An unusual complication of a myocardial electrode--apatite mantle on the platinum-iridium spurs.

A case of a high excitation threshold that occurred 2 years 5 months after the initial implantation of pacemaker electrodes is described in a girl 4 years 3 months of age. This complication was considered to be due to calcification of the platinum-iridium electrode spurs. The calcified material was shown to be a kind of apatite using the X-ray powder diffraction method. This complication is rare, but it must be kept in mind since battery longevity has markedly improved in recent years.