Optimal Programming of the Atrioventricular Delay Using the Phonocardiogram

To predict the optimal atrioventricular (AV) delay using the phonocardiogram (PCG).We studied 12 recipients of cardiac resynchronization therapy (CRT) system and eight recipients of dual-chamber pacemakers implanted for AV block with normal left ventricular (LV) function. The amplitude of the first heart sound (S1) was recorded by PCG and the LV outflow tract (OT) time-velocity integral (TVI) was measured by pulsed Doppler echocardiography. The AV delay was prolonged in 20-ms increments, from 60 ms to 240 ms. Ishikawa's method was used for the echocardiographic optimization of the AV delay. The relation between S1 amplitude and the AV delay was analyzed.The correlation between the amplitude of S1 and the length of AV delay showed an S-shaped curve. The AV delay at the inflection point of each patient's S-shaped curve (161.2 +/- 19.5 ms) was positively correlated with the optimal AV delay determined by echocardiography (148.3 +/- 16.9 ms, r = 0.83, P < 0.001). In addition, there was a positive correlation between the AV delay at the maximal TVI of LVOT (150.8 +/- 22.7 ms) and the AV delay at the inflection point of the S-shaped curve (159.5 +/- 24.9 ms, r = 0.87, P < 0.001). In two CRT system recipients, an optimal AV delay could not be found by echocardiography; however, an optimal AV delay could be determined by PCG.A high correlation was observed between the optimal AV delay determined by phonocardiography versus echocardiography.