Abstract: A method for rapidly and accurately determining defibrillation thresholds. The method comprises the steps of delivering an initial shock series to a patient, the shock series comprising at least two shocks of differing energy levels, determining an estimated shock level adjustment based on the initial shock series, and delivering at least one adjusted shock of a predetermined energy level based on the estimated shock level adjustment. The technique uses optimized search criteria as opposed to the conventional step-wise decrease and increase techniques. An apparatus for implementing the method is also disclosed.

Abstract: An implantable cardioverter defibrillator for treating cardiac dysrhythmias utilizing an interrupted discharge output provided by a switch control means to vary the duty cycle of a switch incorporated within the output circuitry of the implanted cardioverter defibrillator so as to increase the efficiency by extending the duration of the discharge for capacitor systems having time constants, tau, less than about the chronaxie value of the human heart. As a result, the implantable cardioverter defibrillator produces a more favorable rectangular-like waveform from the discharge of a significantly smaller capacitor than the capacitors used in existing implantable cardioverter defibrillators.