such that the shape-memory metal alloy resiliently returns to the deployed configuration upon heating in the body after implantation.
17. The method of claim 15 , wherein the material is a polymer-based material that is set by reflow and that remains sufficiently flexible when set so that the plurality of tines can fold inward against a lead when constrained within a sheath to facilitate implantation of the neurostimulation lead anchor when affixed on the lead.
18. The method of claim 15 further comprising:
affixing the neurostimulation lead anchor to an anchoring portion of a neurostimulation lead.
19. The method of claim 18 , wherein the neurostimulation lead anchor is dimensioned such that, when attached to the neurostimulation lead in the constrained configuration, the neurostimulation lead anchor has a cross sectional profile sufficiently small to facilitate delivery through a 5 French sheath.
20. The method of claim 18 , wherein the neurostimulation lead comprises one or more neurostimulation electrodes, and wherein the neurostimulation lead comprises a sacral neuromodulation lead configured for advancing through a sacral foramen until the one or more neurostimulation electrodes are positioned at a sacral nerve.