Hypothermic cardiopulmonary bypass in paramyotonia congenita: a case report.

Paramyotonia congenita is a non-progressive disease characterised by myotonia (failure of muscle relaxation) induced by the exposure of the affected muscles to cold. Episodes of flaccid paralysis occur and may be related to hyperkalaemic periodic paralysis. Proximal myopathy or muscular hypertrophy may occur. The condition is inherited as an autosomal dominant.' Severe paralysis may occur with comparatively slight increases in plasma potassium concentration. During an attack of paralysis there is loss of potassium from muscle cells, which become depolarised. With these biochemical and clinical features, difficulties might be anticipated in undertaking open-heart surgery in patients with this condition. This report concerns the events surrounding mitral valve replacement using hypothermia during cardiopulmonary bypass in a patient with paramyotonia congenita.