A rabbit model to study regression of ventricular hypertrophy

Background: The purpose of this study is to develop and characterise a reproducible rabbit model of LVH regression following pressure-induced myocardial hypertrophy.

Materials and methods: Without endotracheal intubation and mechanical ventilation, a median sternotomy was performed. The median incision was made exactly along the midline of the sternum. Ascending aortic diameter was reduced 50% above the aortic valve, which lead to an approximate 75% reduction in crosssectional area. The sham-operated rabbits underwent the same procedures without actual ligation of the aorta. The animals of early DB group and late DB group were subjected to the second operation for removing the ligation eight weeks or 16 weeks after the initial banding surgery, respectively. Echocardiography, haemodynamic assessment, histology, and electron microscopy were used to assess functional and structural aspects of myocardial hypertrophy at each time point.

Results: The pressure overload resulted in robust LVH assessed by echocardiography, haemodynamic assessment, LV weight/body weight ratios, histology, and electron microscopy. Ascending aortic debanding completely or partially reversed LVH. The degree of LVH regression was association with the duration of pressure overload, proved by the fact that restoration of LV structure and function was complete in animals subjected to eight weeks of aortic banding but incomplete in animals subjected to 16 weeks of aortic banding. The animals did not experience severe mechanical ventilatory impairment.

Conclusions: These results demonstrate an efficient and reproducible method of promoting LVH regression in rabbits without endotracheal intubation and mechanical ventilation.