Aortic tissue Doppler imaging after tetralogy of Fallot repair: beyond aortic diameters

Purpose: Structural abnormalities of the aortic wall have been described in tetralogy of Fallot (ToF) and could be responsible for aortic stiffening leading to aortic dilatation. We aimed to study if aortic root stiffness indices assessed by tissue Doppler imaging (TDI) could be related to the aortic diameter late after ToF repair. Methods: We included adult (≥ 18 years) patients (pts) with surgically repaired ToF followed at a terciary care center from January till December 2012. We defined two groups based on the Cornell data-based z-score formulae for two-dimensional transthoracic echocardiographic diameter of the aortic root at the level of the sinuses of Valsalva (AoZ), in parasternal long-axis view: group 1 - with Ao dil (AoZ > 2) and group 2 - without Ao dil (AoZ ≤ 2). Aortic root M-mode systolic and diastolic diameters and TDI variables were measured, including systolic maximum anterior wall expansion velocity (SAo), early (EAo) and late (AAo) diastolic retraction velocity and time to peak systolic (TAo). Strain, distensibility and stiffness index of the aortic root were determined noninvasively. Results: We included 43 pts (mean age 32±11 years; 58% female); mean follow-up time since ToF repair was 22±8 years. In 21 pts (49%) an aortopulmonary (AP) shunt was done prior to complete repair, with a median interval of 3 years. In 15 pts complete repair used a transannular patch. In 10 pts (23%) we identified Ao dil (mean age 32±11 years; 5 males). Only 1 pt had moderate aortic regurgitation. Both group 1 and 2 were similar concerning age, gender, body surface area, age at ToF repair and follow up time after repair. Also, no differences could be found in systemic blood pressure, pulse pressure, and TDI variables. There was a trend to a positive correlation between the aortic root z-score and the aortic stiffness index, whereas a trend to a negative correlation was found for the aortic strain and distensibility. The aortic stiffness index was significantly increased in group 1 (14.8±6.3 vs 8.5±6.8, p=0.019) and in univariate and multivariate analysis, the aortic stiffness index was an independent predictor of aortic dilatation (odds ratio 1.30, 95% confidence interval 1.02-1.65, p=0.033). Conclusions: TDI can assess the aortic elastic properties noninvasively in this subset of pts and the aortic stiffness index may be a predictor of aortic dilatation late after ToF repair.