Cardiac manifestations of malignant hyperthermia susceptibility.

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Abstract
Malignant hyperthermia is a disease resulting from defective cellular membranes, usually presenting as drug-induced pyrexic crises. Four patients with life-threatening ventricular arrhythmias or chest pain in the absence of pyrexic crises are described. Three presented with life threatening arrhythmias and the 4th, with severe atypical chest pain. Two patients had a family history of multiple sudden deaths. Resting CK [creatine kinase], was elevated in 3 patients; CK-MB was elevated in 1. Resting ECG were abnormal in 3. Three patients had recurrent ventricular tachycardia, 2 had recurrent ventricular fibrillation and multiple cardiac arrests. Cardiac catheterization showed abnormal left ventricular wall motion in 2 and minimal mitral valve prolapse in 1 while all had normal coronary arteries. Myocardial imaging using 201Tl demonstrated large perfusion defects in the patients with ECG Q waves and normal coronary arteries. Myocardial involvement was demonstrated by clinical, ECG, hemodynamic, angiographic and myocardial imaging abnormalities. Malignant arrhythmias occurred in these patients in the absence of pyrexic crises or drug administration. Abnormal Ca release in the myocardium, as documented in skeletal muscle membranes, may be a unifying concept for the various manifestations described.