Cardioversion by venepuncture in sustained stable supraventricular tachycardia.

Two cases are described of cardioversion from stable supraventricular tachycardia after venepuncture. In both cases usual vagal manoeuvres at home and in the casualty department were unsuccessful. However, attempts to site intravenous cannulas by the attending medical staff terminated his supraventricular tachycardia. Venepuncture is probably the commonest vagal manoeuvre performed in hospital but has not previously been reported as a method of cardioversion.