Atrial fibrillation precipitated by acute hypovolaemia.

Six patients with varying degrees of acute cardiorespiratory failure were seen. All patients deteriorated noticeably when rapid atrial fibrillation developed. In all patients intravenous digitalis failed to slow the ventricular response, and in three patients misguided attempts at electrical cardioversion failed. Haemodynamic monitoring showed a normal or low pulmonary artery occlusion pressure in all patients. Controlled expansion of plasma volume was associated with an immediate slowing of the heart rate in all patients, and the heart rate in all patients returned to sinus rhythm within 30 minutes of transfusion. It is suggested that hypovolaemia in critically ill patients may contribute to the development of atrial fibrillation.