[The atrioventricular valve opening time on the normal echocardiogram].

54 healthy volunteers were examined. In 48 the time from the beginning of the QRS complex to the opening of the atrioventricular (AV) valves (point D in the echocardiogram), the Q-Dt for the tricuspid valve (TV) and for the mitral valve (MV), was measured by echocardiography. In the other 6 subjects this was done by atrial stimulation using an esophageal probe. The Q-D period is dependent on heart rate and embraces the total electromechanical systole (Q-S2) of the left or right ventricle and the isovolumic relaxation time (IRT). The time for the opening of the TV is 408 ms (+/- 86 ms) [2 SD] and that for the MV 428 ms +/- 86 ms at a mean heart rate of 73 beats/min and 72 beats/min respectively. However, this 20-ms difference between the opening times of TV and MV was not seen under stimulation with the esophageal probe. In order to compare Q-Dts measured at different heart rates, all values were corrected to correspond to a heart rate of 72 beats/min by using the regression line of Q-Dt/heart rate. Prolongation of Q-Dt TV and Q-Dt MV in comparison to normal values is discussed in 9 patients. Of 6 patients with left heart failure, 2 had delayed opening of the MV; in 5 early diastolic filling was delayed or there was exclusively late diastolic filling of the right ventricle. It can be assumed that prolongation of Q-Dt TV or Q-Dt MV is due to a dysfunction of isovolumic relaxation. The time taken to reach the early diastolic AV pressure gradient seems to play an important role in determining the length of the IRT. A lengthening of the IRT and the electromechanical systole is discussed in 3 patients with right ventricular load and prolongation of the Q-Dt TV.