Left Ventricular Assist Device–Associated Infections

Design and optimisation of an Intra-Aortic Shrouded rotor axial pump

Undesirable side effects in patients with a LVAD (Left Ventricular Assist Device) pump fitted include blood damage, thrombosis, blood traumatisation, and End-Organ Disfunctions. These side effects have generally been attributed to the high wall shear stresses and the induced turbulent flow. In this study, we introduce a novel design to address these effects by lowering the rotational speed and providing an optimum flow path design to minimise blood damage. We present an initial scheme for a new Intra-Aortic Shrouded Rotary Axial Pump and develop a sequence of pump geometries, for which the Taguchi Design Optimisation Method has been applied. We apply CFD tools to simulate the pressure rise, pump performance, hydraulic efficiency, wall shear stress, exposure time and mass flow rate. A prototype pump has been tested in a mock cardiovascular circuit using a water-glycerol solution. The optimum design delivered the desired pressure/mass flow rate characteristics at a significantly low rpm (2900 rpm). As a result, the estimated blood damage index is low, matching the design requirements. The theoretical performance was matched by experimental results.

Colonization and Infection of Indwelling Medical Devices by Staphylococcus aureus with an Emphasis on Orthopedic Implants

The use of indwelling medical devices has constantly increased in recent years and has revolutionized the quality of life of patients affected by different diseases. However, despite the improvement of hygiene conditions in hospitals, implant-associated infections remain a common and serious complication in prosthetic surgery, mainly in the orthopedic field, where infection often leads to implant failure. Staphylococcus aureus is the most common cause of biomaterial-centered infection. Upon binding to the medical devices, these bacteria proliferate and develop dense communities encased in a protective matrix called biofilm. Biofilm formation has been proposed as occurring in several stages-(1) attachment; (2) proliferation; (3) dispersal-and involves a variety of host and staphylococcal proteinaceous and non-proteinaceous factors. Moreover, biofilm formation is strictly regulated by several control systems. Biofilms enable staphylococci to avoid antimicrobial activity and host immune response and are a source of persistent bacteremia as well as of localized tissue destruction. While considerable information is available on staphylococcal biofilm formation on medical implants and important results have been achieved on the treatment of biofilms, preclinical and clinical applications need to be further investigated. Thus, the purpose of this review is to gather current studies about the mechanism of infection of indwelling medical devices by S. aureus with a special focus on the biochemical factors involved in biofilm formation and regulation. We also provide a summary of the current therapeutic strategies to combat biomaterial-associated infections and highlight the need to further explore biofilm physiology and conduct research for innovative anti-biofilm approaches.

Using Graphene-Based Materials for Stiff and Strong Poly(ethylene glycol) Hydrogels

Blood-contacting devices are increasingly important for the management of cardiovascular diseases. Poly(ethylene glycol) (PEG) hydrogels represent one of the most explored hydrogels to date. However, they are mechanically weak, which prevents their use in load-bearing biomedical applications (e.g., vascular grafts, cardiac valves). Graphene and its derivatives, which have outstanding mechanical properties, a very high specific surface area, and good compatibility with many polymer matrices, are promising candidates to solve this challenge. In this work, we propose the use of graphene-based materials as nanofillers for mechanical reinforcement of PEG hydrogels, and we obtain composites that are stiffer and stronger than, and as anti-adhesive as, neat PEG hydrogels. Results show that single-layer and few-layer graphene oxide can strengthen PEG hydrogels, increasing their stiffness up to 6-fold and their strength 14-fold upon incorporation of 4% w/v (40 mg/mL) graphene oxide. The composites are cytocompatible and remain anti-adhesive towards endothelial cells, human platelets and Staphylococcus aureus, similar to neat hydrogels. To the best of our knowledge, this is the first work to report such an increase of the tensile properties of PEG hydrogels using graphene-based materials as fillers. This work paves the way for the exploitation of PEG hydrogels as a backbone material for load-bearing applications.

No Association between Clinical Periodontal Conditions and Microbiological Findings on Driveline of Patients with Left-Ventricular Assist Devices (LVAD)

The aim of this retrospective study was to investigate whether there would be an association between periodontal disease parameters and positive bacterial findings at the driveline of patients with a left ventricular assist device (LVAD). Patients with an LVAD, who underwent a full oral and microbiological examination between 2016 and 2018, were included. During oral examination, periodontitis severity (stage and grade) and the periodontal inflamed surface area (PISA) were evaluated. A microbiological analysis was performed from swabs of the driveline, whereby different bacterial species were cultivated and analyzed. A total of 73 patients were included in the current study. The majority of participants (80.8%) had at least one positive bacterial finding during the study period. Most patients had a periodontitis stage of III-IV (80.9%). The determined PISA of the total group was 284.78 ± 352.29 mm². No associations were found between the periodontal disease parameters and the bacterial findings in general, the bacterial findings on the day of oral examination or the bacterial findings 12 months prior to/after the oral examination (p > 0.05). Periodontitis is not associated with cultivated microbiological findings at the driveline of patients with an LVAD and thus appears not to be a risk indicator for driveline colonization. Nevertheless, the high periodontal burden in LVAD patients underlines the need for their improved periodontal care.

HFSA/SAEM/ISHLT clinical expert consensus document on the emergency management of patients with ventricular assist devices

Mechanical circulatory support is now widely accepted as a viable long-term treatment option for patients with end-stage heart failure (HF). As the range of indications for the implantation of ventricular assist devices grows, so does the number of patients living in the community with durable support. Because of their underlying disease and comorbidities, in addition to the presence of mechanical support, these patients are at a high risk for medical urgencies and emergencies (Table 1). Thus, it is the responsibility of clinicians to understand the basics of their emergency care. This consensus document represents a collaborative effort by the Heart Failure Society of America, the Society for Academic Emergency Medicine, and the International Society for Heart and Lung Transplantation (ISHLT) to educate practicing clinicians about the emergency management of patients with ventricular assist devices. The target audience includes HF specialists and emergency medicine physicians, as well as general cardiologists and community-based providers.

An unusual case of Scedosporium apiospermum fungaemia in an immunocompetent patient with a left ventricular assist device and an implantable cardiac device

Left ventricular assist device (LVAD)-related infections are a leading cause of morbidity and mortality, with fungal infections being particularly difficult to manage. We report a case of an immunocompetent 39-year-old male with an LVAD and an implantable cardiac device (ICD) who developed fatal Scedosporium apiospermum fungaemia. To the best of our knowledge, this is the first reported case of LVAD-related S. apiospermum fungaemia.

Infections in children with left ventricular assist device

BACKGROUND

There are limited data about pediatric left ventricular assist device (VAD) infections in developing countries. This study aimed to investigate device postimplantation infectious complications and their pathogenic profile.

METHODS

Data were analyzed from patient charts involving 27 patients with dilated cardiomyopathy who underwent left VAD implantation at a leading tertiary care center in Turkey.

RESULTS

The study included 17 boys and ten girls with a median age of 12.22 years (range 17 months to 18 years). Nineteen patients were diagnosed with idiopathic, and three were diagnosed with familial dilated cardiomyopathy. Twenty-two out of 27 subjects (%81.48) developed 80 infection episodes in total. The most common type of left VAD-specific infection was the exit site of the driveline. Infected patients with left VAD had a significantly prolonged hospitalization compared with the patients without infection (P = .014). Infection-induced pediatric intensive care unit (ICU) admission was higher in patients with fungal infection(P = .023). Gram-positive staphylococci were the most commonly isolated bacterial pathogens, followed by Gram-negative bacteria. Five patients developed fungal infections. None of the fungal infection patients underwent transplantation(P = .035). Seven deaths occurred in our study group. All deaths were in the infected group. Mortality was associated with the presence of multidrug-resistant Gram-negative bacterial infections (P = .015), an increased number of infection episodes (P = .003), and hospitalization due to infection (P = .003).

CONCLUSION

Ventricular assist device-related infections were frequent among our study patients. The predominantly isolated agents were Gram-positive bacterial pathogens. However, the emergence of relatively high rate of Gram-negative bacterial and fungal infections was associated with mortality before the transplantation. Establishing local programs for surveillance data, controlling for infection rates, and antibiotic stewardship are essential to reduce mortality of VAD patients in developing countries.

Bloodstream Infections in Continuous Flow Left Ventricular Assist Device Recipients: Diagnostic and Clinical Implications

Bloodstream infection (BSI) is a common complication of left ventricular assist device (LVAD) support and particularly difficult to treat. The presentation is often variable because of altered physiology and augmentation of cardiac output by the device. We studied LVAD recipients at a single institution. Multivariate logistic and Cox (with time-varying parameters) regression were implemented. Of 212 patients, 58% experienced infections. Driveline infection (DLI) affected 31%, with 60% of them having deep-tissue involvement. Sixty-six patients (31%) suffered from 135 BSIs. Systemic inflammatory response syndrome (SIRS) was present in 47% of BSIs at presentation and associated with increased mortality. Right heart failure, destination therapy, Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) profile, morbid obesity, and deep-DLI were independent risk factors for BSI. The BSI was independently associated with mortality. Bridge-to-transplantation (BTT) patients were more likely to receive transplant if they did not have BSIs. Among 104 BTT patients who received heart transplantation, development of BSI was associated with shorter time-to-transplantation. Diagnosis of BSI poses diagnostic and prognostic challenges because of the hemodynamic profile of LVAD patients who may not mount the expected physiologic response to sepsis. Although SIRS criteria lack sensitivity in the LVAD population, SIRS signifies increased risk for death. Deep DLI was the strongest predictor of BSI. Despite the upgrade in listing status of BTT-LVADs with BSIs and shorter time-to-transplantation, BSI remain a major cause of mortality. BSIs are associated with significant mortality and should be regarded as a serious complication, similar to pump thrombosis and stroke.

Understanding and Addressing Variation in Health Care-Associated Infections After Durable Ventricular Assist Device Therapy: Protocol for a Mixed Methods Study

BACKGROUND

Durable ventricular assist device (VAD) therapy is reserved for patients with advanced heart failure who have a poor estimated 1-year survival. However, despite highly protocolized management processes, patients are at a unique risk for developing a health care-associated infection (HAI). Few studies have examined optimal strategies for HAI prevention after durable VAD implantation, despite variability in rates across centers and their impact on short- and long-term outcomes.

OBJECTIVE

The objective of this study is to develop recommendations for preventing the most significant HAIs after durable VAD implantation. The study has 3 specific aims: (1) identify determinants of center-level variability in HAI rates, (2) develop comprehensive understanding of barriers and facilitators for achieving low center-level HAI rates, and (3) develop and disseminate a best practices toolkit for preventing HAIs that accommodates various center contexts.

METHODS

This is a sequential mixed methods study starting with a cross-sectional assessment of current practices. To address aim 1, we will conduct (1) a systematic review of HAI prevention studies and (2) in-depth quantitative analyses using administrative claims, in-depth clinical data, and organizational surveys of VAD centers. For aim 2, we will apply a mixed methods patient tracer assessment framework to conduct semistructured interviews, field observations, and document analysis informed by findings from aim 1 at 5 high-performing (ie, low HAIs) and 5 low-performing (ie, high HAI) centers, which will be examined using a mixed methods case series analysis. For aim 3, we will build upon the findings from the previous aims to develop and field test an HAI preventive toolkit, acquire stakeholder input at an annual cardiac surgical conference, disseminate the final version to VAD centers nationwide, and conduct follow-up surveys to assess the toolkit's adoption.

RESULTS

The project was funded by the Agency for Healthcare Research and Quality in 2018 and enrollment for the overall project is ongoing. Data analysis is currently under way and the first results are expected to be submitted for publication in 2019.

CONCLUSIONS

This mixed methods study seeks to quantitatively assess the determinants of HAIs across clinical centers and qualitatively identify the context-specific facilitators and barriers for attaining low HAI rates. The mixed data findings will be used to develop and disseminate a stakeholder-acceptable toolkit of evidence-based HAI prevention recommendations that will accommodate the specific contexts and needs of VAD centers.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

PRR1-10.2196/14701.

Prevalence of Implanted Medical Devices in Medicine Inpatients

Implanted medical devices (IMDs) are extremely common, yet they are not systematically documented on hospital admission. Through structured patient interviews, we determined the prevalence of IMDs in hospital inpatients. Using medical record review, we evaluated the sensitivity of the medical record reporting of IMDs on an academic medical inpatient service. Fifty-eight percent of 191 interviewees reported 1 or more IMDs. Participants who reported greater than 1 IMD were older and had more frequent hospitalizations. The most common devices reported were surgical mesh, screws, plates, or wires (n = 47); intravascular stents (n = 25); and prosthetic joint replacements (n = 17). Forty-six patients (24%) reported greater than 1 IMD that had not been recorded in their admission history and physical examination. The prevalence of IMDs in hospitalized patients is high and underestimated in the medical record and may have significant implications for patient care.

Finite Element Driven Design Domain Identification of a Beating Left Ventricular Simulator

Almost ten percent of the American population have heart diseases. Since the number of available heart donors is not promising, left ventricular assist devices are implemented as bridge therapies. Development of the assist devices benefits from both in-vivo animal and in-vitro mock circulation studies. Representation of the heart is a crucial part of the mock circulation setups. Recently, a beating left ventricular simulator with latex rubber and helically oriented McKibben actuators has been proposed. The simulator was able to mimic heart wall motion, however, flow rate was reported to be limited to 2 liters per minute. This study offers a finite element driven design domain identification to identify the combination of wall thickness, number of actuators, and the orientation angle that results in better deformation. A nonlinear finite element model of the simulator was developed and validated. Design domain was constructed with 150 finite element models, each with varying wall thickness and number of actuators with varying orientation angles. Results showed that the combination of 4 mm wall thickness and 8 actuators with 90 degrees orientation performed best in the design domain.

Single Versus Multidrug Regimen for Surgical Infection Prophylaxis in Left Ventricular Assist Device Implantation

Infection is a serious complication of left ventricular assist device (LVAD) therapy. However, an optimal antimicrobial surgical infection prophylaxis (SIP) regimen for LVAD implantation is not well established. We retrospectively reviewed all adults who underwent continuous-flow LVAD implantation from February 2007 to March 2015 at Mayo Clinic Rochester. Left ventricular assist device infection (LVADI) was defined using criteria published by the International Society for Heart and Lung Transplant. Patients excluded from the analysis included those who did not have HeartMate II or HeartWare device, patients with incomplete documentation of SIP, and those with an actively treated infection at the time of LVAD implantation. We compared risk of LVAD-specific and LVAD-related infections and all-cause mortality between SIP regimens at postoperative day 90 and 1 year using Kaplan-Meier time-to-event analyses. During study period, 239 adults underwent continuous-flow LVAD implantation at our institution where 199 patients received single-drug and 40 received multidrug SIP regimen. Median patient age was 62 years. Left ventricular assist device infection occurred in three patients (1.5%) in the single-drug group versus two patients (5.0%) in the multidrug group at 90 days (p = 0.4). There was no difference in infection-free (p = 0.4) and overall survival (p = 0.9) between two groups at 1 year. In conclusion, there was no clear benefit of using multidrug regimen as it did not impact infection-free survival or all-cause mortality compared with single-drug regimen. Prospective clinical trials are needed to further define the optimal SIP regimen for LVAD implantation.

Risk factors and prognostic impact of left ventricular assist device-associated infections

BACKGROUND

Left ventricular assist device (LVAD)-associated infections may be life-threatening and impact patients' outcome. We aimed to identify the characteristics, risk factors, and prognosis of LVAD-associated infections.

METHODS

Patients included in the ASSIST-ICD study (19 centers) were enrolled. The main outcome was the occurrence of LVAD-associated infection (driveline infection, pocket infection, or pump/cannula infection) during follow-up.

RESULTS

Of the 652 patients enrolled, 201 (30.1%) presented a total of 248 LVAD infections diagnosed 6.5 months after implantation, including 171 (26.2%), 51 (7.8%), and 26 (4.0%) percutaneous driveline infection, pocket infection, or pump/cannula infection, respectively. Patients with infections were aged 58.7 years, and most received HeartMate II (82.1%) or HeartWare (13.4%). Most patients (62%) had implantable cardioverter-defibrillators (ICDs) before LVAD, and 104 (16.0%) had ICD implantation, extraction, or replacement after the LVAD surgery. Main pathogens found among the 248 infections were Staphylococcus aureus (n = 113' 45.4%), Enterobacteriaceae (n = 61; 24.6%), Pseudomonas aeruginosa (n = 34; 13.7%), coagulase-negative staphylococci (n = 13; 5.2%), and Candida species (n = 13; 5.2%). In multivariable analysis, HeartMate II (subhazard ratio, 1.56; 95% CI, 1.03 to 2.36; P = .031) and ICD-related procedures post-LVAD (subhazard ratio, 1.43; 95% CI, 1.03-1.98; P = .031) were significantly associated with LVAD infections. Infections had no detrimental impact on survival.

CONCLUSIONS

Left ventricular assist device-associated infections affect one-third of LVAD recipients, mostly related to skin pathogens and gram-negative bacilli, with increased risk with HeartMate II as compared with HeartWare, and in patients who required ICD-related procedures post-LVAD. This is a plea to better select patients needing ICD implantation/replacement after LVAD implantation.

Methicillin-resistant Staphylococcus aureus in solid organ transplantation-Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

These updated guidelines from the American Society of Transplantation Infectious Diseases Community of Practice review the epidemiology, diagnosis, prevention, and management of methicillin-resistant Staphylococcus aureus (MRSA) infections in solid organ transplantation. Despite an increasing armamentarium of antimicrobials active against MRSA, improved diagnostic tools, and overall declining rates of infection, MRSA infections remain a substantial cause of morbidity and mortality in solid organ transplant recipients. Pre- and post-transplant MRSA colonization is a significant risk factor for post-transplant MRSA infection. The preferred initial treatment of MRSA bacteremia remains vancomycin. Hand hygiene, chlorhexidine bathing in the ICU, central-line bundles that focus on reducing unnecessary catheter use, disinfection of patient equipment, and the environment along with antimicrobial stewardship are all aspects of an infection prevention approach to prevent MRSA transmission and decrease healthcare-associated infections.

Ventricular assist device-related infections and solid organ transplantation-Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

The Infectious Diseases Community of Practice of the American Society of Transplantation has published evidenced-based guidelines on the prevention and management of infectious complications in SOT recipients since 2004. This updated guideline reviews the epidemiology of ventricular assist device (VAD) infections and provides recommendations for the management and prevention of these infections. Almost one half of those awaiting heart transplantation are supported with VADs. Despite advances in device technologies, VAD infections commonly complicate mechanical circulatory support and remain typified by common components and anatomic locations. These infections have important implications for transplant candidates, most notably increased wait-list mortality. Strategic management of these infections is crucial for successful transplantation. Coincidentally, explantation of all VAD components at the time of transplantation is often the definitive cure for the device-associated infection. Highlighted in this updated guideline is the reported success of transplantation in patients with a variety of pre-existing VAD infections and guidance on post-transplant management strategies.

Approach to Complications of Ventricular Assist Devices: A Clinical Review for the Emergency Provider

BACKGROUND

Heart failure is a major public health problem in the United States. Increasingly, patients with advanced heart failure that fail medical therapy are being treated with implanted ventricular assist devices (VADs).

OBJECTIVE

This review provides an evidence-based summary of the current data for the evaluation and management of implanted VAD complications in an emergency department context.

DISCUSSION

With a prevalence of >5.8 million individuals and >550,000 new cases diagnosed each year, heart failure is a major public health problem in the United States. Increasingly, patients with advanced heart failure that fail medical therapy are being treated with implanted VADs. As the prevalence of patients with VADs continues to grow, they will sporadically present to the emergency department, regardless of whether the facility is a designated VAD center. As a result, all emergency physicians must be familiar with the basic principles of VAD function, as well as the diagnosis and initial management of VAD-related complications. In this review, we address these topics, with a focus on contemporary third-generation continuous flow VADs. This review will help supplement the critical care skills of emergency physicians in managing this complex patient population.

CONCLUSIONS

The cornerstone of managing the unstable VAD patient is rapid initiation of high-quality supportive care and recognition of device-related complications, as well as the identification and use of specialist VAD teams and other resources for support. Emergency physicians must understand VADs so that they may optimally manage these complex patients.

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.

Single versus multi-drug antimicrobial surgical infection prophylaxis for left ventricular assist devices: A systematic review and meta-analysis

Infection remains the Achilles heel of left ventricular assist device (LVAD) therapy. However, an optimal antimicrobial surgical infection prophylaxis (SIP) regimen has not been established. This study evaluated the efficacy of a single-drug SIP compared to a multi-drug SIP on clinical outcomes in patients undergoing continuous-flow LVAD (CF-LVAD) and pulsatile LVAD (P-LVAD) implantation. An electronic search was performed to identify studies in the English literature on SIP regimens in patients undergoing LVAD implantation. Identified articles were assessed for inclusion and exclusion criteria. Fourteen articles with 1,311 (CF-LVAD: 888; P-LVAD: 423) patients were analyzed. Overall, 501 (38.0%) patients received single-drug SIP, whereas 810 (62.0%) received multi-drug SIP. Time to infection was comparable between groups. There was no significant difference in overall incidence of LVAD-specific infections [single-drug: 18.7% vs. multi-drug: 24.8%, P = 0.49] including driveline infections [single-drug: 14.1% vs. multi-drug: 20.8%, P = 0.37]. Compared to single-drug SIP, patients who received multi-drug SIP had a significantly lower survival rate [single-drug: 90.0% vs. multi-drug: 76.0%, P = 0.01] and infection-free survival rate [single-drug: 88.4% vs. multi-drug: 77.3%, P = 0.04] at 90 days. However, there were no significant differences in 1-year survival and 1-year infection-free survival between groups. No survival differences were observed in the CF-LVAD subset as well. This study demonstrated no additional advantage of a multi-drug compared to a single-drug regimen for SIP. Although there was a modest advantage in early survival among CF-LVAD and P-LVAD patients who received single-drug SIP, there were no significant differences in the 1-year survival and 1-year infection-free survival.

Instillation Negative Pressure Wound Therapy: A Role for Infected LVAD Salvage

Objective: To determine the utility of instillation negative pressure wound therapy (NPWT) in achieving eradication of infection and definitive wound closure in patients with infected left ventricular assist device (LVAD). Approach: A retrospective review was performed in a series of patients with infected and exposed LVADs who were treated with instillation NPWT in conjunction with surgical debridement. Results: Three consecutive patients were included who developed periprosthetic infection subsequent to LVAD implantation. In all cases, the utilization of a vacuum-assisted closure with instillation (VACi) along with surgical debridement and IV antibiotics eradicated infection resulting in successful retention of hardware. Cases 1 and 2 received definitive wound closure within 3 and 12 days of starting treatment, respectively. Case 3 initially deferred surgery in favor of local wound care. Eventually the patient elected for surgical treatment and underwent closure 164 days after initial presentation. All three patients healed completely without residual evidence of infection. Flap reconstruction with a pedicled rectus flap was used to achieve definitive closure in all patients. One patient subsequently required pump replacement secondary to thrombosis and mechanical pump failure. Innovation: LVAD infections are met with high morbidity and mortality rates, and timely salvage is critical. In this initial series, VACi has proven a viable therapy option to help control and eradicate infection without LVAD removal. Conclusion: This series illustrates the value of newer techniques such as VACi in combination with surgical debridement and antibiotic therapy in effectively salvaging LVADs that were infected.

Perioperative Prophylaxis for Total Artificial Heart Transplantation

BACKGROUND

Practice variation regarding perioperative antimicrobial prophylaxis in total artificial heart transplantations (TAH-t) across institutions is unknown. The aim of our survey was to assess the current practices for prevention of infection in TAH-t recipients among different programs.

METHODS

An electronic survey was sent to programs that implant Syncardia TAH (Syncardia Systems, Tuscon, Ariz, USA). Proportions were analyzed for categorical variables; means and SDs were analyzed for continuous variables.

RESULTS

The majority of centers (80.8%) had a formal surgical infection prophylaxis protocol. For non-penicillin-allergic patients, five (20.1%) institutions reported using a 4-drug regimen, seven (29.2%) used a 3-drug regimen, five (20.1%) used a 2-drug regimen, and seven (29.2%) used a cephalosporin alone. Similar data was seen in the penicillin-allergic patients. Infections were reported to occur postoperatively in 52.2% centers. During the first month after TAH-t, bacteremia represented 27.3%, driveline infections 27.2%, pulmonary infections 9%, and mediastinal infections 18.2%. The most common organisms seen within the first month were Candida spp., Escherichia coli, and Pseudomonas aeruginosa (21.4%). In 65% of centers, the mean rate of death post-TAH-t due to infection was 14.5% (SD, 22.3%). The mean rate of patients surviving until orthotopic heart transplantation was 58.6% (SD, 27.7%).

CONCLUSIONS

Preventing infections post-TAH-t is key to decreasing morbidity and mortality. All institutions administered perioperative prophylaxis for TAH-t with significant variation among the centers. The majority of the centers have a formal perioperative prophylactic protocol.

Colonization of medical devices by staphylococci

The use of medical devices in modern medicine is constantly increasing. Despite the multiple precautionary strategies that are being employed in hospitals, which include increased hygiene and sterilization measures, bacterial infections on these devices still happen frequently. Staphylococci are among the major causes of medical device infection. This is mostly due to the strong capacity of those bacteria to form device-associated biofilms, which provide resistance to chemical and physical treatments as well as attacks by the host's immune system. Biofilm development is a multistep process with specific factors participating in each step. It is tightly regulated to provide a balance between biofilm expansion and detachment. Detachment from a biofilm on a medical device can lead to severe systemic infection, such as bacteremia and sepsis. While our understanding of staphylococcal biofilm formation has increased significantly and staphylococcal biofilm formation on medical devices is among the best understood biofilm-associated infections, the extensive effort put in preclinical studies with the goal to find novel therapies against staphylococcal device-associated infections has not yet resulted in efficient, applicable therapeutic options for that difficult-to-treat type of disease.

Targeting Cardiovascular Implant Infection: Multimodality and Molecular Imaging

Owing to their success in clinical practice, the prevalence of cardiovascular implants is continuously increasing. Implant infection is a relevant complication but remains a diagnostic challenge because echocardiography as a first-line test may be limited. Accordingly, a multimodality approach is increasingly used for diagnostic workup and supported by recent guidelines. As reviewed here, computed tomography and nuclear imaging provide incremental diagnostic value and may be combined in a single hybrid imaging session using positron emission tomography/computed tomography or single photon emission computed tomography/computed tomography. Molecular or cellular imaging helps to overcome the limitations of morphological imaging in implants. Larger-scale clinical studies, earlier application in the time course of diagnosis, monitoring of therapy success, technical advances, and novel radiopharmaceuticals will all contribute to sustained growth of advanced infection-targeted imaging in cardiovascular medicine.

Rotary mechanical circulatory support systems

A detailed survey of the current trends and recent advances in rotary mechanical circulatory support systems is presented in this paper. Rather than clinical reports, the focus is on technological aspects of these rehabilitating devices as a reference for engineers and biomedical researchers. Existing trends in flow regimes, flow control, and bearing mechanisms are summarized. System specifications and applications of the most prominent continuous-flow ventricular assistive devices are provided. Based on the flow regime, pumps are categorized as axial flow, centrifugal flow, and mixed flow. Unique characteristics of each system are unveiled through an examination of the structure, bearing mechanism, impeller design, flow rate, and biocompatibility. A discussion on the current limitations is provided to invite more studies and further improvements.

Current status of mechanical circulatory support for treatment of advanced end-stage heart failure: successes, shortcomings and needs

INTRODUCTION

Heart failure (HF) remains a major global burden in terms of morbidity and mortality. Despite advances in pharmacological and resynchronization device therapy, many patients worsen to end-stage HF. Although the gold-standard treatment for such patients is heart transplantation, there will always be a shortage of donor hearts. Areas covered: A left ventricular assist device (LVAD) is a valuable option for these patients as a bridge measure (to recovery, to candidacy for transplant, or to transplant itself) or as destination therapy. This review describes the current indications for and complications of the most commonly implanted LVADs. In addition, we review the potential and promising new LVADs, including the HeartMate 3, MVAD, and other LVADs. Studies investigating each were identified through a combination of online database and direct extraction of studies cited in previously identified articles. Expert commentary: The goal of LVADs has been to fill the gap between patients with end-stage HF who would likely not benefit from heart transplantation and those who could benefit from a donor heart. As of now, the use of LVADs has been limited to patients with end-stage HF, but next-generation LVAD therapy may improve both survival and quality of life in less sick patients.

Infections in Patients with a Total Artificial Heart Are Common but Rarely Fatal

Patients who received a total artificial heart (TAH) at Virginia Commonwealth University (VCU) between January 1, 2010 and December 31, 2011 were identified from the VCU Mechanical Circulatory Support Clinical Database. Retrospective data extraction from the medical records was performed from the time of TAH implantation until heart transplantation or death. Infections were classified as confirmed or suspected. Twenty-seven men and five women, mean age 49.5 years (range 24-68 years) received a TAH. The mean duration of TAH support was 225 days (range 1-1,334 days). Of the 32 patients, 4 (12.5%) died and 28 (87.5 %) underwent heart transplantation. Causes of death were pneumonia (n = 1), TAH malfunction (n = 1), refractory cardiogenic shock (n = 1), and respiratory failure (n = 1). Seventy documented and 13 suspected infections developed in 25 patients (78%). The most common sources of infection were urinary tract (n = 26), respiratory tract (n = 18), and bloodstream (n = 11). There were five pump infections and two driveline infections. The number of infections per patient ranged from 0 to 10. Sixteen different pathogens were identified; the most common were: Klebsiella pneumoniae (n = 15), coagulase-negative Staphylococci (n = 10), Enterococcus species (n = 9), and Enterobacter species (n = 8). Mortality directly attributable to infection was infrequent.

Left ventricular assist device-related infections: a multicentric study

OBJECTIVES

The implantable left ventricular assist device (LVAD) is a major therapeutic development for end-stage heart failure in selected patients. As their use is expanding, infectious complications are emerging, with limited data available to guide their management. We aimed to better characterize LVAD-related infections.

METHODS

We enrolled all consecutive patients diagnosed with LVAD-related infections in three referral centres in France, using a standardized definition of infections in patients with LVAD. Data were collected from medical charts using a standardized questionnaire.

RESULTS

Between 2007 and 2012, 159 patients received LVAD for end-stage heart failure. Among them, 36 (22.6%; 5 women, 31 men) presented at least one infectious complication, after a median time of 2.9 months from LVAD implantation (interquartile range, 1.8-7.5), with a median follow up of 12 months (interquartile range 8-17). Main co-morbidities were alcoholism (33%), diabetes (11%) and immunosuppression (11%). Mean age at implantation was 51 (±11) years. LVAD were implanted as bridge-to-transplantation (n=22), bridge-to-recovery (n=8), destination therapy (n=4), or unspecified (n=2). LVAD-related infections were restricted to the driveline exit site (n=17), had loco-regional extension (n=13), or reached the internal pump (n=3). The main bacteria isolated were Staphylococcus aureus (n=20), coagulase-negative staphylococci (n=7), Enterobacteriaceae (n=14), Pseudomonas aeruginosa (n=10) and Corynebacterium sp. (n=7), with polymicrobial infections in 19 cases. LVAD could be retained in all patients, with the use of prolonged antibacterial treatment in 34 (94%), and debridement in 17 (47%). One patient died due to LVAD-associated infection.

CONCLUSIONS

LVAD-related infections are common after LVAD implantation, and may be controlled by prolonged antibiotic treatment.

Late sequelae of left ventricular assist device infection presenting after heart transplant

The long-term use of left ventricular assist devices (LVADs) is becoming more common among the end-stage heart failure population. At the time of heart transplantation, most of the LVAD is removed, but some of its components might be retained. Retained LVAD prosthetic material can lead to serious infection post heart transplant. We report 4 such cases. Our goal is to highlight the importance of complete prosthetic material removal at the time of cardiac transplant to prevent late-onset infection, especially in patients with preceding infection, but also in patients without evidence of LVAD infection prior to orthotopic heart transplantation.

Left Ventricular Assist Device Driveline Infections

Heart failure is a chronic progressive disease that affects millions of people in the United States. Although medical management of heart failure has helped improve quality of life and survival, end-stage heart failure ultimately requires a heart transplant or long-term left ventricular assist device (LVAD) support. With more patients awaiting transplant, the demand for hearts outweighs the supply of donor hearts. The use of LVADs is increasing in patients with advanced heart failure as a treatment option for those awaiting a heart transplant or as a long-term solution if they are ineligible for a transplant. Although the LVAD is a marvel of modern medicine, infection is a cause of concern because today’s LVADs are powered externally through a percutaneous driveline that can be a major source of infection.

Mechanical Ventricular Assistance as Destination Therapy for End-Stage Heart Failure: Has it Become a First Line Therapy?

Patients with end-stage heart failure have poor quality of life and prognosis. Therapeutic options are scarce and are not available for all. Only few patients can be transplanted every year. Several medical and surgical strategies have shown limited ability to influence prognosis and quality of life. In the past years, technological progress has realized devices capable of providing appropriate hemodynamic stabilization and recovery of secondary organ failure. Recently, these devices have been assessed as definitive treatment for patients who do not qualify for transplantation or/and instead to transplantation (“destination therapy”). This indication is increasingly considered following the results of newest clinical study reporting long-term survival without device correlated adverse events using last generation devices, and acceptable quality of life. The current knowledge about destination therapy and some original data from the DAVID Study (an Italian multicenter prospective study designed to evaluate the patient’s survival rate and quality of life of patients implanted with these new devices as long-term support or destination therapy) are summarized herein.

Suspected involvement of EPTFE membrane in sterile intrathoracic abscess and pericardial empyema in a multi-allergic LVAD recipient: a case report

Device-related infections in recipients of left ventricular assist devices (LVAD) have been recognized as a major source of morbidity and mortality. They require a high level of diagnostic effort as part of the overall burden resulting from infectious complications in LVAD recipients. We present a multi-allergic patient who was treated for persistent sterile intrathoracic abscess formation and pericardial empyema following minimally invasive LVAD implantation including use of a sheet of e-polytetrafluoroethylene (ePTFE) membrane to restore pericardial integrity. Sterile abscess formation and pericardial empyema recurred after surgical removal until the ePTFE membrane was removed, suggesting that in disposed patients, ePTFE may be related to sterile abscess formation or sterile empyema.

Role of gallium SPECT-CT in the diagnosis of left ventricular assist device infections

Infection remains a well-established complication after the placement of left ventricular assist devices (LVADs). Defining the extent of infection is a challenging task as there are few effective imaging modalities and no standardized guidelines regarding imaging in the diagnosis of device-related infections (DRIs). The use of gallium with single photon emission tomography-computed tomography (Ga-SPECT-CT) has not been previously reported in localizing DRIs. We reviewed the charts and images of five patients with LVADs who underwent Ga-SPECT-CT for the diagnosis of various types of DRIs. Gallium SPECT-CT further clarified the extent of infections among LVAD patients, allowing for patient-specific tailored treatments including surgical debridement. Gallium SPECT-CT is a useful tool when diagnosing LVAD infections and could potentially be the imaging modality of choice in the near future. With improved imaging studies, such as Ga-SPECT-CT, allowing for earlier and more accurate diagnoses of DRIs, the outcome of such infections is likely to improve.

Management of the ACC/AHA Stage D patient: mechanical circulatory support

From humble beginnings in 1963 with a single desperately ill patient, mechanical circulatory support has expanded exponentially to where it is a viable alternative for advanced heart failure patients. Some of these patients are awaiting transplant but others will have a mechanical heart pump as their ultimate treatment. The history of MCS devices is reviewed, along with the 4 trials that define the modern era of circulatory support. The practical aspects of life with an MCS device are reviewed and common problems encountered with MCS devices. Future trends including miniaturization and development of completely contained MCS systems are reviewed.

Relationship between early inflammatory response and clinical evolution of the severe multiorgan failure in mechanical circulatory support-treated patients

Background. The mechanical circulatory support (MCS) is an effective treatment in critically ill patients with end-stage heart failure (ESHF) that, however, may cause a severe multiorgan failure syndrome (MOFS) in these subjects. The impact of altered inflammatory response, associated to MOFS, on clinical evolution of MCS postimplantation patients has not been yet clarified. Methods. Circulating cytokines, adhesion molecules, and a marker of monocyte activation (neopterin) were determined in 53 MCS-treated patients, at preimplant and until 2 weeks. MOFS was evaluated by total sequential organ failure assessment score (tSOFA). Results. During MCS treatment, 32 patients experienced moderate MOFS (tSOFA < 11; A group), while 21 patients experienced severe MOFS (tSOFA ≥ 11) with favorable (B group) or adverse (n = 13, C group) outcomes. At preimplant, higher values of left ventricular ejection fraction (LVEF) and estimated glomerular filtration rate (eGFR) were the only parameter independently associated with A group. In C group, during the first postoperative week, high levels of interleukin-8 (IL-8) and tumor necrosis factor (TNF)-α, and an increase of neopterin and adhesion molecules, precede tSOFA worsening and exitus. Conclusions. The MCS patients of C group show an excessive release to IL-8 and TNF-α, and monocyte-endothelial activation after surgery, that might contribute to the unfavourable evolution of severe MOFS.

Evolution and impact of drive-line infection in a large cohort of continuous-flow ventricular assist device recipients

BACKGROUND

Drive-line infections (DLIs) frequently complicate ventricular assist device (VAD) support. We sought to describe the detailed effects of DLIs over time in patients with continuous-flow VADs, including the onset, risk factors, organisms involved, association with invasive infections, and outcomes.

METHODS

We reviewed data for patients with HeartMate II VADs (HMII) who were implanted at the Cleveland Clinic from October 2004 to September 2011 and followed through December 2011. DLIs were defined according to published criteria.

RESULTS

DLIs developed in 45 of 194 HMII VADs over a median period of 232 days (range 22 to 883 days). Hazard for DLI was 2.0%/month, but transiently peaked at 11%/month at 7.5 months after implant. Pseudomonas aeruginosa accounted for 31%, 42% and 55% of initial, final and deep DLIs, respectively. Of the 40 superficial DLIs, 13 (32.5%) became deep. DLI-associated bacteremia and hospitalization occurred in 14 of 45 (31%) and 30 of 45 (67%), respectively. All patients received antibiotics (median 171 days), but only 3 of 44 (6.8%) developed an antibiotic complication. DLIs increased the risk for death while on VAD support (HR 2.20, 95% CI 1.20 to 4.05; p = 0.01). Six and 12 months after DLI, mortality was 9.8% and 31%, but the competing event of transplantation occurred successfully in 20% and 28%, respectively.

CONCLUSIONS

Most DLIs begin superficially with peak hazard at 7.5 months after implant. Depth of infection and infecting organism may evolve over months on support, with Pseudomonas becoming more prominent. Although effectively managed for prolonged periods, DLIs are associated with reduced survival on VAD support. Earlier transplantation is the most successful approach to treatment.

A simple device to secure ventricular assist device driveline and prevent exit-site infection

OBJECTIVES

Driveline infections are one of the most common and important complications in patients with left ventricular assist device (LVAD). One of the causes favouring the development of this complication is the traumatism of the exit site, which occurs in response to movement of the driveline. In this work, we present a simple and feasible method to immobilize the driveline at the level of the exit site.

METHODS

From April 2013 until November 2013, 6 patients underwent implantation of HeartWare LVAD (HVAD) for an end-stage heart failure. When the patient has begun to mobilize after the implantation of the device, we have combined the use of two components with the aim of securing the driveline to the patient's skin: a StatLock system and a silicone suture.

RESULTS

No case of local traumatism and no case of local infection at the driveline were observed during the follow-up. No patient reported pain or swelling at the driveline exit site. All patients were satisfied with their quality-of-life and they do not report any limitations in their daily activities.

CONCLUSIONS

One of the major long-term complications in patients with LVAD is the development of infections of the exit site of the driveline. The trauma of this skin region promotes the onset and maintenance of an inflammatory process and local infectious. Avoiding excessive mobilization of the driveline is likely to reduce the incidence of infections of the exit site and improve the quality-of-life.

Management of patients with implanted ventricular assist devices for noncardiac surgery: a clinical review

While originally primarily used as bridge to cardiac transplantation and bridge to recovery, more commonly ventricular assist devices (VADs) are being inserted as destination therapy. These patients are being discharged from transplant and mechanical assist centers, living as outpatients, and thus the pool of community-dwelling patients with VADs continues to expand. Not infrequently they present for surgical procedures either directly related to the device itself or more often incidental to the fact that they have a VAD. This scenario may be more common in patients with VADs placed for destination therapy because these patients tend to be older and have more comorbidities and are living longer with their device. Thus, it is important for all anesthesiologists to be aware of the special anesthesia needs of patients with VADs requiring noncardiac surgery.

Ethical dilemmas surrounding the use of ventricular assist devices in supporting patients with end-stage organ dysfunction

Successful practice of cardiovascular medicine requires familiarity with the complex ethical issues that accompany therapeutic innovation and diffusion. Even as technologies transition from experimental to standard care, challenges remain. Mechanical circulatory support devices, for instance, are increasingly conceptualized as conventional therapies. Despite this, or perhaps because of it, the ethical issues surrounding the use of these devices in patients with end-stage organ dysfunction are becoming increasingly apparent. In this paper, we provide an introduction to ethical considerations related to the use of ventricular assist devices (VADs) in end-stage organ failure, focusing on three stages or decision points: initiation, continued use, and deactivation. Our goal is not to exhaustively resolve these dilemmas but to illustrate how ethical considerations relate to decision making.

Impact of adverse events on ventricular assist device outcomes

Left ventricular assist devices have been proven to be superior to medical therapy for advanced heart failure patients awaiting heart transplantation and viable alternatives to transplantation for destination therapy patients. Improvements in the design of ventricular assist devices have been rewarded by a decrease in adverse events and an increase in survival. Despite significant progress, even the latest generation left ventricular assist devices are burdened by a significant long-term adverse events profile that will increasingly challenge physicians as patients survive longer on implantable mechanical circulatory support. In this review, we analyze the impact of long-term adverse events on clinical outcomes in the major trials of continuous flow left ventricular assist devices. We discuss several of the more pertinent and interesting adverse events, examine their potential causes, and explore their future implications.