Determination of Pulmonary to Systemic Flow Ratio and Prediction of Pulmonary Arterial Pressure in Children by Pulsed Doppler Echocardiography

Sohn, Sejung; Hong, Chang Yee

Abstract

The purpose of this study is to evaluate pulsed Doppler echocardiographic method (PD) for the measurement of pulmonary to systemic flow ratio (QP/Qs) and pulmonary arterial pressure in children. We studied 32 children with left to right shunt who had undergone cardiac catheterization, 11 children who had heart diseases without shunt and 14 normal children. Velocity time intergral (VTI) was calculated by triangulated meansurement [1/2(maximum blood velocityxejection time)]. Doppler blood flow was calculated from the equation : Doppler blood flow=VTIxcross sectional areaxheart rate. The following Doppler time intervals and ratio of intervals were also measured : preejection period(PEP), acceleration time(AT), ejection time (ET), PEP/AT, PEP/ET and AT/ET. Qp/Qs measured by PD was 1.09+/-0.15 (mean+/-SD) in children with no shunt and normal children. A high correlation was found between Fick and Doppler-derived Qp/Qs in children with left to right shunt (r=0.87). All the children with Qp/Qs less than 1.5 showed no significant discrepancy between two methods. The best correlation with pulmonary arterial pressure was achieved by the PEP/AT (r=0.84 vs systolic pressure). Sensitivity and specificity of PEP/AT for predicting pulmonary arterial hypertension were 79% and 95%, respecitively. In conclusion, it is thought that determination of Qp/Qs and prediction of pulmonary arterial pressure in children by PD is a useful, noninvasive method and triangulated measurement may be used as a simple and easy method for the measurement of Qp/Qs.