Abstract 4948: Wasted Energy and Right Ventricular Volumes in Patients after Tetralogy of Fallot Repair - A Key to Understanding Right Heart Function?
Quantifying right ventricular (RV) power loss (PL) and efficiency in pts with repaired tetralogy of Fallot (TOF) may help in determining timing for pulmonary valve replacement. We hypothesized that pulmonary regurgitation (PR) would force the RV to expend excess power. We sought to quantify RV output power, RV efficiency, and pulmonary regurgitation fraction (PRF) in pts with TOF, and to correlate these to RV function. Cardiac catheterization followed by cardiac magnetic resonance imaging was performed in 13 pts (age=22±17yrs) with TOF. Using pressure and flow measurements in the main pulmonary artery, cardiac output, PRF, RV power output, efficiency, and losses were evaluated. RV systolic power was 1.08 ± 0.62 Watts (W) with 20.2 ± 8.5% PL due to PR resulting in a net power efficiency of only 79.8 ± 8.5 % (0.84 ± 0.73 W). Cardiac output was 4.24 ± 1.8 L/Min with a mean PRF=40.5 ± 13.8 %. Normalized RV power efficiency (figure⇓) had a significant negative correlation with RV end diastolic volume index (RVEDVI) (p<0.001, R=0.95) and RV end systolic volume index (RVESVI) (p<0.001, R=0.89) with a rapid drop in RV power efficiency with increasing RV volume. After 150 cc/m2, the curve flattened out. PL significantly correlated with RVEDVI (p = 0.04, R=0.56), and RVESVI (p=0.05, R=0.59). There was no correlation between PRF and RV diastolic function. Significant PL is present in pts with repaired TOF. There is a rapid decrease in efficiency with increasing RV volumes under 150 cc/m2 suggesting intervention should be done earlier than this RVEDVI to preserve function.
This research has received full or partial funding support from the American Heart Association, AHA Greater Southeast Affiliate (Alabama, Florida, Georgia, Louisiana, Mississippi, Puerto Rico & Tennessee).