NORD gratefully acknowledges Sheila M. Muldoon, MD, Maria Voelkel, and John Capacchione, MD, Uniformed Services University of the Health Sciences, Department of Anesthesiology, for assistance in the preparation of this report.
Malignant hyperthermia (MH) is a dominantly inherited disorder of skeletal muscle that predisposes susceptible individuals to a life threatening adverse reaction (fulminant MH event) upon exposure to potent volatile anesthetics (halothane, isoflurane, sevoflurane, desflurane, etc.) and the skeletal muscle relaxant succinylcholine.
The anesthetic drugs trigger an uncontrolled calcium (Ca2+) release from the sarcoplasmic reticulum (SR) through the ryanodine receptor (RYR1) causing a rapid and sustained rise in myoplasmic Ca2+. The high intracellular Ca2+ activates Ca2+ pumps at the SR and the sarcolemma to reuptake calcium into SR or to transport it into the extracellular space respectively. The energetic cost to regain cellular Ca2+ control causes a need for ATP, which in turn produces heat. Muscle membrane integrity is compromised leading to hyperkalemia and rhabdomyolysis.1 If not treated promptly, by withdrawing the anesthetic and administering dantrolene, mortality can be greater than 70%.2 In some individuals, fulminant MH events can be induced by stress, exercise and high environmental temperatures in the absence of anesthetics.3 Pediatric patients may be at greater risk.4
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