3d echocardiography in known or suspected pulmonary hypertension: feasibility and significance

Background: Right ventricular failure is the major cause of morbidity and mortality in patients with pulmonary hypertension yet the best noninvasive modality to assess right ventricular structural changes and function is unclear. Methods: Patients referred to the Echocardiography Laboratory for assessment of known or suspected pulmonary arterial hypertension were prospectively enrolled. All patients underwent a standard dedicated 2D and Doppler pulmonary hypertension echocardiogram which includes assessment of Doppler hemodynamics, measures of longitudinal systolic function including tricuspid annular plane systolic excursion (TAPSE), and peak systolic velocity of the tricuspid annulus by tissue Doppler and right ventricular systolic speckle-tracking strain. All patients also underwent 3D assessment of right ventricular size and function with volumes indexed to body surface area and reported ejection fraction. All images were obtained on Vivid E7 (n=20) or E9 (n=81; General Electric) with 3D analysis done on Tomtec independent platform. Results: A total of 101 patients were enrolled (68% female, age 60±16 years). Ten percent had an oxygen saturation ≤ 88%. The average estimated right ventricular systolic pressure was 54±20 mmHg with an estimated right atrial pressure of 8±4 mmHg. The average right ventricular ejection fraction was 48±7% with RV end diastolic volume index of 87±20 mL/m2. 2-D measurements of the right ventricle correlated well with right ventricular volumes with the best correlation seen with the basal right ventricular dimension. Measures of longitudinal right ventricular contractility such as TAPSE, tissue Doppler, and systolic free-wall strain all correlated well with the degree of NT-proBNP elevation, functional class and 6 minute walk distance. Right ventricular ejection fraction correlated with NT-proBNP measures however, not with functional class or 6 minute walk distance. Conclusions: 3D echocardiography is feasible to assess right ventricular size and ejection fraction in patients with known or suspected pulmonary hypertension. Simpler measures of right ventricular dimensions correlate well with right ventricular volumes and measures of longitudinal right ventricular systolic function appear to correlate as well or better than right ventricular ejection fraction with functional capacity.