Comparison between mercury and lithium chemical systems for pacemaker energy source applications

Over the past decade several types of chemical systems have been developed as energy sources for implantable pacemakers. The most widely used system is the mercuric oxide-zinc cell. Historically, mercury-zinc systems were the first to be used to power an implantable pacemaker; they have undergone several developments and modification in order to improve their performance characteristics. Recently, several new power sources have been designed and developed exclusively for implantable pacemakers, the most promising of which are chemical systems based upon lithium metal as anode material. This paper reviews the basic chemical, physical, and electrical characteristics of mercuric oxide-zinc and lithium based systems and evaluates their suitability for pacemaker applications based upon analysis of their inherent characteristics.