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A 60 year old man presented with increasing breathlessness one month following an uncomplicated mitral valve repair. An echocardiogram showed a moderately sized pericardial effusion of 2 cm. Subxiphoid drainage of the pericardial effusion yielded 200 ml of blood stained fluid. Ten hours later the patient complained of palpitations, and telemetry showed a “broad complex tachycardia” (see 12 lead ECG below). The patient was haemodynamically stable.
The patient was initially treated with 100 ml of intravenous lignocaine and subsequently converted to sinus rhythm (right upper panel) after synchronised cardioversion with a 200 J shock. Looking back at his ECG, he was in atrial flutter with 2:1 block (right lower panel) before drainage of his pericardial effusion.
Close inspection of the 12 lead ECG (below) showed several features to suggest that this may not be ventricular tachycardia. Firstly, not all the QRS complexes in all 12 leads are broad (that is, > 120 ms), particularly in limb lead III. Secondly, the QRS complexes in the anterior leads give a false impression of being broad because the up sloping portion of the ST segment can easily be mistaken as part of the QRS complexes. There is no evidence of atrioventricular dissociation.
After DC cardioversion, the patient remained in sinus rhythm without the need for any antiarrhythmics. There were no further recurrence of his pericardial effusion or tachycardia.