Intraoperative Pulsus Alternans Caused by Iatrogenic Hypovolemia

Pulsus alternans is usually caused by severe cardiac contractility failure, dilated cardiomyopathy or aortic stenosis/regurgitation. It is rarely caused by pure diastolic dysfunction. We herein presented a patient with uncommon manifestations whose pulsus alternans was induced by iatrogenic hypovolemia during neurosurgery. This patient received mitral valve replacement with a bileaflet mechanical prosthetic valve several years ago and has had normal left ventricular contractility. The occurrence of pulsus alternans for him was precipitated by impeded ventricular filling due to mannitol-related iatrogenic hypovolemia and smaller effective orifice area of mechanical valve than indigenous mitral valve. His pulsus alternans dissipated progressively with fluid resuscitation afterwards. This case agreed with the theory that alternating loading condition operates more than contractility failure in the pathogenesis of pulsus alternans.