Symptomatic Sinus node dysfunction rarely occurs in children with structurally normal hearts. Three children with syncope and bradycardia are described. Noninvasive and invasive testing revealed isolated Sinus node dysfunction and normal cardiac anatomy. Electrophysiologic evaluation showed abnormalities of sinus node automaticity and sinoatrial conduction. All three patients were treated with permanent ventricular pacemakers and have remained asymptomatic. Sinus node dysfunction should be considered in the differential diagnosis whenever a child is seen with unexplained dizziness or syncope.
