Pulmonary hypertension
Assessment of Pulmonary Vascular Resistance by Doppler Echocardiography in Patients With Pulmonary Arterial Hypertension

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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.

Section snippets

Patients

The study group included 42 patients with pulmonary vascular disease studied prospectively during evaluation for medical treatment or lung transplantation. Patients with left-sided heart disease or increased PCWP were excluded from the study. Patients’ characteristics are summarized in Table 1. Thirty-two patients had PAH according to the World Health Organization (WHO) clinical classification. We included 8 patients with chronic pulmonary embolism, 1 with sarcoidosis and 1 with multiple

Catheterization Data

Pulmonary artery pressures, TPG, mean RAP, CO and PVR values are shown in Table 2. Most patients had severe pulmonary hypertension with markedly increased PVR. In 1 patient, PCWP was not obtained due to the unstable wedge position of the catheter. Right atrial pressure at the time of the opening of the pulmonary valve was lower than mean RAP (mean difference 2 mm Hg, range −2 to 7 mm Hg, p < 0.0001). In 2 patients, CO determination was not possible due to high variability between the

Discussion

This study is the first to demonstrate that a comprehensive hemodynamic assessment, including TPG and PVR, can be obtained by Doppler echocardiography in patients with PAH. This finding may be of clinical relevance because the prognosis in patients with PAH is closely related to hemodynamic indices of right ventricular function.2

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    Copyright © 2007 International Society for Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.