Development of malignant hyperthermia during mitral valve replacement.

Malignant hyperthermia is a genetically predisposed, potentially fatal disorder triggered by anesthetic agents. The early diagnosis and treatment of malignant hyperthermia is essential, yet often difficult, because the signs and symptoms of this disorder are not unique to the disease. When the patient is also undergoing cardiopulmonary bypass this disorder may be very difficult to recognize. In this article, we report a case of malignant hyperthermia diagnosed during mitral valve replacement and discuss the preoperative and postoperative management possibilities. The unusualness of this case stems from the fact that the patient had centronuclear myopathy. Although reported with other types of myopathies, centronuclear myopathy has rarely been associated with malignant hyperthermia. This episode of malignant hyperthermia was diagnosed by intraoperative measurements showing increased oxygen consumption despite hypothermic cardiopulmonary bypass.