Adenosine is a purine-based nuclobase. The main clinical uses of adenosine are the investigation of supraventricular tachycardias and attempts at termination of supraventricular tachycardias.
Adenosine activates potassium channels in the heart which ultimately results in:
- Negatively chronotropic effect on sinoatrial node – minor effect so not clinically useful
- Negatively dromotrophic effect on atrioventricular node – 90% effective at terminating SVTs
Adenosine also causes coronary vasodilation.
It has a short half life, so the heart block induced by adenosine typically lasts only 5 to 10 seconds.
For treatment of SVTs 6mg adenosine is given as a rapid IV bolus with ECG monitoring in place. If this is unsuccessful, a further 12mg is given. If this is also unsuccessful, another 12mg IV is given.
Side effects of adenosine include:
- Bronchospasm – use with caution in asthmatic patients
- Chest pain
- Facial flushing
- Dyspnoea
- Arrhythmias
- Most commonly bradycardia
- Rarely asystole or conversely tachyarrhythmias
- Rarely a metallic taste
Effect of adenosine is increased by dipyridamole and carbamazepine
Effect of adenosine is decreased by theophylline and caffeine
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