Method and apparatus for cardiac shock therapy

Abstract

An apparatus and method for delivering defibrillation shock therapy employing a multi-terminal pulse output circuit. In such a circuit, at least three electrode lead terminals are switchably connected to the positive and negative terminals of an energy storage capacitor. By serially switching selected electrode lead terminals to the capacitor terminals, a variety of shock pulse waveforms may be generated.

1 . An apparatus for delivering cardiac shocks, comprising: 
 pulse output circuitry for producing voltage pulses between positive and negative terminals;    at least three electrode lead terminals with each such electrode lead terminal switchably connected to the positive and negative terminals;    control circuitry for switching two selected electrode lead terminals to either the positive or negative terminal to impose a voltage produced by the pulse output circuitry between the two selected electrode lead terminals; and,    wherein the control circuitry is configured to deliver a shock pulse by serially switching a plurality of selected pairs of electrode lead terminals to selected ones of the positive and negative terminals to thereby deliver a multiphasic shock pulse which varies both temporally and spatially.    
   
   
       2 . The apparatus of  claim 1  further comprising shock electrodes for connection to selected electrode lead terminals and disposition in proximity to the heart.  
   
   
       3 . The apparatus of  claim 2  wherein the shock electrodes include a first electrode adapted for disposition within the coronary sinus, a second electrode adapted for disposition within the superior vena cava or right atrium, and a third electrode.  
   
   
       4 . The apparatus of  claim 3  wherein the third electrode is adapted for disposition in the right ventricle.  
   
   
       5 . The apparatus of  claim 3  wherein the third electrode is an implantable housing.  
   
   
       6 . The apparatus of  claim 1  further comprising a device housing and wherein the electrode lead terminals are connected to a four electrode arrangement which includes the device housing as one electrode and shocking electrodes disposed in the superior vena cava, the coronary sinus, and the right ventricle.  
   
   
       7 . The apparatus of  claim 2  further comprising a device housing and wherein at least one of the electrode lead terminals is connected to the device housing.  
   
   
       8 . The apparatus of  claim 1  further comprising: 
 a sensing channel for detecting electrical events in the heart and producing sensing signals in accordance therewith;    processing circuitry for detecting the occurrence of a tachyarrhythmia from the sensing signals; and,    wherein the control circuitry is configured to deliver a multiphasic shock pulse upon detection of a tachyarrhythmia.    
   
   
       9 . The apparatus of  claim 8  wherein the sensing channel is a ventricular sensing channel and the processing circuitry is configured to detect the occurrence of ventricular tachyarrhythmias by measuring a heart rate via the ventricular sensing channel.  
   
   
       10 . The apparatus of  claim 8  wherein the sensing channel is an atrial sensing channel and the processing circuitry is configured to detect the occurrence of atrial tachyarrhythmias by measuring a heart rate via the atrial sensing channel.  
   
   
       11 . A method for delivering cardiac shocks, comprising: 
 producing voltage pulses between positive and negative terminals;    switching two selected electrode lead terminals among a group of at least three such electrode lead terminals to either the positive or negative terminal to impose a voltage produced by the pulse output circuitry between the two selected electrode lead terminals; and,    delivering a shock pulse by serially switching a plurality of selected pairs of electrode lead terminals to selected ones of the positive and negative terminals to thereby deliver a multiphasic shock pulse which varies both temporally and spatially.    
   
   
       12 . The method of  claim 11  further comprising disposing shock electrodes connected to selected electrode lead terminals in proximity to the heart.  
   
   
       13 . The method of  claim 12  further comprising disposing a first electrode within the coronary sinus and a second electrode within the superior vena cava or right atrium.  
   
   
       14 . The method of  claim 13  further comprising disposing third electrode in the right ventricle.  
   
   
       15 . The method of  claim 13  wherein the third electrode is an implantable housing.  
   
   
       16 . The method of  claim 11  further comprising employing the device housing as one shock electrode and disposing other shocking electrodes in the superior vena cava, the coronary sinus, and the right ventricle.  
   
   
       17 . The method of  claim 11  further comprising connecting a device housing to at least one of the electrode lead terminals.  
   
   
       18 . The method of  claim 11  further comprising: 
 detecting electrical events in the heart and producing sensing signals in accordance therewith;    detecting the occurrence of a tachyarrhythmia from the sensing signals; and,    delivering a multiphasic shock pulse upon detection of a tachyarrhythmia.    
   
   
       19 . The method of  claim 18  further comprising detecting the occurrence of ventricular tachyarrhythmias by measuring a heart rate via a ventricular sensing channel.  
   
   
       20 . The method of  claim 18  further comprising detecting the occurrence of atrial tachyarrhythmias by measuring a heart rate via an atrial sensing channel.