Permanent pacing of the heart: 1952 to 1976

Permanent cardiac pacing

Implantation of a permanent pacemaker is the most commonly performed surgical operation involving the heart. The modern cardiac pacemaker is a complex device that can sense and pace in both the atrium and ventricle. It also modulates the pacing rate based on sensed physiologic parameters. This article reviews the fundamental principles of pacemaker technology and provides the emergency physician with approaches to common pacemaker problems.

Late unheralded pacemaker pocket infection due to Staphylococcus epidermidis: a new clinical entity

Late pacemaker pocket infections in the absence of predisposing factors such as multiple pacemaker related procedures, skin erosion, chest wall trauma or generalized sepsis have been rarely reported. In the past year, we have seen three late pocket infections (18, 32 and 47 months post-implantation) due to Staphylococcus epidermidis (S. epidermidis). All three patients with late S. epidermidis infections presented with painless swelling over the pulse generator site and had been well until shortly before admission. The patients denied febrile illnesses or chest trauma in the preceding year and no skin erosion was evident. All had been seen regularly in clinic and bimonthly transtelephonic recordings had shown normal pacemaker function. Local drainage, antibiotics and removal of the pacing system was successful in all three patients. We conclude that late pacemaker pocket infections due to S. epidermidis may become an important clinical problem in this era of long-lasting pulse generators. In light of the insidious nature of S. epidermidis infections, regular inspection of the pocket area by both patient and physician is mandatory.

The small-tined pacemaker lead--absence of dislodgement

The Medtronic 6961 unipolar transvenous ventricular lead has four symmetrically placed, small tines that protrude backward just proximal to the tip, and are designed to become entrapped beneath or between right ventricular trabeculae. One hundred leads were implanted. Initially, the leads were more difficult to position at the right ventricular apex as the tines tended to anchor on intracardiac structures. This was overcome by rotating the lead. The time of negotiating the lead from right atrium to right ventricular apex averaged 3.1 minutes for all leads. The first 20 procedures averaged 4.2 minutes and the last 20 averaged 2.1 minutes. In this latter group, 11 of the 20 passages took 60 seconds or less. Once adequate positioning was obtained, the lead was retracted using slight tension to demonstrate tip entrapment. There were no lead dislodgements. Eight deaths occurred following institution of pacing and lead dislodgement was not detected in any of these cases. Four patients had complications associated with pacing, two transient diaphragmatic pacing not requiring reoperation, one right ventricular perforation and one raised threshold with intermittent failure of pacing without lead perforation or dislodgement. Because of the absence of dislodgement, this lead appears to have significant advantages over conventional leads.

Comparison of active and passive adhering leads for endocardial pacing

The frequency of lead failure requiring invasive correction in a total of 276 implants of four different transvenous leads (6907, continuous lead, IE-65-I, and MIP 2000) was observed during a one-and-one-half year period with a minimum of two months follow-up post-implant. Implants were on a successive sequential basis, randomly distributed between the two surgeons normally performing implants, and unselected for presumed ease or difficulty of the procedure. Failure rates with the 6907 and continuous leads were 7 of 76, or 9.2%; with the IE-65-I, 2 of 76, or 2.6%; and with the MIP 2000, 8 of 45, or 17.8%. The difference between the IE-65-I and the two conventional leads was significant at the 5% level, and between the IE-65-I and the group of the other three at the 1.6% level. The MIP 2000 was significantly different from the other three leads at the 2.7% level. Previous clinical experience with 849 implants with continuous and 6807 leads indicated that the overall data was similar to that obtained in the present evaluation. No significant differences in failure rates between surgeons and no measurable "practice effect" could be detected. It was concluded that the design of the lead is a major factor in the differing need for early secondary intervention.

Clinical trials with one type of lithium pacemaker generator

Cardiac Pacemakers, Inc. (CPI) solid-state, lithium-powered pulse generators were implanted in 100 patients by one surgeon in a twenty-eight-month period. Eleven CPI pacer generators were replaced, none due to pacer failure. Ninety-nine percent of the patients were followed for a total of 1,397.55 patient-months; 12 patients died, but no deaths appeared to be pacemaker related. The average age of the patients at the time of implantation was 72.8 years. If the warranty period of six years is achieved, the number of pacemaker generator changes required by many of the patients in this group could foreseeably be zero.