Lead for implantable cardiac prosthesis, including protection against the thermal effects of mri fields

Abstract

A heat dissipating housing to be positioned at a distal end of a stimulation/defibrillation lead, the housing including a housing body having a distal contact face at a distal end, an inner wall, and an outer wall. The housing further includes an anchoring screw, wherein at least a portion of the anchoring screw extends axially from the distal end of the housing body. The anchoring screw is configured to secure the distal contact face in contact with tissue of a patient to form a thermal bridge between the tissue and the housing body. The housing body is electrically insulated and thermally conductive to dissipate heat transferred through the thermal bridge to the outer wall of the housing body.

What is claimed is: 
     
         1 . A heat dissipating housing to be positioned at a distal end of a stimulation/defibrillation lead, the housing comprising:
 a housing body having a distal contact face at a distal end, an inner wall, and an outer wall; and   an anchoring screw, wherein at least a portion of the anchoring screw extends axially from the distal end of the housing body;   wherein the anchoring screw is configured to secure the distal contact face in contact with tissue of a patient to form a thermal bridge between the tissue and the housing body; and   wherein the housing body is electrically insulated and thermally conductive to dissipate heat transferred through the thermal bridge to the outer wall of the housing body.   
     
     
         2 . The heat dissipating housing of  claim 1 , further comprising an electrode formed by an electrically conductive portion of the anchoring screw. 
     
     
         3 . The heat dissipating housing of  claim 2 , wherein the electrically conductive portion of the anchoring screw is a distal tip of the anchoring screw. 
     
     
         4 . The heat dissipating housing of  claim 2 , wherein the electrically conductive portion of the anchoring screw is a portion of the length of the anchoring screw, not including a distal tip. 
     
     
         5 . The heat dissipating housing of  claim 1 , having a thermal conductivity of at least 5 W/mK. 
     
     
         6 . The heat dissipating housing of  claim 1 , wherein the housing body comprises an electrically insulating surface coating, wherein the electrically insulating surface coating is a thermally conductive material. 
     
     
         7 . The heat dissipating housing of  claim 1 , further comprising a deployment mechanism configured to deploy the anchoring screw out from the housing to a deployed position wherein the anchoring screw extends axially from the distal end of the housing body. 
     
     
         8 . The heat dissipating housing of  claim 1 , further comprising portions of a thermally conductive material inserted between the turns of the anchoring screw so as to fill the space existing between the turns. 
     
     
         9 . The heat dissipating housing of  claim 1 , wherein the inner wall of the housing defines a cavity, and wherein the cavity is filled with a thermally conductive material. 
     
     
         10 . A heat dissipating housing to be positioned a distal end of a stimulation/defibrillation lead, the housing comprising:
 a housing body having a distal contact face at a distal end, an inner wall, and an outer wall;   an electrode positioned near a distal portion of the housing;   an anchoring mechanism extending from the distal end of the housing body, to anchor the distal contact face to tissue of a patient;   a first and a second thermal bridge for transferring heat from the tissue to the housing;   wherein the first thermal bridge is formed between the tissue and the distal contact face of the housing body; and   wherein the second thermal bridge is formed between the anchoring mechanism and inner wall of the housing body.   
     
     
         11 . The heat dissipating housing of  claim 10 , wherein the first and the second thermal bridge provide for transfer of heat to the outer wall of the housing body to dissipate the heat to an area surrounding the outer wall. 
     
     
         12 . The heat dissipating housing of  claim 10 , wherein the anchoring mechanism comprises a helical screw that has an electrically conductive portion comprising the electrode. 
     
     
         13 . The heat dissipating housing of  claim 12 , wherein the electrically conductive portion is a distal tip of the helical screw. 
     
     
         14 . The heat dissipating housing of  claim 10 , wherein the anchoring mechanism comprises anchoring tines projecting outside of the tubular housing. 
     
     
         15 . The heat dissipating housing of  claim 10 , having a thermal conductivity of at least 5 W/mK. 
     
     
         16 . The heat dissipating housing of  claim 10 , wherein the housing body comprises an electrically insulating surface coating, wherein the electrically insulating surface coating is a thermally conductive material. 
     
     
         17 . The heat dissipating housing of  claim 10 , further comprising a deployment mechanism configured to deploy the anchoring mechanism out from the housing to a deployed position wherein the anchoring mechanism extends from the distal end of the housing body. 
     
     
         18 . The heat dissipating housing of  claim 12 , further comprising portions of a thermally conductive material inserted between the turns of the helical screw so as to fill the space existing between the turns. 
     
     
         19 . The heat dissipating housing of  claim 10 , wherein the inner wall of the housing defines a cavity, and wherein the cavity is filled with a thermally conductive material.