The EGG was recorded from a 42 year old woman who was known to have rheumatic valvular disease. She developed rapid palpitation and became acutely dyspnoeic, faint and hypotensive.
ECG. Rhythm: The ventricular (QRS) rate is approximately 185 per minute. No recognizable P waves or other form of co-ordinated atrial activity is seen in any lead. The baseline is irregular and chaotic atrial activity is best seen in the lead II rhythm strip where a baseline waveform irregular in both amplitude and frequency is recorded. The QRS complexes are irregular – the R – R intervals vary unpredictably. There is no recognizable relationship between the QRS complexes and atrial acuvity: atrial fibrillation is present.
Morphology: The sum of the S wave in VI + R wave in V6 = 45mm, the S waves in VI and V2 are greater than 25 mm and these changes satisfy the voltage criteria for left ventricular hypertrophy.
Comment. Ventricular premature beats are common following myocardial infarction and certain patterns (frequent premature beats and occurrence in pairs) are said to indicate an increased risk of ventricular fibrillation. It is a worthwhile exercise to plot the positions of the P waves in this ECG and note the way that these distort the premature beats.