Infectious Disease Compendium

Pacemaker Infection /Defibrillator/Left Ventricular Assist Device Infections

Diagnosis

Rubor, dolor, calor, tumor over the pacer pocket or, less commonly, a wire infection presenting as bacteremia without a focus.

Epidemiologic Risks

A pacer plus bad luck = infection.

S. aureus bacteremia has about a 30% chance of seeding the pacer wire

"On univariate analysis, previous PPM infection, malignancy, long-term corticosteroid use, multiple device revisions, a permanent central venous catheter, the presence of >2 pacing leads, and a lack of antibiotic prophylaxis at the time of PPM placement were associated with an increased risk of PPM infection. A multivariable logistic regression model identified long-term corticosteroid use and the presence of >2 pacing leads versus 2 leads as independent risk factors for PPM infection. In contrast, use of antibiotic prophylaxis prior to PPM implantation had a protective effect (PubMed)."

A PET scan would be $6000 dollar test that may help diagnose the infection; there is an interesting literature suggesting it is a great test:"Sensitivity, specificity, positive predictive value, and negative predictive value for 18F­FDG PET/CT were 82%, 96%, 94%, and 87%, respectively (Pubmed)." (PubMed).

Microbiology

Skin flora (S. aureus and coag negative staphylococcus) are most common, but anything can infect the pocket or the wire. It is very rare for gram negative rods to seed a pacemaker (PubMed). Like never.

For Ventricular assist devices, Staphylococcus aureus, Staphylococcus, coagulase negative, Enterococcus, and Pseudomonas aeruginosa lead the list, but others have case reports. Candida albicans was cause for those who received TPN and has a 90% mortality rate (PubMed).

Staphylococcus aureus, P. aeruginosa, or S. marcescens (PubMed) in the blood have a high likelyhood of infecting the device. Other gram negative rods are much less likely to infect a cardiac device. And yes, I know S. aureus is not a gram negative rod.

Empiric Therapy

Given the huge rates of MRSA in my community, I start with vancomycin pending cultures, cefazolin OR nafcillin / oxacillin would also be reasonable. Local resistance patterns, as always, rule. Once the organism is identified, if bacteremic I usually treat presumptively for right sided endocarditis.

High dose daptomycin 6-10 mg/kg/d) was used in one series (after lead removal) with good success (PubMed).

The pacer system needs to come out. In the Oxford English Dictionary the third definition of futile is medical therapy of a pacer infection. And the longer you delay removing the device, the more likely the patient will die: "early and complete device removal was associated with improved outcomes. (PubMed)." Now, try and convince your cardiologist.

If it is a pacer pocket infection only, I change to po antibiotics 24 hours after the generator is removed. Often I continue the po until the old pocket is healed; there is always a fear, probably unfounded, that the bacteria will mysteriously transport from the old system to the new.

For ventricular assist devices, given the microbiology, vancomycin and anti-pseudomonal. Add an echinocandin if on TPN.

From the largest case series (PubMed): "The most common type of LVADIs were driveline infections (47%), followed by bloodstream infections (24% VAD related, and 22% non-VAD related). The most common causative pathogens included gram- positive cocci (45%), predominantly staphylococci, and nosocomial gram-negative bacilli (27%). Almost half (42%) of the patients were managed by chronic suppressive antimicrobial therapy. While 14% of the patients had intraoperative debridement, only 3 underwent complete LVAD removal. The average duration (±SD) of LVAD support was 1.5±1.0 years. At year 2 of follow-up, the cumulative incidence of all-cause mortality was estimated to be 43%."

Chronic suppression has a reasonable chance of keeping the infection at bay if the system cannot be removed (PubMed).

Pearls

Occasionally a cause of right sided endocarditis. To give a rabbit endocarditis, you put a wire across the valve and make the rabbit bacteremic; most will get endocarditis as a result. Sound familiar? Once, in a brilliant flash, I thought of treating a wire infection with urokinase to strip off the clot and the organisms. It went badly. I recommend against it.

Rants

You have to pull the pacemaker system, maybe just the generator if a pocket infection, but if the wires are infected they have to go as well. This is one prosthetic infection you can NEVER cure medically. The cardiologist with whine and complain about the complications and difficulties of pulling a pacer (and rightly so). And so you will try to salvage it medically. And you will fail. So bite the bullet and remove it.