Role of Doppler echocardiography for assessing right ventricular cardiac output in patients with atrial septal defect

Background: Although Doppler echocardiography is routinely used to assess left ventricle cardiac output, there are limited data about the feasibility of Doppler echocardiography for right ventricular (RV) cardiac output assessment in patients with left-to-right shunt. The purpose of the study was to determine the correlation between Doppler-derived and Fick-derived RV cardiac index (CI), and the interobserver correlation in Doppler-derived RV CI assessment. Methods: Retrospective study of patients (age ≥18 years) with unrepaired atrial septal defect who underwent cardiac catheterization and echocardiography (within 3 days), 2004-2017. RV CI was calculated using the hydraulic orifice formula: [.785 × (right ventricle outflow tract diameter)² × right ventricular outflow tract (RVOT) time velocity integral × heart rate]/body surface area. Results: A total of 128 patients (age 52 ± 17 years; female 88 [69%]) met the inclusion criteria. There was a modest correlation between Doppler-derived and Fick-derived RV CI (r =.57, P <.001), and the mean difference between Doppler-derived and Fick-derived RV CI was −.3 (95% confidence interval of agreement, −.8 to +.9) L/min/m². There was also a modest correlation between Doppler-derived RV CI from observer #1 and observer #2 (r =.62, P <.001), and the mean difference between Doppler-derived RV CI from observer #1 and observer #2 was −.2 (95% confidence interval of agreement, −.9 to +.6). Conclusions: The current study demonstrated a modest correlation between Doppler-derived and Fick-derived RV cardiac output, and a modest interobserver correlation in Doppler-derived RV cardiac output assessment. Further studies are required to validate these results and to explore other potential applications such as in patients with chronic pulmonary regurgitation.