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 cardio myopathic hamsters (CMH) is not totally characterized. We investigated its hemodynamic and histomorphometric characteristics at 140, 180, 220, 260, an d 300 days of age. Forty CMH and 40 controls were investigated (8 at each s tage). Mean arterial pressure (MAP, carotid artery catheter) and cardiac ou tput and femoral blood flow (CO, FBF, transit time method) were measured in anesthetized animals. Systemic (SVR) and femoral (FVR) vascular resistance s were calculated. Atria, left and right ventricles (LV, RV), lungs, and li ver were weighed. LV cavity area, LV and RV wall thicknesses and collagen d ensities 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 a ge 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, where as LV (-40%) and RV (-23%) wall thicknesses were significantly decreased. A t 260 and 300 days, CMH showed significant pulmonary congestion without hep atic alteration. Bio TO-2 CMH progressively develop an alteration of cardia c function leading to decreased MAP and musculo-cutaneous blood flow associ ated with cardiac remodeling including atria hypertrophy and LV dilation, w all thinning and a rise in collagen density.