Abstract 9904: The Impact of Energy Loss on Cardiac Function in Fontan Circulation
Background: There have been several numerical studies discussing the flow energy loss (EL) at Fontan anastomosis that reflects flow efficiencies and which would lead to increase the cardiac workload. However, in-vivo clinical measurements of EL have never been reported. In this study, we measured EL in Fontan patients with simultaneous measurements of pressure and velocity, and revealed its influence to the cardiac functions of the single ventricles.
Methods: Catheter exams measuring pressure and velocity simultaneously were performed 1 year after the Fontan procedure in 9 patients (mean age 27.4 ± 3.2 months). EL was calculated using the averaged pressure and velocity data of 20 cardiac cycles in the superior and inferior vena cava and the bilateral pulmonary arteries. Systolic functions were evaluated with max dp/dt during the isovolumic systolic phase (Sdpdt), ejection fraction (EF), and cardiac output (CO); whereas diastolic functions were evaluated with max -dp/dt (Ddpdt) and time constant tau in the isovolumic diastolic phase. The ratio of Ddpdt/Sdpdt was examined to detect heart failure with preserved systolic function. Tei index was also examined.
Results: EL significantly correlated with Sdpdt (r=0.842), but not with EF or CO (r=0.472 and -0.199, respectively), indicating that high EL reflected afterload increase. EL significantly correlated with Ddpdt and tau (r=-0.574 and 0.795, respectively). EL strongly correlated with Ddpdt/Sdpdt and Tei index (r=0.889 and 0.757, respectively), indicating that diastolic function was impaired when EL increased, while systolic function was preserved.
Conclusions: EL is a novel and sensitive parameter detecting early heart failure with preserved systolic function with increased afterload and impaired diastolic function, and could be an index to decide the indication of medication therapy with vasodilator such as angiotensin-converting enzyme inhibitor for heart failure after Fontan procedure.
- © 2012 by American Heart Association, Inc.