Anatomical variations of the aortic arch branching pattern using CT angiography: a proposal for a different morphological classification with clinical relevance

The aortic arch (AA) branching pattern variations are usually asymptomatic, but they may lead to complications during cardiovascular procedures. In this retrospective study, we aimed to analyze the frequency of anatomical variations of the AA and to develop a different approach of morphological classification based on radiological criteria. 1026 computed tomography angiography scans of adults were evaluated and the presence of left-sided (LAA) and right-sided (RAA) AA were determined in 1023 (99.71%) and 3 (0.29%) of patients, respectively. According to the number of branches, LAA branching pattern of each patient was subclassifed in five morphological types. Based on the order and type-specific reference points, an anomalous LAA variants were classified into 20 subtypes. Type 1 (Typical branching pattern) LAA was identifed in 781 (76.12%) of the patients. Among 242 aberrant LAA variants (four types, 23.58%), the most common subtypes; Type 2A with brachiocephalico-carotid trunk (BCT), Type 4A1 with an aberrant left vertebral artery (ALVA), and Type 3A1, in which BCT coexisted with ALVA, were observed in 17.6%, 3.6%, and 0.88% of the cases, respectively. The frequency of remaining LAA variants ranged from 0.39% to 0.097%. In addition, Type 3B2 and Type 4C were first identified in our study. We observed Type I and II RAA in one female (0.097%) and two cases (male and female, 0.19%), respectively. Knowledge of AA branching variations is of great interest in neck and thoracic surgery and the new morphological types in clinically applicable form recommended in this study can be used in endovascular interventions.