ECG of the Week: ECG of the Week - 1st January 2018

Wednesday, 3 January 2018

ECG of the Week - 1st January 2018 - Interpretation

The following ECG's are from a 23 yr old female with a known history of pre-excitation and prior ablation.

Click to enlarge

Key features

Sinus tachycardia ~120 bpm
P waves visible in leads I, II, V1
PR normal ~180ms
RBBB morphology
Relatively pronounced ST/ T wave changes in right precordial leads

Impression

Sinus tachycardia
Nil evidence of pre-excitation / AP conduction
RBBB
ST / T changes could be secondary to RBBB but may reflect additional abnormality e.g hyperventilation, ischaemia etc.

Click to enlarge

Key features:

Rate 100 bpm
Preceding P waves with short pr
Typical LBBB morphology
Initial deflection in QRS appears slurred ? associated delta wave

Now things get complicated ! I sent these ECG's to one of our blog co-authors and electrophysiologist. I don't have a great deal of clinical information on the case regarding this presentation or more importantly their prior EP findings and ablation technique.
There are a number of differentials for these second ECG findings including:

1. SVT with LBBB morphology

Atrial tachycardia with maximal pre-excitation utilising most likely right sided accessory pathway given negative delta wave V1
AV node re-entry with maximal pre-excitation utilising most likely right sided accessory pathway

2. Ventricular tachycardia

Emanating from RV septum (mid to high level)
Bundle branch re-entrant VT --> ? related to prior ablation

3. Pre-excited tachycardia

Atriofasciscular pathway with AV re-entrant tachycardia
Nodofascicular pathway with AV re-entrant tachycardia
Nodoventricular pathway with AV re-entrant tachycardia
Pathway to pathway re-entrant tachycardia

Atriofascicular and nodoventricular pathways are something we don't encounter often in clinical practice and are much rarer than those patients with WPW accessory pathways. You can read more about them in the following articles: