Dual-chamber implantable stimulation device having adaptive AV intervall and method for treating cardiomyopathy thereof

A method of operating a dual-chamber implantable pacemaker in order to maximize cardiac output of a patient by pacing in the ventricle, if needed, at a time in a cardiac cycle that is near the patient's natural conduction time, the pacemaker having a PV/AV interval that defines the maximum time permitted by the pacemaker after atrial activity before a ventricular stimulation pulse (V-pulse) is generated, comprising:

• (a) measuring a PR/AR interval as the time interval between atrial activity and a natural ventricular depolarization (R-wave), where atrial activity comprises either a natural atrial depolarization (P-wave) or an atrial stimulation pulse (A-pulse), whichever occurs first in a given cardiac cycle;
• (b) setting the PV/AV interval of the pacemaker to be equal to the measured PR/AR interval .+-..DELTA., where .DELTA. is a prescribed time increment;
• and
• (c) repeating steps (a) and (b) in accordance with a prescribed schedule so that the PV/AV interval of the pacemaker tracks the measured PR/AR interval within .+-..DELTA., and so that a V-pulse is generated and applied to the patient's ventricle at the conclusion of the PV/AV interval in each cardiac cycle in which an R-wave does not occur.

A dual-chamber pacemaker for controlling ventricular pacing in order to increase cardiac output in a patient suffering from cardiomyopathy by preemptively stimulating a ventricle of the patient's heart, comprising:

• an atrial lead having an electrode in contact with one of the atria of the heart, and a ventricular lead having an electrode in contact with one of the ventricles of the heart;
• means for sensing a natural conduction time interval of the patient through the electrodes of the atrial and ventricular leads, the natural conduction time interval comprising the time interval between atrial activity, whether sensed or paced, and a natural ventricular depolarization (R-wave);
• pulse generator means for generating a ventricular stimulation pulse (V-pulse) upon the timing out of an AV time interval and applying the V-pulse to the electrode of the ventricular lead;
• and
• timing means, coupled to the pulse generator means, for defining the AV time interval to begin with atrial activity, and for setting the AV time interval to a value that, for ventricular pacing, is always less than the natural conduction time interval by a prescribed amount;
• whereby the V-pulse is generated by the pulse generator means and applied to one of the ventricles of the heart prior to the occurrence of natural ventricular activity for preemptively stimulating the ventricle to thereby increase cardiac output.

A method of treating cardiomyopathy using an implanted dual-chamber pacemaker, the pacemaker including means for sensing atrial and ventricular events, means for generating a ventricular stimulation pulse (V-pulse), and means for delivering the V-pulse to an apex of the ventricle, said method comprising:

• measuring a natural conduction time as the difference between an atrial event and a natural ventricular event within a given cardiac cycle;
• and
• generating and delivering the V-pulse to the ventricular apex at a time that is less than the measured natural conduction time;
• whereby the V-pulse preempts a natural ventricular event, the V-pulse thereby triggering an apical mechanical contraction sequence that improves cardiac output.