Accuracy of Doppler-estimated pulmonary vascular resistance in patients before liver transplantation.

The hyperdynamic circulation associated with cirrhosis is typically characterized by high cardiac output and low systemic and pulmonary vascular resistance (PVR). Approximately 4% of cirrhotic patients develop portopulmonary hypertension, which is an important predictor of hemodynamic instability after orthotopic liver transplantation. Doppler estimation of pulmonary artery systolic pressure (PASP) is used as a screening test for the presence of portopulmonary hypertension. We tested the accuracy of a noninvasive measurement of PVR (ratio of peak tricuspid regurgitant velocity [TRV] to right ventricular outflow tract velocity time integral [VTI RVOT]) to detect increased PVR in a population before liver transplantation. We compared test characteristics of the TRV/VTI RVOT ratio to echocardiographically derived PASP for detection of invasively measured PVR >1.5 Wood units. There was no significant correlation between Doppler-derived PASP and invasively measured PVR. There was a moderate and significant correlation between TRV/VTI RVOT ratio and invasively measured PVR. Compared with Doppler-derived PASP, the TRV/VTI RVOT ratio was a more accurate test for PVR >1.5 Wood units. Using a cut-off value of TRV/VTI RVOT >0.12, the sensitivity and negative predictive value for PVR >1.5 Wood units were 100%. In conclusion, the TRV/VTI RVOT ratio is a more accurate screening test for the presence of portopulmonary hypertension than PASP in patients undergoing orthotopic liver transplantation. Routine use of this ratio may decrease the need for invasive hemodynamic assessment in this patient population.