Instructions
You are a medical student on placement in general practice. Hayley Fraser, 19, a state-league netballer, has come in two days after her heart suddenly raced for about 30 minutes during a game. She feels well today and wants to know if she can play on Saturday. Her notes and ECG are below.
Interpret the ECG provided
Outline to the examiner:
- Your findings
- Your most likely diagnosis
- You do not need to take a history or examine the patient
- Ms Fraser is in the waiting room; you will speak to the examiner
- The examiner will ask you one question at the end
Practice nurse's note
Saturday, third quarter of a game: heart suddenly raced "like a switch", fast and regular, with pounding in the neck, light-headedness and breathlessness; no faint or chest pain. Her watch read 208 to 214. It stopped suddenly after about 30 minutes as she bent forward and strained.
Background
Two shorter episodes of a few minutes at training in the past year; the club physio thought this one was a panic attack. No medical conditions, medicines, supplements, energy drinks or drugs. No family history of sudden death, fainting or heart disease.
GP examination today
Well and relaxed. Pulse regular. Heart sounds normal, no murmur. Chest clear. No tremor or goitre. No ankle swelling.
12-lead ECG recorded at the practice this morning
| Item | Value | Reference range |
|---|---|---|
| Rate | 72 /min | 60-100 /min |
| Rhythm | Regular; an upright P wave before every QRS in II | Sinus |
| Axis | +20 degrees | -30 to +90 degrees |
| P waves | Normal shape and size; upright in I and II | Normal |
| PR interval | 100 ms | 120-200 ms |
| QRS duration and morphology | 120 ms. Each QRS starts with a slurred, slowly rising upstroke lasting about 40 ms before the steep rise of the R wave, clearest in I, aVL and V4 to V6; mainly negative in V1. No notched M-shaped R wave in V6 and no RSR' in V1 | 70-100 ms |
| ST segments | Downsloping depression of 1 mm in I, aVL, V5 and V6; isoelectric elsewhere | Isoelectric |
| T waves | Inverted in I, aVL, V5 and V6, opposite in direction to the main QRS deflection; upright elsewhere | Upright in I, II and V3-V6 |
| QTc | 440 ms | <460 ms |
Labelled Hayley Fraser, 19. Recorded at the practice at 9.15 am today, at 25 mm/s and 10 mm/mV.