Patent ID: 6405084
Filing Date: 2002-06-11
Classification: A61N

Abstract:
An implantable atrial defibrillator apparatus comprising:a plurality of defibrillation electrodes adapted to be applied to the heart muscle of at least one atrium and to deliver electric defibrillation shocks thereto, first sensor means for detecting an occurrence of atrial fibrillation and for generating a first signal indicative thereof; second sensor means for detecting a ventricular electrogram and an absolute refractory period of the ventricular myocardium and generating a second signal indicative thereof; control means connected to receive the first and second signals for selectively supplying a defibrillation pulse sequence to the electrodes in response to the occurrence of atrial fibrillation, the defibrillation pulse sequence including a plurality of voltage pulses separated in time by a pulse interval, the pulse sequence being configured by the control means to have a time of duration no greater than the absolute refractory period of the ventricular myocardium as detected by the second sensor means, the control means being connected to supply the pulse sequence to the electrodes so that the pulses are applied to the heart muscle only during the absolute refractory period of the ventricular myocardium, the control means being adapted to selectively vary at least one characteristic of the voltage pulses, the at least one characteristic selected from the group of waveform of the voltage pulses, the duration of the voltage pulses, the interval between successive voltage pulses, and the electrodes to which a voltage pulse is applied at any particular time such that application of the defibrillation pulse sequence to the heart muscle creates an electric defibrillation field of variable geometry dependent on the selective variations of the at least one characteristic of the voltage pulses.