Mechanism of pressure-overload right ventricular hypertrophy in infant rabbits.

Although pressure-overload right ventricular hypertrophy is a long-term risk in some congenital heart diseases such as tetralogy of Fallot, how it develops is unclear. The aim of this study was to investigate the mechanism of development of this right ventricular heart failure.Pulmonary artery banding in 10-day-old rabbits induced pressure-overload right ventricular hypertrophy as they grew. Comparisons were made with age-matched sham controls (n = 24 per group). In weekly serial echocardiography, the right ventricular contraction and diastolic function decreased from 3 weeks after surgery (P < 0.01), and the right ventricle became hypertrophic from 4 weeks after (P < 0.05). Pressure-overload increased cardiomyocyte apoptosis from 4 weeks postoperatively (TUNEL staining and Western blotting analysis, P < 0.05); and fibrosis occurred in the right ventricular cardiomyocytes at 8 weeks after operation (Masson's trichrome stain, P < 0.01). In our model, pressure-overload to the right ventricle caused the right ventricular disorder, hypertrophy, and fibrosis. Apoptosis of right ventricular cardiomyocytes was involved in progression. We have shown for the first time the mechanism whereby pressure-overload right ventricular hypertrophy develops in an infant rabbit model.