Congenital Isolation of a Common Carotid Artery: A Review of Cases, Phenotypes, and Embryology of a Rare Anomaly of the Aortic Arch System.

Rare malformations of the aortic arch system may be of minor relevance for general medical practice. Their abnormal arterial patterns, however, sometimes can represent a challenge not only for experts in cardiovascular medicine but also for the validity of well-established concepts traditionally used to explain the embryology of normal and abnormal patterning of the aortic arch system. The present article provides a review of (1) the pathomorphological features, (2) associated cardiac and extracardiac malformations, and (3) embryology of a very rare malformation of the aortic arch system, called isolation of a common carotid artery. It is shown that this diagnosis does not characterize a single pathomorphological entity. Among 28 previously documented cases we can distinguish two different subsets. One of these subsets is of general interest since it challenges the traditional concept of the embryology of congenital malformations of the aortic arch system. It is shown that malseptation of the embryonic aortic sac and cardiac outflow tract may play a fundamental role in the pathogenesis of this malformation.