Balloon dilatation of primary infundibular stenosis of the right ventricular outflow tract

Abstract

Primary infundibular stenosis is an uncommon cause of right ventricular outflow tract obstruction.1-4 Most such cases have an associated ventricular septal defect that is usually smalll; some patients develop infundibular stenosis after spontaneous29 s or surgical closure4 of the ventricular septal defect. Infundibular pulmonic stenosis progresses more rapidly than valvular pulmonic stenosis L s and surgery has been the only treatment.l, 6 Balloon dilatation is the treatment of choice for valvular pulmonic stenosis and has been found useful in palliating the condition in infants and children with obstruction to the right ventricular outflow tract.7-s Welo have recently shown that balloon dilatation is partially effective in reducing the outflow tract gradient in double-chambered right ventricle (DCRV). In this paper we report a patient with infundibular puimonic stenosis in whom balloon dilatation was successful in reducing the outflow tract gradient. A 15-year-old girl presented with a history of dyspnea on exertion of 5 years’ duration that had progressed to class III (New York Heart Association) over the last year. She was in sinus rhythm, without heart failure, and was not cyanotic. Clinically, she had features of severe right ventricular outflow tract obstruction. The electrocardiogram (ECG) showed right axis deviation (110 degrees), right ventricular hypertrophy, and upright T waves in the right precordial leads. There was no poststenotic dilatation of the pulmonary artery in the chest x-ray film. Echocardiography showed hypertrophy of the right ventricle, a large pulmonary artery, a narrowed right ventricular outflow tract, and intact atria1 and ventricular septa. Doppler echocardiography demonstrated a gradient of 77 mm Hg across the right ventricular outflow tract without valvular regurgitation. Cardiac catheterisation (Table I, Fig. 1) showed infundibular stenosis of the right ventricle with a gradient of 80 mm Hg. Angiography confirmed the diagnosis of infundibular pulmonic stenosis with good ventricular systolic function (Fig. 2). The stenosed segment was dilated with the double balloon technique using 20 and 18 mm balloons (Boston Scientific Carp, Mansfield, Mass.) (Fig. 2). A total of five inflations reduced the gradient to 45 mm Hg. She was discharged on a regimen of o-blockers (propranolol, 120 mg/