[Effects of heart rate increase by transesophageal stimulation on the left ventricular filling in the normal subject. A pulsed echo-Doppler study].

The effects of increasing the heart rate on left ventricular filling were studied by Doppler echocardiography in 12 mildly sedated normal subjects. The heart rate was increased by 10, 20 and 30 bpm with respect to the basal rhythm by transoesophageal pacing. Four stages were thereby defined: S0, S1, S2 and S3. The principal results were: absence of variation of the isovolumic relaxation period in absolute values (92 +/- 14, 86 +/- 16, 87 +/- 16, 78 +/- 11 ms); absence of variation of the duration of the rapid filling period (246 +/- 36 at 50 vs 220 +/- 28 ms at 53); no change in peak filling velocity (72 +/- 11 at 50 vs 61 +/- 11 ms at 53) or in the timing of peak velocity (77 +/- 12 at 50 vs 72 +/- 13 ms at 53); increased contribution of atrial systole during tachycardia (Vmax 43 +/- 7 at 50 vs 76 +/- 17 cm/s at 53). Therefore, of these Doppler echo parameters, only atrial systole changed during the range of tachycardia rates which were studied. Its increase compensated the loss of diastolic diastasis. These changes should be born in mind in Doppler echocardiographic studies of left ventricular diastolic function.