AVNRT presenting as Wide complex tachycardia

A 52 years old male came to the emergency with history of palpitation of one hour duration. There was no history of  Diabetes mellitus, hypertension or coronary artery diseases. ECG of the patient is shown below.

ECG 1(Click on the ecg to enlarge it)

ECG is showing wide QRS complex tachycardia at the rate of 230 beats per minutes, right axis, QRS is of RBBB morphology, after each qrs complex ?? small P waves were seen which were merged into the ST segment,RP interval is 80 msec, shorter than PR interval of 240 mse there is no Fusion complex, no capture beat. Also there is no AV dissociation. So the differential diagnosis of the ECG is either Atrioventricular nodal reentrant tachycardia (AVNRT) or Atrioventricular reentrant tachycardai (AVRT) or rare possibility of ventricular tachycardia (VT).

ECG 2 (Another tachycardia ECG of the patient) 

Sinus ECG

 
ECG is showing normal sinus rhythm at 90 beats per minute, normal axis, no significant ST-T wave changes seen.

Patient underwent Electrophysiological study which showed AVNRT with slow-fast pathway. Patient underwent successful slow pathway ablation.

Lets discuss how to diagnose AVNRT

Thank you.

Praveen Gupta