RANGE-GATED PULSED DOPPLER ECHOCARDIOGRAPHY: ITS ROLE IN DETECTING DUCTAL SHUNTING IN PREMATURE INFANTS

Abstract

To evaluate the effectiveness of the range-gated pulsed doppler system in detecting the presence of ductal shunting in small pre-term infants on assisted ventilation for respiratory insufficiency, 21 infants with BW under 1500 grams were studied with a 5MHz system developed by Advanced Technology Laboratories, Inc. In each, an umbilical or radial artery catheter was used to obtain a contrast aortogram. Also, a two year old child with a documented aortopulmonary (AP) window was studied. Nine of the infants had no doppler evidence of patent ductus arteriosus (PDA), 8 had negative aortograms. In 13 there was an audible continuous turbulence superior to the pulmonary valve approximately 2 cm below the transducer. Each had a positive aortogram. Auscultation revealed a systolic or continuous murmur at the ULSB in 9 of the 13 infants; in 3, no murmur was appreciated. In the child with an AP window, there was a continuous turbulence at the level of the pulmonary valve. This noninvasive bedside technique appears to be very sensitive and specific for detecting the presence of ductal shunting, even in the absence of an audible precordial murmur. Its use permits the expedient indentification of a PDA in the patients who cannot be weaned from the ventilator and it facilitates appropriate timely therapy, such as the phannacologic manipulation or surgical ligation of the ductus, as a means of preventing the complications of protracted ventilation.