Thyrotoxic periodic paralysis with ventricular fibrillation.

Electrocardiographic conduction disturbances and nonspecific interval changes are not uncommon during hypokalemic periodic paralysis. Although premature ventricular contractions may occur during the paretic episodes associated with hyperkalemic, normokalemic, and hypokalemic periodic paralysis, ventricular tachycardia is rare; to my knowledge, ventricular fibrillation has not been previously reported. In 1977 a 40-year-old man of Puerto Rican descent was resuscitated from ventricular fibrillation and subsequently received a diagnosis of thyrotoxic hypokalemic periodic paralysis. Following thyroid suppression the patient has been asymptomatic; ambulatory ECG monitor, maximal exercise stress test, and echocardiograms have been normal. This case documents the occurrence of ventricular fibrillation in thyrotoxic periodic paralysis.