To the Editor.— I would question the medical wisdom of having patients use a magnet at home to change their demand pacemaker to the fixed rate (222:1379, 1972). The first time a physician encounters a ventricular fibrillation in a patient and the patient dies, he is going to be liable not only for wrongful death, but for punitive damages, because of his lack of concern for the patient's safety. Although my experience is limited, I have had three occasions in which ventricular tachycardia developed while the patient with a fixed rate pacemaker was in the hospital. The first case fortunately occurred while I was in the hospital. The nurses had effected defibrillation by the time I got there, however, the patient again underwent ventricular fibrillation, necessitating turning off the pacemaker, by using the rate control needle. This is the one advantage of regulation of the rate with a unit. The