New Developments in Cardiac Pacemakers

For >50 years, bradycardic patients have enjoyed the benefits of cardiac pacing, a therapy that can improve and, in some instances, prolong their lives. Although initially this unique electric therapy aimed just to maintain an acceptable cardiac output that would support life, contemporary pacemakers mimic the function of the native conduction system of the heart ever more closely while eliminating disturbances of the production and propagation of the electric impulse. Pacemakers nowadays are able to ensure atrioventricular (AV) synchrony and to adapt the heart rate according to the peripheral tissue energy demand while incorporating a large number of useful algorithms. In addition, they have the ability to record and store cardiac electrograms, providing valuable information about other rhythm disturbances such as atrial fibrillation (AF) or ventricular arrhythmias that are not uncommon in paced patients. At the same time, a better understanding of the natural history of bradyarrhythmias and the recently published results of large, randomized, controlled trials have enabled us to revise older guidelines, to develop new indications for cardiac pacing, and to optimize the selection of the proper pacing mode for each indication on the basis of existing evidence. Finally, in an attempt to minimize iatrogenic adverse effects caused by pacing from the right ventricular apex (RVA) and right atrial appendage (RAA) and to improve the outcome of cardiac pacing, alternative pacing sites are under evaluation, and leadless pacing and biological pacemakers are among the expectations for the future. Most pacemakers worldwide are implanted because of AV block and sick sinus syndrome (SSS); other indications such as bundle-branch block and neurally mediated syncope are less common. Even more rarely, pacing is done to improve hemodynamics, as in first-degree AV block with a very long PR interval or in hypertrophic obstructive cardiomyopathy, and for indications for specific diseases such as …