Pulmonary Vascular Resistance

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J Am Coll Cardiol. 2001 Jun 1;37(7):1813-9.
Accurate noninvasive estimation of pulmonary vascular resistance by Doppler echocardiography in patients with chronic failure heart failure.
Scapellato F, Temporelli PL, Eleuteri E, Corra U, Imparato A, Giannuzzi P.
Division of Cardiology, Salvatore Maugeri Foundation, IRCCS, Medical Center of Rehabilitation, Veruno, Italy. fscapellato@fsm.it

OBJECTIVES: This study was undertaken to explore further the relationship between Doppler-derived parameters of pulmonary flow and pulmonary vascular resistance (PVR) and to determine whether PVR could be accurately estimated noninvasively from Doppler flow velocity measurements in patients with chronic heart failure. BACKGROUND: The assessment of PVR is of great importance in the management of patients with heart failure. However, because of the inconclusive and conflicting data available, Doppler estimation of PVR is still considered unreliable. METHODS: Simultaneous Doppler echocardiographic examination and right heart catheterization were performed in 63 consecutive sinus rhythm heart failure patients with severe left ventricular systolic dysfunction. Hemodynamic PVR was calculated with the standard formula. The following Doppler variables on pulmonary flow and tricuspid regurgitation velocity curve were correlated with PVR: maximal systolic flow velocity, pre-ejection period (PEP), acceleration time (AcT), ejection time, total systolic time (TT), velocity time integral, and right atrium-ventricular gradient. RESULTS: At univariate analysis, all variables except maximal systolic flow velocity and velocity time integral showed a significant, although weak, correlation with PVR. The best correlation found was between AcT and PVR (r = -0.68). By regression analysis, only PEP, AcT and TT entered into the final equation, with a cumulative r = 0.87. When the function (PEP/AcT)/TT was correlated with PVR, the correlation coefficient further improved to 0.96. Of note, this function prospectively predicted PVR (r = 0.94) after effective unloading manipulations. CONCLUSIONS: The analysis of Doppler-derived pulmonary systolic flow is a reliable and accurate tool for estimating and monitoring PVR in patients with chronic heart failure due to left ventricular systolic dysfunction.

J Am Coll Cardiol. 2003 Mar 19;41(6):1021-7.
A simple method for noninvasive estimation of pulmonary vascular resistance.
Abbas AE, Fortuin FD, Schiller NB, Appleton CP, Moreno CA, Lester SJ.
Division of Cardiovascular Diseases, Mayo Clinic, 13400 East Shea Boulevard, Scottsdale, Arizona 85259, USA.

OBJECTIVES: We sought to test whether the ratio of peak tricuspid regurgitant velocity (TRV, ms) to the right ventricular outflow tract time-velocity integral (TVI(RVOT), cm) obtained by Doppler echocardiography (TRV/TVI(RVOT)) 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/TVI(RVOT) was 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/TVI(RVOT) correlated 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/TVI(RVOT) x 10 + 0.16, showed satisfactory limits of agreement (mean 0 +/- 0.41). A TRV/TVI(RVOT) cutoff 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.

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