What is the most common composition of a pacemaker battery?

The most common composition of a pacemaker battery is lithium-iodine. This type of battery is favored for its high energy density, long shelf life, and reliability in providing consistent voltage over time. Lithium-iodine batteries are particularly well-suited for pacemakers because they can deliver a stable power supply for several years, which is crucial considering that pacemakers are implanted devices meant to function uninterrupted and without frequent replacement.

In contrast, other battery types, such as nickel-cadmium and alkaline, either do not provide the same discharge characteristics or have shorter lifespans, making them less ideal for use in medical devices that require long-term stability. Lithium-polymers, while useful in other applications, have not been the primary choice for pacemaker batteries due to varying performance under the precise demands of cardiac pacing.

Thus, the selection of lithium-iodine as the most common composition is grounded in its optimal performance characteristics suited for the unique requirements of pacemakers.