Feasibility and accuracy of transthoracic Doppler echocardiographic estimation of pulmonary capillary wedge pressure applying different methods.

Abstract

Pulmonary wedge pressure (PWP) is an established index of cardiac function and an essential component in the management of patients with congestive heart failure and in critically ill patients. To evaluate feasibility and accuracy of non-invasive prediction of PWP by Doppler echocardiography in daily clinical practice. Agreement was assessed between values predicted by Doppler vs. invasively measured PWP. Forty-five consecutive patients [mean (S.D.) age 62 (10) years] with CAD (44%), DCMP (40%) and without structural heart disease (16%) were studied (EF< or =40% in 58% of the patients). Doppler transmitral and pulmonary venous flow velocity profiles were recorded. For binary and quantitative prediction of PWP, four different methods and five different linear equations, suggested previously in the literature, were evaluated. Predictive values to identify elevated PWP were highest for pulmonary venous flow reversal exceeding the duration of forward mitral flow during atrial systole (PPV 1 and NPV 0.96). Likewise, agreement with measured PWP was highest for equations comprising both transmitral and pulmonary venous flow variables (relative mean difference 0.11, S.D.+/-4.01 mmHg for the most accurate equation). Feasibility was slightly, but not statistically, lower when pulmonary venous flow was considered vs. transmitral flow parameters alone for binary prediction (87 vs. 93%) as well as for quantitative assessment (82 vs. 93%). Semiquantitative prediction of elevated PWP by Doppler echocardiography is feasible as well as accurate in daily clinical practice. However, accuracy of numeric estimates is limited. Hence, invasive measurement of PWP is still necessary in certain clinical settings.