**6. Treatment and prevention of LVAD infections**

of blood bacterial cultures before antibiotics are administered should be obtained, in addition to routine laboratories: complete blood count (CBC); complete chemistries including LDH; coagulation studies (fibrinogen, platelets, d-Dimer, Factor VIII, INR, PTT); erythrocyte sedimentation rate, C-reactive protein). Procalcitonin is elevated in the initial postoperative period and does not appear to be a useful marker of infectious complications [63]. Imaging of the driveline and pump pocket using ultrasound has been suggested by some groups to assess for fluid in the pump pocket or tracking along the driveline. Computed tomography (CT) scanning is of limited utility due to the reflective properties of the pump body. However positron emission tomography (PET-CT) [64]; or gallium single photon emission computed tomography (SPECT-CT) [64–66], reviewed in [40]) have been used to diagnose infection of LVAD components as well as to assess for metastatic sites of infection often found with prolonged bacteremia with pathogens such as *S. aureus* and *P. aeruginosa* (reviewed in [40, 67, 68]). Erba et al. [69] showed that 99mTc-hexamethypropylene amine oxime labeled autologous white blood cell (99mTc-HMPAO-WBC) SPECT-CT had 94% sensitivity at detecting cardiac implantable electronic device infections, with 95% negative predictive value in patients with other sources of infection. Inflammation from driveline trauma may result in a positive PET-CT image, even in the absence of infection. Transesophageal echocardiography is utilized in the setting of positive blood cultures to look for vegetations on native valves or on device components [26, 44, 62]. However, it has been previously acknowledged that echocardiography may be of limited use in evaluating for vegetations, due to reflections off of the device's reflective metal surfaces [50]. The role of echocardiography [70] and the application of newer techniques such as real time three dimensional (3D) echo has been reviewed [71] and discusses utility in evaluating native

LVAD parameters such as flow rates may also be an indication of infectious complications [61]. Elevations of B-type natriuretic peptide (BNP) were also found to be a marker of serious adverse events in LVAD patients, including severe infections such as sepsis, mediastinitis and pump pocket infections [72]. Thrombosis, alteration in coagulation parameters, stroke, acute renal failure may also be early indicators of infection as well as more routine signs

Additional microbiologic techniques such as fluorescent *in situ* hybridization (FISH) and polymerase chain reaction (PCR) have been used to identify additional pathogens in biofilm obtained from explanted LVADs and may provide supplemental information on which to

Clinical outcomes for LVAD implantation have been extensively reviewed (see for example [10, 61, 74, 75]) including for infection. It is estimated that 15% of LVAD recipients die due to infectious complications, with the majority of deaths occurring within the first 30 days of receipt [76]. More than half of the data available for review is for patients receiving CF devices for BTT indications. Overall rates of infection for CF devices in trials and registries with more

such as fever, leukocytosis and localizing signs and symptoms.

valves and presence of thrombus.

178 Advanced Concepts in Endocarditis

base antimicrobial selection [73].

**5. Outcomes in LVAD infections**

Management of LVAD infections is related to the specific LVAD infectious clinical syndrome [13, 26, 27, 30, 31, 42, 43]. Typically, combined medical-surgical treatment is needed, with infectious disease consultation to determine the best selection of empiric and microbiologically driven antimicrobials. Site infections and driveline infections are typically managed with local wound care and a combination of intravenous then oral antibiotics if possible as dictated by the organism isolated from the infected site. Percutaneous site infections have even been treated with topical agents such as crystal violet [85]. Sometimes the tunnel must be excised, and a new tunnel created with the application of a vacuum wound device to close the defect. Certain infections have been prevented by reducing exposed driveline material (velour) by keeping it entirely in the subcutaneous tunnel [82]. Preventing trauma to the driveline by use of anchoring devices [86], and use of sterile technique when changing the driveline dressing are key in preventing driveline infections. Standardized strategies for driveline dressings, and in overall LVAD infection control within hospitals are also helpful in preventing infections [86–88]. Pocket infections must typically be managed with surgical debridement in the operating room with techniques such as omental wrapping of the pump housing to cover exposed metal and to close surgical defects [89, 90]. In rare instances, extrapolating from the orthopedic surgery literature, antibiotic impregnated beads have been placed in the pocket (reviewed in [91, 92]) although this has not been studied in a rigorous manner. Arguably, tissue levels of parenteral antibiotics are sufficient to treat residual infection once source control has been achieved. Placement of an additional foreign body in the pocket may not be advised, especially since the antibiotic concentrations from the beads will eventually wane, requiring subsequent bead exchange or removal. Repeated exposure to sub-inhibitory concentrations of antibiotic can lead to selection of antibiotic resistant organisms. Indolent pathogens such as *M. chimaera* or in the case of fungal infections may necessitate exchange of the pump and other components that are involved. LVAD endocarditis requires explanation and extended antimicrobial therapy, potentially with lifelong suppression if re-implanted or if cardiac transplantation occurs [42, 48, 50].

date. An LVAD infection increases the risk of infections in persons who undergo cardiac transplantation. Infections include percutaneous site, driveline, pump pocket and pump/cannula infections; sepsis, bacteremia, mediastinitis and endocarditis. Diagnosis is achieved by monitoring LVAD flow parameters and observing typical clinical and laboratory manifestations of infection (fever, local induration, erythema, abdominal pain, high flow LAVD parameters, leukocytosis, elevated inflammatory markers such as ESR, CRP; markers of coagulopathy). Elevated BNP may herald severe infection such as sepsis and pump pocket infection. PCR and FISH microbiologic techniques increase diagnostic yield of specific pathogens in biofilm on drivelines and other device components. Imaging such as PET-CT or SPECT-CT imaging can be helpful to establish a diagnosis of pump pocket infection. Echocardiography may aid in detecting native valve endocarditis and thrombus associated with the LVAD. The most common pathogens include *Staphylococcus*, *Corynebacterium*, *Enterococcus*, *Pseudomonas* and *Candida* spp. Treatment requires targeted antimicrobials plus surgical debridement of infected tissue and device components. In cases of pump/cannula/LVAD endocarditis, especially if fungal pathogens or *Mycobacterium chimaera* are involved, LVAD removal/re-implantation vs. transplant is necessary, combined with extended antimicrobial therapy. The "holy grail" of future mechanical circulatory support is a fully implantable device that relies on transcutaneous energy supplies. Devices of the future would be less prone to infectious complications potentially but would not entirely eliminate infectious complications. Smaller devices with magnetically levitated pumps, minimally invasive techniques and uniform infection control practices are the state-of the art in preventing infectious complications of LVADs today.

Left Ventricular Assist Device Infections http://dx.doi.org/10.5772/intechopen.74621 181

The author would like to acknowledge the editor, Dr. Michael Firstenberg and Dr. Robert

Dr. Skalweit is an employee of the Department of Veterans Affairs. The opinions expressed here are her own and not those of her employer. Dr. Skalweit has no conflicts to declare.

Infectious Disease Section, Departments of Medicine and Biochemistry, Louis Stokes

Cleveland Department of Veterans Affairs Medical Center, Case Western Reserve University,

Bonomo for critical reading and suggestions to improve this manuscript.

Address all correspondence to: marion.skalweit@case.edu

**Acknowledgements**

**Conflict of interest**

**Author details**

Marion J. Skalweit

Cleveland, Ohio, USA

Optimal peri-implant antibiotic prophylaxis has not been established in a rigorous trial. However, "best evidence" was provided in a review by Acharya et al. [93] and consists of antibiotic coverage for Staphylococci, Enterococci, *Pseudomonas* and *Candida* spp. They concluded that use of an extended spectrum beta-lactam plus vancomycin in areas where rates of methicillin resistant *S. aureus* are high, a fluoroquinolone, fluconazole and mupirocin ointment (nasal application) in the "peri/post-operative" period (~3 days) was recommended. Prophylactic antibiotics are not recommended to prevent driveline infection after the immediate post-operative period [94].
