Chronic hypercalcaemia secondary to hyperparathyroidism: a risk factor during anaesthesia?

Hypercalcaemia (increased plasma total calcium concentration, [Ca]) has been associated with serious ventricular arrhythmia and sudden cardiac arrest in patients with hyperparathyroidism. To support our impression that the occurrence of such complications during surgery is rare, we examined the records and e.c.g. of 193 patients with moderate hypercalcaemia ([Ca] = 2.89 +/- 0.02 mmol litre-1, mean +/- SEM) secondary to histologically demonstrable parathyroid hyperfunction, who were admitted to hospital between 1974 and 1978 We found that ventricular arrhythmia was not recorded for any patient, and A-V junctional rhythm was present at the beginning of operation in two. Before operation a statistically significant although minimal shortening of corrected values of Q-T interval occurred compared with a control group (n = 60). However, duration of the corrected Q-T interval was not diagnostic of increased [Ca] in a given patient with hyperparathyroidism.