Reliability of Doppler-Based Measurement of Pulmonary Vascular Resistance in Congenital Heart Disease with Left-to-Right Shunt Lesions

BackgroundPulmonary vascular resistance (PVR) is a crucial parameter in the management of patients with left-to-right shunt lesions. Cardiac catheterization (Cath) is the gold standard test to assess PVR (PVRcath), but it is invasive and hence, risky in children with pulmonary arterial hypertension (PAH). A noninvasive tool to assess PVR is desirable. Ratio of tricuspid regurgitation velocity (TRV) and time-velocity integral of right ventricular outflow tract (TVIRVOT) by Doppler was previously shown to be a reliable noninvasive method for estimation of PVR in acquired PAH. MethodsPeak TR velocity and TVIRVOT were recorded from 63 prospective patients with various congenital shunt lesions. Subsequently, the patients were subjected to cath in less than 2hours. The patients were subdivided into four subsets based on age and pulmonary arterial mean pressure (PAMP). A regression equation was developed for calculation of PVR from TRV/TVIRVOT (PVREcho) which was indexed for BSA (PVRIEcho). Bland-Altman analysis was done for agreement between PVRIcath and PVRIEcho. Receiver operating characteristic (ROC) curves were plotted to test the identity of the two methods and also the applicability of PVRIEcho across a wide range of Wood units. ResultsReceiver operating characteristic curve plotted between the two methods showed good identity. Bland-Altman analysis showed excellent agreement between the two methods with negligible bias. ROC curves showed that PVRIEcho was accurate in distinguishing different cutoff values of PVR in each of the 4 groups. ConclusionNoninvasive Doppler estimation of PVR is reliable in patients with shunt lesions over a wide range of PVR.