The goal of this study was to identify predictors for mortality and to review adverse events after ASO for TGA (coronary stenoses, distortion of the pulmonary arteries, dilatation of the neoaortic root, and aortic regurgitation). This study confirms that ASO can be performed with acceptable early and late outcome in patients with TGA even in a small centre after a learning process and modifications of the perioperative setting.
The possible deterioration of neoaortic valve function with a dilatation of neoaortic root  and presence of coronary stenosis  is one of the major concerns of ASO. In the present study, the need of surgical re-intervention of coronary stenosis in the follow up was low (4.5%). Similar results have been described by Bonhoeffer et al. for late stenoses after ASO . In our patient population, 23 of the survivors who have been evaluated by angiography, 2 were found to have complete occlusion of the right coronary artery and 1 had left coronary artery occlusion. The patients with the affected right coronary artery had Yacoub’s type E coronary pattern and showed clinical symptoms, which were associated with myocardial ischemia in the year five and seven postoperatively. They were treated surgically with an internal mammary artery grafting, which is one of the possible approaches to manage coronary stenoses after ASO . Although in both patients a good result were achieved with this approach, we recommend a regular follow up by angiography in view of the lack of long-term follow up studies about internal mammary grafting in children. The patient with occluded left coronary artery coronary (Yacoub’s type A coronary pattern) was treated conservatively, as the routine angiography revealed a good collateralisation and the patient had no clinical signs of a myocardial ischemia. In the latest follow up, this patient was in functional NYHA class I with no symptoms referable to the cardiovascular system.
Several investigators have noted that a deterioration of neoaortic valve function and dilatation of neoaortic root were frequently observed in patients after ASO [12, 13]. In the present series two patients developed severe aortic regurgitation (AR) and required an aortic valve replacement at 6 and 8 years after ASO. One of them had a VSD which was also closed during the ASO procedure. Interestingly, both of them had Yacoub’s type E coronary pattern and received an internal mammary artery grafting as well, but there is no explanation for the combined occurrence. It was reported that the risk of moderate or severe AR with a significant left ventricular dilatation followed by an aortic valve replacement is low after ASO and the results in this study are similar to other studies [7, 13]. Risk factors for AR following ASO included prior history of PA band, Taussig-Bing hearts, and development neo-aortic root enlargement . Surprisingly, in our series the patients with AR who required aortic valve replacement had none of these risk factors. Moreover, we did not observe a neo-aortic root enlargement at all in the follow-up and this is in contrast to other studies which state that that is one of the major concerns of ASO . This could be because of the small size of our series. Although several factors for neo-aortic root enlargement are described, these are speculative and require further investigations. The incidence of pacemaker implantation due to the complete AV block in two and the sick sinus syndrome in one was not different from that in another study .
The postoperative mortality and morbidity in this series was higher compared to the recently reported series. We observed an all over mortality rate of 15% (n = 8). The mortality rate seems to be high compared with other published series; however, the mortality was seen only during first 4 years of the observation period which was early nineties. Reasons for that improved outcome after 1994 could be that the ICU treatment made a progress and also the learning curve regarding the surgery has improved in a short time. Moreover, more patients were presented in a better clinical condition in the second time interval.
Seven patients died in the early postoperative period (30 days) and five of them within first 24 hrs. Cause of death was dominated mostly by postoperative refractory left heart failure. In our statistical analysis preterm birth, long duration between cardiac catheterization and surgery, older age at surgery, necessity of associated procedures, redo- surgery, prolonged ischemia, and no treatment with prostaglandin prior surgery were associated with mortality and were partly in line with other published series [6, 15]. Maybe it is possible that some of the patients could be supported by an extracorporeal membrane oxygenation (ECMO) in the initial early postoperative phase; however this kind of circulatory support was first introduced in our department in the late nineties.
Interestingly, in our series the presence of a complex coronary anatomy including intramural course was not a significant risk factor for mortality and corroborates with the study of Blume et al. . The results of this study show that the impact of well described risk factors influencing the mortality diminishes with surgical experience. The experience after 1994 has further improved early survival after ASO and may also result in less mid-term complications. After 1994, no postoperative deaths were observed. This result is gratifying and compares favourably with other big series [3, 15].
We acknowledge that this study has several limitations being an observational assessment of outcomes. The patients were not randomly assigned to various therapies, and comparison between inherently dissimilar groups is problematic. Data regarding follow-up and re-interventions were incomplete in some patients; however continued study will be necessary for a truly long-term follow-up.