Relation of sympathetic activation and stress-induced hypertension in atherosclerosis of the thoracic aorta: a cadaveric study

Abstract

Background: The autonomic nervous system (ANS) has been associated with numerous atherosclerosis-induced cardiovascular events, such as myocardial infarction and aortic disease. Although evidence suggests a relationship between autonomic dysfunction and atherosclerotic disease, the underlying mechanisms are still under investigation. The purpose of this study is to investigate the effect of ANS to the development of atherosclerosis and vice versa, in human thoracic aorta.Methods: An autopsy analysis from three segments of the thoracic aorta was performed; ascending aorta, aortic arch, descending aorta, using 52 unselected adult cadavers (38 male, 14 female – mean age 64.4 years; age range 19-90 years). Subjects were divided in two age groups (<65 years – N=26, >65 years – N=26). Tissue specimens were macroscopically examined and histopathologically divided into 7 grades of scoring for atherosclerosis (ATHERO, from 0=intact, to 6=thrombi formation). The relationship between ANS and atherosclerosis was depicted by further immunohistochemical analysis for detection of neuron terminals onto the aortic wall. All data were evaluated according to the subjects’ demographic and clinical characteristics.Results: Total 96.2% of all subjects had atherosclerosis of variable degree in one or more segments. No aneurismal change was found. The presence of atheromas were common in all subjects regardless of age and segment, with atherosclerosis increasing by age; ascending aorta (r=0.571, p<0.001), aortic arch (r=0.655, p<0.001), descending aorta (r=0.659, p<0.001). Hypertension was a significant factor in the development of atherosclerosis in adults >65 years (r=0.450, p=0.023). In addition, a positive history of hypertension was statistically significant regarding both the presence of atherosclerosis and neuron terminals in all three aortic wall segments; ascending aorta (p=0.037), Aaortic arch (p=0.046), descending aorta (p=0.045). Furthermore, there was a strong negative correlation between the ATHERO score and the presence of neuron terminals in all three aortic segments; ascending aorta (r=-0.264, p=0.041), aortic arch (r=-0.400, p=0.003), descending aorta (r=-0.234, p=0.047).Conclusions: Human cadaveric studies are extremely useful in understanding the pathophysiology of ANS, along with clinical and animal studies that are most commonly performed. These data suggest that there is a link between autonomic disfunction and the presence of atherosclerosis in human thoracic aorta, especially when hypertension is present. It is therefore possible that stress-induced hypertension can be considered as a potential risk factor for the development of atherosclerosis.