Aortic root dilatation in tetralogy of fallot — why does it exist and persist?

Background Aortic root dilatation may result from the embryologic maldevelopment that causes Tetralogy of Fallot (TET). It could also relate to haemodynamic factors since the aorta carries a larger fraction of the combined cardiac output. Methods Retrospective data analysis and review of echocardiographic, catheterisation and follow up data on children who underwent TET repair between 1985 and 1990. The tirst part of the study focused on impact of arteriopulmonary shunts on aortic root size. The second part of the study focused on the comparative aortic root sizes in children who had been repaired in infancy as against those who had been repaired postinfancy. Results In the first part of the study, there were 147 infants at ages 3.4 f 2.9 months with complete M-Mode echo studies. Their aortic annulus was significantly larger than expected for age. Catheterisation data was available in 54 patients in whom systemic saturation did not correlate with aortic root diameter on echo studies done within a 3month period. There were 46 infants who underwent palliative arteriopulmonary shunts with a further important increase in aortic annular dimension. The second part of the study compared aortic root size in those who had been repaired before 1 years of age (n = 43) and after 1 years of age (n = 385) with a follow up between 1 and 35 years. In cases that were corrected in infancy, the aortic annulus size approached upper limit of normal by 6 years of age whereas aortic annular dilatation persisted in those corrected post infancy. Conclusion The study was unable to differentiate the relative contributions of maldevelopment and haemodynamic factors in aortic root dilatation in TET. Aortic root dilatation persists in patients repaired beyond infancy, and seems to ‘regress’ in those operated in infancy