DIASTOLIC LEFT-TO-RIGHT SHUNTING IN UNCOMPLICATED VENTRICULAR SEPTAL-DEFECT

The systolic left-to-right shunt in patients with uncomplicated ventri cular septal defect is associated with a classic loud murmur, and is w ell described. The additional diastolic left-to-right shunt, always si lent, is less well recognized. Left-to-right diastolic shunt flow is d irectly related to the defect size, to the diastolic pressure gradient between. the left and right ventricle, and to the duration of diastol e. The purpose of this study was to evaluate by Doppler echocardiograp hy the duration, magnitude, and flow velocity characteristics of the d iastolic left-to-right shunt. There were 30 adult patients with uncomp licated ventricular septal defects studied by color, pulsed, and conti nuous wave Doppler echocardiography. In each patient, the uncomplicate d ventricular septal defect was visualized by two-dimensional echocard iography and/or Doppler echocardiography, and the systolic and diastol ic left-to-right shunt flow was identified by Doppler echocardiography . Accurate Doppler flow velocity peas twice, in beginning and again. a t end diastole. The mean diastolic flow velocity was 0.5-1.5 msec (ave rage 0.83 +/- 22 msec). This flow velocity was markedly lower than the mean systolic shunt flow velocity (2.4-5.3 msec, average 3.8 +/- .7 m sec). The Doppler flow velocity integral was 0.17-0.64 m (average 0.36 +/- 0.14), markedly smaller than the systolic flow velocity integral (0.8-1.8 m, average 1.3 +/- 0.3). The diastolic left-to-right shunt fl ow teas 12-41% (average 21 +/- 8) of total (systolic and diastolic) sh unt flow. In conclusion: Diastolic left-to-right shunts can be identif ied in all patients with uncomplicated ventricular septal defects, and analyzed in the majority of patients. A significant degree of the lef t to right shunting in. uncomplicated ventricular septal defects occur during diastole.