Middle-aged patient presenting with palpitations and dizziness. What does the ECG show?
Describe and interpret this ECG
ECG ANSWER and INTERPRETATION
This ECG shows a regular broad complex tachycardia with an RSR’ pattern in V1.
The differential diagnosis could include:
On closer inspection, the ECG demonstrates some classic features of ventricular tachycardia:
- Northwest axis — QRS is positive in aVR, negative in I and aVF
- The taller left rabbit ear sign — There is an atypical RBBB pattern in V1, where the left “rabbit ear” is taller than the right
- Negative QRS complex (R/S ratio < 1) in V6
These findings indicate VT rather than SVT with aberrancy.
- Taller left rabbit ear = VT
- Taller right rabbit ear = RBBB
Other factors that increase the likelihood of VT in patients presenting with regular broad complex tachycardia include:
- Age > 35 (positive predictive value of 85%)
- Structural heart disease — e.g. IHD, CCF, cardiomyopathy
- Family history of sudden cardiac death or arrhythmogenic conditions such as HOCM, Brugada syndrome or ARVD that are associated with episodes of VT