Medical system including a novel bipolar pacing pair

Abstract

A medical system includes a first low voltage electrode adapted for intimate contact with tissue at an implant site, in order to provide pacing stimulation in conjunction with a second low voltage electrode. A porous layer is formed over the second electrode; the porous layer allows conduction therethrough while preventing contact between the second electrode and tissue in proximity to the implant site.

1 . A medical electrical lead, comprising:
 an elongated lead body including, a first elongated insulated conductor, a second elongated insulated conductor, and a connector formed at a proximal end, the connector including a first electrical contact and a second electrical contact;   a first low voltage electrode, joined to the lead body and coupled to the first contact of the connector via the first conductor, the first electrode having an exposed conductive surface adapted for intimate contact with tissue at an implant site in order to provide pacing stimulation;   a second low voltage electrode having a conductive surface, joined to the lead body in proximity to the first electrode and coupled to the second contact of the connector via the second conductor, the second electrode isolated from the first electrode and adapted to function in conjunction with the first electrode to provide bipolar sensing of near-field signals, the shortest distance between the second electrode and the first electrode being less than approximately 9 millimeters; and   a porous layer formed over the second electrode, allowing conduction therethrough while preventing contact between the conductive surface of the second electrode and tissue in proximity to the implant site.   
   
   
       2 . The lead of  claim 1 , wherein the second electrode includes an outer surface, the porous layer includes an outer surface, and the lead body includes an outer surface; the outer surface of the second electrode recessed from the outer surface of the lead body and the outer surface of the porous layer isodiametric with the outer surface of the lead body. 
   
   
       2 . The lead of  claim 1 , wherein the shortest distance is between approximately 2 millimeters and approximately 9 millimeters. 
   
   
       3 . The lead of  claim 1 , wherein the shortest distance is between approximately 5 millimeters and approximately 9 millimeters. 
   
   
       4 . The lead of  claim 1 , wherein the shortest distance is between approximately 2 millimeters and approximately 5 millimeters 
   
   
       5 . The lead of  claim 1 , wherein the porous layer has a thickness between approximately 0.005 inch and approximately 0.020 inch. 
   
   
       6 . The lead of  claim 1 , wherein the porous layer includes pores having sizes ranging, on average, between approximately 0.4 micron and approximately 50 microns. 
   
   
       7 . The lead of  claim 1 , wherein the first electrode is positioned distal to the second electrode. 
   
   
       8 . The lead of  claim 1 , wherein the first electrode includes a helix for fixation of the first electrode to the implant site. 
   
   
       9 . The lead of  claim 1 , further comprising tines for fixation of the first electrode to the implant site. 
   
   
       10 . A method of cardiac pacing, comprising:
 implanting in a patient's heart a first pacing lead having a first low voltage electrode having an exposed conductive surface adapted for intimate contact with tissue at an implant site in order to provide pacing stimulation and a second low voltage electrode having a conductive surface, the second electrode isolated from the first electrode, the shortest distance between the second electrode and the first electrode being less than approximately 9 millimeters and, the second electrode provided with a porous layer formed thereover allowing conduction therethrough while preventing contact between the conductive surface of the second electrode and tissue in proximity to the implant site;   delivering pacing pulses between the first and second electrodes, to stimulate heart tissue.   
   
   
       11 . The method of  claim 10 , wherein the implanting step comprises implanting a lead wherein the porous layer includes an outer surface, and the body of the lead includes an outer surface; the outer surface of the second electrode recessed from the outer surface of the lead body and the outer surface of the porous layer isodiametric with the outer surface of the second lead body. 
   
   
       12 . The method of  claim 10 , wherein the shortest distance is between approximately 2 millimeters and approximately 9 millimeters. 
   
   
       13 . The method of  claim 10 , wherein the shortest distance is between approximately 5 millimeters and approximately 9 millimeters. 
   
   
       14 . The method of  claim 10 , wherein the shortest distance is between approximately 2 millimeters and approximately 5 millimeters. 
   
   
       15 . The method of  claim 10 , wherein the porous layer has a thickness between approximately 0.005 inch and approximately 0.020 inch. 
   
   
       16 . The method of  claim 10 , wherein the porous layer includes pores having sizes ranging, on average, between approximately 0.4 micron and approximately 50 microns. 
   
   
       17 . The method of  claim 10 , wherein the first low voltage electrode is implanted in a cardiac vein of the patient's heart. 
   
   
       18 . The method of  claim 10 , wherein the first low voltage electrode is implanted adjacent an atrium of the patient's heart. 
   
   
       19 . The method of  claim 10 , wherein the first low voltage electrode is implanted in an atrium of the patient's heart. 
   
   
       20 . The method of  claim 10 , further comprising sensing electrical signals between the first and second electrodes.