Malignant Hyperthermia - 2

Malignant hyperthermia (MH) is a pharmacogenetic hypermetabolic state of skeletal muscle induced in susceptible individuals by inhalational anesthetics and/or succinylcholine (and maybe by stress or exercise). The term pharmacogenetic refers to the fact that, in almost all cases, two essential elements are required to induce the hypermetabolic state of skeletal muscle referred to as malignant hyperthermia:

drugs + genes pharmagenetic

So, MH is a very abnormal hypermetabolic state of skeletal muscle. In order for this state to occur in an individual, that individual must have inherited the appropriate abnormal gene(s) AND then be exposed to inhalational anesthetic agents and/or succinycholine ("triggering agents" or "triggers"). Such an individual when not exposed to triggering agents would not have MH, but rather would be said to be malignant hyperthermia susceptible or MHS. Exposing an MHS individual to triggers makes MH a possible, but not a certain, result. We are unable today to predict which exposures to triggers of which MHS individuals will lead to MH. Therefore, the safest policy is to always avoid triggering agents in all MHS individuals.

Greg Gordon MD