Application of pulsed-Doppler tissue imaging in patients with dual chamber pacing: the importance of conduction time and AV delay on regional left ventricular wall dynamics.

Abstract

Pulsed-Doppler tissue imaging (pDTI) is able to measure myocardial wall velocities (systolic: S; early diastolic: E; late diastolic: A) and their timings. Relationships have been demonstrated between the pre-ejection period and indexes of left ventricular systolic function. This study was designed to examine with pDTI the effects of variations in atrioventricular delay (AVD) (100 ms, 150 ms, 200 ms) on myocardial dynamics and on their timings at the basal interventricular septum (IVS) from an apical approach and at the posterior wall (PW) from the parasternal view. These data were compared with stroke volume measurements recorded from the left ventricular outflow tract. Seventeen patients with dual chamber pacemakers (7 because of complete heart block, 10 with sick sinus syndrome and first-degree AV block) were studied; full atrial and ventricular capture was present at any AVD. These data were also compared with those obtained in 10 age-matched healthy volunteers with comparable heart rates. Optimal atrial contribution to left ventricular filling and, consequently, best systolic performance were achieved when AVD was programmed such that a mean interval of 77 ms was allowed between the end of the A wave and the beginning of the S wave, similar to what was measured in the healthy control group by pDTI. The noninvasive measurement of timings of the cardiac cycle by pDTI is helpful to determine the optimal AVD in individual patients.