Action on the heart: When administered intravenously, adenosine causes transient heart block in the AV node of the heart.

In individuals suspected of suffering from a Supra Ventricular Tachycardia (SVT), adenosine is used to help identify the rhythm. Certain SVTs can be successfully terminated with adenosine. This includes any reentrant arrhythmia that requires the AV node for the re-entry [e.g., AV Reentrant Tachycardia (AVRT), AV Nodal Reentrant Tachycardia (AVNRT)].

In addition, atrial tachycardia can sometimes be terminated with adenosine. The pharmacological effects of adenosine are blunted in individuals who are taking methylxanthines e.g. caffeine (found in coffee) and theophylline (found predominantly in tea).