Objective: To compare cardiac structural changes in experimental pressure and volume overload models.
Methods: The study analysis included renovascular hypertensive rats (RVH, n = 8), normotensive rats with volume overload caused by an aortocaval fistula (ACF, n = 10) and control rats (CONT, n = 8). After four weeks, tail cuff blood pressure (SBP) was recorded. Rats were killed, the hearts were excised and the right and left ventricles (RV&LV) were weighed (RVW&LVW). Using histological sections, myocyte cross sectional areas (MA). LV wall thickness (LVWT) LV cavity diameter (LVD), normalized LVWT (LVWT/LVD) and collagen volume fraction (CVF) were measured. The comparisons were made using the ANOVA and Tukey test for a significance level of 5%.
Results: Tail cuff blood pressure (mmHg) was higher in the RVH group (RVH = 187 +/- 22; CONT = 125 +/- 10; ACF = 122 +/- 6, p < 0.05). LV hypertrophy was observed in the RVH and ACF groups. The ACF group presented a significant increase in size of LVD, compared to CONT and RVH. The absolute and normalized ventricular wall thickness were similar among the groups. The RVH group presented a significant increase in CVF compared to CONT group and ACF group.
Conclusion: Cardiac remodeling patterns following volume or pressure overload are distinct, suggesting that their implications on ventricular dysfunction are not interchangeable.