Comparison of cerebral protective effect and mechanism of different cerebral perfusion methods in elderly acute aortic dissection

[Objective] To investigate the cerebral protection effect of different cerebral perfusion methods in elderly patients with acute aortic dissection and its mechanism. [Methods] (1)A total of 206 elderly cases of acute type Stanford A aortic dissection admitted to the same surgery group in the cardiac surgery department of the First Affiliated Hospital of Xinjiang Medical University from January 2015 to January 2023 were selected as the study subjects. According to the degree of internal carotid artery stenosis, it was divided into three groups: A (stenosis <50%, 68 cases), B (stenosis from 50%-70%, 68 cases) and C (stenosis>70%, 70 cases). Group B and C were divided into four subgroups: B1 (34 cases), B2 (34 cases), C1 (35 cases) and C2 (35 cases). In group A and group B1, selective cerebral perfusion was 5-10 mL/(kg·min); in group B2 and group C1, selective cerebral perfusion was 10-15 mL/(kg·min); in group C2, bilateral perfusion was 10-15 mL/(kg·min). Brainstem auditory evoked potential (BAEP), Wechsler memory scale and Glasgow coma score were used to detect preoperative and postoperative neurological function. (2)Experimental animals selected 48 white pigs, male and female, weight 8-10 kg. Blood vessel clip or suture technology were used to cause different degrees of stenosis. According to the infusion method, they were divided into five groups: A (16 mice), B1 (8 mice), B2 (8 mice), C1 (8 mice) and C2 (8 mice). In animal experiments, the perfusion method and volume of each group were the same as in study (1). Protein immunoblotting was performed to detect the levels of B-cell lymphoma 2 (Bcl-2) and Bcl-2 related X protein (Bax) in the blood of each group of animals. [Results] (1) One day before surgery, there was no significant difference in BAEP between the groups (P>0.05); on the first day after surgery, there were significant differences in BAEP between the groups (P<0.05), and BAEP in group B1 was greater than that in group A (P<0.05), BAEP in group B2 was less than that in group B1 (P<0.05), group C1 was greater than that in group B2 (P<0.05), and BAEP in group C2 was less than that in group C1 (P<0.05). There was no significant difference in Wechsler memory scale results between the groups 1 day before surgery and 7 days after surgery (P>0.05), but on the 7th day after surgery, the Wechsler memory scale results of groups B1, B2, C1, and C2 were lower than those on the 1st day before surgery (P<0.05). There were no significant differences in Glasgow coma scale between the groups 1 day before surgery and 1 day after surgery (P>0.05). On the first day after surgery, the Glasgow coma score in groups B1, B2, C1, and C2 was lower than that on the first day before surgery, and the differences were statistically significant (P<0.05). In group B1, 1 patient had coma and recovered on the 7th day after surgery; in group C1, 1 patient had disorientation and recovered on the 5th day after surgery; no complications were found in the other groups, and there was no significant difference in the occurrence of complications between the groups (P>0.05). (2) On the 7th day after surgery, there were significant differences in the relative expression of Bax and Bcl-2 among the groups (P<0.05), and the relative expression of Bax gradually decreased and the relative expression of Bcl-2 gradually increased in groups A, B1, B2, C1, and C2. [Conclusion] Different cerebral perfusion methods may have different degrees of protection in acute aortic dissection surgery in the elderly. Higher perfusion volume or bilateral perfusion can have a positive effect on neurological function. Different modes of perfusion can regulate the apoptosis pathway, but the specific mechanism needs further investigation.