Implantable lead and method of manufacture

Abstract

An implantable, substantially isodiametric, low resistance implantable lead having at least one electrode positioned in a stimulation/sensing portion of the lead as well as a method of manufacturing the same. At least the stimulation/sensing portion is unitized through partially surrounding and supporting insulation and conductive element(s) of the stimulation/sensing portion with a fused matrix of material having mechanical properties consistent with a body of the lead.

What is claimed is:  
     
         1 . An implantable lead comprising: 
 a lead body having a distal end and a proximal end;    an electrode positioned at the distal end of the lead body;    a terminal positioned at the proximal end of the lead body; and    a conductor, electrically coupling the electrode and the terminal and extending along an interior passage defined by the lead body, wherein the conductor has a resistance equal to or less than 25 ohms for a conductor length equal to or less than 60 cm.    
     
     
         2 . An implantable lead in accordance with    claim 1   , wherein the conductor is formed of stranded wire.  
     
     
         3 . An implantable lead in accordance with    claim 1   , wherein an outer diameter of the lead body is approximately 0.05 inches.  
     
     
         4 . An implantable lead in accordance with    claim 1   , further comprising a stylet guide, positioned within the interior passage defined by the lead body, wherein an inlet of the stylet guide is at the proximal end of the lead body.  
     
     
         5 . An implantable lead in accordance with    claim 1   , wherein the implantable lead is substantially isodiametric.  
     
     
         6 . A method for forming a substantially isodiametric lead having a prescribed diameter and at least one electrode separated from at least one terminal by a lead body, wherein the at least one electrode is electrically coupled to the at least one terminal by a conductor passing through a passage defined by the lead body, comprising the steps of: 
 assembling the at least one electrode and the at least one terminal relative to the lead body to form an assembly, including connecting the at least one electrode to the at least one terminal via the conductor;    over-molding the assembly with a first material to form an intermediate assembly, wherein the first material is compatible with and has mechanical properties consistent with a material of the lead body; and    removing all material of the intermediate assembly in excess of the prescribed diameter.    
     
     
         7 . A method in accordance with    claim 6   , wherein the at least one electrode has an outer diameter greater than the prescribed diameter prior to the removing step.  
     
     
         8 . A method in accordance with    claim 6   , wherein the at least one terminal has an outer diameter greater than the prescribed diameter prior to the removing step.  
     
     
         9 . A method in accordance with    claim 6   , wherein the removing step involves subjecting the intermediate assembly to at least a centerless grinding process.  
     
     
         10 . A method for forming a substantially isodiametric lead having a prescribed diameter and a first region separated from a second region by a lead body, the first region having a plurality of electrodes, and the second region having a plurality of terminals, each terminal being respectively and electrically joined to at least one electrode by a conductor passing through a passage defined by the first region, second region, and lead body, comprising the steps of: 
 assembling the plurality of electrodes and plurality of terminals relative to the lead body to form an assembly, this step including electrically coupling each terminal to at least one electrode by a conductor; and    unitizing at least that portion of the assembly corresponding to the first region of the lead, wherein subsequent to unitization, each electrode is separated by an insulative material, and the passage defined by at least the first region is substantially filled with the insulative material.    
     
     
         11 . A method in accordance with    claim 10   , further comprising unitizing that portion of the assembly corresponding to the second region of the lead, wherein subsequent to unitization, each terminal is separated by a second insulative material, and the passage defined by at least the first region is substantially filled with the second insulative material.  
     
     
         12 . A method in accordance with    claim 11   , wherein the second insulative material has mechanical properties consistent with the material of the lead body.  
     
     
         13 . A method in accordance with    claim 10   , wherein the insulative material has mechanical properties consistent with the material of the lead body.  
     
     
         14 . A method for forming a substantially isodiametric lead having a prescribed diameter and a first region separated from a second region by a lead body, the first region having a plurality of electrodes, and the second region having a plurality of terminals, each terminal being respectively and electrically joined to at least one electrode by a conductor passing through a passage defined by the first region, second region, and lead body, comprising the steps of: 
 assembling the plurality of electrodes and plurality of terminals relative to the lead body to form an assembly, this step including electrically coupling each terminal to at least one electrode by a conductor; and    unitizing at least that portion of the assembly corresponding to the first region of the lead, wherein each electrode is separated by an insulative material, and the passage defined by at least the first region is substantially filled with the insulative material,    wherein the step of unitizing involves over-molding the assembly with a second material to form an intermediate assembly, wherein the second material is compatible with and has mechanical properties consistent with the material of the lead body.    
     
     
         15 . A method in accordance with    claim 14   , wherein the second material and the insulative material are the same.  
     
     
         16 . A method in accordance with    claim 14   , further comprising the step of removing all material of the intermediate assembly in excess of the prescribed diameter.  
     
     
         17 . A method in accordance with    claim 16   , wherein the step of removing involves subjecting the intermediate assembly to at least a centerless grinding process.  
     
     
         18 . A method in accordance with    claim 16   , wherein the at least one electrode has an outer diameter greater than the prescribed diameter prior to the removing step.  
     
     
         19 . A method in accordance with    claim 16   , wherein the at least one terminal has an outer diameter greater than the prescribed diameter prior to the removing step.