Untangling the Mysteries of MAPCAs with the Identification of Different Patterns and Types

We continue to learn from the unique experience from Stanford with major aortopulmonary collateral artery (MAPCA) surgery. These patients are characterized by heterogeneity in both numbers and distribution of MAPCAs as well as a variable relationship between the native pulmonary artery system and the MAPCAs themselves. Previous work has emphasized the importance of recognizing sole supply vs dual supply, and the central importance of unifocalization as the primary goal in surgical management. In this issue of The Annals of Thoracic Surgery, the study from Mainwaring and colleagues1Mainwaring R.D. Adamson G. Hanley F.L. To unifocalize or not to unifocalize?: a comparison of retroesophageal verses anterior collaterals.Ann Thorac Surg. 2022; 113: 875-883Google Scholar now takes things further by starting to classify the MAPCAs themselves according to their origin and their relationship to the bronchus and esophagus. This study focuses on the retroesophageal MAPCAs (REMs) that run posteriorly into the lung, usually remaining behind the bronchus. This series builds on their previous experience where around two thirds of MAPCA patients were found to have REMs. There are several important characteristics of REMs that are highlighted: First, they are very likely to be the sole supply to their region of lung, being so in 83% of cases (compared with 65% of anterior MAPCAs). Second, they are twice as likely to occur in patients who have absent central pulmonary arteries; and third, over 80% have some sort of proximal stenosis—usually related to where they pass behind (or through) the esophagus. When present, there are usually only 1 or 2 of these REMs but they supply a median of 4 lung segments and so are valuable vessels. The message is that REMs need to be recruited in 96% of cases, and usually have adequate length to be able to exclude the stenosed region and connect them successfully into the unifocalized vessels. Most of them enter the lung posteriorly and remain posterior to the bronchus. Starting to recognize these different anatomic and physiologic characteristics of different MAPCA “types” is further helpful advice in the all-important preoperative assessment that enables the surgeon to plan out the operative strategy and achieve optimal results. It will be interesting to follow through these patients to see how these REM vessels behave in comparison with native pulmonary arteries and anterior MAPCAs over time. To Unifocalize or Not to Unifocalize?: A Comparison of Retroesophageal Versus Anterior CollateralsThe Annals of Thoracic SurgeryVol. 113Issue 3PreviewThe anatomy of major aortopulmonary collateral arteries (MAPCAs) can be highly variable with regard to number, anatomic origin, course, and relationship to the native pulmonary arteries. Some MAPCAs travel behind the esophagus (retroesophageal) and bronchus before entering the lung parenchyma. This study compared the physiologic and surgical characteristics of retroesophageal vs anterior located MAPCAs. Full-Text PDF Editor’s Choice: Landmark in XenotransplantationThe Annals of Thoracic SurgeryVol. 113Issue 3PreviewOn Friday January 7, 2022, David Bennett, a 57-year-old man, received a heart transplant from a genetically modified pig. The extensive media coverage that ensued, starting with a full-length article in The New York Times the following Monday, reveals that Mr Bennet had been supported with extracorporeal membrane oxygenation for several weeks, disqualifying him from heart transplant at major centers his team approached, and that he was doing well after a technically straightforward operation, with extracorporeal membrane oxygenation successfully weaned a few days postoperatively. Full-Text PDF