Control of arbitrary waveforms for constant delivered energy

A system for delivering an arbitrary waveform to a subject while monitoring the voltage on an energy storage capacitor in a cardiac defibrillator, comprising:

• means for determining a voltage stored on a storage capacitor and the size of the storage capacitor to derive a total amount of energy stored on the storage capacitor;
• means for truncating an arbitrary waveform after the voltage on the storage capacitor decays to a threshold value;
• and
• means for delivering a specific amount of the total amount of energy via the truncated arbitrary waveform irrespective of the load resistance of a subject.

A system of delivery constant energy to stabilize cardiac rhythm in a patient, the system comprising:

• means for monitoring a portion of a delivered energy being delivered to a portion of cardiac tissue of a patient using an arbitrary waveform in an attempt to successfully terminate an arrhythmia;
• means for calculating a load impedance value of said patient;
• and
• means for adjusting a remaining portion of the delivered energy supplied by the arbitrary waveform based on scaling an amplitude characteristic of the remaining portion of the delivered energy so a desired constant amount of energy is delivered.

A method of delivering a desired, predetermined and constant amount of energy to a portion of tissue, comprising the steps:

• charging a storage capacitor;
• measuring a load impedance of a portion of tissue using at least two electrodes disposed about said portion of tissue;
• measuring the magnitude of an electrical potential present in the storage capacitor;
• delivering an arbitrary waveform from the storage capacitor to the portion of tissue through a switching power converter circuit while simultaneously re-measuring the load impedance;
• and
• in response to changes in the re-measured load impedance, adjusting the arbitrary waveform so that a predetermined, constant amount of energy is ultimately delivered to the portion of tissue.