Implantable power-sources: a review

It has now been 25 years since the first pacemakers were implanted. It is indeed fascinating to see the breadth and the vision of the early investigators on both sides of the ocean, most of them friends of the author, in the almost desperate search for a power source that would enable the pacemaker to last as long as the expected lifetime of the average patient. Every conceivable method of power generation, power storage, and energy conservation was studied. The result was an orderly transition from zinc-mercury batteries, to lithium-iodine batteries, to the newest lithium oxyhalide systems of the coming decade, all of which coincided with tentative sidesteps into rechargeable batteries and nuclear batteries. This paper traces this 25 years of progress and salutes the many investigators who have brought the implantable pacemaker and its power source to their present state of acceptance by the medical profession.