Supraventricular tachycardia (SVT, PAT, PSVT)
The most common abnormal tachycardia in young people is SVT. It is also known as paroxysmal atrial tachycardia (PAT). It may occur when an extra or accessory pathway (electrical circuit) exists between the atrium and ventricle or around the mid-center portion of the heart (AV node). This is not a life-threatening condition for most people. Patients may complain of palpitations, fatigue, chest discomfort, dizziness, excessive sweating, upset stomach, a throbbing sensation on the back of their tongue, paleness and difficulty breathing. Pulse during SVT rate in children is usually greater than 220 beats per minute or over 180 beats per minute in adolescents and young adults. The pulse rate is usually so fast that you may not be able to count it. A few heart conditions, such as mitral valve prolapse, Ebstein’s anomaly of the tricuspid valve, Transposition of the Great Arteries, cardiomyopathy and Wolff-Parkinson-White syndrome, may be associated with SVT. Infants with an SVT episode may breath faster than normal, feed poorly or be sleepier than usual. This situation requires diagnosis and treatment to return the pulse rate back to normal.
Diagnosis is usually confirmed by means of an electrocardiogram, 24-hour Holter recording or transtelephonic memory event recorder. Vagal maneuvers may be used to terminate SVT. (See Table 1: Vagal Maneuvers).
Quickly drinking ice-cold water
Straining by sealing the nose and closing your mouth while trying to breath out hard
Using tension by pushing hard against a wall and holding your breath
Diving reflex (immersion of face into ice cold water)
Placing an ice cold cloth on the face
You should go to the nearest emergency room if you are experiencing symptoms or the episode of SVT has lasted longer than 15-30 minutes (in a patient with an otherwise normal heart) or earlier, if any associated risk factors such as a congenital heart defect or history of heart failure are present.
Medications can help slow the heart rate and prevent SVT from recurring. Older children, especially with recurrent SVT, may benefit of endocardial catheter ablation after consultation with a cardiac electrophysiologist such as Dr. Villafañe. For many infants, SVT is a time-limited arrhythmia. Treatment with medication is often discontinued after 12-24 months. Older children are more likely to have recurrent episodes of SVT and that is why they are more likely to need longer medical treatment or endocardial catheter ablation.
Patients with SVT usually enjoy normal activities and have no restrictions except to avoid caffeine (coffee, chocolate, soft drinks, power drinks, etc).