In vivo assessment of left ventricular hypertrophy in rats: Necropsy validation

Development of left ventricular hypertrophy (LVH) is a compensatory response to hemodynamic overload and echocardiography is a noninvasive, sensitive method to study the process of myocardial remodeling and functional changes. In this study we assessed in vivo the time-course of the left ventricular structural and functional changes after aortic banding and validated them by necropsy. Wistar rats were subjected to abdominal aorta banding (AAB) or sham operation. A control group of age- and sex-matched, were maintained and sacrificed in parallel with operated animals. Echocardiographic assessment was performed before and at days 10, 15, 20, 25, 35 and 45 post-operation. Some rats were euthanized at each time point to obtain body and organ weights. Echo left ventricular wall thickness (LVWT) increased progressively on the 10^th and the 15^th day, then there was a reduction on the 20^th day, followed by a second marked increase on the 25^th day and after 35^th day it presented a plateau. On the 45^th day LVWT in AAB rats increased to 35% compared with SH. The percentage of left ventricular fractional shortening was similar in different groups at each time point. These parameters remained stable in control groups. Echocardiographic parameters and actual whole heart mass were well coincided. Echo LVWT correlated well with actual whole heart mass (r=0.724, P < 0.001). We developed an easier model of significant LVH in rats, not requiring thoracotomy. The progression of myocardial hypertrophy is a time-dependent, stage developing process. The model is suitable to study the mechanisms governing the development of left ventricular hypertrophy for therapeutic benefit.