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Episode #30 – Shape of My VAD

30 Cover Art OPT

Summary

Dr. Rebecca Kumar joins Sara to provide overview of ventricular assist device infections!

Credits

Host: Sara Dong

Guest: Rebecca Kumar

Writing/Producing/Editing/Cover Art/Infographics: Sara Dong

Our Guest

Rebecca Kumar, MD, MS

Dr. Rebecca Kumar is a Transplant ID physician and assistant professor at MedStar Georgetown University Hospital in the Division of Infectious Diseases and Tropical Medicine.  She previously completed her internal medicine residency at Medstar Georgetown University Hospital in Washington DC followed by fellowship in infectious diseases at Northwestern University in Chicago.

Culture

Rebecca mentioned a few pop punk bands to check out!

Consult Notes

Consult Q

assistance in work-up of fever and pain/purulent drainage from driveline exit site

One-liner

70 year old male with CAD s/p CABG and ischemic HFrEF s/p LVAD who presented with fevers with pain and purulence from driveline site.  He was found to have deep driveline infection.

Key Points

Jump to:

We started this episode with an overview of ventricular assist devices or VADs.

These devices are mechanical pumps that provide circulatory support by augmenting the ability of a failing heart to deliver blood flow in patients with refractory heart failure

    • VADs are usually continuous flow, now with a centrifugal pump (sort of like a rotor floating between two magnets)
    • The newer pumps tend to last longer with less hemorrhagic and thrombotic complications that were seen in earlier pulsatilla pumps (a look at continuous flow devices from NEJM here)
    • Use different speeds to mimic increases/decreases in flow
    • Newer VADs are also smaller, implanted directly into the pericardium (previously there were preperitoneal pump pockets), and have smaller caliber drivelines (which are more durable)
    • Some possible brands/devices you may hear: HeartMate 2, 3 (Abbott); Heartware HVAD (Medtronic), Jarvik Heart

Components of the VAD mentioned on the show

    • VADs can be implanted in right or left ventricle, but vast majority are going to be left = LVADs
    • Inflow cannula, which connects pumps itself to the heart and allows blood flow
    • Outflow cannula, which pumps blood to rest of body
    • Driveline runs through the chest and abdomen before exiting in lower abdomen
    • Driveline is connected to controller (where cardiologists can adjust) — this is the component that will alarm with outflow obstruction, etc
        • Driveline itself has piece of velour near exit site which should stick inside peritoneal space, and this exists to help with granulation tissue formation and seal around driveline.
        • When this is pulled out / exposed, it is a great place for bacteria to grow
    • Battery pack (external)

VADs improve survival, functional status, and quality of life.  As mentioned on the show, annual reports from the INTERMACS (Interagency Registry for Mechanically Assisted Circulatory Support) database provide information from >20k patients, >180 hospitals, >4000 cases of LVADs

Infection remains one of the most common complications of VAD therapy and contributes to mortality on the transplant wait list — but many pts with infections are transplanted with excellent outcomes!

As explained by Rebecca and in the document above:

  • VAD-specific infections are related to the VAD itself and include:
      • Pump pocket and/or cannula infections (the mechanical pump itself or the inflow/outflow cannula has infection)
      • Pocket infections (this was more of an issue when the VADs were in preperitoneal pockets)
      • Driveline exit site infections, which can be divided into superficial or deep infection (deep implying involvement of musculature and/or soft tissue near driveline site) **most common**
  • VAD-related infections include bloodstream infections, infective endocarditis, and mediastinitis.  These are infections that are complicated by the presence of a VAD
  • Non-VAD infections include items such as UTI, C.difficile, and so on

Next we discussed the initial work-up approach when you suspect an LVAD infection

Check out these resources

In general, the work-up is going to include:

    • Blood cultures and other labs
    • Evaluation of device, heart valve/CIED involvement (echo)
    • Evaluation for local infection (CT or US)
    •  
    •  Check out this flow chart from the Nienaber paper noted above:

What organisms typically cause VAD infections?

  • There is a predominance of Staphylococci (often skin flora, especially in setting of driveline exit site infection)
  • Nosocomial gram negative pathogens such as Pseudomonas are a concern as well
  • Fungal infections are relatively uncommon

Typical empiric antibiotic coverage for VAD infections would be:

  • Based on prior antibiotic exposure, infection history, extent of infection
  • Generally will include MRSA coverage as well as additional gram negative (including Pseudomonal) coverage
  • +/- anaerobic coverage based on factors noted above

This episode’s case involved a patient with prior superficial driveline infection who had a subsequent deep driveline infection with the same organism.  Let’s take a look at general recommendations for management of VAD specific infections in this table

A few final pearls from the episode

Other miscellaneous mentions and notes:

Episode Art & Infographics

Goal

Listeners will be able to identify and evaluate for ventricular assist device infections

Learning Objectives

After listening to this episode, listeners will be able to:

  • Describe key components of ventricular assist devices (VADs)
  • Define the spectrum of VAD-specific, VAD-related, and non-VAD infections
  • Describe the epidemiology and distribution of pathogens in VAD-specific infections
  • Discuss the management of VAD-specific infections, especially superficial and deep driveline infections

Disclosures

Our guest (Rebecca Kumar) as well as Febrile podcast and hosts report no relevant financial disclosures

Citation

Kumar, R., Dong, S. “#30: Shape of My VAD”. Febrile: A Cultured Podcast. https://player.captivate.fm/episode/5154e0a3-29fc-4e61-b52f-eef110b32f4e

Transcript

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