1 - ECG Hallmarks

Question 1

What are the ECG hallmarks of V-Tach?

Answer 1

1. Northwest axis — QRS is positive in aVR, negative in I and aVF
2. The taller left rabbit ear sign — There is an atypical RBBB pattern in V1, where the left “rabbit ear” is taller than the right.
   (* This is the most specific finding in favour of VT.*)
3. Negative QRS complex (R/S ratio < 1) in V6

Question 2

When you see a regular narrow complex tachycardia at 150 bpm, you should think of four main diagnoses:

Answer 2

• Atrial flutter with 2:1 block (especially in elderly, IHD, CCF)
• AV-nodal reentry tachycardia (“SVT”)
• Orthodromic AV reentry tachycardia in WPW
- Orthodromic -
• Sinus tachycardia — should see P waves but may be hidden in the T waves (e.g. with concurrent 1st degree AV block). There should also be some HR variability compared to the other 3 rhythms.