Cardioversion and defibrillation lead system

DETAILED DESCRIPTION The present, invention is directed toward the construction of a lead system having the optimum characteristics for use with an implantable cardioversion or defibrillation pulse generator.
Because the pulse generator is likely to be battery powered, it is extremely desirable that the electrode system be configured to allow defibrillation or cardioversion of the heart with the minimum expenditure of energy.
Increasing the efficiency of the electrode system allows an increase in the number of pulses that can be delivered before capacity of the batteries is exhausted.
More importantly, by reducing the energy level applied to the heart, chances for tissue damage due to the defibrillation pulse are also reduced.
The present application discloses several configurations of lead systems developed with the purpose of maximizing the efficiency of electrical energy in depolarizing the cells of the heart, and terminating tachycardia or fibrillation.
In one embodiment of the invention, the orthogonal electrode configuration of the Purdue application is utilized.
However, by altering the regime for applying pulses and optimizing electrode size and placement, efficiency of the electrode system is substantially improved.
A first novel pulse regime employs all four orthogonally located electrodes pulsed simultaneously during two sequential pulses.
In this regime, two adjacent electrodes have positive polarity and the other two electrodes have negative polarity, concentrating defibrillation energy in the heart wall, rather than through the center of the heart.
Two or more such pulses are applied, with a reverse in polarity of one pair of opposing electrodes, between each pulse.
This system is referred to as the peripheral rotating pulse regime.
A second novel pulse regime for use with orthogonal electrodes is a quadripolar single pulse regime in which polarity of the four electrodes alternates with each adjacent electrode, and in which all four electrodes are used simultaneously to defibrillate the heart