Single Origin of Right and Left Pulmonary Artery Branches from Ascending Aorta with Nonbranching Main Pulmonary Artery: Relevance to a New Understanding of Truncus Arteriosus

Abstract

We report the third known case of origin of the right and left pulmonary artery branches from the ascending aorta via a short common pulmonary artery. A large unbranching main pulmonary artery opened through a patent ductus arteriosus into the descending thoracic aorta. Preductal coarctation of the aorta and multiple congenital anomalies were also present. This rare cardiovascular malformation facilitates a new anatomic and developmental understanding of truncus arteriosus.

Persistent truncus arteriosus

“…Coronary anatomy and truncal valve anatomy have been described and are not included in the classification system because they are variable and not specific to any given pulmonary artery pattern [2,3,5,6,[9][10][11][12][13][14][15][16][17][18]. Efforts to more accurately describe the cardiac anatomy are ongoing in regard to PTA [17,19,20].…”

The bronchopulmonary foregut malformation complex

“…In this particular child, neither the right nor the left pulmonary arteries originated from the ascending aorta, as has been observed in most of the reported cases in which the pulmonary trunk itself is non-bifurcating. [140][141][142][143] Rather, the only source of arterial supply to the lungs in our patient was from persistent intersegmental arteries, exactly reminiscent of the direct systemicto-pulmonary collateral arteries seen in many patients with tetralogy of Fallot and pulmonary atresia. 7 In the bigger group of patients with such systemic supply to otherwise normal lungs, it is unclear why there is the predilection for the left lower lobe, yet a similar predilection is observed in patients with extralobar sequestration.…”

Normally and Abnormally Related Great Arteries

“…Why do we think that? Because we have seen 2 rare cases, 21 with normal {S,D,S} segmental anatomy, which had the following: no VSD; a main pulmonary artery arising from the right ventricle, giving off no pulmonary artery branches and passing through a slightly narrowed patent ductus arteriosus into the descending thoracic aorta; and an aorta arising normally from the left ventricle, giving off coronary arteries normally and then part way up the ascending aorta, giving origin to the right and left pulmonary artery branches, then forming an aortic arch and giving off the brachiocephalic arteries normally, and continuing through the aortic isthmus into the descending thoracic aorta. 21…”

“…Truncus arteriosus 13,20,21 is the only infundibuloarterial (conotruncal) anomaly in which the great arteries themselves are primarily malformed. Again, the classic AP malseptation hypothesis was used to explain the embryogenesis of truncus arteriosus communis (common arterial trunk, Latin).…”

“…When one of our colleagues, an eminent cardiovascular radiologist, saw these angiocardiograms, he quipped the following: “Get rid of it. It’s impossible.” But why is this anomaly 21 relevant to truncus arteriosus type 2? Because the pulmonary artery branches originate from the aorta (ie, from the aortic sac part of the distal truncus arteriosus).…”