TABLE 63.2 COMMON CAUSES OF PALPITATIONS Exercise Anxiety/hyperventilation syndrome Emotional arousal Drug induced (e.g., caffeine, over-the-counter sympathomimetic agents) Supraventricular tachycardia Premature atrial or ventricular contractions TABLE 63.3 LIFE-THREATENING CAUSES OF PALPITATIONS Cardiac Wolff–Parkinson–White syndrome Prolonged QT syndrome Hypertrophic cardiomyopathy Congenital heart disease/postoperative cardiac repair Myocarditis/acute rheumatic fever Mitral valve prolapse Sick sinus syndrome Complete heart block Myocardial ischemia Noncardiac Hypoxemia Hypoglycemia Hyperkalemia Hypocalcemia Pheochromocytoma Poisoning ( Table 63.4 ) Premature atrial contractions produce the most common arrhythmia of childhood, with 50% of normal children experiencing at least one premature