Young lady with PSVT ?What is your diagnosis.

34 years old female came to JIPMER emergency, India with history of acute onset palpitation along with atypical chest pain, giddiness, breathlessness two month back. Patient ECG done which was suggestive of tachycardia with rate around 220 per minute.Blood pressure was 100/60 mmhg 

ECG-1

Description of the ECG-Narrow QRS complex regular tachycardia with rate around 200 per minute, Negative P wave seen in lead 2,3,avF, Pseudo R in lead V1, RP interval 160 msec, PR interval 200 msec, no ST-T wave abnormality, no QRS alternans 

Impression PSVT, Short RP tachycardia

                   Patient was given intravenous injection adenosine 6 mg, tachycardia not reverted

ECG-2

 so again patient was given 6 mg injection adenosine and tachycardia reverted to sinus rhythm. 

Sinus ECG is shown below

ECG-3

Description of the ECG-Normal sinus rhythm at rate 120 per minute, normal axis, no ST-T wave changes, no evidence of pre-excitation seen in the ECG

 Diagnosis of tachycardia ECG-PSVT, Short RP tachycardia Differential diagnsosis--1) AVNRT, 2)AVRT, 3) Atrial tachycardia ( as RP interval is longer than > 70 msecc)

Algorithm for diagnosis of Narrow QRS tachycardia