A cardiac catheter enclosing an extensible blade was used to enlarge the interatrial opening in seven patients. Two patients with transposition of the great arteries who had balloon atrial septostomy as newborns subsequently presented with clinical evidence of a restrictive interatrial opening at 1 and 4 months of age. Cardiac catheterization confirmed restenosis of the interatrial opening and inadequate intracardiac mixing. After blade atrial septostomy the systemic arterial oxygen saturation increased by 20% and 30%, respectively. Five patients with mitral atresia complex, ages 2 months-9 1/2 years, had a restrictive interatrial communication and severe pulmonary venous hypertension (mean left atrial pressures ranged from 20-38 mm Hg). Following blade atrial septostomy, the pressure gradient between the atria was almost completely abolished and prompt clinical improvement was observed in each patient. All patients tolerated the procedure without complications. Blade atrial septostomy was a safe, effective procedure for enlarging the interatrial communication in this limited series of patients with an interatrial septum too thick to permit adequate rupture by conventional balloon atrial septostomy.

During the past 4 years, five institutions have collaborated in evaluating the efficacy of blade atrial septostomy. The procedure was performed in 52 patients, including 31 with transposition of the great arteries, 10 with mitral atresia, five with tricuspid atresia and six with miscellaneous anomalies. The patient's ages ranged from 1 day to 12 years (mean 13 months). Improvement occurred in 41 of 52 patients (79%). Four patients had an intact interatrial septum, and blade atrial septostomy was successfully performed by a transseptal technique. One patient died from a lacerated left atrial wall; other complications occurred in four patients. Blade atrial septostomy is an effective palliative procedure, even when the interatrial septum is thickened or intact.

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SUMMARY Forty cases of left atrioventricular valve (LAV) atresia without aortic stenosis or atresia were reviewed. Thirty-one had mitral atresia and nine had left tricuspid atresia. Eleven had associated pulmonary outflow tract obstruction. Twenty-two (55%) underwent cardiac catheterization and 12 had more than one study. Left atrial pressure was normal in seven infants younger than 2 weeks of age. Twelve patients had an elevated mean left atrial pressure (16-38 mm Hg), including two who had normal left atrial pressures at an earlier study. This suggests that an initially adequate interatrial opening has the potential to become restrictive. Therefore, balloon atrial septostomy is recommended in all patients with LAV atresia who are less than 1 month of age at initial study. Thereafter, serial cardiac catheterizations should be performed to assess changing hemodynamics.Twenty-three patients (56%) had palliative operations to decrease left atrial hypertension (atrial septectomy) and/or optimize pulmonary blood flow (pulmonary artery banding, ductus ligation or systemic-topulmonary anastomosis). Nine survivors (23%) have been followed from 13 months to 23 years (median 7 years). Eight of these had at least one surgical procedure. Prognosis was best in patients with mild-tomoderate pulmonic stenosis and worst in cases with pulmonic atresia. Palliative surgery may improve survival in selected patients with LAV atresia.LEFT ATRIOVENTRICULAR VALVE (LAV) atresia with a normal aortic valve is a rare congential heart defect with clinical and physiologic features that differ from aortic stenosis or atresia with a hypoplastic left ventricle.'-8 Moreno in 1976 reviewed 86 cases of mitral atresia with a normal aortic valve, and reported his initial cardiac catheterization data in nine patients.8 Only 9% in his series survived the first year of life. Few patients have reached adolescence or young adulthood. Although no corrective operation is presently available for LAV atresia, survival to early adulthood may be possible with improved surgical and nonsurgical palliation. The purpose of this article is to report a 23% survival rate with LAV atresia and to review our experience with serial cardiac catheterization before and after palliative surgery in this anomaly. Cases of left tricuspid atresia with corrected transposition are considered together with cases of mitral atresia because both defects exert a similar hemodynamic effect. PatientsForty cases of LAV atresia with a normal aortic valve were identified at Children's