Study On Morphological Change Of Atrial Myocytes And Expression Of Connexins In Patients With Rheumatic Heart Disease And Atrial Fibrillation

Background and Objective: Atrial fibrillation (AF) is not most common perpetual tachycardia and the underlying mechanism of AF is not well defined. Radical treatment to AF is not completely established yet. So, exploring the pathogeny and treatment of AF has become an important aspect of cardiology. There have been some reports of Cx40 and Cx43 relation to the occurrence and maintenance of AF. This study was designed to investigate the influence of AF to Cx40, Cx43 as well as Cx45 and identify the morphological change of left and right atrial myocytes when the patients with rhematic heart disease suffered from AF or not.Methods: We investigated 31 patients undergoing cardiac surgery for correction to valvular defect. The patients with AF were divided into two groups according to the duration of AF: 11 of experimental Ⅰgroup were ≤6 months and 12 in experimental Ⅱgroup＞6 months. 8 without AF were control group. Atrial muscle samples of left atrial appendage (LAA) and right atrial appendage (RAA) were cut off when heart valve replacement. Morphological assay were examined by light microscope and electron microscope. Expression of Cx40 and Cx43 were detected by immunohistology and immunoblotting.Results :1. Through analyzing the clinical characteristics of each patients, we concluded that the luminal diameter of left atrium augmented significantly and the dimension of mitral valve decreased dramatically.2. Aschoff 's body scattered in atrial tissue according to the examination of light microscope: the positive percent in control was 37.5%(3/8); experimental Ⅰgroup were 46%(5/11); experimental Ⅱgroup were 50% (6/12). The local interstitial proliferation, vacuolation, nuclear degeneration as well as a few of lymphocytes infiltration were detected in all samples. No significant difference was found between left and right atrium in each patients and every patients in each groups 3. Myolysis, accumulation of glycogen as well as fibrosis were detected by electron microscope in each groups. The patients with AF were more obvious than patients without AF in myolysis and fibrosis, but there was no obviously difference in myolysis and fibrosis between experimental Ⅰgroup and experimental Ⅱgroup.4. No obvious change was measured in the level of Cx43 and Cx40 between left and right atrium in each patients and every patients in each groups (P＞0.05). Comparing with the control group, the level of Cx40 was marked decreased in experimental Ⅰgroup (P＜0.05)and experimental Ⅱgroup (P＜0.01＝. The level of Cx43 was similar in three groups.5. Cx43 positive staining was coincident distribution in three groups and no obvious different among groups. Cx43 positive staining was coincident distribution in control group but not coincident distribution in experimental Ⅰgroup and experimental Ⅱgroup.6. Expression of Cx45 was not been detected with anti-Cx45 antibody by immunoblotting.Conclusion:1. In the late stage of rhematic heart disease, there were similar pathological changes between left and right atrium.2. The interstitial fibrosis of atrial tissue was involved in the occurrence and maintenance of AF.3. Down-regulation of level of Cx40 was an important agent in the occurrence and maintenance of AF.4. Heterogeneous distribution of Cx40 was associated with the occurrence and maintenance of AF...