Ten-year retrospective cohort analysis of ventricular assist device infections.

BACKGROUND: The number of patients treated by ventricular assist devices (VAD) and the duration of VAD treatment is increasing. One of the main complications in terms of morbidity and mortality for VAD patients are microbial infections. With this study, we aimed to investigate the epidemiology and microbiological characteristics of infections occurring in a VAD population to identify modifiable factors. METHODS: We retrospectively analyzed patient characteristics, treatments and outcomes of VAD-specific/related infections. All patients implanted in our institution with a continuous flow VAD between January 2009 and January 2019 were included. Risk factors for VAD infection were assessed using simple and multiple linear regressions. RESULTS: Of the 104 patients screened, 99 were included in the analysis, the majority of which were men (78%). At implantation, the mean age was 56 years and the median time on VAD support was 541 days. The overall infection rate per year per patient was 1.4. Forty-seven patients (60%) suffered from VAD-specific/related infection. Half of all infection episodes occurred in the first 4 months but the proportion of VAD-specific/related infection was higher after the first 4 months (74% of all infection). Using regression models, no patient specific risk factors were associated with VAD-specific/related infections. CONCLUSION: No predictive factors for infection during VAD support were identified in this study. By extension, diabetes, renal insufficiency, age or high BMI are not sufficient to deny a patient access to ventricular support.

Missing the blind spot in a HeartMate 3 LVAD outflow graft obstruction caused by fungal infection.

A patient was admitted in cardiogenic shock and a constant decrease of pump flow requiring combined inotropic support. To evaluate the cause, echocardiography and a ramp test were performed. The results suggested a LVAD related problem - particularly a suspected outflow graft obstruction. Wether CT scan nor angiography confirmed the assumption. However, a post-mortem LVAD examination revealed an outflow obstruction caused by a fungal thrombus formation invisible for standard imaging procedures.

On the function of biosynthesized cellulose as barrier against bacterial colonization of VAD drivelines.

Bacterial colonization of drivelines represents a major adverse event in the implantation of left ventricular assist devices (L-VADs) for the treatment of congestive heart failure. From the external driveline interface and through the skin breach, pathogens can ascend to the pump pocket, endangering the device function and the patient's life. Surface Micro-Engineered Biosynthesized cellulose (BC) is an implantable biomaterial, which minimizes fibrotic tissue deposition and promotes healthy tissue regeneration. The topographic arrangement of cellulose fibers and the typical material porosity support its potential protective function against bacterial permeation; however, this application has not been tested in clinically relevant animal models. Here, a goat model was adopted to evaluate the barrier function of BC membranes. The external silicone mantle of commercial L-VAD drivelines was implanted percutaneously with an intervening layer of BC to separate them from the surrounding soft tissue. End-point evaluation at 6 and 12 weeks of two separate animal groups revealed the local bacterial colonization at the different interfaces in comparison with unprotected driveline mantle controls. The results demonstrate that the BC membranes established an effective barrier against the bacterial colonization of the outer driveline interface. The containment of pathogen infiltration, in combination with the known anti-fibrotic effect of BC, may promote a more efficient immune clearance upon driveline implantation and support the efficacy of local antibiotic treatments, therefore mitigating the risk connected to their percutaneous deployment.

Experience of cardiac implantable electronic device lead removal from a South African tertiary referral centre.

BACKGROUND: The rate of cardiac implantable electronic device (CIED) implantation in low- and middle-income countries is increasing. Patients recieving these devices are frequently older and with multiple co-morbidities, which may later lead to complications requiring CIED removal. CIED removals are associated with life-threatening complications. However, high sucesss rates are reported in high-income countries. The purpose of this study was to report on the experience of CIED removal in a resource-constrained setting. METHODS: In this retrospective study, we included consecutive adult patients admitted to Groote Schuur Hospital and the University of Cape Town Private Academic Hospital for CIED removal from 1 January 2008 to 31 December 2019. RESULTS: During the study period, 53 patients underwent CIED removal (26 extractions and 27 explants). The patients had a mean (standard deviation) age of 59.1 (16.0) years. A history of systemic hypertension was present in 50.9% of patients, diabetes mellitus in 30.2% and dilated cardiomyopathy in 47.2%. Complete heart block was the leading indication for CIED implantation (37.7%), and device infection was the leading indication for removal (69.2%). CIEDs were removed after a median (interquantile range) of 243 (53-831) days. There were 40 leads extracted and 35 explants. Lead extractions were perfomed in the cardiac catheterisation laboratory under general anaesthesia via a percutaneous transvenous superior approach. There was one major and one minor complication related to lead extraction. CONCLUSIONS: CIED infections were the primary indication for CIED removal in a tertiary referral centre in South Africa. Despite being a low-volume centre, we report a high percutaneous transvenous extraction success rate with low complication rate; results which are comparable to high-volume centres.

Characterization of infected, explanted ventricular assist device drivelines: The role of biofilms and microgaps in the driveline tunnel.

BACKGROUND: Driveline infections remain a major complication of ventricular assist device (VAD) implantation. This study aimed to characterize in vivo microbial biofilms associated with driveline infections and host tissue integration of implanted drivelines. METHODS: A total of 9 infected and 13 uninfected drivelines were obtained from patients with VAD undergoing heart transplantation in Australia between 2016 and 2018. Each driveline was sectioned into 11 pieces of 1.5 cm in length, and each section was examined by scanning electron microscopy (SEM) and viable counts for microbial biofilms. Microorganisms were cultured and identified. Host tissue integration of clinical drivelines was assessed with micro-computed tomography (CT) and SEM. An in vitro interstitial biofilm assay was used to simulate biofilm migration in the driveline tunnel, and time-lapse microscopy was performed. RESULTS: Of the 9 explanted, infected drivelines, all had organisms isolated from varying depths along the velour section of the drivelines, and all were consistent with the swab culture results of the clinically infected exit site. SEM and micro-CT suggested insufficient tissue integration throughout the driveline velour, with microgaps observed. Clinical biofilms presented as microcolonies within the driveline tunnel, with human tissue as the sub-stratum, and were resistant to anti-microbial treatment. Biofilm migration mediated by a dispersal-seeding mechanism was observed. CONCLUSIONS: This study of explanted infected drivelines showed extensive anti-microbial-resistant biofilms along the velour, associated with microgaps between the driveline and the surrounding tissue. These data support the enhancement of tissue integration into the velour as a potential preventive strategy against driveline infections by preventing biofilm migration that may use microgaps as mediators.

Over 870 days of successful antibiotic suppression therapy for VRE-infected left ventricular assist device.

Left ventricular assist devices (LVADs) are used in patients with advanced heart failure. Infections are common complications following device placement; however, the efficacy of chronic antimicrobial suppression therapy for deep-seated infections is not well characterized. We report the case of a 49-year-old male with a HeartMate II LVAD who presented with a methicillin-sensitive Staphylococcus aureus pump pocket infection that was subsequently treated with antibiotics and HeartMate III pump exchange. A vancomycin-resistant Enterococcus faecium (VRE) pump pocket infection then developed and responded to surgical drainage followed by long-term suppression with daptomycin then linezolid for over 870 days. A second pump exchange was not required. To our knowledge, this represents the longest reported use of daptomycin (341 days) without symptomatic adverse events. Managing infections caused by multidrug-resistant pathogens presents a clinical challenge. This case demonstrates the potential for antimicrobial suppression therapy to allow for successful retention of a VRE-infected LVAD.

Biofilm formation and migration on ventricular assist device drivelines.

OBJECTIVES: Driveline infections remain an important complication of ventricular assist device therapy, with biofilm formation being a major contributor. This study aimed to elucidate factors that govern biofilm formation and migration on clinically relevant ventricular assist device drivelines. METHODS: Experimental analyses were performed on HeartWare HVAD (HeartWare International Inc, Framingham, Mass) drivelines to assess surface chemistry and biofilm formation. To mimic the driveline exit site, a drip-flow biofilm reactor assay was used. To mimic a subcutaneous tissue environment, a tunnel-based interstitial biofilm assay was developed. Clinical HVAD drivelines explanted at the time of cardiac transplantation were also examined by scanning electron microscopy. RESULTS: Common causative pathogens of driveline infections were able to adhere to the smooth and velour sections of the HVAD driveline and formed robust biofilms in the drip-flow biofilm reactor; however, Pseudomonas aeruginosa and Candida albicans had greater biomass. Biofilm migration within the interstitial driveline tunnel was evident for Staphylococcus epidermidis, Staphylococcus aureus, and C albicans, but not P aeruginosa. Biofilm formation by staphylococci was 500 to 10,000 times higher in the tunnel-based model compared with our exit site model. The 3-dimensional structure of the driveline velour and the use of silicone adhesive in driveline manufacturing were found to promote biofilm growth, and explanted patient drivelines demonstrated inadequate tissue in-growth along the entire velour with micro-gaps between velour fibers. CONCLUSIONS: This work highlights the predilection of pathogens to different parts of the driveline, the importance of the subcutaneous tunnel to biofilm formation and migration, and the presence of micro-gaps in clinical drivelines that could facilitate invasive driveline infections.

Staphylococcal driveline infections are the predominant type of left ventricular assist device associated infections in Singapore.

BACKGROUND: Left ventricular assist device (LVAD) associated infections (LVADIs) have substantial morbidity and mortality. We aim to describe the incidence and epidemiology of LVADIs in an Asian cohort. This is currently not well studied. METHODS: We conducted a retrospective review of 52 patients who underwent LVAD implantation from 1 May 2009-31 December 2014 in National Heart Centre Singapore. LVADIs were defined based on definitions proposed by the International Society for Heart and Lung Transplantation. RESULTS: There were 39 males and 13 females. Seventy-three percent had Heartmate II LVAD implant while 27% received Heartware HVAD. Eighty-one percent were implanted as bridge to heart transplantation, 19% as destination therapy. Forty-five episodes of LVADIs occurred in 25 patients. Overall LVADI incidence was 47.5 cases per 100 patient-years. Driveline infections (58%) were the commonest type of LVADI. The commonest causative organisms were coagulase-negative staphylococci (33%), Staphylococcus aureus (31%) and Corynebacterium species (19%). Twelve percent of patients with LVADI required surgical debridement and one patient required pump exchange due to pump pocket infection. All-cause mortality was 13%. CONCLUSIONS: The findings of our study add to the understanding and epidemiology of LVADIs, particularly in the Asian setting. This can contribute to the development of evidence based strategies to prevent and manage LVADIs.

Ruptured Intracranial Mycotic Aneurysm in Infective Endocarditis With Left Ventricular Assist Device and Implantable Cardiac Defibrillator Device: A Clinical Course.

We report the first case of a ruptured intracranial aneurysm-related Staphylococcus epidermidis bacteremia in a patient supported by a continuous flow left ventricular assist device (LVAD). Mycotic aneurysms (MAs) are aneurysmal degeneration of the arterial wall as a result of infection. Current recommendations for management of intracranial mycotic aneurysms are based on a few retrospective case studies. There are only a few cases of intracranial MA reported in patients with LVAD infections caused by Pseudomonas aeruginosa and Klebsiella rhinos. Here, we describe the first case of a ruptured intracranial aneurysm caused by a less virulent organism (Staphylococcus epidermidis) and conclude that screening for asymptomatic MA should be strongly considered in patients with persistent LVAD- and implantable cardiac defibrillator pacemaker-associated infections.

Ventricular Assist Device Infections.

This article reviews the diagnostic criteria for ventricular assist device (VAD) infection, pathogenesis, and microbiology as well as the diagnostic pathway when patients present with signs and symptoms concerning for VAD infection. Recommendations regarding infection prevention and management are reviewed as well.

VAD infection during bridge-to-transplant, unique aspects of treatment and prevention.

PURPOSE OF REVIEW: VAD infections remain a frequent complication of VAD care and can markedly affect patient management before and after transplantation. This review highlights the standard-of-care approaches offered by recent guidelines as well as published data that may improve the care for patients with these challenging and often persistent infections. RECENT FINDINGS: Prevention and management of VAD infections has become more standardized with updated consensus guidelines published in 2017. Unfortunately, advanced devices have not markedly affected the incidence of VAD infection. Efforts to improve, yet streamline, the prevention of VAD-specific infections are ongoing. However, the data provided in the best of recent publications are rarely effectively comparative. Granular data on management strategies are limited to a few studies. Nevertheless, several publications provide more detailed posttransplant outcomes for patients with pretransplant VAD infections and demonstrate overall excellent posttransplant survival. SUMMARY: Prevention and management of VAD-specific and VAD-related infections are the ongoing work of all VAD programs. Consensus guidelines are a marker of progress for this field. Despite very good posttransplant outcomes for these patients, more granular data are required to understand how such patients arrive successfully to transplantation and how their posttransplant course is affected.

F-fluorodeoxyglucose-positive emission tomography/CT imaging for left ventricular assist device-associated infections in children.

Left ventricular assist device implantation is an important therapeutic option for children with end-stage heart failure. However, device-related complications such as infection may occur while the patient is supported. Device-associated infection can be life-threatening, and early detection is critical. F-fluorodeoxyglucose positron emission tomography and CT is a highly sensitive imaging modality for the detection of an inflammatory response and is useful to evaluate the response to antibiotic therapy. We present two case reports of a left ventricular assist device-associated infection detected by F-fluorodeoxyglucose positron emission tomography and CT in children.

Staphylococcus aureus bloodstream infection in patients with ventricular assist devices-Management and outcome in a prospective bicenter cohort.

OBJECTIVES: Ventricular assist devices (VAD) are increasingly implanted in patients with terminal heart failure. Here we describe the clinical course, management and outcome of VAD patients with S. aureus bloodstream infection (SAB). METHODS: We conducted a post hoc analysis of data from 1073 patients who had been prospectively enrolled in two consecutive SAB bicenter cohort studies. Patients with VAD in situ at the onset of SAB were identified. Follow-up of patients was at least 90 days. RESULTS: Twelve VAD patients with SAB were identified. Compared to the overall cohort, patients with VAD presented more often with fever (92% vs. 65%) and septic shock (33% vs. 23%) and showed higher C-reactive protein levels (mean 244 vs. 132 g/ml). The median time to onset of SAB after device implantation was 161 days (range 24-790 days). 30-day mortality was comparable to the whole cohort (17% vs. 19%). Infection-related surgical interventions were performed in six patients. Hematogenous dissemination to distant foci was not found in any patient. One out of nine surviving patients required continuous suppressive antibiotic therapy. CONCLUSIONS: Mortality rates for VAD patients with SAB were comparable to SAB without VAD. No hematogenous disssemination or persistent infections were recorded, which might be associated with the prompt and aggressive antibiotic and surgical management in VAD patients. SAB per se does not preclude successful transplantation.

Therapy and Outcome of Staphylococcus aureus Infections of Intracorporeal Ventricular Assist Devices.

Infection of the driveline or pump pocket is a common complication in patients with ventricular assist devices (VADs) and Staphylococcus aureus is the main pathogen causing such infections. Limited evidence is currently available to guide the choice of antibiotic therapy and the duration of treatment in these patients. Patients at the University Medical Center Utrecht who developed a VAD-related S. aureus infection between 2007 and 2016 were retrospectively assessed. Blood culture isolates were typed by whole genome sequencing to differentiate between relapses and reinfections, and to determine whether antibiotic therapy had led to acquisition of resistance mutations. Twenty-eight patients had S. aureus VAD infections. Ten of these patients also suffered S. aureus bacteremia. Discontinuation of antibiotic therapy was followed by relapse in 50% of the patients without prior S. aureus bacteremia and in 80% of patients with bacteremia. Oral cephalexin could ultimately suppress the infection for the duration of follow-up in 8/8 patients without S. aureus bacteremia and in 3/6 patients with S. aureus bacteremia. Clindamycin failed as suppressive therapy in 4/4 patients. Cephalexin appears an adequate choice for antibiotic suppression of VAD infections with methicillin-susceptible S. aureus. In patients without systemic symptoms, it may be justified to attempt to stop therapy after treatment of the acute infection, but antibiotic suppression until heart transplant seems indicated in patients with S. aureus bacteremia.

Colonization With Multiresistant Bacteria: Impact on Ventricular Assist Device Patients.

BACKGROUND: Although the effect of infections with multidrug-resistant bacteria (MDRB) in left ventricular assist device (LVAD) recipients is well characterized, the influence of perioperative colonization on the development of infections in this patient cohort remains unknown. The study evaluated the effect of MDRB colonization on patient outcomes after LVAD implantation. METHODS: We retrospectively analyzed the microbiological screening studies of nasal, throat, wound, and rectal swabs in 82 consecutive patients who received an LVAD at our center between 2010 and 2015. Four categories of MDRB were determined: methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus, and Gram-negative bacterium resistant to three or four of four predefined pharmacologic categories of antibiotics. We also compared the long-term outcome of patients with and without colonization. RESULTS: There were 28 patients (34.1%) diagnosed as being colonized with at least 1 species of an MDRB. MDRB colonization was associated with the occurrence of fatal infections from any pathogen (MDRB positive, 63.2%; MDRB negative, 34.4%; p = 0.04) and fatal MDRB-specific infections (MDRB positive, 31.6%; MDRB negative, 6.3%; p = 0.04), significantly longer intensive care unit stay (p < 0.0001), and longer cumulative hospital stay (p = 0.04). CONCLUSIONS: Our study demonstrates that the colonization with MDRB is a highly prevalent risk factor for infection-associated death in the vulnerable LVAD population. Routine screening for MDRB before and after LVAD implantation should be considered to identify high-risk individuals and facilitate effective prevention of infectious complications.

Ceftolozane/tazobactam for the treatment of MDR Pseudomonas aeruginosa left ventricular assist device infection as a bridge to heart transplant.

BACKGROUND: Ceftolozane/tazobactam (C/T) is a novel antibiotic with enhanced microbiological activity against multidrug-resistant (MDR) gram-negative bacteria, including MDR Pseudomonas aeruginosa. CASE REPORT: Five months after left ventricular assist device (LVAD) implantation, a 49-year old man developed fever and blood culture was positive for MDR P. aeruginosa, susceptible only to aminoglycosides, ciprofloxacin and colistin. A diagnosis of LVAD-related infection was made based on persistent bacteremia associated with moderate 18 F-fluorodeoxyglucose positron emission tomography/CT uptake in the left ventricular apex. Disk diffusion testing for C/T was performed (MIC 2 µg/mL) and intravenous antibiotic therapy with C/T and amikacin was started, with clinical and microbiological response. Initial conservative management with 6 weeks of systemic antibiotic therapy was attempted, but the patient relapsed one month after antibiotic discontinuation. Priority for transplantation was given and after 4 weeks of antibiotic therapy (C/T + amikacin), LVAD removal and heart transplant were performed, with no infection relapse. CONCLUSIONS: We reported the first off-label use of C/T in the management of MDR P. aeruginosa LVAD infection as a bridge to heart transplant. C/T has shown potent anti-pseudomonal activity and good safety profile making this drug as a good candidate for suppressive strategy in intravascular device-associated bloodstream infections caused by MDR P. aeruginosa.

Successful heart transplantation in patients with active Staphylococcus bloodstream infection and suspected mechanical circulatory support device infection.

BACKGROUND: An active bloodstream infection (BSI) is typically considered a contraindication to heart transplantation (HT). However, in some patients with Staphylococcus bacteremia and mechanical circulatory support device infection, positive blood cultures may persist until removal of the infected device, and eradicating the infection prior to HT may not be possible. We report the outcomes of six patients with active Staphylococcus BSI at the time of HT. METHODS: All cases of HT performed at The Mount Sinai Hospital from 2009 through 2015 were reviewed. All patients with a mechanical circulatory support device and an active Staphylococcus BSI at the time of HT were included. RESULTS: Six patients with active Staphylococcus bacteremia and suspected mechanical circulatory support device infection underwent HT. All patients were bacteremic with Staphylococcus species at the time of HT. All were managed with antimicrobial therapy, radical debridement at the time of HT, and limited use of immunosuppression, and all survived until hospital discharge with no evidence of relapsed Staphylococcus infection. CONCLUSION: These results suggest that some carefully selected patients with active Staphylococcus bacteremia and suspected mechanical circulatory support device infection may safely undergo HT, and that HT may effectively eliminate the underlying infection.

Infection of Ventricular Assist Device Detected and Monitored by 18F-FDG PET/CT.

We report a case of a 59-year-old man who presented with fever, sepsis, and left cervicothoracic cutaneous inflammation 13 months after implantation of Jarvik 2000 device. Device infection was suspected and F-FDG PET/CT showed an intense and homogeneous uptake along driveline cable. Bacteriological local sample showed Staphylococcus aureus. After adapted antibiotherapy, control F-FDG PET/CT displays treatment efficacy with no residual uptake in driveline. F-FDG PET/CT could be an important tool for early noninvasive detection of left ventricular assist device infection and monitoring antibiotherapy response.