By Pedro Arzuaga
NOTE: This is an overview of the entire article, which appeared in the June 2014 issue of the IEEE Instrumentation and Measurement Magazine.
Click here to read the entire article.
Pacemakers, the first active implantable devices, are now almost as commonly used as aspirin or antibiotics. This article provides an overview of the evolution of the pacemaker and a look at what the future holds for these incredible devices.
The author presents basic concepts about the physiology of the heart beginning with a description of the heart’s electrical system. Under normal conditions, the heart’s electrical activity is originated in the sinoatrial (SA) mode in a rhythmic and spontaneous manner travelling through the rest of the heart by specialized channels. These channels enable an orderly and sequential activation of the heart chambers, assuring maximum mechanical efficiency. The SA mode is, under normal conditions, the structure that generates the electrical impulse that activates the whole heart, being the primary natural pacemaker of the heart.
The article reveals some of the history of the implantable pacemaker. The first pacemaker was implanted on October 8, 1958 in Sweden. Unfortunately, it lasted only 8 hours and a second device implanted the next day lasted only two days. On February 3, 1960, a little more than a year later, Dr. Orestes Fiandra and Dr. Roberto Rubio of Montevideo, Uruguay implanted the first pacemaker to work successfully in a human being. Since that time, improvements in the electronics of the pacemaker became highly reliable and devices were made that could last years.
Modern pacemakers are programmable after implantation to accommodate variations in patient needs. The rate of stimulation can be automatically adjusted to patient needs and activity levels. The article outlines two specific examples of adjustment: response to minute ventilation (the amount of air that enters the lungs each minute) and the QT interval (the period of time between the start of heart depolarization and the repolarization).
In conclusion, the author highlights areas in which pacemaker design is advancing. In the future, it is possible that pacemakers will be automatically programmed according to patients’ physiological needs, particularly automatic adjustment of stimulation amplitude, or the magnitude of the current applied to the ventricle. Leadless pacemakers are in trial implementations, and rexsearchers are studying ways to harvest bodily energy to recharge a pacemaker’s battery. Home monitoring of pacemakers is already possible and implemented by the major pacemaker companies. Pacemaker technology has improved the quality of life for many patients, and the failure rate is low enough to be considered a very safe therapy.
ABOUT THE AUTHOR
Pedro Arzuaga (firstname.lastname@example.org) is an Electronic Engineer, graduated from the Universidad de la República del Uruguay, and has more than twenty years of experience in the design of active medical implantable systems. He joined CCC Medical Devices in 1989 and has since actively participated in the design and development of several implantable devices including cardiac pacemakers and neurostimulators. In many of these projects, he was appointed as the Project Manager. Since 2005 he serves as the Engineering Manager at CCC.