Assessment of pulmonary vascular resistance by Doppler echocardiography in patients with pulmonary arterial hypertension.

Background: Assessment of pulmonary artery pressures, cardiac output (CO) and pulmonary vascular resistance (PVR) is crucial in the management of patients with pulmonary arterial hypertension (PAH). The aim of the present study was to investigate whether Doppler echocardiography can be used to determine PVR in patients with PAH.

Methods: Forty-two patients were included and Doppler echocardiography was performed simultaneously (n = 22) and non-simultaneously (n = 60) with right heart catheterization. The tricuspid regurgitation velocity was used to estimate pulmonary arterial peak systolic and diastolic (PADP) pressures (Bernoulli equation). At the time of pulmonary valve opening, right ventricular pressure equals PADP. The tricuspid regurgitation velocity at the time of pulmonary valve opening was measured by superimposing the time from the QRS to the onset of pulmonary flow on the tricuspid regurgitation velocity envelope. Pulmonary capillary wedge pressure, right atrial pressure and CO were assessed using standard Doppler echocardiography methods. Right heart catheterization was performed using Swan-Ganz catheters and thermodilution for CO determination.

Results: The differences (mean +/- SD) between catheter and simultaneous/non-simultaneous Doppler echocardiography were 0.3 +/- 0.8 (p = 0.10)/-0.3 +/- 1.1 (p = 0.06) liter/min for CO, 2.9 +/- 5.1 (p = 0.02)/-1.2 +/- 7.4 (p = 0.2) mm Hg for the transpulmonary gradient (TPG) and 0.3 +/- 2.1 (p = 0.65)/0.8 +/- 2.4 (p = 0.02) Wood unit for PVR. The correlation coefficients between catheter and simultaneous/non-simultaneous Doppler echocardiography were 0.86/0.75 for CO, 0.92/0.90 for TPG and 0.93/0.92 for PVR.

Conclusions: A comprehensive hemodynamic assessment that includes CO, TPG and PVR can be provided by Doppler echocardiography in patients with severe pulmonary hypertension.