Determinants of Aortic Size and Stiffness and the Impact on Exercise Physiology in Patients After the Fontan Operation

: The pathophysiology of congenital heart disease includes aortic dilation and increased stiffness. However, the clinical determinants and significance remain unclear in patients after the Fontan operation.Size and stiffness index (SI) of the ascending and descending aorta (aAO and dAO, respectively) were assessed using angiography in 130 consecutive Fontan patients and 30 age-matched controls. Compared with controls, Fontan patients showed a dilated aAO and smaller dAO (P < 0.0001) with greater SI (3.2 ± 0.7 versus 2.2 ± 0.3 for aAO and 2.7 ± 0.6 versus 2.2 ± 0.3 for dAO, P < 0.0001 for both). aAO was stiffer than dAO (P < 0.0001) and the greater aAO size was independently determined by the presence of pulmonary atresia, older age at Fontan operation, and low arterial oxygen saturation (P < 0.05-0.01). High plasma levels of brain natriuretic peptide (BNP) and glucose were independently associated with aAO SI (P < 0.05-0.01) and the SI ratio of aAO to dAO SI, whereas body mass index, plasma levels of highsensitivity C-reactive protein, and dAO size were independently associated with dAO SI (P < 0.05-0.01). A greater aAO and aAO/dAO ratio predicted an impaired exercise blood pressure response (P < 0.0001). Furthermore, in addition to age at Fontan operation and BNP level, the aAO SI independently predicted a lower peak oxygen uptake (P < 0.05).Fontan patients have a stiffer dilated aAO with rapidly tapering smaller dAO that predicts exercise pathophysiology. In addition to intrinsic aortic structural abnormalities, heart failure severities as well as traditional cardiovascular risk factors are also involved in the aortic structural and functional abnormalities.