HYPERTROPHIC OBSTRUCTIVE CARDIOMYOPATHY IN PEDIATRIC-PATIENTS - RESULTS OF SURGICAL-TREATMENT

Between April 1975 and May 1995, 25 pediatric patients on one hospital service underwent extended left ventricular septal myectomy because o f hypertrophic obstructive cardiomyopathy. Ages ranged from 2 months t o 20 years (mean, 11.2 years). Seventeen patients had moderate to seve re mitral valve insufficiency. Medical therapy had failed in all patie nts and one patient had undergone dual-chamber pacemaker implantation without improvement. Left ventricular outflow tract gradients ranged f rom 50 to 154 mm Hg (mean, 99.9 +/- 25.2), Concomitant cardiac procedu res included mitral valve repair (n = 2), automatic implantable cardio verter defibrillator implantation (n = 1), and closure of atrial septa l defect (n = 1). Intraoperative premyectomy left ventricular outflow tract gradients ranged from 20 to 117 mm Hg (mean, 60.4 +/- 26.2) and postmyectomy gradients ranged from 0 to 20 mm Hg (mean, 6.6 +/- 5.9). Postmyectomy mitral insufficiency was reduced to a regurgitant fractio n of 0% to 12%, and no patient required mitral valve replacement. One patient required a pacemaker because of complete heart block; on subse quent follow-up, normal sinus rhythm had returned. There was no early mortality and no instance of aortic or mitral valve injury or ventricu lar septal defect. Follow-up ranged from 10 months to 20 years (mean, 6.4 years). There were no late deaths. Left ventricular outflow tract gradients by echocardiography were a mean of 14.2 mm Hg with a median of 5.0 mm Hg. All patients had normal sinus rhythm. Reoperation becaus e of recurrent left ventricular outflow tract obstruction was necessar y in two patients at 3.2 years and 12.4 years after initial myectomy, respectively. All patients but one have New York Heart Association cla ss I or II function. We conclude that extended septal myectomy is a sa fe and effective means of relieving cardiac symptoms and left ventricu lar outflow tract obstruction in pediatric patients,vith severe hypert rophic obstructive cardiomyopathy unresponsive to medical management, and late survivorship compares favorably with the natural history of t he disease.