Reliability of Doppler echocardiography in the assessment of high pulmonary vascular resistance in patients with severe pulmonary arterial hypertension

Abstract

Background: The objective is to assess whether the squaring of tricuspid regurgitation velocity (TRV) gives an improved estimate of pulmonary vascular resistance (PVR) or is equivalent to the ratio of TRV and time velocity integral of right ventricular outflow tract (TVI_RVOT) (TRV/TVI_RVOT) for assessing PVR in patients with high PVR values.

Methods: Thirty patients predicted to have PVR >6 WU by Doppler were included in the present study. TRV and TVI_RVOT were measured by echo Doppler. TRV/TVI_RVOT and TRV²/TVI_RVOT were calculated. PVR_CATH was estimated within 2 h of Doppler study. Regression equations for calculating PVR from TRV/TVI_RVOT (PVR_ECHO1) and TRV²/TVI_RVOT (PVR_ECHO2) were developed. Bland-Altman analysis for agreement between PVR_CATH and PVR_ECHO1, PVR_ECHO2 was carried out.

Results: The mean value of PVR_CATH was found to be 15.08 ± 7.03 WU. The calculated values of PVR_ECHO1 and PVR_ECHO2 were found to be 15.08 ± 6.34 WU and 15.05 ± 6.08 WU, respectively. The linear regression analysis carried out for PVR_CATH and TRV/TVI_RVOT showed good correlation (R = 0.84). Bland-Altman analysis showed excellent agreement between the two Doppler methods and invasive PVR with negligible bias.

Conclusion: Noninvasive estimation of PVR by Doppler is reliable even in patients with high PVR (>6 WU) and, squaring TRV is not superior to TRV alone.

Keywords: Doppler echocardiography; Pulmonary hypertension; Pulmonary vascular resistance; Tricuspid regurgitation velocity.