An evaluation of range gated pulsed Doppler echocardiography for detecting pulmonary outflow tract obstruction in d-transposition of the great vessels.

The aim of this study was to determine the accuracy of range gated pulsed Doppler (RGPD) echocardiography for detecting obstruction to the pulmonary outflow tract in children with d-transposition of the great vessels (d-TGV). Twenty-one children were randomly selected for those available with d-TGV and were studied by precordial and suprasternal RGPD echocardiography. Three were excluded, leaving a population of 18 subjects. The exclusive criterion used to judge the RGPD results was the output of the time interval histogram (TIH). Coherence of the TIH was considered to represent laminar flow. Dispersion of the TIH was considered evidence of flow disturbance and obstruction to the outflow tract. With the range gating feature, the first site of disturbance could be localized. Information was handled by a technique that decreased bias. RGPD results were then compared to diagnoses of the outflow tract established at cardiac catheterization or operation. Comparison of these results indicated that all seven children with obstruction were correctly identified by RGPD study, and the level of the first obstruction was correctly identified. With one exception, all children without pulmonary obstruction were correctly identified by the examination.