Methods and systems for reducing discomfort from cardiac defibrillation shocks

A cardiac system for treating arrhythmia in a subject in need thereof, comprising:

• an arrhythmia detector configured to determine when a cardiac arrhythmia is occurring and to detect the cardiac cycle from electrical activity sensed from the heart of a subject;
• a controller operatively associated with the detector;
• and
• a shock generator operatively associated with the controller;
• wherein the controller is configured to direct the shock generator to deliver a defibrillation shock to one or more electrodes placed in operative association with the heart at a time during the cardiac cycle at which atrial blood volume is reduced.

A cardiac system for treating arrhythmia in a subject in need thereof, comprising:

• an arrhythmia detector configured to determine when a cardiac arrhythmia is occurring from electrical activity sensed from the heart of a subject;
• a controller operatively associated with the detector;
• and
• a shock generator operatively associated with the controller;
• the controller configured to direct the shock generator to deliver a biphasic waveform shock through one or more defibrillation electrodes placed in operative association with the heart, the biphasic waveform shock having a first ascending phase and a second phase of opposite polarity, the first ascending phase maintaining an effective voltage greater than about 50 to about 80% of the peak voltage for a duration greater than 0.5 to about 1.0 ms.

A method for reducing discomfort associated with atrial defibrillation comprising:

• determining the time of the fibrillation cycle length;
• and
• delivering a first defibrillation shock to the heart;
• delivering a second defibrillation shock to the heart, wherein the second defibrillation shock is spaced apart from the defibrillation shock by about 80% to about 90% of the time of the fibrillation cycle length;
• delivering a third defibrillation shock to the heart, wherein the third defibrillation shock is spaced apart from the second defibrillation shock by about the time of the fibrillation cycle length.

A method for reducing discomfort associated with atrial defibrillation comprising:

• selectively administering at least two of a plurality of treatment techniques, the treatment techniques comprising:
• (a) selecting and administering a shock waveform that requires a reduced shock energy, voltage, or current;
• (b) selecting and administering a shock waveform or sequence of waveforms that is intrinsically less painful;
• (c) timing a defibrillation shock based on a sensed signal of the fibrillation electrical complex;
• (d) administering a defibrillation shock at the onset of fibrillation;
• (e) administering drugs that lower the defibrillation threshold;
• (f) administering drugs that decrease the discomfort associated with the shock;
• (g) administering a plurality of shocks in succession;
• (h) performing pacing before or after the defibrillation shock;
• and
• (i) delivering one shock, sequential shocks, or overlapping shocks from three or more electrodes.