present with palpitations or syncope during strenuous exercise caused by atrial fibrillation or ventricular arrhythmia
Myocarditis
most commonly viral in origin, with Coxsackie virus B and other enteroviruses accounting for most cases. Clinical findings of myocarditis include tachycardia out of proportion to fever, poor perfusion, and signs of heart failure.
Sick sinus syndrome
Pacemaker malfunction
Life threatening non-cardiac conditions
Hypoglycemia
Early manifestations of hypoglycemia in children and adolescents are caused by the autonomic response to hypoglycemia and may include tachycardia with palpitations, sweating, weakness, tremor, and feelings of nervousness and/or hunger.
These symptoms and signs usually occur at higher blood glucose concentrations (between 40 and 70 mg/dL) than the neuroglycopenic signs and symptoms (lethargy, irritability, behavioral abnormalities, seizures, or coma), and may function as a “warning system.”
Toxic exposure
Pheochromocytoma
are rare neoplasms in children
classic triad of symptoms in these disorders consists of
episodic headache
sweating
tachycardia
hypertension
Common conditions
Premature atrial contractions
Premature ventricular contractions
Fever, Anemia – Increased metabolic rate
Exercise
Catecholamine release
associated with exercise, emotional arousal, and psychiatric distress (eg, anxiety, panic attack)