1511 RANGE-GATED PULSED DOPPLER DETERMINATION OF ASCENDING AORTIC FLOW IN HEALTHY NEONATES

Abstract

Ascending aortic blood flow was determined in 6 healthy neonates by range-gated pulsed Doppler technique in the 1st 72 hrs. of life. None of the infants had evidence of structural heart disease or patent ductus arteriosus by 2-D Echo. and all were AGA. The descending aorta was visualized by 2-D Echo. from a subcostal view and Doppler spectral waveforms were obtained within the ascending aorta. Mean flow velocity during systole was determined by digitizing and integrating the area under the Doppler flow during 3 consecutive systolic intervals with a microsonics computer. Ascending aortic blood flow during systole was calculated by using the formula: mean flow velocity × cross-sectional area of the aorta. Ascending aortic blood flow per minute was computed by the formula: systolic ascending aortic blood flow × heart rate. Heart rate was obtained by simultaneously recorded EKG. Mean ascending aortic blood flow was 187±17 ml/min/kg for these 6 neonates. These results are comparable to historical standards for systemic blood flow as determined by the thermodilution and Fick principle derived systemic blood flow. Our study confirms that range-gated pulsed Doppler technique offers a reliable method for non-invasive determination of ascending aortic blood flow.