Electrical cardiac output forcer

Abstract

An electrical method and apparatus for stimulating cardiac cells causing contraction to force hemodynamic output during fibrillation, hemodynamically compromising tachycardia, or asystole. Forcing fields are applied to the heart to give cardiac output on an emergency basis until the arrhythmia ceases or other intervention takes place. The device is used as a stand alone external or internal device, or as a backup to an ICD, atrial defibrillator, or an anti-tachycardia pacemaker. The method and apparatus maintain some cardiac output and not necessarily defibrillation.

1 . A method for forcing cardiac output during hemodynamically compromising malfunction in a patient, comprising: 
 (a) detecting the presence of a hemodynamically compromising malfunction in the patient;    (b) delivering a first electrical signal through at least a portion of the patient's body, the first electrical signal including at least one pulse having sufficiently high energy for achieving a defibrillating effect in the patient; and    (c) delivering a second electrical signal through at least a portion of the patient's body, the second electrical signal having energy insufficient to achieve a defibrillating effect in the patient but sufficient to achieve a hemodynamic effect in the patient.    
   
   
       2 . The method of  claim 1 , wherein delivering the second electrical signal includes causing cardiac output in the patient by forcing contraction in at least some of the patient's muscles.  
   
   
       3 . The method of  claim 1 , wherein delivering the second electrical signal includes controlling the second electrical signal to have a periodicity that corresponds to a desired heartbeat rhythm in the patient.  
   
   
       4 . The method of  claim 1 , and further comprising: 
 controlling the second electrical signal to correspond in time with pumping of the patient's atria.    
   
   
       5 . The method of  claim 1 , further comprising the steps of reassessing the presence of a hemodynamically compromising malfunction and, if a hemodynamically compromising malfunction is detected, delivering a third electrical signal through at least a portion of the patient's body, the third electrical signal including at least one pulse having energy sufficient to achieve a defibrillating effect in the patient.  
   
   
       6 . The method of  claim 1 , further comprising the steps of reassessing the presence of a hemodynamically compromising malfunction and, if a hemodynamically compromising malfunction is detected, continuing delivery the second electrical signal.  
   
   
       7 . The method of  claim 1 , wherein delivering the first electrical signal is performed before delivering the second electrical signal.  
   
   
       8 . The method of  claim 1 , wherein delivering the second electrical signal is performed before delivering the first electrical signal.  
   
   
       9 . The method of  claim 1 , and further comprising: 
 positioning, in the patient's heart region, a plurality of electrodes through which the first electrical signal and the second electrical signal are conducted.    
   
   
       10 . The method of  claim 1 , and further comprising: 
 providing at least one sensor adapted to detect a presence of a hemodynamically compromising malfunction in the patient.    
   
   
       11 . The method of  claim 1 , and further comprising: 
 monitoring the patient's cardiac output; and    controlling the second electrical signal to maintain a desired level of cardiac output.    
   
   
       12 . The method of  claim 11 , wherein the controlling includes adjustment of at least one parameter selected from the list consisting of: 
 signal amplitude pulse duration; and    pulse rate.    
   
   
       13 . The method of  claim 1 , and further comprising: 
 shaping a waveform of the second electrical signal to reduce its effect on one of non-cardiac muscles, skeletal muscles, and cardiac muscles and skeletal muscles.    
   
   
       14 . The method of  claim 1 , wherein the second electrical signal is delivered during at least a majority of a 30-minute period.  
   
   
       15 . The method of  claim 1 , wherein the second electrical signal includes a plurality of pulses delivered at a rate of between about 60 and 200 pulses per minute.  
   
   
       16 . The method of  claim 1 , wherein the second electrical signal includes pulses that are each between 2 and 100 ms in width.  
   
   
       17 . The method of  claim 1 , wherein the second electrical signal includes electrical current pulses having a peak amplitude greater than 140 mA.  
   
   
       18 . The method of  claim 1 , wherein the second electrical signal includes a train of at least 10 pulses.  
   
   
       19 . The method of  claim 1 , wherein the second electrical signal includes a plurality of electrical bursts, wherein each burst includes a plurality of shorter pulses.  
   
   
       20 . The method of  claim 1 , wherein the second electrical signal is delivered at a voltage of between 10 and 350 volts.  
   
   
       21 . An at least partially implantable device for maintaining some cardiac output of a patient's heart during hemodynamically compromising malfunction using electrical forcing fields, comprising: 
 a power supply circuit;    a hemodynamically compromising malfunction detector circuit (HCMD) operatively coupled with the power supply circuit;    electrotherapy circuitry operatively coupled with the HCMD and the power supply circuit, and adapted to deliver first type and second type electrotherapy signals to at least a portion of the patient's upper body region, wherein the first type electrotherapy signal includes at least one pulse having sufficiently high energy for achieving a defibrillating effect in the patient and the second type electrotherapy signal has energy insufficient to achieve a defibrillating effect in the patient but sufficient to achieve a hemodynamic effect in the patient; and    a controller circuit operatively coupled with the power supply circuit and interfaced with the HCMD and the electrotherapy circuitry, the controller circuit configured to: 
 recognize a hemodynamically compromising malfunction in the patient based on an indication from the HCMD; and  
 cause the electrotherapy circuitry to deliver at least one of the first type and second type electrotherapy signals.  
   
   
   
       22 . The method of  claim 21 , wherein the second type electrotherapy signal is adapted to cause cardiac output in the patient by forcing contraction in at least some of the patient's muscles.  
   
   
       23 . The device of  claim 21 , wherein the controller circuit is further configured to control the second type electrotherapy signal to have a periodicity that corresponds to a desired heartbeat rhythm in the patient.  
   
   
       24 . The device of  claim 21 , wherein the controller circuit is further configured to control the second type electrotherapy signal to correspond in time with pumping of the patient's atria.  
   
   
       25 . The device of  claim 21 , wherein the controller circuit is further configured to reassess the presence of a hemodynamically compromising malfunction based on an indication by the HCMD and, if a hemodynamically compromising malfunction is detected, to cause delivery of one of the first type electrotherapy signal, the second type of electrotherapy signal and the first type of electrotherapy signal before causing delivery of the second type electrotherapy signal to at least a portion of the patient's upper body region.  
   
   
       26 . The device of  claim 21 , wherein the controller circuit is configured to cause delivery of the second type electrotherapy signal before causing delivery of the first type electrotherapy signal.  
   
   
       27 . The device of  claim 21 , wherein the HCMD includes at least one circuit selected from the group consisting of the following sensor circuits: 
 an electrophysiological signal sensing circuit;    a pressure sensing circuit;    an oxygen sensing circuit; and    a flow measuring circuit.    
   
   
       28 . The device of  claim 21 , wherein the HCMD is adapted to detect an arrhythmia.  
   
   
       29 . The device of  claim 21 , further comprising a therapeutic effectiveness measuring circuit.  
   
   
       30 . The device of  claim 29 , wherein the therapeutic effectiveness measuring circuit includes a blood pressure sensor adapted to monitor cardiac output.  
   
   
       31 . The device of  claim 29 , wherein the controller circuit is configured to adjust at least one electrotherapy parameter to maintain a desired therapeutic effect on the patient.  
   
   
       32 . The device of  claim 31 , wherein the at least one electrotherapy parameter is selected from the list consisting of: 
 signal amplitude    pulse duration; and    pulse rate.    
   
   
       33 . The device of  claim 21 , wherein the controller circuit is configured to stop administration of electrotherapy signals in response to an indication by the HCMD indicating an absence of a hemodynamically compromising malfunction.  
   
   
       34 . The device of  claim 21 , wherein the controller is configured to assess the hemodynamically compromising malfunction based on indication from the HCMD and, based on the assessment, to select from among the first type and the second type electrotherapy signals to administer.  
   
   
       35 . The device of  claim 21 , wherein the power supply circuit and the electrotherapy circuitry are adapted such that electrotherapy signaling can be maintained for at least 30 minutes.  
   
   
       36 . The device of  claim 21 , wherein the electrotherapy circuitry is adapted to deliver the second type electrotherapy signal at a periodicity of between about 60 and 200 pulses per minute.  
   
   
       37 . The device of  claim 21 , wherein the electrotherapy circuitry is adapted to deliver second type electrotherapy signals that include pulses that are between 2 and 100 ms in width.  
   
   
       38 . The device of  claim 21 , wherein the second type electrotherapy signal has a wave shape adapted to stimulate cardiac muscles to a greater degree than non-cardiac muscles.  
   
   
       39 . The device of  claim 21 , wherein the second type electrotherapy signal has a wave shape that includes pulses, each pulse comprising a plurality of narrow pulses.  
   
   
       40 . The device of  claim 21 , wherein the second type electrotherapy signal has a wave shape in which edges are rounded.  
   
   
       42 . The device of  claim 21 , wherein the second type electrotherapy signal has a peak voltage between 10 and 100 volts.  
   
   
       43 . The device of  claim 21 , wherein the electrotherapy circuit operates to produce a cardiac output of between about 10% and about 90% of the normal maximum cardiac output for the patient.