PACEMAKER ARTIFACT IN LUNG SCAN.

To the Editor:— An artifact which simulated a pulmonary embolus was produced in a lung scan by an indwelling cardiac pacemaker. Postmortem study confirmed the absence of such emboli. It was found that the battery pack of the pacemaker absorbs approximately 50% of the 131 I gamma emission from the injected radioactive pharmaceutical. Report of a Case:— A 74-year-old white man with diabetes who had an indwelling cardiac pacemaker implanted because of heart block was admitted to the surgical service on June 23, 1968. Gangrene involving the toes of the right foot was present. Five days later an amputation was performed below the knee of the right leg. The postoperative course was complicated by persistant irregularity of the cardiac rhythm without clinical, electrocardiographic, or chemical evidence of myocardial damage, and on Aug 12, the patient was taken to the operating room for exploration of the pacemaker apparatus. The device was