**4. Diagnosis of LVAD infections**

LVAD infections can manifest in many ways from indolent infections in patients that are minimally symptomatic to septic patients requiring intensive care. Most sources [13, 27, 39, 40, 43, 61, 62] agree on general investigations that should occur in order to diagnose an LVAD related or device specific infection. If LVAD infection is suspected, driveline and three sets 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 valves and presence of thrombus.

than 100 patients were follows: local site infections 20–49%; driveline infections 12–22%; pocket infections 2–5%; sepsis 3–36%; other types of infections 26–35% [10]. It is estimated from the INTERMACS registry data [12] that there are 8 infectious complications per 100 patient-months in CF LVAD recipients. The European Registry for Patients with Mechanical Circulatory Support (EUROMACS), a European registry of LVAD recipients includes data from 52 hospitals from 2681 patients with 2947 implants since 2014 [77]. Overall serious infection rates were 6.18 per 100 patient months within the first 3 months of implantation. Three year survival was only 44% in patients with CF devices, and 20% of the deaths were attributable to infections. In a retrospective study of 88 CF LVAD implantations (22% DT) between 2006 and 2014 at the Toronto General Hospital, 129 readmissions occurred, of which 17% were related to infections [78]. Despite this readmission rate (63% with at least one readmission), outcomes were excellent with only 6 deaths. Other analysis of the INTERMACS registry revealed that 19% of LVAD recipients developed a percutaneous site infection within 12 months of receiving a CF LVAD [79]. Ten percent of patients with these infections died, with sepsis being the most common cause of death (26%) [79]. In general, DT is associated with greater infection risk, and recurrence of infection, especially driveline infections. The majority of these infections are driveline infections and outcomes are generally good (reviewed in [80, 81]). Fortunately with infection control techniques, rates of driveline infections appear to be decreasing [82]. Pocket infections are less common but can confer greater risks of morbidity including hemorrhagic stroke [56, 57]. In a large prospective study of infections after cardiac operations, Perrault et al. found that LVAD and transplant patients experienced 5.8 times higher rates of mediastinal infections (95% CI 2.36–14.33) with five times higher readmission and mortality rates [83]. Nearly all cases of LVAD endocarditis will require explanation and replacement of the device as well as prolonged antimicrobial therapy, and the risks associated with these [42]. Outcomes are improving overall however. Among 156 patients who survived more than 4 years in one center, the mean survival was 7 years with ~1 readmission per year [84]. In terms of overall quality of life, 92% of these patients were NYHA Class I or II. The most

Left Ventricular Assist Device Infections http://dx.doi.org/10.5772/intechopen.74621 179

common reason for readmission was infection (10%).

**6. Treatment and prevention of 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

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 such as fever, leukocytosis and localizing signs and symptoms.

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 base antimicrobial selection [73].
