Clinical study: pulmonary hypertension
A simple method for noninvasive estimation of pulmonary vascular resistance

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Abstract

Objectives

We sought to test whether the ratio of peak tricuspid regurgitant velocity (TRV, ms) to the right ventricular outflow tract time-velocity integral (TVIRVOT, cm) obtained by Doppler echocardiography (TRV/TVIRVOT) provides a clinically reliable method to determine pulmonary vascular resistance (PVR).

Background

Pulmonary vascular resistance is an important hemodynamic variable used in the management of patients with cardiovascular and pulmonary disease. Right-heart catheterization, with its associated disadvantages, is required to determine PVR. However, a reliable noninvasive method is unavailable.

Methods

Simultaneous Doppler echocardiographic examination and right-heart catheterization were performed in 44 patients. The ratio of TRV/TVIRVOTwas then correlated with invasive PVR measurements using regression analysis. An equation was modeled to calculate PVR in Wood units (WU) using echocardiography, and the results were compared with invasive PVR measurements using the Bland-Altman analysis. Using receiver-operating characteristics curve analysis, a cutoff value for the Doppler equation was generated to determine PVR >2WU.

Results

As calculated by Doppler echocardiography, TRV/TVIRVOTcorrelated well (r = 0.929, 95% confidence interval 0.87 to 0.96) with invasive PVR measurements. The Bland-Altman analysis between PVR obtained invasively and that by echocardiography, using the equation: PVR= TRV/TVIRVOT× 10 + 0.16 , showed satisfactory limits of agreement (mean 0 ± 0.41). A TRV/TVIRVOTcutoff value of 0.175 had a sensitivity of 77% and a specificity of 81% to determine PVR >2WU.

Conclusions

Doppler echocardiography may provide a reliable, noninvasive method to determine PVR.

Abbreviations

CI
confidence interval
ICC
intraclass correlation coefficient
MPAP
mean pulmonary artery pressure
PASP
pulmonary artery systolic pressure
PCWP
pulmonary capillary wedge pressure
PVR
pulmonary vascular resistance
PVRCATH
invasive pulmonary vascular resistance
PVRECHO
pulmonary vascular resistance calculated by echocardiography
Qp
transpulmonary flow
Δp
transpulmonary pressure gradient
RAP
right atrial pressure
TRV
peak tricuspid regurgitant velocity
TVIRVOT
right ventricular outflow tract time-velocity integral
WU
Wood units

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