Tuesday January 12, 2010


Q: Adenosine can cause

A) Asystole
B) Atrial fibrillation
C) Ventricular fibrillation
D) All of the above



Answer: D

Certain SVTs can be successfully terminated with adenosine. This includes any re-entrant arrhythmias - AV reentrant tachycardia(AVRT), AV nodal reentrant tachycardia (AVNRT) - by causing transient heart block in the AV Node. This is mediated via the A1 receptor, inhibiting adenylyl cyclase, reducing cAMP and so causing cell hyperpolarization by increasing outward K+ flux.

Adenosine has an indirect effect on atrial tissue causing a shortening of the refractory period and may initiate atrial fibrillation. In individuals with accessory pathways, the onset of atrial fibrillation can lead to a life-threatening ventricular fibrillation.