Co‐Presentation of a Circumflex Retroesophageal Right Aortic Arch and Persistent Left Superior Vena Cava in a Human Cadaver
Authors: Snow Ethan , McCumber Travis , Cassidy Keely , Latacha Matthew 
Published: April 2020

The present study concerns a unique finding of two cardiovascular anomalies in a 57 y.o. human female Caucasian cadaver whose death was determined as non‐cardiovascular. She presents with a circumflex retroesophageal right aortic arch (CReRAA) that gives rise to an aberrant left subclavian artery from a diverticulum of the proximal descending aorta. A left ligamentum arteriosum completes a vascular ring with the CReRAA around her trachea and esophagus. She also presents with persistent left superior vena cava (PLSVC) amid regular right superior vena cava (SVC) (i.e., double SVC) with an innominate vein bridging the two. Her PLSVC leads to a dilated coronary sinus coursing the posterior left coronary sulcus to the right atrium. Albeit separately rare anomalies, simultaneous presentation of CReRAA and PLSVC appears to be unrecorded. The objective of the present study is to assemble a comprehensive case report illustrating gross presentation, embryological explanation, histological examination, and clinical considerations of the CReRAA co‐presenting with PLSVC.

Gross presentation of the CReRAA and PLSVC was compared to anatomical norm, and embryological explanations for the anomalies were hypothesized. Cross‐sectioned segments of the trachea, esophagus, and coronary sinus were examined grossly and histologically for anomalous changes in lumen diameter and tissue integrity.

Embryologically, CReRAA is caused by left 4th branchial arch regression with right dorsal aorta persistence. As a result, the right 4th branchial arch becomes the aortic arch giving off its typical branches in reverse succession before branching an aberrant left subclavian artery from the vestige of the distal left dorsal aorta (Kommerell’s diverticulum) at the proximal descending aorta. The left 6th branchial arch regresses to form ligamentum arteriosum. PLSVC results from a persisting caudal portion of the left anterior cardinal vein which normally regresses as the ligament of Marshall to separately form the coronary sinus. Gross measurements reveal tracheoesophageal constriction from the CReRAA vascular ring and coronary sinus dilation from the PLSVC. Histological analysis of the tracheoesophageal and coronary sinus tissues has yet to be performed.

This case report substantiates known clinical implications of CReRAA and PLSVC in new light of being co‐presented. Complete vascular rings can be challenging to identify since their atretic components are not fillable with contrast medium and present serious clinical sequelae (chiefly respiratory distress and esophageal dysphagia) from tracheoesophageal compression. As such, CReRAA should be a differential diagnosis when these otherwise unexplained symptoms occur. Additionally, PLSVC has important implications for placing cardiovascular implantable electronic device (CIED) transvenous leads through the right SVC via the left subclavian vein. When encountered, alternative access through the PLSVC and into the heart via the coronary sinus or right subclavian venous access should be considered. Increasing available knowledge of such anomalies benefits both physicians and patients.