Automated image analysis of myocardial collagen pattern in pressure and volume overload in rat cardiac hypertrophy.

An automated image analysis system was used to analyze the collagen pattern in picrosirius-stained sections of the left ventricular myocardium from 27 rats: 9 sham-operated animals (controls), 9 animals with one-clip, two-kidney Goldblatt renovascular hypertension (RVH) and 9 animals with an aortocaval fistula (ACF) model of volume overload hypertrophy. The collagen content and fiber thickness were significantly increased in the RVH group as compared to the ACF and sham-operated groups (P less than .001). These parameters were correlated to the left ventricular wall thickness (R = .66; P less than .01). On the other hand, form factors were significantly increased in both treated groups as compared to the controls. These findings indicate that increased collagen formation and increased left ventricular wall thickness probably depend on the type of load and were particularly important when afterload is increased.