The past, present, and future of pacemaker therapies.

Since its introduction into clinical practice, electronic pacing has saved many lives. Despite continuous improvements, electronic pacemakers have important shortcomings, which stimulated the development of biological alternatives. Biological pacemakers generate the cardiac impulse using genes or cells to treat bradycardias. Over the past decade, significant improvements have been made in biological pacemakers, but issues remain in relation to long-term outcomes and safety. Concurrently, efforts to improve electronic pacemakers have also intensified. Whether new generations of electronic pacemakers will erase lingering concerns with regard to electronic pacing or whether biologicals will ultimately supplement or supplant electronics remains to be seen.