INDUCTION OF RIGHT-VENTRICULAR HYPERTROPHY WITH OBSTRUCTING BALLOON CATHETER - NONSURGICAL VENTRICULAR PREPARATION FOR THE ARTERIAL SWITCH OPERATION IN SIMPLE TRANSPOSITION

Background. Recently, a successful result with a rapid two-stage arter ial switch operation (ASO) was reported for patients with transpositio n of the great arteries (TGA) with low left ventricular pressure. In t his procedure, the interval between pulmonary arterial banding and ASO was approximately 1 week. This successful result indicates the possib ility of a nonsurgical ventricular preparation procedure using an obst ructing balloon catheter prior to ASO. Methods and Results. A 5F atrio septostomy catheter was inserted directly into the main pulmonary arte ry in six lambs aged 20 to 38 days. After the chest was closed, the ba lloon was inflated twice a day for a period of 2 to 2.5 hours. This pr ocedure was performed for 4 consecutive days. After the final inflatio n, the ratio of right ventricular weight to total ventricular weight w as compared with that in an age-matched control group. After the final inflation, the peak systolic right ventricular pressure and the perce ntage of peak systolic right ventricular to peak systolic aortic press ure rose to 85.6+/-4.7 mm Hg (mean+/-1 SD) and 79.6+/-8.6%, respective ly. The percentages of the right ventricular weight to the total ventr icular weight were significantly higher after the balloon inflation th an those in the control group in terms of wet heart weight (29.5+/-1.2 % versus 23.0+/-1.0%; P<.0001) and dry heart weight (27.0+/-2.0% versu s 21.0+/-1.1%; P<.0001). Conclusions. The myocardial mass in the right ventricle increased after 4 days of intermittently applied pressure o verload. Nonsurgical preparation of the ventricle for ASO in TGA is fe asible.