Incidence of Branching Patterns Variations of the Arch in Aortic Dissection in Chinese Patients

Several authors have described anatomic variations of the aortic arch in 13% to 20% of the patients who do not have aortic disease. However, few studies have evaluated these patterns in the thoracic aortic dissection (TAD). In the authors' knowledge, this is the first survey that specifically investigates the frequency of these variations in a broad, nonselected group of Chinese patients with aortic dissection. Furthermore, it compares this group with a group of patients without aortic disease.The objective of this study was to define the variation frequency of the aortic arch branches pattern using the tomographic studies of 525 Chinese patients with a diagnosis of TAD. The Stanford classification was used to set the site of the initial tear of the dissection. In addition, we performed an epidemiological analysis of the aortic arch anatomic variations in TAD, and its possible implications for surgical or endovascular treatment. The general hypothesis proposal asserted that Chinese patients with dissection of the aorta have a similar incidence of variations of the aortic arch to the patients without aortic disease.A retrospective study of cases and controls was carried out using the tomographic studies (CT) of all patients admitted to the First Affiliated Hospital of Zhengzhou University, located at Henan-China, with a confirmed diagnosis of aortic dissection from January 2012 until December 2014. The group of cases consisted of 525 patients: 374 men and 151 women, with a mean age of 52.27 years (range, 20-89). The average age of the patients with Stanford A and B aortic dissection was 49.46 and 53.67, respectively. The control group consisted of 525 unselected patients without TAD who underwent a CT scan of the chest due to other indications. This group consisted of 286 men and 239 women, with a mean age of 53.60 years (range, 18-89). All the patients with aneurysm or dissection were excluded from the control group. We performed a statistical analysis of demographic data.The study found 7 different patterns of the aortic arch on both groups of cases and controls. Within the 525 patients with TAD were observed 85 (16.19%) anatomical variations, while the control group showed 112 variations (21.33%); P = 0.033. The most common anatomical variant was the bovine arch, found in 62 (11.80%) cases of TAD compared with 77 (14.66%) in the control group; P = 0.172. Anatomical variations were observed in 14.32% of the patients with Stanford A dissection and 17.09% of the patients with Stanford B dissection; P = 0.425. Patients with Stanford A dissection showed the pattern of bovine arch in 23 (13.21%) of 174 cases. In contrast, the patients with Stanford B dissection showed it in 39 (11.11%) of 351 cases; P = 0.481. The anatomical variant defined as vertebral artery of direct origin of the aortic arch was more frequent in the patients with Stanford B dissection (5.12%). The patients with Stanford A dissection presented this pattern in 1.14% of the cases; P = 0.025. This study observed an increased frequency of aortic dissection in the subgroup from 41 to 60 years old. In the subgroup from 41 to 60 years old without TAD, a greater frequency of anatomical variations were found than in the patients with TAD (20.81% vs 14.23%; P = 0.050). The same fashion was seen in patients older than 80 years (27.27% vs 0%; P = 0.030). The anatomical variations of the aortic arch with TAD occurred in 14.97% of the male patients and 19.20% of the female patients compared to 21.67% to 20.92% in the control group; P = 0.026 and P = 0.681, respectively.The aortic arch variations were found less frequently in the TAD group than in the control group in the present Chinese series. The bovine arch was considered the variant pattern of the major frequency in the patients with TAD and the control group. The anatomical variant of 4 branches, defined as vertebral artery of direct origin of the aortic arch, was more frequent in patients with Stanford B aortic dissection than in the patients with Stanford A.This finding might show an association between the geometry of the aortic arch and the site of onset of first intimal tear of dissection.