Serial assessment of left ventricular morphology and function in a rodent model of ischemic cardiomyopathy

Left ventricular remodelling (LVr) occurs post myocardial infarction (MI), predisposing people to heart failure (HF). LV mechanics and morphology are important in this process. We hence sort to characterize LV mechanics and geometry in a post-MI rodent model. Thirty-two male Sprague-Dawley rats (150-200 g) sustained MI (n = 24) or sham (Sham; n = 8) surgery. In another six sham rats invasive blood pressure measurements were performed. Ultrasound imaging was done at baseline, and 1, 3, 7, 14, 30 and 60 days following surgery, and LV mechanics and morphology assessed. LV volumes increased with time (p < 0.01), at a greater rate in the MI group than the Sham group (p < 0.01). Strain was impaired in MI rats at day 1 (13.50 ± 6.64 vs. 25.71 ± 4.94%, p < 0.01) and remained impaired at day 60 (14.07 ± 5.37 vs. 22.98 ± 5.87%, p < 0.01). Strain rate was lower at day 1 (4.11 ± 1.29 vs. 8.10 ± 2.18%/s, p < 0.01), remained lower throughout follow-up (p < 0.01), and decreased at a greater rate in MI rats (p < 0.01). Mean systolic (204 ± 43 vs. 322 ± 75 1/m, p < 0.01) and diastolic (167 ± 21 vs. 192 ± 11 1/m, p < 0.01) curvature was lower in the MI rats at day 1 post surgery and throughout follow-up (p < 0.01). Maximum principal curvature decreased throughout time (p < 0.01), while minimum principal curvature did not (p = 0.86). Wall stress increased significantly after infarction in MI rats (p < 0.01). ST-elevation myocardial infarction (STEMI) changed LV shape and contractile function. The assessment of these indices may prove useful in understanding LVr and the development of HF.