EVALUATION OF ASYNCHRONOUS LEFT-VENTRICULAR RELAXATION BY DOPPLER-ECHOCARDIOGRAPHY DURING VENTRICULAR PACING WITH AV-SYNCHRONY (VDD) - COMPARISON WITH ATRIAL-PACING (AAI)

The effect of right ventricular pacing on left ventricular relaxation was studied in 13 patients (age 62 +/- 3 years), with the atrial sensi ng ventricular pacing mode (VDD). A control group of similar age (64 /- 4 years) consisted of fl patients with atrial pacing (AAI). The tim ing of events was determined in both groups at similar R-R intervals ( 921 +/- 77 ms vs 967 +/- 37 ms). The loading conditions as estimated b y peak systolic wall stress (afterload) and end-diastolic left ventric ular dimensions (preload) were approximately the same in both groups. The ratio of late to early filling velocities were similar in both gro ups, Dominant changes were: increased preejection period (142 +/- 13 m s vs 95 +/- 15 ms); and higher velocities of isovolumic relaxation flo w (60 +/- 34 cm/s vs 25 +/- 4 cm/s) in patients with ventricular pacin g The isovolumic relaxation time was longer in patients with VDD pacin g (127 +/- 14 ms vs 108 +/- 12 ms), Anterior systolic interventricular septal motion (paradoxal motion) was recorded in nine patients with V DD pacing and in none of the patients with AAI pacing. Isovolumic rela xation flow was detected during atrial pacing in five (45%) patients a nd in 13 (100%) patients during atrial sensing ventricular pacing, ind icating asynchronous left ventricular relaxation. This data shows that VDD pacing compared to atrial pacing resulted in an altered activatio n pattern of the left ventricle, associated with delayed onset, asynch ronous contraction with interventricular septal motion abnormalities a nd prolonged asynchronous left ventricular relaxation with abnormal mo tion manifested by the presence of isovolumic relaxation flow.