Abstract 15010: Correlation Between Power Loss of the Total Cavopulmonary Connection and Exercise Oxygen Consumption in Fontan Patients
Background: High energy loss in the Total Cavopulmonary Connection (TCPC) has been hypothesized to have an effect on clinical outcomes in single ventricle physiology. These effects may be magnified with exercise. We assessed the correlation between the TCPC energy dissipation and oxygen consumption at rest and exercise.
Methods: 30 (17 males and 13 females) Fontan patients with TCPC anatomy (age=19±6 years) performed standard graded metabolic exercise testing. Patient-specific anatomies and vessel flow rates were obtained from cardiac magnetic resonance (CMR) and phase encoded velocity mapping data. Exercise CMR images were acquired immediately following lower leg exercise in the supine position using a CMR-compatible cycle ergometer. Computational fluid dynamics simulations were performed to determine power loss of the TCPC anatomies using in-vivo measured anatomies and flows. Power loss was normalized to body surface area and total systemic venous return (iPL). A linear regression was used to correlate minute oxygen consumption (VO2) and iPL (p<0.005 was considered significant).
Results: As shown in figure 1, there was a significant, linear negative correlation between VO2 at anaerobic threshold obtained in the graded exercise test and iPL at exercise (r=-0.5, p<0.005). VO2 at anaerobic threshold was also significantly negatively correlated with iPL at rest (r=-0.6, p<0.005). There was no significant difference between the correlations in females or males. There was no significant correlation between iPL and resting VO2.
Conclusions: In the Fontan TCPC physiology, there was a strong negative correlation of indexed power loss and sub-maximal aerobic capacity as measured by VO2 at anaerobic threshold. These results suggest that aerobic exercise tolerance in this population may in part be a consequence of power loss and that surgical and/or interventional techniques to minimize power loss may result in improved aerobic exercise performance.
- © 2013 by American Heart Association, Inc.