Biomedical Engineering Reference
In-Depth Information
The first artificial pacemakers were external devices commonly attributed to
Hyman (1930, 1935) and Lidwell (1929), (Mond et al., 1982). Hyman used a
hand-cranked pulse generator and needle electrodes inserted in the myocardium
transthoracically. Lidwell's device used a myocardial needle as one electrode
and a saline-soaked plate as another electrode placed on the skin. The early
pacemakers used AC electricity from wall outlets and, as a result, limited patient
mobility to the length of power cords, making uninterrupted power supply
critical. The first fully portable, battery-powered, and transistorized external
pulse generator was developed by Bakken and applied clinically by Lillehei in
1957 (Lillehei et al., 1960). This simple, yet foundational, invention solved the
pacemaker power supply problem. Most importantly, this work greatly promoted
clinical use, research and development, and public acceptance of electrical
stimulation devices; it opened a new industry.
In the following years, a few breakthroughs substantially advanced pace-
maker technology. One was the introduction of the totally implantable
pacemaker by Senning and Elmqvist in 1958 (Elmqvist and Senning, 1960).
Their first device worked for only a short time, but brought the concept of an
implantable device to the forefront. In 1960, Chardack, Gage, and Greatbatch
implanted another self-contained battery-powered device. This device was
combined with the electrodes developed by Hunter and Roth (i.e., Hunter±Roth
electrodes) that could be sutured to the patient's heart and more effectively
concentrate the pacemaker's current where it was needed (Chardack et al.,
1960). The system required about 70% less current than existing electrode
technology of that time; the devices worked for 18 months. Another break-
through was the development of a transvenous lead insertion technique by
Furman in 1958 (Furman and Robinson, 1958). Furman added a wire to the
lumen of a Cournand catheter and passed it into the right ventricle of the
patient's heart through a vein. The use of this insertion technique and an
endocardial electrode eliminated the need to cut the chest open. By combining
an endocardial lead and an implantable pulse generator, Lagergren achieved a
totally implantable transvenous system on 5 June 1962. Parsonnet
accomplished a full transvenous implantation a few months later. In 1965,
Medtronic commercially introduced a wholly implantable transvenous system
(Furman, 2000). These achievements established the fundamental form of
today's pacemakers.
As transvenous leads evolved, it became obvious that they were easier, safer,
and less traumatic to implant than those requiring transthoracic approaches;
however, the results of this method of implantation were not as reliable. Com-
plications such as dislodgment, myocardial perforation, conductor fracture, exit
block, and failure to sense required corrective reoperation in a significant
percentage of implants. Thus, during the 1970s, a plethora of transvenous lead
designs were developed with mechanisms intended to reduce the acute
reoperation rate.
