What action does Adenosine primarily perform in the heart?

Adenosine primarily slows the conduction time through the A-V (atrioventricular) node. This action is particularly important in managing certain types of supraventricular tachycardia (SVT), where the heart beats rapidly due to abnormal electrical conduction. By enhancing the refractory period of the A-V node, adenosine interrupts the reentrant circuits that cause these fast heart rhythms, effectively restoring a normal heart rate.

This mechanism highlights adenosine's role as a crucial antiarrhythmic agent. Its effects are rapid but brief, as adenosine has a very short half-life, allowing for swift termination of certain arrhythmias while minimizing prolonged effects on heart function. Understanding this action is essential for healthcare providers when administering adenosine in emergency situations involving tachycardias.