Reduced proximal aortic compliance and elevated wall shear stress after early repair of tetralogy of Fallot.

OBJECTIVE: Patients with tetralogy of Fallot are at risk for late aortic complications due to progressive aortic root dilation and decreased aortic compliance. Early repair normalizes aortic dimensions by preadolescence. It is not known if early repair normalizes aortic wall histology and compliance or reduces late aortic complications. We used 4-dimensional flow magnetic resonance imaging to determine if children with tetralogy of Fallot repaired in infancy had normal aortic dimensions and to characterize the aortic wall hemodynamic state and luminal flow parameters in these patients.

METHODS: Comprehensive aortic analysis with 4-dimensional flow magnetic resonance imaging was performed in 18 patients with tetralogy of Fallot who were repaired in infancy and compared with 18 normal volunteers. Peak systolic and time-averaged wall shear stress, relative area change, and distensibility were evaluated in standardized aortic planes. Qualitative grade scale flow analysis with interactive pathline visualization was used to detect pathologic flow patterns.

RESULTS: Thoracic aortic dimensions did not differ between groups, and all tetralogy of Fallot aortas were in normal range. In the tetralogy of Fallot group, ascending and descending aortic relative area change and distensibility were significantly reduced, and both peak systolic and time-averaged wall shear stress were elevated throughout the aorta. Supra-physiologic systolic helical formations occurred in the ascending aorta of 14 patients with tetralogy of Fallot (78%) versus 0 controls.

CONCLUSIONS: Despite early repair and normal aortic dimensions, preadolescents and adolescents with tetralogy of Fallot had elevated wall shear stress, increased stiffness, and pathologic systolic flow formations in the proximal aorta. Although early repair normalizes aortic dimensions in childhood, our findings suggest that patients with tetralogy of Fallot remain at risk for late aortic complications.