Electrodes for intra-cardiac pacemaker

Abstract

A pacemaker has a housing and a therapy delivery circuit enclosed by the housing for generating pacing pulses for delivery to a patient's heart. An electrically insulative distal member is coupled directly to the housing and at least one non-tissue piercing cathode electrode is coupled directly to the insulative distal member. A tissue piercing electrode extends away from the housing.

What is claimed is: 
     
         1 . A pacemaker comprising:
 a housing having a proximal end, a distal end and a longitudinal sidewall extending from the proximal end to the distal end;   a therapy delivery circuit enclosed by the housing for generating pacing pulses for delivery to a patient's heart;   a first electrode located along the housing;   an electrically insulative distal member coupled to the housing distal end; and   at least one non-tissue piercing stimulation electrode coupled directly to the insulative distal member and electrically coupled to the therapy delivery circuit for delivering at least a portion of the generated pacing pulses via a pacing electrode vector including the at least one non-tissue piercing stimulation electrode and the first electrode;   a tissue piercing electrode comprising:
 an electrically insulated shaft extending from a distal shaft end to a proximal shaft end that is coupled to the housing distal end; and 
 a tip electrode at the distal shaft end; 
   a sensing circuit enclosed by the housing;   an atrial sensing channel electrically coupled to the non-tissue piercing stimulation electrode, wherein the atrial sensing channel is configured to receive a first cardiac electrical signal indicative of a P-wave of the patient's heart;   a ventricular sensing channel electrically coupled to the tissue piercing electrode, wherein the ventricular sensing channel is configured to receive a second cardiac electrical signal indicative of an R-wave of the patient's heart; and   a delivery tool interface member extending from the housing proximal end for receiving a delivery tool for advancing the tip electrode into a first heart chamber tissue for pacing the first heart chamber and advancing the at least one non-tissue piercing stimulation electrode along a second heart chamber tissue for pacing the second heart chamber.   
     
     
         2 . The pacemaker of  claim 1 , wherein the electrically insulated shaft is coupled to the housing distal end by the electrically insulative distal member. 
     
     
         3 . The pacemaker of  claim 1 , wherein the at least one non-tissue piercing stimulation electrode is peripheral to the tissue piercing electrode. 
     
     
         4 . The pacemaker of  claim 1 , wherein the electrically insulated shaft is helical. 
     
     
         5 . The pacemaker of  claim 1 , further comprising at least one of a control circuit or a pacing circuit configured to deliver a first pacing pulse via the at least one non-tissue piercing stimulation electrode and deliver a second pacing pulse via the tissue piercing electrode following an atrioventricular pacing interval after the first pacing pulse. 
     
     
         6 . The pacemaker of  claim 1 , wherein the at least one non-tissue piercing stimulation electrode has a raised surface relative to the insulative distal member. 
     
     
         7 . The pacemaker of  claim 1 , wherein:
 the atrial sensing channel is configured to determine when the P-wave crosses a P-wave sensing threshold and communicate a signal indicative of the first cardiac electrical signal when the P-wave crosses the P-wave sensing threshold, and   the ventricular sensing channel is configured to determine when the R-wave crosses an R-wave sensing threshold and communicate a signal indicative of the second cardiac electrical signal when the R-wave crosses the R-wave sensing threshold.   
     
     
         8 . The pacemaker of  claim 1 , wherein:
 the non-tissue piercing stimulation electrode is configured to deliver a first portion of the generated pacing pulses,   the pacemaker is configured to inhibit the first portion of the generated pacing pulses based on the first cardiac electrical signal received by the atrial sensing channel,   the pacemaker is configured to schedule a second portion of the generated pacing pulses when the pacemaker inhibits the first portion of the generated pacing pulses, and   the pacemaker is configured to inhibit the second portion of the generated pacing pulses based on the second cardiac electrical signal communicated by the ventricular sensing channel.   
     
     
         9 . The pacemaker of  claim 1 , wherein the atrial sensing channel is configured to receive the first cardiac electrical signal from the at least one non-tissue piercing stimulation electrode. 
     
     
         10 . The pacemaker of  claim 1 , wherein the ventricular sensing channel is configured to receive the second cardiac electrical signal from the tissue piercing electrode. 
     
     
         11 . The pacemaker of  claim 1 , wherein the tissue piercing electrode is configured to deliver a portion of the generated pacing pulses via a pacing electrode vector including the tissue piercing electrode and the first electrode. 
     
     
         12 . The pacemaker of  claim 1 , wherein the first electrode is an anode electrode and the stimulation electrode is a cathode electrode. 
     
     
         13 . The pacemaker of  claim 1 , wherein at least one of the atrial sensing channel is configured to communicate a signal indicative of the first cardiac electrical signal to the sensing circuit or the ventricular sensing channel is configured to communicate a signal indicative of the second cardiac electrical signal to the sensing circuit. 
     
     
         14 . A pacemaker comprising:
 a housing having a proximal end, a distal end and a longitudinal sidewall extending from the proximal end to the distal end;   a therapy delivery circuit enclosed by the housing for generating pacing pulses for delivery to a patient's heart;   a first electrode located along the housing;   an electrically insulative distal member coupled to the housing distal end;   at least one non-tissue piercing stimulation electrode coupled directly to the insulative distal member and electrically coupled to the therapy delivery circuit for delivering a first portion of the generated pacing pulses via a first pacing electrode vector including the at least one non-tissue piercing stimulation electrode and the first electrode;   a tissue piercing electrode extending away from the housing distal end for delivering a second portion of the generated pacing pulses;   a sensing circuit enclosed by the housing;   an atrial sensing channel electrically coupled to the non-tissue piercing stimulation electrode, wherein the atrial sensing channel is configured to receive a first cardiac electrical signal of the patient's heart; and   a ventricular sensing channel electrically coupled to the tissue piercing electrode, wherein the ventricular sensing channel is configured to receive a second cardiac electrical signal of the patient's heart;   wherein the tissue piercing electrode is configured to deliver the second portion of the generated pacing pulses via a second pacing electrode vector including the tissue piercing electrode and the at least one non-tissue piercing electrode.   
     
     
         15 . The pacemaker of  claim 14 , wherein the at least one non-tissue piercing stimulation electrode includes a plurality of non-tissue piercing stimulation electrodes coupled directly to a periphery of the insulative distal member. 
     
     
         16 . The pacemaker of  claim 14 , wherein the electrically insulative distal member defines a distal-facing surface of the pacemaker, wherein the at least one non-tissue piercing stimulation electrode includes a plurality of non-tissue piercing stimulation electrodes, and wherein at least a portion of the plurality of non-tissue piercing stimulation electrodes extend along the distal-facing surface. 
     
     
         17 . The pacemaker of  claim 14 , wherein the at least one non-tissue piercing stimulation electrode is peripheral to the tissue piercing electrode. 
     
     
         18 . The pacemaker of  claim 14 , wherein the tissue piercing electrode is an active fixation member comprising:
 an electrically insulated shaft extending from a proximal shaft end coupled to the housing distal end to a distal shaft end; and   a tip electrode at the distal shaft end.   
     
     
         19 . The pacemaker of  claim 18 , wherein the electrically insulated shaft is helical. 
     
     
         20 . The pacemaker of  claim 14 , further comprising at least one of a control circuit or a pacing circuit configured to deliver a first pacing pulse via the at least one non-tissue piercing stimulation electrode and deliver a second pacing pulse via the tissue piercing electrode following an atrioventricular pacing interval after the first pacing pulse. 
     
     
         21 . The pacemaker of  claim 14 , wherein the at least one non-tissue piercing stimulation electrode has a raised surface relative to the insulative distal member. 
     
     
         22 . The pacemaker of  claim 14 , wherein:
 the first cardiac electrical signal is a P-wave of the patient's heart and the atrial sensing channel includes first cardiac event detection circuitry configured to detect the P-wave, and   the second cardiac electrical signal is an R-wave of the patient's heart and the ventricular sensing channel includes second cardiac event detection circuitry configured to detect the R-wave.   
     
     
         23 . The pacemaker of  claim 14 , wherein:
 the atrial sensing channel is configured to determine when a P-wave of the patient's heart crosses a P-wave sensing threshold and communicate a signal indicative of the first cardiac electrical signal when the P-wave crosses the P-wave sensing threshold, and   the ventricular sensing channel is configured to determine when an R-wave of the patient's heart crosses an R-wave sensing threshold and communicate the signal indicative of the second cardiac electrical signal when the R-wave crosses the R-wave sensing threshold.   
     
     
         24 . The pacemaker of  claim 14 , wherein:
 the pacemaker is configured to inhibit the first portion of the generated pacing pulses based on the first cardiac electrical signal communicated by the atrial sensing channel,   the pacemaker is configured to schedule the second portion of the generated pacing pulses when the pacemaker inhibits the first portion of the generated pacing pulses, and   the pacemaker is configured to inhibit the second portion of the generated pacing pulses based on the second cardiac electrical signal received by the ventricular sensing channel.   
     
     
         25 . The pacemaker of  claim 14 , wherein the atrial sensing channel is configured to receive the first cardiac electrical signal from the at least one non-tissue piercing stimulation electrode. 
     
     
         26 . The pacemaker of  claim 14 , wherein the ventricular sensing channel is configured to receive the second cardiac electrical signal from the tissue piercing electrode. 
     
     
         27 . The pacemaker of  claim 14 , wherein the tissue piercing electrode is configured to deliver the second portion of the generated pacing pulses via a second pacing electrode vector including the tissue piercing electrode and the first electrode.