Cardiac Device Infections (Pacemakers/ICD's)

This refers to infections of pacemakers or ICD’s, which are becoming increasingly common and problematic given the increasing use of these devices and our older, sicker population.

Two types of infections:
1. Pocket Infections – more common – involves the generator and/or surrounding space, and does NOT involve the transvenous portion of the leads. This most commonly occurs from perioperative contamination of the pocket with skin flora, and less commonly from erosion of the lead or device through the skin and subsequent contamination.

2. Deeper Infections – involves the transvenous portion of the leads, with or without concomitant pocket infection. This can happen either from tracking down of a pocket infection from the subcutaneous part of the device, or seeding from bacteremia/endovascular infection.

The biggest risk factor for either type of infection is recent device manipulation (e.g., recent implantation, device revision, or generator change).

Microbiology: The biggest offender is Staphylococcus, both coag negative staph and Staph aureus. Other bugs that commonly cause infection are Streptococci, Corynebacterium, Propionibacterium, Gram negative rods, and Candida.

Be very scared of staph aureus bacteremia in patients with any hardware in general, including ICD’s/pacemakers – the rate of bacteremia leading to device infection is extremely high and ranges from 30-70% of cases!! These patients often need complete device explantation to cure their infection. This is in contrast to Gram negative rods, which rarely seed the device or other hardware – so in cases of GNR bacteremia, in the absence of obvious hardware infection, the device does NOT need to be explanted.

Clinical Presentation of Device-Related Endocarditis:

Generally presents like subacute, right-sided endocarditis. Note that up to 50% of cases have concomitant valve vegetation (usually on the tricuspid valve), but valve vegetations can also occur without lead infection.
In addition to the usual manifestions of right-sided endocarditis, pulmonary abnormalities (PNA, lung abscess, septic/pulmonary emboli) are very common.
Tricuspid stenosis (due to an obstruction vegetation on the lead) or regurgitation are also common.

Diagnosis:

The modified Duke criteria can be applied to make the diagnosis of device-related endocarditis. Remember that TEE is vastly superior to TTE for detection of lead vegetations!

Management can be complicated and outside the scope of this review, but a few general principles to remember:

Treatment involves both antibiotics (empiric choice is generally Vancomycin for coag negative staph and MRSA coverage) and consideration of device explantation, including the leads.
Removing the device (i.e. pacemaker/ICD without the leads) is generally fairly safe and straightforward. On the other hand, removing the transvenous leads is technically more challenging, and carries the risk of vascular and cardiac injury. This is because over time, the leads get partially endothelialized and incorporated into the wall of the heart by connective tissue. This is good for protecting against infection but makes it tricky to remove. There is more of a risk of damage with ICD leads vs pacemaker leads since ICD leads are larger and have more components, like coils.
Generally, whenever there is evidence that the device pocket or leads are infected, the entire device including the leads should be explanted. For staph aureus bacteremia without an alternative source, the entire device should be explanted. For other bacteremias without an alternate source and that persists/recurs despite abxs, the entire device should be explanted.
Of course, you must take into account the patient’s comorbidities, the indication for the pacemaker/ICD, and overall goals of care, especially in a patient such as in our case.

(Chanu Rhee MS, 5/19/11)