Chronic hibernating myocardium in sheep can occur without degenerating events and is reversed after revascularization

• Published in: Cardiovascular pathology 2014-05, Vol.23 (3), p.160-168
• Main Authors: Verheyen, F, Racz, R, Borgers, M, Driesen, R.B, Lenders, M.-H, Flameng, W.J
• Format: Article
• Language: English
• Subjects: Animals; Cardiomyopathy; Chronic Disease; Coronary artery stenosis; Coronary Circulation; Coronary Stenosis - complications; Coronary Stenosis - pathology; Coronary Stenosis - physiopathology; Coronary Stenosis - therapy; Disease Models, Animal; Fibrosis; Hibernation; Hypertrophy, Left Ventricular - etiology; Hypertrophy, Left Ventricular - pathology; Hypertrophy, Left Ventricular - physiopathology; Morphology; Myocardial blood flow; Myocardial Stunning - etiology; Myocardial Stunning - pathology; Myocardial Stunning - physiopathology; Myocardial Stunning - therapy; Pathology; Percutaneous Coronary Intervention; Severity of Illness Index; Sheep; Time Factors; Ventricular Dysfunction, Left - etiology; Ventricular Dysfunction, Left - pathology; Ventricular Dysfunction, Left - physiopathology; Ventricular Function, Left
• ISSN: 1054-8807; 1879-1336
• DOI: 10.1016/j.carpath.2014.01.003

Abstract Introduction Our goal was to show that blunting of myocardial flow reserve is mainly involved in adaptive chronic myocardial hibernation without apparent cardiomyocyte degeneration. Methods and results Sheep chronically instrumented with critical multivessel stenosis and/or percutaneous transluminal coronary angioplasty (PTCA)-induced revascularization were allowed to run and feed in the open for 2 and 5 months, respectively. Regional myocardial blood flow (MBF) with colored microspheres, regional and global left ventricular function and dimensions (2D echocardiography), and myocardial structure were studied. In sheep with a critical stenosis, a progressive increase in left ventricular end-diastolic and end-systolic cavity area and a decrease in fractional area change were found. Fraction of wall thickness decreased in all left ventricular wall segments. MBF was slightly but not significantly decreased at rest at 2 months. Morphological quantification revealed a rather small but significant increase in diffusely distributed connective tissue, cardiomyocyte hypertrophy, and presence of viable myocardium of which almost 30 % of the myocytes showed depletion of sarcomeres and accumulation of glycogen. The extent of myolysis in the transmural layer correlated with the degree of left ventricular dilation. Structural degeneration of cardiomyocytes was not observed. Balloon dilatation (PTCA) of one of the coronary artery stenoses at 10 weeks revealed recovery of fraction of wall thickness and near normalization of global subcellular structure at 20 weeks. Conclusion These data indicate that chronic reduction of coronary reserve by itself can induce ischemic cardiomyopathy characterized by left ventricular dilatation, depressed regional and global function, adaptive chronic myocardial hibernation, reactive fibrosis and cardiomyocyte hypertrophy in the absence of obvious degenerative phenomena. Summary Reduction of myocardial flow reserve due to chronic coronary artery stenosis in sheep induces adaptive myocardial hibernation without involvement of degenerative phenomena.