Paediatrics (RCH) - Theses
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ItemOutcomes of surgery for the spectrum of atrioventricular septal defects( 2018)Atrioventricular septal defects (AVSDs) are a spectrum of diseases affecting the atrioventricular septum, junction and valves. Disease severity varies from mild, in the form of partial AVSD, to severe in the form of unbalanced AVSD. Regardless of the severity, all patients require surgery in childhood to improve long-term survival. At each end of the spectrum, research has been relatively limited compared to the amount of attention focused on the commonest form, complete AVSD. Partial AVSD (pAVSD) has been considered a relatively minor defect, often grouped with secundum atrial septal defects, but this ignores the fact that pAVSD shares much of the anatomical complexity of other forms of AVSD. Unbalanced AVSD (uAVSD) is frequently not amenable to complete repair, requiring staged palliation resulting in a Fontan circulation. Early results of palliative strategies in these patients were very poor, and there has been relatively little attention paid to the single ventricle palliation strategy in recent years. This project focuses on these two less studied forms of AVSD, in order to determine current results, and risk factors for poor outcomes. For each condition we have followed the largest series of patients ever reported in the literature, with over 30 years of follow-up. In children with partial AVSD, we have demonstrated that survival is excellent, yet there is a very high rate of reoperation in the long-term. We found that closing the cleft of the left atrioventricular valve (LAVV) improved outcomes, even when that valve was not incompetent. Reoperation in this group was shown to be mostly due to LAVV regurgitation, and we demonstrated that improved rates of repair could be achieved with a novel patch augmentation technique. While some groups have advocated performing repair in infancy, we demonstrated, in a propensity score matched analysis, that better survival was achieved with repair after one year of age. In children with unbalanced AVSD, we found that, although there was a high attrition rate, children who achieved Fontan completion had much better outcomes than previously thought possible. We demonstrated that atrioventricular valve (AVV) regurgitation was a major cause of reoperation and morbidity and that outcomes were very poor in children in whom repair failed. Importantly, we found that mechanical prosthetic replacement may be preferable if an adequate repair cannot be achieved. Finally, we examined the impact of pulmonary artery banding in children with complex AVSD, and demonstrated that it did not worsen AVV regurgitation and allowed the majority of patients to progress to delayed complete repair or Fontan completion.