Patent ID: 7151963

Claim:
A system for controlling waveform to deliver constant energy from a device to terminate a cardiac fibrillation condition, the system comprising: means for measuring a load impedance of a subsystem between at least a pair of electrodes over a duration to deliver an initial portion of energy via a mono-phasic ramp-type waveform beginning from an essentially null amplitude; means for measuring a length of time it takes a storage capacitor voltage to decay by a certain percentage; and means for calculating the impedance of the load that a voltage-controlled or current-controlled output mono-phasic ramp-type waveform is delivered into based on the length of time; means for extending a delivery time interval that the voltage-controlled or current-controlled output waveform requires to deliver a pre-programmed total amount of energy irrespective of the load impedance, wherein said amount of energy includes the initial portion of energy; and means for truncating the mono-phasic ramp-type waveform to the essentially null amplitude.