Phenytoin therapy for ventricular arrhythmias occurring late after surgery for congenital heart disease.

Sudden death late after surgery for congenital heart disease is usually attributed to ventricular dysrhythmias, which may be difficult to suppress. In this study 19 consecutive patients with ventricular premature complexes (VPCs) documented by 24-hour ambulatory ECG monitoring were treated with phenytoin orally. Sixteen patients had undergone previous repair of the tetralogy of Fallot; three had undergone aortic valve surgery. Nine of these children had been unresponsive to previous antiarrhythmic therapy. Before treatment, four patients had ventricular tachycardia, three had couplets, six had frequent multiform VPCs, four had infrequent multiform VPCs, and two had frequent uniform VPCs. During treatment with phenytoin, the arrhythmia was decreased in all 19 patients and was completely suppressed in 15; the four remaining patients had only uniform VPCs on repeat ambulatory ECG. The mean serum level was 16.8 micrograms/ml (range 12 to 25 micrograms/ml) with a mean dose of 3.4 mg/kg (range 2 to 4 mg/kg). In one patient a skin rash led to discontinuation of phenytoin; no other side effects occurred. In summary, phenytoin was used to successfully suppress ventricular dysrhythmias in 19 consecutive patients with VPCs late after surgery for congenital heart disease. Phenytoin would appear to be the drug of choice for this patient group.