Echocardiographie Study of the Variability of the Peak Rate of Left Ventricular Filling

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Abstract
Peak rate of left ventricular (LV) filling was found to be diminished in many cardiovascular diseases. This measurement has been frequently obtained from M-mode echocardiography. Since LV chamber size is influenced by venous return, it was important to determine the variability and reproducibility of this measurement in consecutive cardiac cycles during normal resting respiration. Twenty normal subjects volunteered for échocardiographie recording. Their age varied from 16 to 44 years. LV end-diastolic dimension (EDD) and the peak rate of change in LV dimension (+dD/dt) were determined at rest. +dD/dt varied from 10.5 to 14.7 cm/s in 5 consecutive cardiac cycles. The mechanism of these variations could not be related to changes in R-R intervals. Moreover, it was not related to changes in venous return since there was no correlation between variations of +dD/dt or +dD/dt corrected for cardiac cycle length and instantaneous LV diameter. Therefore, we studied the effect of respiration on the variability of dD/dt in consecutive cardiac cycles. For this purpose, dD/dt was assessed in 15 of the 20 normal volunteers with simultaneous recording of respiratory excursions. The peak rate of LV dimension reduction during systole (-dD/dt) decreased significantly at end-inspiration in association with a significant decrease in LV EDD (from 4.82 ± 0.4 cm at end-expiration to 4.55 ± 0.4 cm at end-inspiration). On the other hand, +dD/dt and +dD/dt corrected for instantaneous LV dimension were not altered by respiration. These data show that the variations of +dD/dt during respiration are not due to hemodynamic factors. They are possibly related to mechanical events such as cardiac rotation during diaphragmatic respiratory movement.

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