The EGG was recorded from a 33 year old woman with a history of repeated self limiting attacks of atrial fibrillation. Mitral valve prolapse had been diagnosed from the clinical features of a late systolic murmur associated with a mid systolic click, and this had been confirmed echocardiographically. She was taking Sotalol (a class 3 antiarrhythmic agent which has beta blocking activity) in an attempt to limit the frequency andseverity of the attacks.
Rhythm: No recognizable P waves or other form ofco-ordinated atrial activity is seen in any lead. The baseline is irregular and chaotic atrial activity is best seen in lead VI where a 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 activity:atrial fibrillation is present.
Morphology: The QRS waves ST segments and T waves are normal.
Mitral valve prolapse is a common condition and is often associated with arrhythmias. The Sotalol that she was takinghas not prevented this attack but has slowed the ventricularrate to 78 per minute- slower than would be expected without treatment.