Effect of programmed atrioventricular delay on the patterns of mitral and pulmonary vein flow profiles and their durations in patients with dual- chamber pacemakers

Cardiac pacemakers are increasingly used in patients with dilated and hypertrophic cardiomyopathy. In these patients, unusually short atrioventricular (AV) delays are used. Changing the AV delay has been shown to affect the mitral E/A velocity ratio, but its effect on the duration of left ventricular (LV) isovolumic relaxation time, LV filling time, or pulmonary vein flow pattern has not been investigated. Twelve patients with dual-chamber pacemakers were studied. The pacemaker was set at a rate of 70 beats/min, and the AV delay was programmed from 25 to 250 msec in 25-msec increments. At each stage, mitral and pulmonary vein flow velocities were recorded using pulsed-wave Doppler technique. Increasing AV delay resulted in a shortened LV diastolic filling period, a change in LV isovolumic relaxation time, a reduction in the E/A velocity ratio, and an increase in A - AR wave duration. These findings have implications not only in the optimization of LV filling but also in the interpretation of mitral and pulmonary vein flow profiles in the evaluation of LV diastolic function and filling pressures.