A method and apparatus for selection of one or more ventricular chambers to stimulate
for ventricular resynchronization therapy. Intrinsic intracardia electrograms that
include QRS complexes, are recorded from a left and right ventricle. A timing relationship
between the intrinsic intracardia electrograms recorded from the left and right
ventricle is then determined. In one embodiment, the timing relationship is determined
using a delay between a left ventricular and a right ventricular sensed intrinsic
ventricular depolarizations and a duration interval of one or more QRS complexes.
In one embodiment, the duration of QRS complexes is determined from either intracardiac
electrograms or from surface ECG recordings. One or more ventricular chambers in
which to provide pacing pulses are then selected based on the timing relationship
between intrinsic intracardia electrograms recorded from the right and left ventricle,
and the duration of one or more QRS complexes.