Devices and techniques for anchoring an implantable medical device

Abstract

Anchoring mechanisms for an implantable electrical medical lead that is positioned within a substernal space are disclosed. The anchoring mechanisms fixedly-position a distal portion of the lead, that is implanted in the substernal space.

What is claimed is: 
     
         1 . An implantable medical system comprising:
 a stimulation therapy generator;   a first elongate lead coupled to the stimulation therapy generator having a proximal end and a distal end;   an electrode coupled to the distal end of the first elongate lead; and   an anchoring mechanism disposed along a length of the first elongate lead configured to fixedly-secure the first elongate lead within a substernal space underneath the sternum.   
     
     
         2 . The implantable medical system of  claim 1 , wherein the anchoring mechanism comprises a reinforcement member coupled to the distal end of the lead that is configured to prevent movement of the lead responsive to a dislodgment force from the tissue at the implant location. 
     
     
         3 . The implantable medical system of  claim 1 , wherein the anchoring mechanism comprises a canted distal portion formed at the distal end of the lead such that the canted distal portion engages tissue within the substernal space to anchor the lead. 
     
     
         4 . The implantable medical system of  claim 1 , wherein the anchoring mechanism comprises a distal section of the lead that is configured having a material that includes a greater stiffness coefficient relative to the proximal section of the lead. 
     
     
         5 . The implantable medical system of  claim 1 , wherein the anchoring mechanism is configured to position the electrode in a pre-determined orientation relative to a target stimulation therapy site that is not within the substernal space. 
     
     
         6 . The implantable medical system of  claim 1 , wherein the anchoring mechanism comprises a flange having at least one major surface that is oriented in a parallel configuration with a length of the lead. 
     
     
         7 . The implantable medical system of  claim 1 , wherein the anchoring mechanism is configured to fixedly-secure the first elongate lead at an access point into the substernal space, wherein a distal end of the lead is configured to be tunneled through a pathway across subcutaneous tissue for insertion into the substernal space. 
     
     
         8 . The implantable medical system of  claim 1 , wherein the anchoring mechanism includes a porous structure disposed at the distal end of the lead. 
     
     
         9 . The implantable medical system of  claim 8 , wherein the anchoring mechanism comprises an in-growth member having a substance configured to promote tissue growth for anchoring the implantable stimulation lead to tissue. 
     
     
         10 . The implantable medical system of  claim 1 , wherein the anchoring mechanism is slidingly-disposed along a length of a body of the first elongate lead, and wherein the anchoring mechanism is moveable along the length of the body during navigation of the lead. 
     
     
         11 . The implantable medical system of  claim 1 , wherein the anchoring mechanism comprises a passive fixator disposed along a length of a body of the first elongate lead and configured to engage tissue. 
     
     
         12 . The implantable medical system of  claim 1 , wherein the anchoring mechanism comprises an active fixator disposed along a length of a body of the first elongate lead and configured to engage tissue. 
     
     
         13 . The implantable medical system of  claim 1 , wherein the anchoring mechanism comprises an expandable coil. 
     
     
         14 . The implantable medical system of  claim 1 , wherein the anchoring mechanism comprises an expandable porous structure having pores for tissue engagement. 
     
     
         15 . The implantable medical system of  claim 1 , wherein the first elongate lead and the anchoring mechanism are configured for deployment into the substernal space through a delivery system such that the anchoring mechanism remains in the first constrained configuration during delivery of the lead to the substernal space and is released to the second expanded configuration subsequent to release of the lead into the substernal space. 
     
     
         16 . The implantable medical system of  claim 1 , further comprising a second elongate lead coupled to the stimulation therapy generator and wherein the second elongate is configured for implantation at a subcutaneous implant location. 
     
     
         17 . A method of implanting a medical system, comprising:
 subcutaneously advancing a first lead through a subcutaneous space from a subcutaneously positioned implantable medical device to an access point into a substernal space;   navigating a distal end of the first lead to an implantation site within the substernal space;   placing the distal end of the first lead within the substernal space;   orienting a fixation element in a pre-determined direction relative to the substernal space; and   fixedly-securing a segment of the first lead at the access point with a fixation element that secures the lead at an intersection between the subcutaneous space and the substernal space.   
     
     
         18 . The method of implanting the medical system of  claim 17 , wherein the orientation of the fixation element is configured to conform to curvature of a transition from the subcutaneous tissue into the substernal space. 
     
     
         19 . The method of implanting the medical system of  claim 17 , further comprising performing an incision at a xiphoid process of a patient to create the access point into substernal space. 
     
     
         20 . The method of implanting the medical system of  claim 17 , further comprising anchoring the distal end of the first lead to the tissue. 
     
     
         21 . The method of implanting the medical system of  claim 20 , wherein the anchoring comprises suturing the distal end to the tissue. 
     
     
         22 . The method of implanting the medical system of  claim 20 , wherein the anchoring comprises deploying a fixation element for coupling with the tissue. 
     
     
         23 . The method of implanting the medical system of  claim 22 , wherein the fixation element is selected from the group consisting of a prong, burb, clip, screw, flange, disk, flap, and a porous structure. 
     
     
         24 . The method of implanting the medical system of  claim 20 , wherein the anchoring comprises deploying an anchoring mechanism oriented in a first retracted configuration into the substernal space such that the deployed anchoring mechanism is oriented in a second expanded configuration when positioned in the substernal space. 
     
     
         25 . The method of implanting the medical system of  claim 20 , wherein the orientation of the anchoring mechanism triggers a corresponding orientation of an electrode of the first lead towards a target stimulation therapy site. 
     
     
         26 . The method of implanting the medical system of  claim 20 , wherein the anchoring mechanism is configured in a first retracted configuration during the navigation of the lead and configured into a second expanded configuration when the lead is placed within the substernal space. 
     
     
         27 . The method of implanting the medical system of  claim 17 , wherein navigating the first lead comprises:
 inserting the first lead into a delivery system having a distal end portion that is positioned within the substernal space, wherein the distal end of the delivery system comprises a sheath having a lumen into which the first lead is disposed;   advancing the distal end of the first lead towards the distal end portion of the delivery system; and   retracting the delivery system over the first lead from the substernal space.   
     
     
         28 . The method of implanting the medical system of  claim 17 , further comprising positioning an electrode disposed on the distal end of the first lead such that a field of an electrical stimulation applied through the electrode is directed toward a stimulation site. 
     
     
         29 . The method of implanting the medical system of  claim 17 , further comprising subcutaneously advancing a second lead for fixation in subcutaneous tissue, wherein the first lead delivers a pacing stimulation therapy and the second lead delivers a defibrillation stimulation therapy. 
     
     
         30 . The method of implanting the medical system of  claim 17 , wherein the first lead delivers a combination therapy including pacing stimulation and defibrillation stimulation.