Accuracy of Doppler echocardiography in the hemodynamic assessment of pulmonary hypertension

Abstract

Rationale: Transthoracic Doppler echocardiography is recommended for screening for the presence of pulmonary hypertension (PH). However, some recent studies have suggested that Doppler echocardiographic pulmonary artery pressure estimates may frequently be inaccurate.

Objectives: Evaluate the accuracy of Doppler echocardiography for estimating pulmonary artery pressure and cardiac output.

Methods: We conducted a prospective study on patients with various forms of PH who underwent comprehensive Doppler echocardiography within 1 hour of a clinically indicated right-heart catheterization to compare noninvasive hemodynamic estimates with invasively measured values.

Measurements and main results: A total of 65 patients completed the study protocol. Using Bland-Altman analytic methods, the bias for the echocardiographic estimates of the pulmonary artery systolic pressure was -0.6 mm Hg with 95% limits of agreement ranging from +38.8 to -40.0 mm Hg. Doppler echocardiography was inaccurate (defined as being greater than +/-10 mm Hg of the invasive measurement) in 48% of cases. Overestimation and underestimation of pulmonary artery systolic pressure by Doppler echocardiography occurred with a similar frequency (16 vs. 15 instances, respectively). The magnitude of pressure underestimation was greater than overestimation (-30 +/- 16 vs. +19 +/- 11 mm Hg; P = 0.03); underestimates by Doppler also led more often to misclassification of the severity of the PH. For cardiac output measurement, the bias was -0.1 L/min with 95% limits of agreement ranging from +2.2 to -2.4 L/min.

Conclusions: Doppler echocardiography may frequently be inaccurate in estimating pulmonary artery pressure and cardiac output in patients being evaluated for PH.

Figure 1.

Bland-Altman plot of Doppler echocardiographic estimates of pulmonary artery pressure and right-heart catheterization measurements. The bias was −0.6 mm Hg and the 95% limits of agreement were +38.8 and −40.0 mm Hg. Triangles represent excellent- and good-quality Doppler signal; circles = fair- and poor-quality Doppler signal; dotted line = bias; dash/dotted line = upper and lower limits of agreement. Abbreviations: DE = Doppler echocardiography; PASP = pulmonary artery systolic pressure; RHC = right-heart catheterization.

Figure 2.

Comparison of right atrial pressure as estimated by Doppler echocardiography and right-heart catheterization. RHC = right-heart catheterization.

Figure 3.

Bland-Altman plot of cardiac output estimated by DE and measured by right-heart catheterization. The bias was −0.1 L/min and the 95% limits of agreement were 2.2 and −2.4 L/min. Diamonds represent difference in CO; dotted line = bias; dash/dotted line = upper and lower limits of agreement. Abbreviations: CO = cardiac output; DE = Doppler echocardiography; RHC = right-heart catheterization.