What is a contraindication for the use of adenosine?

Adenosine is primarily used for the conversion of certain types of supraventricular tachycardias (SVT) back to normal sinus rhythm. However, its use is contraindicated in patients with atrial fibrillation. This is primarily due to the fact that adenosine can cause a transient blockage of conduction through the AV node, which could potentially lead to rapid ventricular response rates. In atrial fibrillation, the atria are fibrillating, and the ventricular rate may already be uncontrolled; administering adenosine could worsen this situation by increasing the ventricular rate if conduction through the AV node is disrupted.

In contrast, adenosine is indicated for SVT, where a rapid heart rate originates above the ventricles. While it's also not effective or recommended for ventricular tachycardia and should certainly not be given for stable ventricular fibrillation, the key point is that the specific contraindication directly relates to its potential to exacerbate an already chaotic rhythm in atrial fibrillation. This makes it important to identify and manage the underlying rhythm appropriately rather than attempting to convert it with adenosine.