When to Use a Pacemaker

Naushad Hirani, BSc, MD
Medical Writer,
Geriatrics & Aging.

For over four decades, permanent implantable pacemakers have been routinely used for the treatment of bradyarrhythmias. In that time, the sophistication, capabilities and potential usefulness of pacemakers for a wide variety of indications have grown tremendously. Most pacemaker recipients are elderly; it is estimated that, currently, more than 70% of pacemaker recipients are over the age of 70. The reasons for this preponderance include the changes in the conduction system associated with normal aging, as well as the increased prevalence of coronary artery disease and primary conduction system disease that is observed as age increases.

Approximately two billion beats are required from an average heart over a typical lifetime. Most of these are initiated in the sinus node. With increasing age, the "P" cells that are the main component of the sinus node are progressively replaced by collagen. In addition, the distal portions of the conduction system, the His bundle and the bundle branches show an age-related loss in conducting cells without a concomitant increase in collagen.