Assessment of left ventricular structure and function in rats subjected to pressure-overload hypertrophy in time

Background: Left ventricular hypertrophy (LVH) is an adaptive response to increased haemodynamic load and an independent risk factor for the development of heart failure. Although the pathophysiological features during the development of cardiac hypertrophy have been extensively studied, the time course of LVH is less clearly defined. Aim: To define the time-dependency of the LVH process in vivo and compare the data by necropsy. Methods: Using abdominal aortic banding (AAB) in male Wistar strain albino rats we assessed the changes of LV structure and function in short intervals of 5 days for a period of 45 days. We determined the changes by serial echocardiography and confirmed the results in a second echocardiographic experiment and by necropsy. Results: In our model the magnitude of the pressure overload was sufficient to produce significant LVH within a 10-day time frame and further progression on the 15^th day after AAB. Interestingly, on the 20^th day after banding a short-lasting regression of LVH (and heart weight and LV wall thickness) was found. It was followed by an increase in the next 15 days (till the 35^th day), after which LVH was roughly complete (as measured at the 45^th day). Conclusions: Following the development of LVH over a relatively long period of time and providing the changes in short intervals, a short lasting regression during ongoing pressure overload was noted. Understanding and targeting the associated signalling underlying this regression may have considerable clinical consequences.