Right Ventricular Outflow Tract VT

This is the initial 12 lead ECG (ECG_0003_A) taken at 1440 hours of a middle aged woman with palpitations and normal vital signs. There is no chest pain and examination is normal. There is no past history of cardiac disease.

This is a second 12 lead ECG (ECG_0003_B) taken at 1550 hours

Describe the ECG findings.

ECG_0003_A

There is a LBBB type broad complex tachycardia with a ventricular rate of about 188 beats per minute.  P waves are not seen. Therhythm is regular. The axis is about +90 degrees.  

Magnified view of V1 and V2 from ECG_0003_A. The width of the R wave is about 0.04 seconds, and the interval from the start of the R wave and the tip of the S wave is 0.08 seconds.

Magnified view of V1 and V2 from ECG_0003_A. The width of the R wave is about 0.04 seconds, and the interval from the start of the R wave and the tip of the S wave is 0.08 seconds.

 Selected leads from  ECG_0003_A are shown below.

Selected leads from ECG_0003_A showing capture beats (red asterisk) and fusion beats (F)

Selected leads from ECG_0003_A showing capture beats (red asterisk) and fusion beats (F)

ECG_0003_B

This shows sinus rhythm at a rate of about 100 beats per minute. There are  no ECG features of ischaemia, and the tracing is within normal limits.

Comment: The initial ECG shows features of ventricular tachycardia: capture beats, fusion beats, a broad r wave and a delay to the S wave nadir in V1 and V2. There is an inferiorly directed axis. The combination of a LBBB type ventricular tachycardia, inferior axis and a structurally normal heart are features of right ventricular outflow tract ventricular tachycardia (RVOT_VT).  RVOT_VT arises from the right ventricular outflow tract, is thought to be caused by delayed after depolarizations (Geek Alert),  and can be terminated by treatment with adenosine or verapamil.