Superior Mesenteric Arterial Flow Pattern is Associated with Major Adverse Events in Adults with Fontan Circulation

Factors contributing to the failure of Fontan circulation in adults are poorly understood. Reduced superior mesenteric arterial (SMA) flow has been identified in pediatric Fontan patients with protein-losing enteropathy. SMA flow has not been profiled in an adult Fontan population and its association with adverse events is unknown. We aimed to examine associations between SMA flow patterns and adverse events in adult Fontan patients. We performed a retrospective review of adult Fontan patients who underwent echocardiograms between 2008 and 2014. SMA Doppler data included peak systolic and end-diastolic velocity and velocity time integral (VTI). Systolic/diastolic (S/D) ratio and resistive index were calculated. The relationship between SMA flow parameters and major adverse events (death or transplantation) was examined using proportional hazard Cox regression analyses. Kaplan-Meyer analysis was conducted to construct survival curve of patients with and without adverse events. 91 post-Fontan adult patients (76 % systemic left ventricle, 20 % atriopulmonary Fontan, mean age 27.9 years) were analyzed. Adverse events occurred in nine patients (death = 4, transplant = 5). When compared with the non-event group, the event group had increased end-diastolic velocity [hazard ratio (HR) 1.5, 95 % confidence interval (CI) 1.1-1.8; p = 0.002], increased systolic VTI (HR 1.5, 95 % CI 1.1-2.2, p = 0.02), increased diastolic VTI (HR 1.7, 95 % CI 1.2-2.4, p = 0.004), decreased S/D velocity ratio (HR 0.32, 95 % CI 0.14-0.71, p = 0.006), decreased S/D VTI ratio (HR 0.76, 95 % CI 0.61-0.97, p = 0.02), and decreased resistive index (HR 0.29, 95 % CI 0.14-0.60, p = 0.0007). Increased end-diastolic velocity and VTI in mesenteric arterial flow, with lower systolic/diastolic ratio and resistive index, were associated with death and need for heart transplant in adult Fontan patients. The mesenteric hyperemic flow was also associated with clinical signs of portal venous outflow obstruction, suggesting the presence of vasodilatory state in end-stage adult Fontan circulation.