Hemodynamic and histomorphometric characteristics of dilated cardiomyopathy of Syrian hamsters (Bio TO-2 strain)

The natural history of the disease of the dilated strain Bio TO-2 of cardiomyopathic hamsters (CMH) is not totally characterized. We investigated its hemodynamic and histomorphometric characteristics at 140, 180, 220, 260, and 300 days of age. Forty CMH and 40 controls were investigated (8 at each stage). Mean arterial pressure (MAP, carotid artery catheter) and cardiac output and femoral blood flow (CO, FBF, transit time method) were measured in anesthetized animals. Systemic (SVR) and femoral (FVR) vascular resistances were calculated. Atria, left and right ventricles (LV, RV), lungs, and liver were weighed. LV cavity area, LV and RV wall thicknesses and collagen densities were determined (computer-assisted image analyzer). Pulmonary and hepatic congestion were assessed (arbitrary scales). Compared with controls, MAP, CO and FBF were significantly lower in CMH throughout the study (on average: -22%, -34%, -33%, respectively), FVR was significantly increased (+15%), but SVR was not significantly modified. Concerning histomorphometric characteristics, differences between groups significantly increased with age for most variables: at 300 days, atria (+292%), RV (+13%), lungs (+44%), and liver (+23%) weights, LV cavity area (+130%), LV (+364%) and RV (+181%) collagen densities were significantly increased in CMH vs controls, whereas LV (-40%) and RV (-23%) wall thicknesses were significantly decreased. At 260 and 300 days, CMH showed significant pulmonary congestion without hepatic alteration. Bio TO-2 CMH progressively develop an alteration of cardiac function leading to decreased MAP and musculo-cutaneous blood flow associated with cardiac remodeling including atria hypertrophy and LV dilation, wall thinning and a rise in collagen density.