Cardaic arrhythmias in chloral hydrate poisoning.

In three patients admitted to hospital after ingestion of an overdose of chloral hydrate, the ECG showed supreventricular and ventricular tachyarrhythmias. The possible mechanism for the arrhythmias may be an enhanced automaticity of supraventricular and ventricular pacemaker cells caused by metabolites of chloral hydrate. The ventricular arrhythmia responded to i.v. treatment with lignocaine in one patient, and to phenytoin in another in whom lignocaine failed to restore a normal sinus rhythm.