[Association between sphericity, ventricular function and size of the infarction in rats].

Background: The left ventricular (LV) sphericity is a factor associated with ventricular dysfunction, but it is not well-characterized in the experimental infarction model in rats.

Objective: To analyze the association between the sphericity index (SI), the ventricular function and the infarcted area in an experimental rat model.

Methods: Six months after the infarction (AMI, n=33) or simulated surgery (SHAM, n=18), the animals were submitted to an echocardiogram. The SI was obtained through the ratio between the diastolic areas at the LV long axis and the short axis.

Results: The AMI group presented the lowest index of sphericity (1.32 x 0.23 vs 1.57 x 0.33; p=0.002), systolic function and relative thickness (0.13 x 0.003 vs 0.18 x 0.04; p<0.001) and the highest index of parietal stress (1.27 x 0.33 vs 0.88 x 0.25; p<0.001). There was a significant correlation between the infarct size and sphericity (p=0.046). At the linear regression analysis, the infarct size (p=0.014), but not the sphericity (p=0.683) and the parietal stress (p=0.176), was the predictive factor of the systolic function. Eccentric remodeling (p=0.011), but not sphericity (p=0.183) or the infarct size (p=0.101), was a predictive factor of parietal stress. Additionally, the infarct size (p=0.046), but not the eccentric remodeling (0.705), was a predictive factor of sphericity. The infarct size (p=0.015) and the parietal stress (p=0.011), but not the sphericity (p=0.705), were the predictors of eccentric remodeling.

Conclusion: The sphericity is associated, but it is not a determinant factor of parietal stress, of eccentric remodeling and ventricular systolic function in an experimental infarction model in rats.