Biphasic waveforms for defibrillation

A method of defibrillating the heart, comprising the steps of:

• placing a first patch electrode over the right ventricle of the heart, configured to conform substantially to the shape and size of the surface of the right ventricle,
• placing a second path electrode over the left ventricle of the heart, configured to conform substantially to the shape and size of the surface of the left ventricle in spaced relationship to the first patch electrode to form a uniform gap between confronting borders of the two patch electrodes in the region of the ventricular septum, while encompassing a substantial portion of the ventricular myocardium between the two patch electrode, toward establishing a uniform potential gradient field through out the entire ventricular mass when a defibrillating electrical waveform is applied to the electrodes, and
• applying a defibrillating electrical waveform constituting a biphasic shock having a first phase of longer duration than the second phase thereof, to the electrodes.

An implantable defibrillator, comprising

• means for detecting fibrillation,
• electrical generating means responsive to the detection of fibrillation for producing a biphasic waveform in which each phase is characterized by an electrical impulse of predetermined polarity, magnitude and duration, the first phase being of greater duration and magnitude than and of opposite polarity to the second phase, and
• means for delivering said waveform to provide electrical shock to the ventricles of the heart.