For coarctation of the aorta in infants younger than three months

Abstract

Recurrent coarctation is a complication which is seen at a consistent rate following repair for coarctation of the aorta in young infants. This retrospective analysis was carried out to compare the results between resection with end-to-end anastomosis (ETE), and resection with extended end-to-end anastomosis (E-ETE), in this age group during late follow-up period. The role of ductus arteriosus is not clearly defined and the second objective of this study was to analyze intimal thickening in aortic coarctation. From 1999 to 2003, 45 patients less than 3 months of age underwent repair of aortic coarctation. Mean age was 24 days (2-89 days), average weight was 3.5 +/- 0.6 kg (2.4-5.2 kg). The method of repair was ETE in 14 (31.1%) patients, E-ETE in 29 (64.4%) patients and other techniques were applied in 2 cases. Demographic, morphometric, clinical and operative variables were analyzed for correlation with recurrent arch obstruction. In order to characterize the components of intimal thickening in coarctation, narrowed segments of aorta resected from 16 neonates during surgery were examined immunocytochemically and by electron microscopy. For light microscopy, the specimens were dehydrated in graded ethanol (70-100%), cleared in xylol and embedded in paraffin. Immunocytochemical staining was performed in 5 microm sections from formaldehyde-fixed paraffin-embedded blocks, using a labeled streptavidin-biotin method with an LSAB kit (Dako). Early mortality was 6.7% (CI 95%, 2.9%-10.4%). All early deaths (3 patients) occurred in infants with associated ventricular septal defects (p<0.05). The mean follow-up for all patients was 30 +/- 21 months (range 1.5-63 months). During mean follow-up of 2 months, recurrent arch obstruction was diagnosed in 9 patients (21.4%). Two patients with associated complex heart defects died before re-intervention, one had mild gradient on catheterization (20 mm Hg) and one is waiting for catheterization. Five patients were reoperated and the mean time to re-intervention was 4 months (range 2.6-6 months). Kaplan-Meier freedom from recoarctation was 78.1 +/- 6.4% at 5 years in the whole group. Freedom from recoarctation was 60.6 +/- 15.4% at 25 months in ETE group and 86.2 +/- 6.4% at 60 months in E-ETE group (p=0.062). Factors associated with recoarctation, obtained by univariable Cox regression, included abnormal right subclavian artery (p=0.003), hypoplastic proximal transverse aortic arch (Z < or = -2, p=0.025) and weight at operation < or = 3 kg (p=0.02). Abnormal origin of the right subclavian artery was the only independent predictor of recoarctation obtained by multivariable Cox regression analysis. All examined specimens had intimal thickening of the posterior aortic wall, with accumulation of smooth muscle cells (SMC) with alpha smooth muscle actin (alpha-SMA) and vimentin-immunoreactivity (but not desmin and MHC) and also expressed PCNA and S-100. In the inner media of the anteromedial wall of the aorta, all specimens had large number of SMC expressing desmin and MHC. SMC in the inner media exhibit contractile phenotype and their origin could be ductal. Both procedures are effective for coarctation repair in young infants. Risk of recoarctation is a function of the complex anatomy of the arch, while residual ductal tissue may play a significant role.