DUAL-CHAMBER PACING IN HYPERTROPHIC CARDIOMYOPATHY - INFLUENCE OF ATRIOVENTRICULAR DELAY ON LEFT-VENTRICULAR OUTFLOW TRACT OBSTRUCTION

The impact of the duration of atrioventricular (AV) delay on obstructi on in hypertrophic cardiomyopathy was evaluated in 12 patients by card iac catheterization, and in 8 of them also by Doppler echocardiography . The AV delay was programmed in random order at 125, 100 and 75 ms in the invasive study and at 120, 100 and 80 ms after pacemaker implanta tion. The arterial pressure did not changed throughout the studies, wh ereas the gradient decreased significantly by reducing the AV delay va lue; the greater gradient reduction was obtained, in both studies, wit h the AV delay set between 75 or 80 and 100 ms. QRS duration increased significantly by reducing the Ati delay during both studies, The wide st QRS was not associated with the smallest gradient in all patients, Changes in gradients were similar during the invasive and noninvasive protocols.