Curriculum · Cardiovascular and Hypertension
Supraventricular tachycardia
What it is
Narrow-complex tachycardias are rhythms with a narrow QRS complex and a ventricular rate greater than 100 beats per min. Although virtually all narrow-complex tachydysrhythmias originate from a focus above the ventricles, the term supraventricular tachycardia is conventionally used to denote those rhythms aside from sinus tachycardia, atrial tachycardia, atrial fibrillation and atrial flutter - that is, atrioventricular nodal reentry tachycardia and atrioventricular reentry tachycardia. SVT is the most common pathologic arrhythmia of childhood. It can occur in children with no structural lesions and is associated with fever, infection, or sympathomimetic drugs such as cold medicine or bronchodilators, but is most often idiopathic.
How it presents
In young children and infants the dysrhythmia is typically well tolerated. It will often present with a history of pallor, poor feeding, tachypnea, and lethargy or irritability; older children will describe palpitations, lightheadedness, and shortness of breath. Signs of congestive heart failure or shock may be present. It is sometimes confused with sinus tachycardia, which usually presents at a rate of less than 225 beats per minute in infants and less than 150 beats per minute in older children and adults. That rate, with variability with respirations and evidence of normal P waves, differentiates sinus tachycardia from SVT.