Supraventricular tachycardia
From IKE
Supraventricular tachycardia is a sustained tachycardia in which the QRS complex appears normal on electrocardiogram (EKG), and has a duration of < 120ms. The term narrow QRS is preferred to supraventricular (although use of the latter term is widespread) because these arrhythmias may involve ventricular tissue.
Supraventricular tachycardia with bundle branch block involves asynchronous activation of the ventricles, caused by the bundle branch block. Because this slows conduction from muscle cell to muscle cell, there is a wide QRS complex akin to ventricular tachycardia. However, when a wide QRS complex is seen, it should always be assumed ventricular tachycardia until proven otherwise, as it is much more common.
The various kinds of supraventricular tachycardia include sinus tachycardia, atrial tachycardia, atrial flutter, atrial fibrillation, junctonal reentrant supraventricular tachycardia (PAT), and Wolf-Parkinson-White syndrome.
Management
The first line of management in patients with SVT is to perform a vagal maneuver, though caution should be used to avoid an embolus from doing something nasty. The next line of management is pharmacological, involving adenosine - a drug that restores cardiac rhythm. The failsafe management strategy for the heart is cardioversion, in which an electric current is delivered to the body to stabilize its rhythm.
