Histopathological Changes in Aorta and Pulmonary Artery in Patients with Dextro- Transposition of Great Arteries undergoing Arterial Switch Operation: A Prospective Study

Background: Following the arterial switch operation (ASO), there is a risk of neoaortic root enlargement, and aortic regurgitation in follow-up. This study is intended to study whether abnormalities in the histopathological findings of the neo-aorta at the time of the arterial switch operation could lead to these complications. Patients and methods: Between 1 st April 2015 to 31 st October 2016, 83 consecutive patients undergoing the arterial switch operation were included in this prospective cohort study. A sufficient representative sample of tissue obtained from the native pulmonary artery and the native aortic root, was fixed in 10% neutral buffer formalin and subjected to histopathological examination. These tissues were conservatively processed and paraffin blocks were made, sections were cut and stained by Hematoxylin & Eosin, Vanhoeff elastic, Van Giessen, Masson’s trichrome stains. Elastic tissue and smooth muscle was systematically accessed, in the native aorta and native pulmonary artery. Simultaneously a note was made of all the patients pre-operative characteristics, etiology, associated cardiac anomalies, echocardiogram findings, cardiac catheterization data (if performed), intra operative details, Comparisons were made between histo-pathological findings of native aorta and native pulmonary artery, comparison with controls available in the literature, postoperative course, follow up, and follow-up echocardiographic data. Results: Eighty-three patients had an ASO for TGA between 1st April 2015- 31st October, 2016. We examined elastic lamellar count of native aorta and native pulmonary artery and compared it with the findings described in the literature. It was found that elastic lamellar counts were similar in both the neo-aorta and the neo-pulmonary artery. Early in age, they were similar histopathologically. With increasing age, it was observed that lamellar count decreases in the neo-pulmonary artery. Conclusions: There were no gross differences between native pulmonary artery and native aorta histopathology but an inverse relation was found between advancing age and elastic lamellar counts in both structures signifying the need for an early arterial switch to prevent long-term complications