Ventricular assist device-related infections

Left ventricular assist device-associated driveline infections as a specific form of complicated skin and soft tissue infection/acute bacterial skin and skin structure infection - issues and therapeutic options

PURPOSE OF REVIEW

This review comments on the current guidelines for the treatment of wound infections under definition of acute bacterial skin and skin structure infections (ABSSSI). However, wound infections around a catheter, such as driveline infections of a left ventricular assist device (LVAD) are not specifically listed under this definition in any of the existing guidelines.

RECENT FINDINGS

Definitions and classification of LVAD infections may vary across countries, and the existing guidelines and recommendations may not be equally interpreted among physicians, making it unclear if these infections can be considered as ABSSSI. Consequently, the use of certain antibiotics that are approved for ABSSSI may be considered as 'off-label' for LVAD infections, leading to rejection of reimbursement applications in some countries, affecting treatment strategies, and hence, patients' outcomes. However, we believe driveline exit site infections related to LVAD can be included within the ABSSSI definition.

SUMMARY

We argue that driveline infections meet the criteria for ABSSSI which would enlarge the 'on-label' antibiotic armamentarium for treating these severe infections, thereby improving the patients' quality of life.

Design of a hybrid left ventricular assist device with a new wireless charging system

BACKGROUND

The objective of this study was to design a new wireless left ventricular assist device (LVAD) that can be charged without using a conventional transcutaneous energy transfer system (TETS).

METHODS

Our new wireless LVAD was a hybrid pump operating in two different modes: magnetic and electric modes. The pump was driven wirelessly by extracorporeal rotating magnets in magnetic mode, whereas it was driven by electricity provided by an intracorporeal battery in electric mode. A magnetic torque transmission system was introduced to wirelessly transmit torque to the pump impeller. The intracorporeal battery was charged in magnetic mode making use of electromagnetic coils as a generator, whereas the coils were used as a motor in electric mode. To demonstrate the feasibility of our system, we conducted a bench-top durability test for 1 week.

RESULTS

Our hybrid pump had shown sufficient pump performance as a LVAD, with a head pressure of approximately 80 mm Hg and a flow volume of 5.0 L/min, for 1 week. The intracorporeal battery was wirelessly charged enough to power electric mode for 2.5 h a day throughout the 1-week durability test.

CONCLUSIONS

Our hybrid wireless LVAD system demonstrated the possibility of a wireless LVAD and has the potential to reduce medical complications of LVAD therapy.

Candida Infectious Endocarditis and Implantable Cardiac Device Infections

Intravascular diseases due to Candida species, including endocarditis and cardiac device-associated infections, are rare yet devastating manifestations of invasive candidiasis affecting an already vulnerable population. Despite their significant associated morbidity and mortality, limited prospective data exist to inform the optimal diagnostic and therapeutic approaches to these entities. Herein, we review the existing literature pertaining to the epidemiology, diagnosis, and management of infectious endocarditis, rhythm management device infections, and circulatory support device infections caused by Candida species and suggest areas for future research.

Bleeding and thrombotic complications and their impact on mortality in patients supported with left ventricular assist device for cardiogenic shock

INTRODUCTION

Thrombosis and bleeding are major complications in patients supported with left ventricular assist devices (LVADs). We aimed to assess the incidence of bleeding and thrombosis in patients supported with a HeartWare left ventricular assist device (HVAD), their predictive factors and their impact on mortality.

METHODS

A single centre retrospective observational study of patients supported with HVAD over 5 years from January 2015 to October 2020.

RESULTS

A total 139 patients (median age 52.5, 72.1% male) were included for analysis. The probability of 1-year survival was 73.1%. Advanced age (>60 years) and EuroSCORE II score (>20%) were independently associated with reduced survival. Major bleeding and thrombosis occurred in 46.8% and 35.3% respectively. Secondary mechanical circulatory support (MCS) increased likelihood of experiencing major bleeding (HR: 2.76, 95%1.65-4.62, p < 0.0001) whilst patients receiving aspirin were protected from bleeding and thrombosis (HR: 0.34 95% CI 0.19-0.58, p < 0.001). Pre-operative anaemia (HR: 3.02, 95% CI: 1.6-5.7, p = 0.014) and use of a secondary MCS device (HR: 2.78, 95% CI: 1.2-6.3, p = 0.001) were associated with an increased risk of thrombosis. Patients with any major bleeding (with or without thrombosis) had a 7.68-fold (95% CI 3.5-16.8) increased risk of death compared to those without. In contrast, 'thrombosis only' patients had 4.23-fold (95% CI 1.8-10.2) increased risk of death compared to those without thrombosis. The risk of mortality was increased in patients with any thrombosis and the risk of death was highest in patients with major bleeding and thrombosis (HR: 16.49 [95% CI 7.7-35.3]).

CONCLUSIONS

Major bleeding and thrombosis significantly increase the 1-year mortality. Optimal perioperative haemostasis and anticoagulation remains crucial in patients supported with HVAD.

Dynamics of bacterial pathogens at the driveline exit site in patients with ventricular assist devices: A prospective, observational, single-center cohort study

BACKGROUND

Driveline infections (DLIs) at the exit site are frequent in patients with left ventricular assist devices (LVADs). The dynamics from colonization to infection are yet to be investigated. We combined systematic swabbing at the driveline exit site and genomic analyses to study the dynamics of bacterial pathogens and get insights into DLIs pathogenesis.

METHODS

A prospective, observational, single-center cohort study at the University Hospital of Bern, Switzerland was performed. Patients with LVAD were systematically swabbed at the driveline exit site between June 2019 and December 2021, irrespective of signs and symptoms of DLI. Bacterial isolates were identified and a subset was whole-genome sequenced.

RESULTS

Fifty-three patients were screened, of which 45 (84.9%) were included in the final population. Bacterial colonization at the driveline exit site without manifestation of DLI was frequent and observed in 17 patients (37.8%). Twenty-two patients (48.9%) developed at least one DLI episode over the study period. Incidence of DLIs reached 2.3 cases per 1000 LVAD days. The majority of the organisms cultivated from exit sites were Staphylococcus species. Genome analysis revealed that bacteria persisted at the driveline exit site over time. In four patients, transition from colonization to clinical DLI was observed.

CONCLUSIONS

Our study is the first to address bacterial colonization in the LVAD-DLI setting. We observed that bacterial colonization at the driveline exit site was a frequent phenomenon, and in a few cases, it preceded clinically relevant infections. We also provided acquisition of hospital-acquired multidrug-resistant bacteria and the transmission of pathogens between patients.

Treatment of fungal infection on left ventricle assist device driveline exit site: a case report and systematic review

OBJECTIVE

The use of ventricular assist devices (VAD) is increasing; however, diagnosis and management of device complications, such as the driveline exit site (DES) being the portal of entry for fungal infection, is not well known.

METHOD

A systematic review involving searching PubMed (2005 to July 2020) was conducted. The case of a 43-year-old female patient who had a left VAD (LVAD) (HeartMate 3, Abbott, US) is also reported.

RESULTS

The patient was successfully treated with ketoconazole cream and oral fluconazole for likely superficial DES fungal infections. We included 36 studies that met our inclusion criteria; however, only one was included in our review. In the literature, five cases of DES fungal infection were reported, with Candida being the only fungal pathogen.

CONCLUSION

LVAD fungal infections are uncommon but can be responsible for high mortality rates, require a prolonged period of treatment, and can present a huge problem when surgical alternatives are not available. However, Candida species are most common. Fungal infections can only produce clear discharge, and so the classic definition of driveline infection based on purulent secretion can vary. Negative skin culture does not exclude the diagnosis of infection of the DES, and so empirical diagnosis may only be clinically based.

New Wound Management of Driveline Infections with Cold Atmospheric Plasma

The use of ventricular assist devices as a bridge to transplant or as destination therapy has increased. Wound complications increase morbidity in this cohort. Cold atmospheric plasma is a source of reactive oxygen and nitrogen species and can reduce the microbial load in skin wounds without negative effects on the surrounding tissue. We evaluated our cold atmospheric plasma treatment for LVAD driveline infections in a retrospective single-center study for peri- and postintervention outcome analysis. Between April 2019 and September 2019, 15 male patients were included (5 HVAD, 10 HeartMate III). The wounds were treated for a mean of 368.5 s with a reduction of bacterial load in treated wounds in 60% of patients, regardless of the pathogen. The most common pathogen was staphylococcus aureus (n = 8 patients). There was a significant reduction of the wound scale (scale 2.80 vs. 1.18; p < 0.001) plus a significant reduction in size (16.08 vs. 1.90 cm3; p = 0.047). Seven patients (46.6%) were free from any signs of local or systemic infection during 1-year follow-up. Five patients (33%) received a heart transplantation. Cold atmospheric plasma treatment is a potent, safe, and painless adjuvant technique for treating driveline infection without the need for repeating surgical interventions.

Wound Infections in Adult Patients after Berlin Heart® EXCOR Biventricular Assist Device Implantation

Simple Summary

Our study shows that the Berlin Heart^® EXCOR as a biventricular assist device in adult patients is an effective strategy in heart failure medicine. Our results may increase the use of the EXCOR with acceptable clinical outcomes despite long support times. With ongoing research to implement the EXCOR as a permanent right ventricular assist device, our results highlight possible arising complications.

Abstract

The Berlin Heart^® EXCOR is a paracorporeal, pulsatile ventricular assist device used in patients of all age groups. However, adolescent and adult patients on EXCOR support are scarcely explored. Herein, we present a detailed description of infectious complications in this patient cohort. From 2006 to 2020, 58 patients received a biventricular assist device (BiVAD) at our institution and were included in this study. Postoperative infections were assessed after BiVAD implantation and subsequent heart transplantation (HTx). A Berlin Heart^® EXCOR BiVAD was implanted as a bridge to transplantation in 58 patients (12–64 years). Most patients were INTERMACS I, and their median age was 49 years. Wound infections (WI) specific to the ventricular assist device (VAD) occurred in 31 (53.4%) patients with a mean time of 113 ± 155 days after BiVAD implantation. HTx was performed in 30 (51.7%) patients and thereof 10 (33.3%) patients developed at least one WI post-HTx. The mean time of WI after HTx was 17 ± 14 days. In four cases, WIs were caused by the same pathogen as before HTx. According to our institutional BiVAD wound classification, the mean wound score was 3. The VAD-specific wound infections were manageable and did not increase mortality nor precluded HTx in Berlin Heart^® EXCOR patients. No specific risk factors for VAD-specific wound infections could be identified.

Local Treatment of Driveline Infection with Bacteriophages

Drive line infections (DLI) are common infectious complications after left ventricular assist devices (LVAD) implantation. In case of severe or persistent infections, when conservative management fails, the exchange of the total LVAD may become necessary. We present a case of successful treatment of DL infection with a combination of antibiotics, debridement and local bacteriophage treatment.

Pre-operative risk factors for driveline infection in left ventricular-assist device patients

AIMS

Implantation of left ventricular-assist devices (LVAD) to treat end-stage heart failure is of increasing relevance due to donor shortage. Infections of the driveline are common adverse events. LVAD infections can lead to high urgency listings for transplantation. However, transplantation in patients with infection leads to worse post-transplantation outcomes. This study aims to evaluate specific risk factors for driveline infections at the time of implantation.

METHODS AND RESULTS

Four hundred forty-one patients receiving either Heartmate II or Heartware system from August 2009 to October 2013 were assessed. An expert committee sorted patients into four different groups concerning the likeliness of infection. Twenty-eight (6%) of discussed infection cases were judged as secured, 33 (7%) as likely, 18 (4%) as possible, and 20 (4%) as unlikely. The remaining 342 (78%) subjects showed either no signs of infection at all times (329 [75%]) or developed signs of infection in a second observation period within 1 year after ending of the first observation period (13 [3%]). For a better discriminatory power, cases of secured and likely infections were tested against the group with no infection at all times in a Cox proportional hazard model. Among all variables tested by univariate analysis (significance level P < 0.15), only age (P = 0.07), LVAD-type (P = 0.12), need for another thoracic operation (P = 0.02), and serum creatinine value (P = 0.02) reached statistical significance. These were subsequently subjected to multivariate analysis to calculate the cumulative risk of developing a drive infection. The multivariate analysis showed that of all the potential risk factors tested, only the necessity of re-thoracotomy or secondary thoracic closure had a significant, protective effect (hazard ratio [95% CI] = 0.45 [0.21-0.95]; P = 0.04).

CONCLUSION

This single-centre cohort study shows that driveline infections are common adverse events. The duration of support represents the major risk factor for LVAD driveline infections.

Decreasing driveline infections in patients supported on ventricular assist devices: a care pathway approach

Background

Driveline infections (DLIs) are a common adverse event in patients on ventricular assist devices (VADs) with incidence ranging from 14% to 59%. DLIs have an impact on patients and the healthcare system with efforts to prevent DLIs being essential. Prior to our intervention, our program had no standard driveline management presurgery and postsurgery. The purpose of this Quality Improvement (QI) initiative was to reduce DLIs and related admissions among patients with VAD within the first year post implant.

Methods

In anticipation of the QI project, we undertook a review of the programs’ current driveline management procedures and completed a survey with patients with VAD to identify current barriers to proper driveline management. Retrospective data were collected for a pre-QI intervention baseline comparison group, which included adult patients implanted with a durable VAD between 1 January 2017 and 31 July 2018. A three-pronged care pathway (CP) was initiated among patients implanted during August 2018 to July 2019. The CP included standardised intraoperative, postoperative and predischarge teaching initiatives and tracking. Using statistical process control methods, DLIs and readmissions in the first year post implant were compared between patients in the CP group and non-CP patients. P-charts were used to detect special cause variation.

Results

A higher proportion of CP group patients developed a DLI in the first year after implant (52% vs 32%). None developed a DLI during the index admission, which differed from the non-CP group and met criteria for special cause variation. There was a downward trend in cumulative DLI-related readmissions among CP group patients (55% vs 67%). There was no association between CP compliance and development of DLIs within 1 year post implant.

Conclusion

The CP did not lead to a reduction in the incidence of DLIs but there was a decrease in the proportion of patients with DLIs during their index admission and those readmitted for DLIs within 1 year post implant. This suggests that the CP played a role in decreasing the impact of DLIs in this patient population. However, given the short time period of follow-up longer follow-up will be required to look for sustained effects.

Does infection predispose to thrombosis during long term ventricular assist device support?

BACKGROUND

Infections and thrombotic events remain life-threatening complications in patients with ventricular assist devices (VAD).

METHODS

We describe the relationship between both events in our cohort of patients (n=220) supported with the HeartWare VAD (HVAD). This is a retrospective analysis of patients undergoing HVAD implantation between July 2009 and March 2019 at the Freeman Hospital, Newcastle upon Tyne, United Kingdom.

RESULTS

Infection was the most common adverse event in HVAD patients, with 125 patients (56.8%) experiencing ≥ one infection (n=168, 0.33 event-per-person-year-EPPY), followed by pump thrombosis (PT) in 61 patients (27.7%, 0.16 EPPY). VAD-specific infections were the largest group of infections. Of the 125 patients who had an infection, 66 (53%) had a thrombotic event. Both thrombotic events and infections were related to the duration of support, though there was only limited evidence that infections predispose to thrombosis. Those with higher than median levels of CRP during the infection were more likely to have an ischaemic stroke (IS) (34.5% vs 16.7%, p=0.03), though not PT or a combined thrombotic event (CTE: first PT or IS). However, in multivariate analysis there was no significant effect of infection predisposing to CTE.

CONCLUSIONS

Infection and thrombotic events are significant adverse events related to the duration of support in patients receiving HVADs. Infections do not clearly predispose to thrombotic events.

Non-patient factors associated with infections in LVAD recipients: A scoping review

BACKGROUND

Infections are the most common complication in recipients of durable left ventricular assist devices (LVAD) and are associated with increased morbidity, mortality, and expenditures. The existing literature examining factors associated with infection in LVAD recipients is limited and principally comprises single-center studies. This scoping review synthesizes all available evidence related to identifying modifiable, non-patient factors associated with infections among LVAD recipients.

METHODS

Published studies were identified through searching 5 bibliographic databases: PubMed, Scopus, EMBASE, CINAHL, and Web of Science Core Collection. Inclusion criteria required examination of factors associated with infections among recipients of contemporary, implantable, continuous flow LVADs. Key study characteristics were extracted by 4 independent reviewers and current literature described narratively. The Systems Engineering Initiative for Patient Safety (SEIPS) model was used to develop a taxonomy for non-patient related factors (e.g., tasks, tools, technologies, organization, and environment) associated with infections following LVAD implantation. All analyses took place between February 2019 and May 2021.

FINDINGS

A total of 43 studies met inclusion criteria. The majority of included studies were observational (n = 37), single-center (n = 29), from the U.S. (n = 38), and focused on driveline infections (n = 40). Among the 22 evaluated sub-domains of non-patient related factors, only two: increasing center experience and establishing a silicone-skin interface at the driveline exit site, were identified as consistently being associated with a lower risk of infection.

CONCLUSION

This review identified 43 studies that described non-patient related factors associated with infection in LVAD recipients. Only two factors were consistently associated with lower infection risk in LVAD recipients: increasing experience and establishing a silicone-skin interface at driveline exit site. The large variability in reporting across multiple studied interventions limited the ability to discern their effectiveness.

Cerebrovascular Disease and Cognitive Outcome in Patients with Cardiac Disease

The pace of understanding cognitive decline and dementia has rapidly accelerated over the past decade, with constantly evolving insights into the vascular contributions to cognitive impairment and dementia (VCID). Notably, more overlap has been discovered in the pathophysiology between what was previously understood to be Alzheimer's disease and VCID, leading to a heightened emphasis on disease prevention through early and aggressive control of vascular risk factors. One particularly vulnerable population may be those with cardiac disease, as they are at risk for cerebrovascular disease, which itself can lead to dementia, and increasing evidence supports cognitive impairment in disease processes such as heart failure and atrial fibrillation, independent of ischemic stroke, suggesting other potential mechanisms. In this article, we review the evidence supporting the relationship between cardiac disease, cerebrovascular disease, and cognitive decline and discuss the ongoing and future research efforts aimed at defining the important relationship between these entities.

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.

Incidence of Infection and Antimicrobial Consumption in Ventricular Assist Device (VAD) Recipients at the Prince Charles Hospital (TPCH): A Retrospective Analysis

BACKGROUND

Ventricular assist devices (VADs) are frequently used as a bridge to heart transplant; however, infections are a common cause of increased morbidity and mortality. The optimal prophylactic antimicrobial regimen has not been effectively evaluated in literature.

METHODS

Forty-three (43) patients received a VAD over the 5-year study period (2012-2017) at The Prince Charles Hospital (TPCH), Brisbane Australia. Of these, 41 patients were followed from implantation until transplantation or death. Antimicrobial prophylactic regimens and individual episodes of infection were recorded. The infection profiles, including types and incidence were compared to published literature using definitions from the International Society for Heart and Lung Transplantation (ISHLT) guidelines for consistency.

RESULTS

Median duration of VAD insertion was 79 days (IQR: 36-167). Patients received aztreonam, fluconazole and vancomycin (median duration 8 days). Twenty-two (22) (53.6%) patients experienced a VAD-specific and/or a VAD-related infective episode. Incidence of infection in the study cohort was 0.60 infections per 100 patient days. Thirteen (13) patients (31.7%) experienced 16 VAD-specific infections which were all driveline infections. Thirteen (13) patients (31.7%) experienced 14 VAD-related infections. The predominant VAD-related infection type was bacteraemia (36%). Predominant bacterial profiles of VAD-specific as well as VAD related infections were gram positive. Only three episodes had a gram negative as a causative pathogen which occurred much later post VAD insertion. Median time till VAD-specific or VAD-related infection was 46 and 15 days respectively. Obesity was significantly associated with increased risk of infection (HR: 3.2; 95% CI: 1.3-7.4).

CONCLUSIONS

Infection is a common complication of VAD implantation. In our study population gram positive bacteria were the predominant causative pathogen. Based on the micro-organism profile there may be scope for a narrowing of the antibiotic regimen. A larger, multicentre study would be able to accurately guide a change. The information gathered in our study offers a strong foundation for such a multicentre study.

Nasal colonization with Staphylococcus aureus is a risk factor for ventricular assist device infection in the first year after implantation: A prospective, single-centre, cohort study

OBJECTIVES

To assess, whether S. aureus nasal colonization is a risk factor for infections in patients with durable ventricular assist device (VAD).

METHODS

Prospective, single-centre, cohort study (i) ascertaining S. aureus nasal colonization status of patients admitted for VAD-implantation and detecting time to first episode of VAD-specific or -related infection according to International Society for Heart and Lung Transplantation criteria during follow-up and (ii) comparing whole genomes of S. aureus from baseline colonization and later infection.

RESULTS

Among 49 patients (17 colonized, 32 non-colonized), S. aureus VAD-infections occurred with long latency after implantation (inter quartile range 76-217 days), but occurred earlier (log-rank test P = 0.006) and were more common (9/17, 52.9% vs. 4/32, 12.5%, P = 0.005; incidence rates 2.81 vs. 0.61/1000 patient days; incidence rate ratio 4.65, 95% confidence interval 1.30-20.65, P = 0.009) among those nasally colonized with S. aureus before implantation. We found a similar but less pronounced effect of colonization status when analysing its effect on all types of VAD-infections (10/17, 58.8% vs. 7/32, 21.9%, P = 0.01). These findings remained robust when adjusting for potential confounders and restricting the analysis to 'proven infections'. 75% (6/8) of paired S. aureus samples from colonization and VAD-infection showed concordant whole genomes.

CONCLUSIONS

In patients with durable VAD, S. aureus nasal colonization is a source of endogenous infection, often occurring months after device-implantation and affecting mostly the driveline. Hygiene measures interrupting the endogenous route of transmission in VAD-patients colonized with S. aureus long-term may about half the burden of infections and require clinical scrutiny.

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.

Magnetically Active Cardiac Patches as an Untethered, Non-Blood Contacting Ventricular Assist Device

Patients suffering from heart failure often require circulatory support using ventricular assist devices (VADs). However, most existing VADs provide nonpulsatile flow, involve direct contact between the blood flow and the device's lumen and moving components, and require a driveline to connect to an external power source. These design features often lead to complications such as gastrointestinal bleeding, device thrombosis, and driveline infections. Here, a concept of magnetically active cardiac patches (MACPs) that can potentially function as non-blood contacting, untethered pulsatile VADs inside a magnetic actuationsystem is reported. The MACPs, which are composed of permanent magnets and 3D-printed patches, are attached to the epicardial surfaces, thus avoiding direct contact with the blood flow. They provide powerful actuation assisting native heart pumping inside a magnetic actuation system. In ex vivo experiments on a healthy pig's heart, it is shown that the ventricular ejection fractions are as high as 37% in the left ventricle and 63% in the right ventricle. Non-blood contacting, untethered VADs can eliminate the risk of serious complications associated with existing devices, and provide an alternative solution for myocardial training and therapy for patients with heart failure.

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.

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.

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.

Efficacy of Antiseptic Solutions in Treatment of Staphylococcus Aureus Infected Surgical Wounds with Patches of Vascular Graft: An Experimental Study in Rats

Background and objectives: Treatment of a prosthetic vascular graft infection (PVGI) remains a challenging problem in vascular surgery. The aim of this study was to design a novel rat model for treatment of peripheral vascular prosthesis infection caused by Staphylococcus aureus (S. aureus) and to determine the efficacy of different antiseptic solutions in suppressing or eradicating infection from the wound and the graft material itself. Materials and methods: A piece of Dacron vascular prosthesis was surgically implanted at the dorsum of 48 Wistar rats and the wounds were infected with 5 McFarland standard inoculum of S. aureus. Suppurating wounds were daily irrigated with different antiseptic solutions: octenidine dihydrochloride, povidone-iodine, chlorhexidine digluconate, and sterile saline. The antimicrobial action of antiseptics was defined according to their capability to eradicate bacteria from the graft surroundings and bacteriological examination of the graft itself. Extended studies on wound microbiology, cytology, and histopathology were performed with an additional group of 10 rats, treated with the most effective antiseptic-octenidine dihydrochloride. Results: Four-day treatment course with octenidine, povidone-iodine, and chlorhexidine resulted in 99.98% (p = 0.0005), 90.73% (p = 0.002), and 65.97% (p = 0.004) decrease in S. aureus colonies in wound washouts, respectively. The number of S. aureus colonies increased insignificantly by 19.72% (p = 0.765) in control group. Seven-day treatment course with octenidine eradicated viable bacteria from nine out of 10 wound washouts and sterilized one vascular graft. Conclusions: A reproducible rat model of PVGI with a thriving S. aureus infection was designed. It is a first PVGI animal model where different antiseptic solutions were applied as daily irrigations to treat peripheral PVGI. Seven-day treatment with octenidine eradicated bacteria from the wound washouts for 90% of rats and one vascular graft. Further studies are needed to investigate if irrigations with octenidine could properly cure vascular bed from infection to assure a successful implantation of a new synthetic vascular substitute.

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.

Driveline Site Is Not a Predictor of Infection After Ventricular Assist Device Implantation

Driveline infections (DLIs) remain a major source of morbidity for patients requiring long-term ventricular assist device (VAD) support. We aimed to assess whether VAD driveline exit site (DLES) (abdomen versus chest wall) is associated with DLI. All adult patients who underwent insertion of a HeartWare HVAD or HeartMate II (HMII) between 2009 and 2016 were included. Driveline infection was defined as clinical evidence of DLI accompanied by a positive bacterial swab and need for antibiotics. Competing risks analysis was used to assess the association between patient characteristics and DLI. Ninety-two devices (59 HMII) were implanted in 85 patients (72 men; median age 57.4 years) for bridge to transplant or destination therapy. VAD DLES was chest in 28 (30.4%) devices. Median time on VAD support was 347.5 days (IQR 145.5, 757.5), with 28 transplants and 29 deaths (27 on device). DLI occurred in 24 patients (25 devices) at a median of 140 days (IQR 67, 314) from implant. Staphylococcus aureus accounted for 15 infections (60%). Freedom from infection was 72.8% (95% confidence interval [CI] 53.1-78.0%) at 1 year and 41.9% (95% CI 21.1-61.5%) at 3 years. In competing risks regression, abdominal DLES was not predictive of DLI (hazard ratio, HR 1.65 [95% CI 0.63, 4.29]), but body mass index (BMI) >30 kg/m was (HR 2.72 [95% CI 1.25, 5.92]). In conclusion, risk of DLI is high among patients on long-term VAD support, and a nonabdominal DLES does not reduce this risk. The only predictor of DLI in this series was an elevated BMI.

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.

The Rehabilitation of Patients With Advanced Heart Failure After Left Ventricular Assist Device Placement: A Narrative Review

Because more patients with advanced heart failure are receiving a left ventricular assist device (LVAD) as destination therapy or a bridge to transplantation, there is increasing attention on functional outcomes and quality of life after LVAD implantation. Rehabilitation providers in the acute inpatient rehabilitation setting increasingly will treat patients with an LVAD and should understand the exercise physiology, medical management, rehabilitation considerations, and outcomes after rehabilitation for patients with an LVAD. The purpose of this article is to provide the physiatrist with a comprehensive understanding of the rehabilitation of patients with advanced heart failure and LVAD implantation. Changes in relevant organ system physiology and exercise physiology after LVAD are summarized. Safety of rehabilitation and program considerations for acute inpatient rehabilitation are reviewed. Recommendations for medical management and prevention of secondary complications seen in patients with an LVAD are outlined. A discussion of outcomes after acute inpatient rehabilitation, the dual diagnosis of stroke and LVAD placement, and long-term cognitive, functional, and quality-of-life outcomes after LVAD placement is presented.

The impact of infection among left ventricular assist device recipients on post-transplantation outcomes: A retrospective review

INTRODUCTION

Left ventricular assist device (LVAD) infections are common, and the consequences of LVAD infections on orthotopic heart transplantation (OHT) outcomes are not well described.

AIMS

The aim of this study was to describe clinical characteristics and evaluate risk factors for developing LVAD infections, and examine outcomes of LVAD-specific infections (VSI) after OHT.

METHODS

We retrospectively investigated the records of 74 consecutive patients at two institutions who had undergone LVAD placement and subsequent OHT between January 2007 and December 2012.

RESULTS

Forty-six of 74 (62%) LVAD recipients who underwent OHT had pre-transplant infections, and 18 (24%) had LVAD-specific infection (VSI), of which 71% were caused by gram-negative organisms. Of pre-transplant non-LVAD infections, Clostridium difficile infection (CDI) was the most common (26%) followed by urinary tract infection (UTI, 16%) and pneumonia (PNA 15%). Univariate analysis comparing subjects with VSI to those without VSI showed a significant association with time spent outside the hospital prior to transplantation (median 231.8 days vs 142.2 days, P < 0.03) and total time between VAD placement and OHT (244.0 days and 150.5 days, P < 0.002). Logistic regression was performed and significant predictors for VAD-related infection were age and the presence of diabetes, with type of device as an effect modifier. Six months post-OHT survival was not significantly affected by the presence of VSI prior to transplant. There was a trend toward an association between the presence of any infection and post-transplant rejection (P < 0.09). There were 10 post-transplant deaths by 6 months. Of these deaths, 4/10 (40%) were cardiopulmonary and 6/10 (60%) were related to infections.

CONCLUSIONS

Advanced age and presence of diabetes were predictors of VSI, as well as type of VAD device, although device choice is likely affected by many clinical factors including age and comorbidities, as well as institution-specific preferences. VSI was not associated with a decrease in 6-month post-OHT survival. However, infections remain the major causes of death by 6 months post-transplant. Certain infections are associated with an increased risk of rejection, which merits further investigation.

Interfacial tissue engineering of heart regenerative medicine based on soft cell-porous scaffolds

Myocardial infarction (MI), occurs when the coronary artery is occluded resulting in the hypoxia of areas in heart tissue, is increasing in recent years because of the population ageing and lifestyle changes. Currently, there is no ideal therapeutic scheme because of the limitation of MI therapeutic strategies due to the lack of regenerative ability of the heart cells in adult humans. Recent advances in tissue engineering and regenerative medicine brings hope to the MI therapy and current studies are focusing on restoring the function and structure of damaged tissue by delivering exogenous cells or stimulating endogenous heart cells. However, attempts to directly inject stem cells or cardiomyocytes to the infract zone often lead to rapid cell death and abundant cell loss. To address this challenge, various soft repair cells and porous scaffold materials have been integrated to improve cell retention and engraftment and preventing left ventricle (LV) dilatation. In this article, we will review the current method for heart regeneration based on soft cell-porous scaffold interfacial tissue engineering including common stem cell types, biomaterials, and cardiac patch and will discuss potential future directions in this area.

Mycobacterium abscessus Left Ventricle Assist Device Driveline Infections: An Emerging Pathogen?

The use of left ventricular assist device is associated with improvement in survival in patients with refractory heart failure. However, driveline infection limits the success of its use as it is associated with significant mortality. We describe the first 2 cases of Mycobacterium abscessus driveline infection. Both patients had persistent infection despite of aggressive antibiotic treatment and local debridement, and only improved after removal of their left ventricular assist devices.

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.

Novel driveline route for prevention from driveline infection: Triple tunnel method

BACKGROUND

The most prevalent and serious infection related to left ventricular assist devices (LVADs) is driveline infection (DLI). From 2014, we employed a revised surgical technique (triple tunnel method), which deployed a longer subfascial driveline (DL) route.

METHODS AND PATIENTS

We retrospectively analyzed 34 patients fitted with either of the two types of axial pumps: HeartMate II (n=23) and Jarvik 2000 (n=11). Prior to 2014, the DL proceeded from the pump pocket just above the posterior sheath of the rectus muscle toward a vertical skin incision at the right lateral border of the rectus muscle. Then, DL was turned leftward into the subcutaneous tissue to redirect its exit to the left side [subcutaneous tissue group (Group S): n=14]. From 2014, we made an additional skin incision below the umbilicus with the aim of lengthening the subfascial DL route [muscle group (Group M): n=20].

RESULTS

DLI occurred in 10 patients (71.4%) in Group S and in 1 patient (5%) in Group M (p<0.05, Chi-square test). The freedom rate from re-admission at 1 year due to DLI was 64% in Group S and 95% in Group M, respectively (p=0.021, log-rank test). Furthermore, logistic regression analysis revealed that DL route was significantly associated with DLI (odds ratio, 10.1; 95% confidence interval, 1.15-275.3).

CONCLUSION

Although a longer follow-up period will be needed, the triple tunnel method may be beneficial in the prevention of DLI.

Outcome of pediatric heart transplantation in blood culture positive donors in the United States

Active donor infection at the time of organ procurement poses a potential infection risk and may increase post-transplant morbidity and mortality in recipients. Our hypothesis was that pediatric heart transplant recipients from blood culture positive donors (BCPD) would have increased morbidity and mortality compared to non-blood culture positive donors (NBCPD). A retrospective analysis of pediatric heart transplant recipients using the organ procurement and transplant network (OPTN) between 1987 and 2015 was conducted. Recipient as well as donor data were analyzed. Propensity score matching with 1:2 ratios was performed for recipient variables. Post-transplant morbidity and mortality were compared for recipients of BCPD and NBCPD. Among 9618 heart transplant recipients, 450 (4.7%) were from culture positive donors. Recipients of BCPD had longer duration of listing as Status 1; diagnosis of congenital heart disease or restrictive cardiomyopathy and required support (IV inotropes, Inhaled NO and LVAD) prior to transplant. Post-transplant survival between the 2 groups was not different. Propensity-matched recipients had similar length of stay; stroke rate; need for dialysis; pacemaker implantation and treated rejection episodes in the first year post-transplant. Careful acceptance of BCPD may have the potential to increase availability of donor hearts in the pediatric population.

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.

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.

Driveline Infection in Ventricular Assist Devices and Its Implication in the Present Era of Destination Therapy

Advances in mechanical circulatory support devices provided the technology to develop long-term, implantable left ventricular assist devices as bridge to transplant, destination therapy, and in a lesser group of patients, as bridge to recovery. Despite the benefits from this innovative therapy, with their increased use, many complications have been encountered, one of the most common being infections. With the driveline acting as a portal to the exterior environment, an infection involving this structure is the most frequent one. Because patients with destination therapy are expected to receive circulatory support for a longer period of time, we will focus this review on the risk factors, prevention, and treatment options for driveline infections.

Identification of Genes Controlled by the Essential YycFG Two-Component System Reveals a Role for Biofilm Modulation in Staphylococcus epidermidis

Biofilms play a crucial role in the pathogenicity of Staphylococcus epidermidis, while little is known about whether the essential YycFG two-component signal transduction system (TCS) is involved in biofilm formation. We used antisense RNA (asRNA) to silence the yycFG TCS in order to study its regulatory functions in S. epidermidis. Strain 1457 expressing asRNA_yycF exhibited a significant delay (~4–5 h) in entry to log phase, which was partially complemented by overexpressing ssaA. The expression of asRNA_yycF and asRNA_yycG resulted in a 68 and 50% decrease in biofilm formation at 6 h, respectively, while they had no significant inhibitory effect on 12 h biofilm formation. The expression of asRNA_yycF led to a ~5-fold increase in polysaccharide intercellular adhesion (PIA) production, but it did not affect the expression of accumulation-associated protein (Aap) or the release of extracellular DNA. Consistently, quantitative real-time PCR showed that silencing yycF resulted in an increased transcription of biofilm-related genes, including icaA, arlR, sarA, sarX, and sbp. An in silico search of the YycF regulon for the conserved YycF recognition pattern and a modified motif in S. epidermidis, along with additional gel shift and DNase I footprinting assays, showed that arlR, sarA, sarX, and icaA are directly regulated by YycF. Our data suggests that YycFG modulates S. epidermidis biofilm formation in an ica-dependent manner.

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.

Tissue Engineering Strategies for Myocardial Regeneration: Acellular Versus Cellular Scaffolds?

Heart disease remains one of the leading causes of death in industrialized nations with myocardial infarction (MI) contributing to at least one fifth of the reported deaths. The hypoxic environment eventually leads to cellular death and scar tissue formation. The scar tissue that forms is not mechanically functional and often leads to myocardial remodeling and eventual heart failure. Tissue engineering and regenerative medicine principles provide an alternative approach to restoring myocardial function by designing constructs that will restore the mechanical function of the heart. In this review, we will describe the cellular events that take place after an MI and describe current treatments. We will also describe how biomaterials, alone or in combination with a cellular component, have been used to engineer suitable myocardium replacement constructs and how new advanced culture systems will be required to achieve clinical success.

Prevention and Infection Management in Mechanical Circulatory Support Device Recipients

There are currently no guidelines for the management of infection and its prevention in mechanical circulatory support (MCS) device recipients. The International Society of Heart and Lung Transplantation (ISHLT) has initiated a multidisciplinary collaboration for the creation of a consensus document to guide clinicians in infection prevention and management in MCS patients. Most medical centers use local protocols that are based on expert opinion. MCS recipients are debilitated and have some immunological dysfunction. Over the years there have been technical advancements with smaller devices and drivelines with improved durability. The pulsatile devices have been replaced with newer-generation continuous-flow devices. Patient are living longer with MCSs for bridge to transplant (BTT) and destination therapy (DT). MCS centers have improved patient management by introducing standardized driveline protocols, leading to reduced infection rates among MCS recipients.

Mechanical Circulatory Support: Heart Failure Therapy “in Motion”

Because the first generation of pulsatile-flow devices was primarily used to bridge the sickest patients to transplantation (bridge-to-transplant therapy), the current generation of continuous-flow ventricular assist devices qualifies for destination therapy for patients with advanced heart failure who are ineligible for transplantation. The first-generation devices were associated with frequent adverse events, limited mechanical durability, and patient discomfort due device size. In contrast, second-generation continuous-flow devices are smaller, more quiet, and durable, thus resulting in less complications and significantly improved survival rates. Heart transplantation remains an option for a limited number of patients only, and this fact has also triggered the discussion about the optimal timing for device implantation. The increasing use of continuous-flow devices has resulted in new challenges, such as adverse events during long-term support, and high hospital readmission rates. In addition, there are a number of device-related complications including mechanical problems such as device thrombosis, percutaneous driveline damage, as well as conditions such as hemolysis, infection, and cerebrovascular accidents. This review provides an overview of the evolution of mechanical circulatory support systems from bridge to transplantation to destination therapy including technological advances and clinical improvements in long-term patient survival and quality of life. In addition, recent changes in device implant strategies and current trials are reviewed and discussed. A brief glimpse into the future of mechanical circulatory support therapy will summarize the innovations that may soon enter clinical practice.

Ventricular assist devices and sleep-disordered breathing

Congestive heart failure is one of the leading causes of morbidity and mortality in the United States, and left ventricular assist devices have revolutionized treatment of end-stage heart failure. Given that sleep apnea results in significant morbidity in these patients with advanced heart failure, practicing sleep physicians need to have an understanding of left ventricular assist devices. In this review, we summarize what is known about ventricular assist devices as they relate to sleep medicine.

Endocarditis in left ventricular assist device

Heart failure is one of the leading causes of death in developed nations. End stage heart failure often requires cardiac transplantation for survival. The left ventricular assist device (LVAD) has been one of the biggest evolvements in heart failure management often serving as bridge to transplant or destination therapy in advanced heart failure. Like any other medical device, LVAD is associated with complications with infections being reported in many patients. Endocarditis developing secondary to the placement of LVAD is not a frequent, serious and difficult to treat condition with high morbidity and mortality. Currently, there are few retrospective studies and case reports reporting the same. In our review, we found the most common cause of endocarditis in LVAD was due to bacteria. Both bacterial and fungal endocarditis were associated with high morbidity and mortality. In this review we will be discussing the risk factors, organisms involved, diagnostic tests, management strategies, complications, and outcomes in patients who developed endocarditis secondary to LVAD placement.

A simple education tool for ventricular assist device patients and their caregivers

BACKGROUND

Ventricular assist devices (VADs) have become an important therapy in the management of patients with end-stage heart failure. Driveline infection is the most common late-onset complication in this group of patients. Patients and their caregivers require education regarding management of the driveline to reduce the risk of infection when they are discharged home with a VAD.

PURPOSE

The aim of this study was to develop an educational booklet on VAD driveline care for patients and their caregivers. A literature review was undertaken to explore the availability of patient education material pertaining to driveline management and to update evidence-informed knowledge that could potentially reduce infection rates in these patients. This information was evaluated by peers, patients, and caregivers to produce the final colored booklet.

CONCLUSIONS

Driveline care is not comprehensively discussed in the literature and lacks detail in the particulars of wound care, patient education, and the adaptation of driveline care to the patient's home environment. An educational booklet was designed to convey what is currently known about preventing driveline infections to those who are responsible for providing the required daily care. Evaluation of patient education material by those using the material is essential. As with all written material, the information will require updating as new evidence becomes available.

CLINICAL IMPLICATIONS

Managing driveline infection risk for patients at home with extended therapy is a critical nursing issue in improving morbidity and mortality. After VAD implantation, patients and caregivers must be educated about the ongoing care of the driveline exit site to minimize the risk of infection. A rigorously developed and patient-evaluated educational booklet on driveline exit site care can be a valuable reference tool for patients and caregivers after hospital discharge.