Cardiopulmonary bypass in malignant hyperthermia susceptible patients: a systematic review of published cases.

OBJECTIVES Malignant hyperthermia susceptibility is an important risk factor during general anesthesia. Affected patients have an asymptomatic but potentially lethal hypermetabolic reaction after contact with volatile anesthetics or succinylcholine. Classic symptoms include hemodynamic instability, combined with acidosis, rigor, and hyperthermia. During cardiopulmonary bypass, these signs may be obscured, delaying correct diagnosis and lifesaving treatment. Malignant hyperthermia-susceptible individuals are more sensitive to heat and stress, so rewarming and catecholamine administration may trigger an episode, necessitating prophylactic measures. METHODS This systematic review identified typical malignant hyperthermia symptoms during cardiopulmonary bypass and investigated other factors in cardiac surgery that might trigger an episode in susceptible individuals. Approaches used to treat and prevent malignant hyperthermia during cardiopulmonary bypass were systematically analyzed. We conducted a systematic search for reports about malignant hyperthermia and cardiopulmonary bypass. Search terms included malignant hyperthermia and cardiopulmonary bypass, extracorporeal circulation, or cardiac surgery. RESULTS We found 24 case reports and case series including details of 26 patients. In 14 cases, malignant hyperthermia crises during or shortly after cardiopulmonary bypass were described. Fourteen reports discussed prevention of an episode. Early symptoms of a malignant hyperthermia episode include excessive carbon dioxide production and metabolic acidosis. Massively increased creatine kinase levels are a strong indicator of a malignant hyperthermia reaction. Rewarming is associated with development of clinical signs of malignant hyperthermia. CONCLUSIONS In potentially susceptible patients, apart from avoiding classic trigger substances, aggressive rewarming should not be applied. Hemodynamic instability in conjunction with the described symptoms should result in a diagnostic algorithm.