[Arrhythmias in the adolescent and adult with a congenital heart defect]

Rhythm disturbances may be observed in the natural history of congenital heart defects, as well as after open heart surgery. About 40-50% of adults with congenital heart defects will experience some type of arrhythmia. In the growing population of postoperative patients, the type of rhythm disturbance depends on the type of heart surgery: after operation at ventricular level, conduction disturbances and ventricular arrhythmias are quite common. After surgery at atrial level (e.g. closure of ASD, but much more after atrial correction of transposition), sick sinus syndrome and supraventricular arrhythmias are chiefly observed. Conduction disturbances may be subdivided into the very common intraventricular conduction defects (right bundle branch block, sometimes with left anterior hemiblock) and complete A-V block. Complete heart block has become less frequent in recent years since surgeons have learnt to avoid the bundle of His during VSD closure. All patients with postoperative complete heart block need a permanent pacemaker. Ventricular arrhythmias after ventricular surgery are commonly found if Holter recordings are done, particularly after correction of tetralogy. They are often asymptomatic but may be a cause of late sudden death (1-3% of patients operated on for tetralogy). Antiarrhythmic treatment is indicated if symptoms are present, or in selected asymptomatic patients with a poor hemodynamic result (severe residual pulmonary stenosis or ventricular dysfunction). Sinus node dysfunction and sick sinus syndrome are common after atrial repair of transposition (Mustard or Senning operation). The manifestations are either sinus bradycardia and sinus arrest with long pauses, or atrial reentry tachycardia (Flutter); these may combine, so that antiarrhythmic medication must be associated with permanent pacemaker implantation.(ABSTRACT TRUNCATED AT 250 WORDS)