Common varieties of supraventricular tachycardia: Differentiation and dangers

Two major types of supraventricular tachycardia (SVT) commonly seen in acute care situations are atrioventricular nodal reentrant tachycardia (AVNRT), and orthodromic atrioventricular reentrant tachycardia (AVRT). Intranodal reentry via fast and slow conduction pathways within the atrioventricular junction is the mechanism by which AVNRT develops. In contrast, reentrant tachycardia across accessory pathways is associated with preexcitation and AVRT. In the setting of Wolff-Parkinson-White syndrome, inappropriate treatment of AVRT may result in a potentially lethal type of atrial fibrillation. Electrocardiographic cues that differentiate between AVNRT and AVRT are discussed. Treatments range from emergency cardioversion to administration of intravenous agents such as adenosine. The tachycardias may be cured with radiofrequency catheter ablation.