Patent ID: 6876881

Claim:
A method of optimizing the site and intersite delay configuration of a dual chamber pacemaker of the type having means for sensing atrial depolarization events, means for sensing ventricular depolarization events and means for applying cardiac stimulating pulses selectively to the right, left or both ventricular chambers at predetermined intersite intervals following detection of atrial depolarization events, comprising the steps of: (a) tracking a patient's intrinsic atrial depolarization events; (b) deriving from a transthoracic impedance signal a cyclic respiratory signal representative of a patient's tidal volume; (c) measuring the patient's cycle length between successive depolarization events over a first predetermined number of heart beats, N 1 , at a first intersite interval and storing the measured cycle lengths as an array in a memory to establish a baseline value; (d) changing at least one of intersite delay interval and pacing site configuration by changing, for a second predetermined number of heart beats, N 2 , less than the first predetermined number of heart beats, (i) the intersite delay interval of the pacemaker from the baseline value to a different intersite delay interval less than the value at which intrinsic atrial depolarization is established, or (ii) the site(s) of the ventricle(s) to which the stimulating pulses are applied; (e) measuring the patient's cycle length between successive atrial depolarization events over the second predetermined number of heart beats and storing the measured cycle lengths in the array in said memory; (f) calculating and storing a cycle length feature value obtained from the patient's cycle length measured in steps (c) and (e); (g) repeating steps (a)-(f) in iterative cycles over a range of intersite delay intervals and ventricular chamber(s) selected for receiving the cardiac stimulating pulses where the second predetermined number of beats, N 2 , for each iterative cycle begins at a corresponding phase of the said cyclic respiratory signal; (h) after step (f) for each pacing site and intersite delay configuration, calculating the average of the cycle length features over all of the occurrences of the configuration; (i) determining the optimal configuration from among the averages determined in step (g); and (j) setting the intersite delay and pacing site configuration of the pacemaker to the optimal intersite delay and pacing site configuration established in step (i).