Implantable Nuclear-Powered Cardiac Pacemakers

OVER the last decade, clinical experience with totally implantable cardiac pacemakers has rapidly accumulated.1 2 3 4 Approximately 50,000 have been manufactured, 20,000 units are currently in use, and 5000 are implanted each year.5 Although these devices have rehabilitated substantial numbers of patients with varying degrees of heart block, their use is still not free of problems (for example, the effective lifetime of currently available implantable chemical batteries is 18 to 24 months, after which pulse-generator replacement is mandatory6). There is a small but definite risk of infection or prolonged hospitalization with each pulse-generator replacement. Moreover, at a cost of $600 to . . .