Abstract
Background
The right atrium (RA) is a highly dynamic chamber with 3 mechanical functions (reservoir, conduit, booster pump) and prognostic implications in heart failure (HF) and pulmonary hypertension (PH). However, RA function and its interplay with the right ventricular (RV) performance in patients (pts) with reduced left ventricular ejection fraction (LVEF) and without PH remain to be clarified.
Methods
We used three-dimensional echocardiography to study 55 pts (61 ± 14 years, 43 men) with LVEF < 40% no more than mild tricuspid regurgitation (TR), and maximum velocity of the TR jet < 3 m/s. We measured the three-dimensional RA total, passive, active ejection volumes (EV) and the respective emptying fractions (EF). In addition, we compared RV volumes and ejection fraction (RVEF) between patients with normal and abnormal RA function.
Results
Mean LVEF was 30 ± 7%. Mean echo-derived pulmonary vascular resistance was 1.64 ± 0.54 Wood units. 28 pts (51%) had reduced RA reservoir function (total EF = 34 ± 9%), 34 pts (62%) had reduced RA conduit function (passive EF = 15 ± 4%), and 10 pts (18%) had reduced RA pump function (active EF = 11 ± 3%). Pts with reduced RA reservoir function showed larger RV end-systolic volume (RVESV 124 ± 48ml vs. 90 ± 32ml; p = 0.004) and lower RVEF (38 ± 8% vs. 46 ± 6%; p < 0.001) than pts with normal RA function. Pts with reduced RA conduit function showed smaller RV stroke volume (RVSV 65 ± 19 ml vs. 80 ± 22ml; p = 0.009). Pts with impaired RA pump function showed larger RVESV (142 ± 45ml vs. 99 ± 41ml; p = 0.02) and lower RVEF (36 ± 6% vs. 43 ± 8%; p = 0.006).
RVESV was positively correlated with total (r2 = 0.47, p < 0.001), passive (r2 = 0.29, p = 0.03) and active (r2 = 0.39, p = 0.003) RAEV, while it was negatively correlated with total (r2=-0.41, p = 0.002), passive (r2=-0.34, p = 0.01) and active (r2=-0.31, p = 0.02) RAEF. RVSV showed a positive correlation with both total (r2 = 0.4, p = 0.002) and passive (r2 = 0.41, p = 0.002) RAEV. Finally, RVEF was positively correlated with total (r2 = 0.51, p < 0.001), passive (r2 = 0.47, p < 0.001), and active (r2 = 0.36, p = 0.007) RAEF.
Conclusions
RA dysfunction is not uncommon in pts with reduced LVEF, even in the absence of PH. In these pts, RA function is associated with significant changes in RV function. The RA acts as a dynamic modulator of RV pump function by redistributing RV filling and ejection force among reservoir, conduit and pump functions in the setting of altered hemodynamics. The clinical and prognostic significance of RA function in pts with reduced LVEF warrant further studies.
Correlation between Three Dimensional Left Ventricular Ejection Fraction (3DLVEF) and Real Time (Single Heart Beat Acquisition) Three Dimensional Left Ventricular Ejection Fraction (rt3DLVEF)
