Cardiac Remodeling In Canine Model Of Acute And Chronic Obstructive Sleep Apnea-related Atrial Fibrillation

Objective: Through echocardiography,myocardial morphology,PAS staining,TUNEL staining,Masson trichrome staining and ultrastructural analysis,to explore the changes of myocardium during acute sleep apnea(6 hours)and chronic sleep apnea(12 weeks),to explore the process of remodeling of atrial structure during the progression of acute OSA to chronic OSA,and its role in the occurrence of atrial fibrillation..Methods: Eighteen adult beagle dogs were used established an OSA model under general anaesthesia.The animals were divided into the control group,acute OSA group,and chronic OSA group,and there were 6 animals in each group.Cardiac ultrasounds of dogs from the three groups were examined.Cardiac tissues were taken for HE staining,PAS staining,TUNEL staining,Masson's trichrome staining and transmission electron microscopy.Results: In the acute OSA model,the left atrial diameter of the dogs began to increase 3 h after ventilation,and this difference was more obvious at 6 h.The morphology of the myocardial cells did not change significantly,but mitochondrial swelling was observed in some atrial myocytes at 3 h.In the chronic OSA model,the left atrial diameter gradually increased,the volume of the right and left atria increased,the glycogen and collagen volume fractions and apoptosis ratio were significantly increased in atrial myocytes,mitochondria swelling and lengthening occurred in some atrial myocytes,the matrix became lighter,the mitochondrial ridge density decreased,and the myofilament arrangement was disordered.The disc was distorted and not continuous,and there was some cardiomyocyte necrosis.Conclusion: With the prolongation of apnea,the atrium gradually enlarges,myocardial cells become disordered,glycogen aggregates,the number of necrotic cells increases,fibrosis worsens,mitochondrial abnormalities occur and the arrangement of the discs are disordered,providing a basis for the maintenance of AF.