An unusual complication of adenosine administration in supraventricular tachycardia

45 years age female presented with acute onset palpitation. On examination she had tachycardia and a blood pressure of 116/70. ECG was suggestive of NCT (Fig. 1). On administration of 6 mg of intravenous adenosine she developed transient AV block followed by irregular wide complex tachycardia (Fig. 2) and systemic hypotension, requiring DC cardioversion. Electrocardiogram in sinus rhythm showed evidence of preexcitation (Fig. 3). Electrophysiological evaluation documented left free wall accessory pathway with inducible atrioventricular reentrant tachycardia. Radiofrequency ablation of the accessory pathway was performed through trans-septal approach. After delta wave disappeared following radiofrequency ablation, intravenous adenosine was