Summary

Adenosine is an effective agent for termination of most re-entrant supraventricular arrhythmias involving the atrioventricular node and often also used as a diagnostic agent for wide QRS tachycardias. Adenosine terminates 90–99% of re-entrant supraventricular tachycardias but it may rarely accelerate tachycardias. Adenosine-induced tachycardia acceleration is a rare phenomenon, as only a handful of cases have been described in the literature. We present a case of a 36-year-old man with a narrow complex, short RP tachycardia at a rate of 165 bpm and an initial blood pressure of 110/78 mm Hg. A bolus of 12 mg of adenosine resulted in slowing of the tachycardia to 150 bpm for 2–3 s, followed by acceleration of the tachycardia to 185 bpm that lasted for approximately 20 s and returned to baseline at 165 bpm. The main mechanism of adenosine-induced acceleration may be the secondary sympathetic stimulation, which may be preceded by transient bradycardia and/or hypotension.