Reversible pulmonary trunk banding with a balloon catheter: Assessment of rapid pulmonary ventricular hypertrophy

Objective: We sought to assess the rapid hypertrophy of the right ventricle of young goats submitted to progressive pressure load by a balloon cathete r. Methods: The hearts of 6 young goats were assessed by means of echocardiogr aphy and cell morphology during and after right ventricular hypertrophy had been produced by a balloon catheter, Myocardial samples of the right ventr icular outflow tract were harvested for microscopic studies. The external d iameter of longitudinally sectioned myocytes was measured at the nucleus le vel, The volume density of mitochondria was also determined. A balloon cath eter was then placed through the right ventricular outflow tract in the pul monary trunk and progressively inflated every 2 days. Postoperative serial echocardiography was performed Lit intervals of 1 to 2 days, The animals we re killed after 2 to 3 weeks of right ventricular training for morphologic analysis. Results: Under optical microscopy, there was a 20.5% increase in the mean d iameter of the myocyte of the trained right ventricle, However, under elect ron microscopy, there was no significant change in the mean volume density of mitochondria from the trained right ventricle, Serial echocardiography s howed equalization of the ventricular thickness over a short interval of 6 to 10 days of progressive balloon inflation. Conclusions: The balloon catheter permits the manipulation of the pressure Load over the right ventricle, causing rapid hypertrophy in a 6- to 10-day period. This study suggests that nonsurgical preparation of the "pulmonary ventricle" in patients with transposition of great arteries with intact ven tricular septum beyond the neonatal period could probably be accomplished w ithin a very few days.