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Ann Thorac Surg 1997;64:1707-1712
© 1997 The Society of Thoracic Surgeons

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Original Articles: Cardiovascular

Cardiac Pacemaker Infection: Surgical Management With and Without Extracorporeal Circulation

Departments of Cardiothoracic Surgery, Cardiology, and Anesthesiology, Institute of Medical Microbiology, University of Muenster, Muenster, Germany

Accepted for publication July 17, 1997.

	Abstract

Top Footnotes Abstract Introduction Patients and Methods Results Comment References

 
Background. Pacemaker infections are rare, but serious complications of pacemaker therapy. The generator pocket, the pacing leads, or both may be involved.

Methods. We report on 12 patients with infected pacemaker systems. Four patients suffered from localized generator pocket infections, 6 had infected leads, and 2 patients had both. Pacemaker systems were completely removed in all patients. When the infection was limited to the generator pocket, the pacemaker system was removed at the original implantation site. Extracorporeal circulation was employed for the explantation of infected pacing leads.

Results. No complications occurred in patients with localized generator pocket infections. One patient with infected leads who was preoperatively already in a serious clinical condition died of septic shock in the early postoperative period; another patient died of pulmonary complications after tricuspid valve replacement 14 months after pacemaker explantation. No recurrent infections were observed.

Conclusions. Explantation of the complete pacemaker system has proved a reliable method to eradicate infection. Complications have been rare, except in patients in a critically ill state who undergo cardiopulmonary bypass.

	Introduction

Top Footnotes Abstract Introduction Patients and Methods Results Comment References

 
Since the first implantation of a completely implantable pacemaker by Elmqvist and Senning in 1958 [1], pacemaker implantation has rapidly become a routine procedure. Most frequently, pacemaker leads are introduced through the cephalic or subclavian vein using direct exposure or introducer techniques and advanced into the right atrium or ventricle. Pulse generators are placed above or beneath the pectoralis major muscle. Alternatively, the leads can be fixed to the epicardium and the generator stored in the anterior or posterior sheath of the rectus abdominis muscle. Among possible complications, pacemaker infection is of particular clinical importance. It is a rare, but serious, complication and can become life-threatening.

In this report we summarize our experience with pacemaker infections and include recommendations for surgical treatment, with special consideration given to the application of cardiopulmonary bypass.

	Patients and Methods

Top Footnotes Abstract Introduction Patients and Methods Results Comment References

 
Patients Characteristics
From January 1992 to October 1996, 12 patients (9 male, 3 female) with an average age of 59.5 ± 15.8 years were referred to our institution for the treatment of infection of their pacemaker system. In 7 patients the original pacemaker had been implanted at a different hospital; 5 patients had undergone pacemaker implantation at our institution. The indication for pacemaker implantation had been sick-sinus syndrome (n = 6), third-degree atrioventricular block (n = 2), bradyarrhythmia (n = 3), and hypersensitive carotid sinus syndrome (n = 1). Six patients had been provided with single-chamber pacemakers and 6 patients with dual-chamber pacemakers. In 11 patients, pacemaker leads had been implanted transvenously through the cephalic or subclavian vein and the pacemaker generators positioned above or beneath the pectoralis major muscle. One patient in whom third-degree atrioventricular block developed intraoperatively after aortic valve replacement (Omnicarbon 29 mm; Medical Incorporated, Inver Grove Heights, MN) had received epicardial leads, with a pacemaker generator located in the rectus sheath. Seven patients had undergone one or more revisions of their pacemaker system before infection. The number of previous pacemaker operations, including implantation and revisions, amounted to four in 1 patient, three in 1 patient, two in 5 patients, and one in 5 patients. The average interval between the last pacemaker operation (first implantation or revision for the management of generator end-of-life or lead dysfunction) and explantation of the pacemaker system was 44.2 ± 33.7 months (Table 1).

Infected pacemaker leads (8 patients) were removed with the aid of extracorporeal circulation. Total cardiopulmonary bypass was instituted after cannulation of the ascending aorta and superior and inferior venae cavae. Intracardiac surgical procedures were performed on an empty, beating, nonworking heart without the application of cardioplegia solution or aortic cross-clamping. Bicaval cannulation allowed the right atrium to be opened in a rather bloodless field, with a sufficient view and exposure of the infected leads, the tricuspid valve, and the right ventricle. Using this access, all leads surrounded by masses of vegetations could be removed from the intracardiac cavity (Figs 1, 2). The pacemaker generators were explanted at the site of implantation.

View larger version (137K): [in this window] [in a new window]   Fig 1. . Intraoperative view into the right atrium, which is almost completely filled by pacemaker lead vegetations. After establishment of extracorporeal circulation and bicaval cannulation, the right atrium was opened and the vegetations surrounding the pacemaker lead were visualized.

View larger version (100K): [in this window] [in a new window]   Fig 2. . Explanted intracardiac lead surrounded by masses of vegetations.

	Results

Top Footnotes Abstract Introduction Patients and Methods Results Comment References

 
Microbiology
In all patients, specimens of infected tissue or swabs from wounds or leads and blood samples were obtained for Gram's staining and culture and susceptibility studies. In 10 of the 12 patients (83.3%), one or more microorganisms were detected, and these consisted of the following: Staphylococcus epidermidis (7 patients), Staphylococcus haemolyticus (2 patients), coagulase-negative staphylococci (1 patient), Pseudomonas sp (1 patient), Escherichia coli (1 patient), Enterobacter cloacae (1 patient), Propionibacterium sp (1 patient), Stenotrophomonas maltophilia (1 patient), Acinetobacter sp (1 patient), Flavobacterium indologenes (1 patient), and Candida glabrata (1 patient) (see Table 2).

Postoperative Course
The mean follow-up interval in all patients after pacemaker explantation was 27.5 ± 18.3 months. No intraoperative or postoperative complication occurred in the patients with infected pacemaker pockets, and the postoperative 30-day-mortality was 0%. After a follow-up of 46.0 ± 10.0 months following pacemaker explantation, all 4 patients were alive and free of infection. No intraoperative or postoperative complications related to the surgical technique were seen in patients with infected leads. One patient, however, who preoperatively was in a highly septic condition died of prolonged septic shock refractory to catecholamine and antibiotic therapy on the fifth postoperative day. Severe tricuspid incompetence developed in another patient who well survived explantation of the pacemaker system using an open heart procedure. This necessitated tricuspid valve replacement with a Carpentier-Edwards 27-mm bioprosthesis (Baxter Healthcare Corp, Edwards CVS Division, Irvine, CA) 14 months later. He died 4 days after operation as a result of severe pulmonary edema complicated by ubiquitous bronchopneumonia. Thus the postoperative 30-day mortality related to removal of infected leads was 12.5%. After a follow-up of 18.3 ± 14.0 months following removal of infected leads using extracorporeal circulation, 6 of 8 patients were alive and free of infection.

In 5 patients who still had a pacemaker indication, a new transvenous pacing system (dual-chamber pacemaker in 2, single-chamber pacemaker in 3 patients) was implanted through a different access after an infection-free interval of 10 to 91 days (36.4 ± 28.7 days). During the interval between explantation of the old and implantation of the new pacemaker, 2 patients were provided with temporary pacemaker stimulation by means of epicardial pacing leads placed at the time of explantation of the preceding pacing system; 3 patients with sufficient heart rate were continuously monitored electrocardiographically without temporary stimulation. In 2 patients an epicardial dual-chamber pacemaker was implanted at the time the infected system was removed. After a mean follow-up of 31.0 ± 20.1 months after implantation of a new pacemaker device, no recurrent infection was observed (see Table 2).

	Comment

Top Footnotes Abstract Introduction Patients and Methods Results Comment References

 
Infection of the pacemaker system may be limited to the pacemaker pocket, it may only involve the leads, or it may include the whole pacemaker system. Infection of the pacing leads results in more severe clinical symptoms, because vegetations attached to the leads may cause infective endocarditis and promote thrombus formation in the superior vena cava and right atrium and ventricle, leading to the development of septicemia and the acute or recurrent formation of a pulmonary embolism. The incidence of pacemaker infection is currently reported to range from 0.5% to 1.5%, which is similar to that at our institution [2, 3]. In our 1,527 patients who have undergone pacemaker implantation as well as in our 1,068 patients who have received an implantable cardioverter-defibrillator, the infection rate was calculated to be 0.55%. However, the risk of infection increases with reintervention [4].

The diagnosis of pacemaker infections is established by the nature of the clinical symptoms and the results of blood testing as well as ultrasonographic and radiologic imaging. Echocardiography is a sensitive method for detecting intracardiac vegetations adherent to the pacing leads. Transesophageal echocardiography is subsequently performed if transthoracic ultrasonography fails to show suspected intracardiac vegetations [5]. In selected cases, intravascular ultrasonography can be used [6]. Findings yielded by microbiologic analysis of specimens of the infected tissue and foreign bodies as well as blood cultures may help to identify the microorganisms so that subsequent adequate antimicrobial therapy can be instituted. The most common bacteria are those that physiologically colonize the skin, such as the various types of staphylococci, among them Staphylococcus epidermidis and Staphylococcus aureus. However, staphylococci that are detected in blood cultures may be phenotypically different from those found on pacing leads of the same patient, though they originate from the same genotype [7]. The fungal colonization of pacemaker systems has also been described, as was the case in 1 of our patients, even occurring in patients who may not necessarily be at risk for fungal infections [8].

The most efficient treatment of pacemaker infection is the complete removal of the pacemaker system, including the generator and leads, regardless of the extent of the infection. We use different therapeutic strategies for infections of the generator pocket and leads. When the infection involves the pacing leads, it is generally accepted that explantation of the leads is necessary, because the mortality increases to 25% in patients whose infected leads are not removed [9]. Most colleagues recommend that removal of the leads at the implantation site be attempted. Various techniques for doing this have been devised, including the use of manual or weighted traction or grasping the leads by different tools such as a pigtail catheter, endomyocardial biopsy forceps, Dotter basket, wire loop placed via the femoral or jugular vein, or recently designed locking stylets and sheaths [10]. It is noteworthy that the United States Lead Extraction Database has shown a fatal or near-fatal complication rate of 2.5% for patients who undergo intravascular lead extraction, with a mortality rate of 0.6% [11]. We prefer to remove infected leads during cardiac operations using extracorporeal circulation because this procedure has several advantages over the intravascular extraction methods, besides being associated with a similar low overall risk. Specifically, the risk of mechanical injury to cardiac structures and dissemination of vegetations is less because the leads are not exposed to mechanical stress and blood circulation through the right heart is interrupted during the procedure. However, the extraction of infected leads through a pursestring suture with the heart beating, as described by Niederhäuser and associates [12], still carries the risk of incompletely removing vegetations, with subsequent dissemination. An open heart operation also allows additional surgical procedures to be performed in the right heart, such as reconstruction of the tricuspid valve or the removal of intracardiac vegetations and thrombi, which was necessary in 7 of our 8 patients. In 4 patients who needed an operation on the tricuspid valve for the management of lead entrapment or removal of attached vegetations, the tricuspid valve could be preserved by reconstructive procedures. One of them, who had undergone thrombectomy of the tricuspid valve, died of septic shock in the early postoperative period. Autopsy showed fibrotic changes related to the previous endocarditis but no fresh vegetations. In the remaining 3 patients, neither tricuspid valve endocarditis nor considerable tricuspid incompetence has been observed so far. Severe tricuspid insufficiency developed more than 1 year later in 1 patient who did not undergo tricuspid valve reconstruction because the valve appeared normal macroscopically.

If the infection is limited to the generator pocket, we explant the complete pacemaker system, including the leads and generator, through the original access. Using this strategy, infection limited to the generator pocket was durably eradicated in all 4 patients. Some authors, however, suggest that preservation of the implanted pacemaker system be attempted as a first step of therapy [13]. This management includes extensive debridement and irrigation of the pocket as well as subfascial pocket relocation [14, 15]. Only if this kind of treatment is unsuccessful, which unfortunately most often occurs, is the pacemaker system removed [16, 17]. Reinfection rates of 51% to 77% have been noted for patients whose infected pacemaker system is only partially explanted [18, 19].

Electron microscopic studies have shown that tiny cracks may develop in the lead surface at the site of suturing or at areas of stress, which are subsequently prone to bacterial colonization refractory to antimicrobial therapy [20]. Coagulase-negative staphylococci form microcolonies that adhere to the lead sheath and are embedded in an extracellular amorphous substance [21]. An alteration of host defense produced by these extracellular substances, the metabolic state of adherent bacteria, and reduced penetration of antimicrobials into the biofilm may all contribute to the clinical difficulty in eradicating infection if pacing leads are not removed [22].

Our perioperative strategy included adequate antimicrobial therapy and temporary pacing, if necessary. Antimicrobial therapy was started when the diagnosis was established and altered when the causative microorganisms were identified. If cultures still grew no organisms, broad-spectrum antimicrobial therapy directed against organisms most commonly responsible for causing pacemaker infections was initiated. Operation was postponed until signs of infection and sepsis had disappeared. If signs of infection persisted despite specific antibiotic treatment, operation had to be performed with an anticipated higher perioperative risk, as was the case in 1 of our patients in whom fatal septic multiple-organ failure developed postoperatively. Temporary pacing was used in only 2 patients who were hemodynamically unstable without a pacing device. They received transitional epicardial leads after an infected pacemaker system was removed during an open heart procedure. A new transvenous pacemaker was implanted at a second operation. The restrictive indication for transitory pacing was the reported higher infection rate in patients who had temporary pacemakers before permanent pacemakers were implanted [3].

The implantation of a new transvenous pacemaker system was performed in a staged procedure after an infection-free interval of at least 10 days following explantation of the infected pacemaker system. The preoperatively started antimicrobial therapy was continued for at least 4 weeks after implantation of the new pacemaker. The new pacemaker was implanted through a different implantation site, usually the contralateral pectoralis region. Alternatively, an epicardial pacemaker system may be implanted in patients who undergo cardiopulmonary bypass during the same procedure right after removal of the old pacemaker as was done in 2 of our patients [13, 23]. All patients in whom this strategy was used and who received a new pacemaker device, including those who were temporarily paced, remain free of infection so far.

In conclusion, the most efficient treatment for pacemaker infections is the complete removal of the pacemaker system. The removal of infected leads during extracorporeal circulation prevents mechanical injury as well as the spread of infection and allows additional intracardiac procedures to be performed, if necessary. The complication rate is low but rises unpredictably if cardiopulmonary bypass has to be performed before the signs of infection have resolved. If the infection is limited to the generator pocket, the pacemaker generator and leads can be explanted through the original implantation site. A new transvenous pacemaker system should be implanted at a different site, either in a second operation after an infection-free interval or immediately after explantation using epicardial leads during extracorporeal circulation. Temporary pacing should be restricted to patients who are hemodynamically compromised without a pacemaker.

	Footnotes

Top Footnotes Abstract Introduction Patients and Methods Results Comment References

 
Address reprint requests to Dr Wilhelm, Klinik und Poliklinik für Thorax-, Herz- und Gefäßchirurgie, Westfälische Wilhelms-Universität, Albert-Schweitzer-Str 33, 48129 Münster, Germany.

	References

Top Footnotes Abstract Introduction Patients and Methods Results Comment References

 

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This Article Abstract Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Christof Schmid Dieter Hammel Sebastian Kerber Hans H. Scheld Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Wilhelm, M. J. Articles by Scheld, H. H. Search for Related Content PubMed PubMed Citation Articles by Wilhelm, M. J. Articles by Scheld, H. H.