The structure of myocardial nerve plexus of human auricle of the right atrium and its relation to myocardial ischemia, functional status of the heart, and age

The aim of this study was to investigate and evaluate morphometrically the relationship between changes in the structure of myocardial nerve plexus of the right atrium auricle and myocardial ischemia, parameters reflecting functional status of the heart, and age. A total of 56 females and males aged 20–94 years were investigated. Ischemic heart disease group consisted of 39 persons (their mean age was 63.83±15.67 years). The control group comprised 17 persons (the mean age was 60.53±9.89 years). Control group consisted of deceased persons who according to the pathologic and anatomic examination were not diagnosed with cardiac pathology leading to heart lesions or overload. Ischemic heart disease group consisted of patients who underwent aorta-coronary artery bypass grafting surgery. In ischemic heart disease group, degree of coronary artery stenosis was evaluated as well as the major indicators reflecting the size of atria and formation of postinfarction scar. After examination, postinfarction scars were found in 18 (46.2%) persons; no scars were found in 21 (53.8%) persons. Neurohistochemical method and video microscopy were employed for the evaluation of quantitative changes in the structure of the myocardial nerve plexus. In ischemic heart disease group, the structures of nerve plexus occupied 5.0±1.0% of the area, perimeter was 10 488±2134 mm, and number of the structures was 2698±981; the same parameters in the control group were 6.0±1.4%, 13 008±443 mm, and 3469±1511, respectively. In persons with postinfarction scar, the number of nerve plexus structures was lower by 9.3%, area by 8.9%, perimeter by 9.7% on average as compared to ischemic heart disease group without a scar. Regression analysis did not reveal any statistically significant correlation between the degree of coronary artery stenosis and quantitive parameters of nerve plexus (P>0.05). Changes in quantitative parameters of nerve plexus were not related to compensatory dilation of the atria – echoscopy parameters of long and short axes. The results showed that the number, area, and perimeter of nerve plexus structures decreases at the same rate both in healthy subjects and patients with ischemic heart disease starting the fifth decade of life.