15-year old patient presenting with rapid palpitations and dizziness. Symptoms resolved en route to hospital. Describe the ECG.
Describe and interpret this ECG
ECG ANSWER and INTERPRETATION
This ECG is diagnostic of the Wolff-Parkinson-White (WPW) syndrome:
- Sinus rhythm with a very short PR interval (< 120ms).
- Broad QRS complexes.
- Delta waves = slurred upstroke to the QRS.
- Dominant S wave in V1 — this “type B” pattern indicates a right-sided accessory pathway.
- Tall R waves and inverted T waves mimic the appearance of LVH — this is an electrical phenomenon due to WPW and not a sign of ventricular hypertrophy.
- ST segments and T waves show typical “discordant” changes — they point in in the opposite direction to the QRS complex, similar to LBBB.