Report from the Japanese Society of Pediatric Cardiology and Cardiac Surgery Research Committee on Cardiovascular Function in Adult Patients with Congenital Heart Disease; Mechanism of Aortic Root Dilation and Cardiovascular Function in Patients with Tetralogy of Fallot

Abstract

The aortic root dilation in the Tetralogy of Fallot (TOF) is a long-term clinical problem because a severely dilated aorta can lead to aortic regurgitation, dissection or rupture, which could be fatal and necessitate surgical intervention. However, the details of the mechanism of aortic root dilation are not unclear. We showed that aortic stiffness is increased in repaired TOF patients and may mirror the histological abnormality of elastic fiber disruption and matrix expansion. This aortic stiffness is closely related to the aortic dilation, indicating that aortic stiffness may become the predictive indicator for prognosis of aortic dilation. Furthermore, the aortic volume overload is a very important determinant of aortic diameter in TOF patients before corrective surgery. In addition, a chromosomal abnormality and TGF-βsignaling pathway, a major contributor to the aortic dilation in Marfan syndrome, also affect this mechanism. In this way, the aortic dilation in TOF patients is suggested to be a multifactorial disorder. In this review, we tried to clarify the mechanism of aortic dilation in TOF patients, focusing on our recent research findings. Studies linking histopathology, mechanical properties, molecular/cellular physiology, and clinical manifestation of aortic dilation lead to appropriate treatment intervention and improvement in the long-term prognosis for TOF patients.