Ventricular Assist Device-Specific Infections

Perioperative interventions for the prevention of surgical wound infection in adult patients undergoing left ventricular assist devices implantation: A scoping review

BACKGROUND

Surgical wound infection is the most frequent type of care health associated infection. Lack of knowledge about the prevention of surgical wound infection in patients undergoing left ventricular assist device implantation could significantly undermine the potential benefits of surgical intervention.

OBJECTIVES

This study aimed to map the recommendations for adult patients undergoing left ventricular assist device implantation.

DESIGN

This is a scoping review, being registered in the Open Science Framework under DOI https://doi.org/10.17605/OSF.IO/Q76B3 (https://osf.io/q76b3/).

METHOD

Left ventricular assist device coordinators and nurse specialists in dermatology and stomatherapy conducted a scoping review in Scopus, The Cochrane Database of Systematic Reviews, Cumulative Index to Nursing and Allied Health Literature (CINAHL), limited to the period between 2015 and 2022. The results of this scoping review will be discussed and presented in separate articles. This paper will synthesize research evidence on the perioperative topic.

RESULTS

The initial searches resulted in 771 studies. Sixty nine met the eligibility criteria and were included in the scoping review. Eight articles addressing the perioperative topic that answered the question of this article were included.

CONCLUSION

Although this scoping review included heterogeneous, and scarce studies with left ventricular assist device patients. As such, there are many promising future research directions for this topic.

IMPLICATIONS FOR CLINICAL PRACTICE

Infection surveillance should be an integral part of left ventricular assist device implantation programs in health care institutions. Velvet completely buried in subcutaneous tissues reduces transmission system infection. Triple tunnel method reduces transmission system infection risk.

Pericardial Closure With Expanded Polytetrafluoroethylene Patch in Left Ventricular Assist Device Surgery

To reduce adhesions after left ventricular assist device (LVAD) implantation, pericardial closure using an expanded polytetrafluoroethylene (ePTFE) patch has been suggested. However, as foreign material, ePTFE patches could increase the risk of infectious complications. In this single-center retrospective study, we investigated outcomes of pericardial closure using an ePTFE patch in LVAD implantation. We included all patients who underwent LVAD implantation at our center between 2011 and 2020 (n = 166). Primary endpoint was development of mediastinitis at any point of time between LVAD implantation and heart transplantation (HTx) or death. Secondary endpoint was overall survival. Preoperative and postoperative clinical data were collected to ensure comparability between the groups. We included 166 patients with LVAD. A total of 116 patients (70%) underwent pericardial closure using an ePTFE patch. There were significant differences between the groups in treatment setting, previous cardiac surgery, Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) level, development of driveline infection, and HTx. Patients with an ePTFE patch developed mediastinitis more frequently (16%) than patients without ePTFE patch (4%) ( p = 0.039). A significant difference in overall survival between the groups could not be confirmed ( p = 0.29). The use of PTFE patches for pericardial closure in LVAD implantation was associated with a higher incidence of mediastinitis, but not with a difference in overall survival.

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.

Time-lapse mesoscopy of Candida albicans and Staphylococcus aureus dual-species biofilms reveals a structural role for the hyphae of C. albicans in biofilm formation

Polymicrobial infection with Candida albicans and Staphylococcus aureus may result in a concomitant increase in virulence and resistance to antimicrobial drugs. This enhanced pathogenicity phenotype is mediated by numerous factors, including metabolic processes and direct interaction of S. aureus with C. albicans hyphae. The overall structure of biofilms is known to contribute to their recalcitrance to treatment, although the dynamics of direct interaction between species and how it contributes to pathogenicity is poorly understood. To address this, a novel time-lapse mesoscopic optical imaging method was developed to enable the formation of C. albicans/S. aureus whole dual-species biofilms to be followed. It was found that yeast-form or hyphal-form C. albicans in the biofilm founder population profoundly affects the structure of the biofilm as it matures. Different sub-populations of C. albicans and S. aureus arise within each biofilm as a result of the different C. albicans morphotypes, resulting in distinct sub-regions. These data reveal that C. albicans cell morphology is pivotal in the development of global biofilm architecture and the emergence of colony macrostructures and may temporally influence synergy in infection.

Anti-infective characteristics of a new Carbothane ventricular assist device driveline

Objectives

Driveline infections are a major complication of ventricular assist device (VAD) therapy. A newly introduced Carbothane driveline has preliminarily demonstrated anti-infective potential against driveline infections. This study aimed to comprehensively assess the anti-biofilm capability of the Carbothane driveline and explore its physicochemical characteristics.

Methods

We assessed the Carbothane driveline against biofilm formation of leading microorganisms causing VAD driveline infections, including Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa and Candida albicans, using novel in vitro biofilm assays mimicking different infection micro-environments. The importance of physicochemical properties of the Carbothane driveline in microorganism-device interactions were analyzed, particularly focusing on the surface chemistry. The role of micro-gaps in driveline tunnels on biofilm migration was also examined.

Results

All organisms were able to attach to the smooth and velour sections of the Carbothane driveline. Early microbial adherence, at least for S. aureus and S. epidermidis, did not proceed to the formation of mature biofilms in a drip-flow biofilm reactor mimicking the driveline exit site environment. The presence of a driveline tunnel however, promoted staphylococcal biofilm formation on the Carbothane driveline. Physicochemical analysis of the Carbothane driveline revealed surface characteristics that may have contributed to its anti-biofilm activity, such as the aliphatic nature of its surface. The presence of micro-gaps in the tunnel facilitated biofilm migration of the studied bacterial species.

Conclusion

This study provides experimental evidence to support the anti-biofilm activity of the Carbothane driveline and uncovered specific physicochemical features that may explain its ability to inhibit biofilm formation.

Driveline dressings used in heartmate patients and local complications: A retrospective cohort

BACKGROUND

Patients with long-term ventricular assist devices (VAD) are predisposed to infection, bleeding, and pressure injuries at the insertion of the driveline. There is no consensus on a driveline dressing protocol. Chlorhexidine is often used to clean the driveline exit site and has been associated with lower rates of infection. For driveline coverage, bacteriostatic agents and transparent film have shown good results, but are costly. The same issue was associated with anchorage devices.

OBJECTIVES

The purpose of this study was to evaluate the types of dressings used in the driveline of patients using HeartMate (HM) and to describe the incidence density of local complications (infection, bleeding, and pressure injury) within 30 days postoperatively.

METHODS

A retrospective cohort study was conducted and included 22 patients admitted to the Intensive Care Unit after implantation of HM II and III in a Brazilian private hospital.

RESULTS

Several types of dressings were used in the drivelines. There were 22 different types of dressings. Dressing type 6 (Chlorhexidine, Excilon, Gauze and IV3000) were the most used (45.4%). Subjects using the Flexi-Trak anchoring device had a higher rate of local bleeding (50.0%) and those who used the Hollister device had more infection (61.1%) and pressure injury associated with a medical device (11.1%), compared to others. Infection was the primary complication (45.4%), followed by local bleeding (27.7%).

CONCLUSION

Despite the high variability of products used in the driveline of patients using HeartMate, the dressing made with chlorhexidine, silver-impregnated absorbent foam and transparent film, and the use of anchoring devices was the most frequently used. Infection was the most common complication.

Transdermal wires for improved integration in vivo

Alternative engineering approaches have led the design of implants with controlled physical features to minimize adverse effects in biological tissues. Similar efforts have focused on optimizing the design features of percutaneous VAD drivelines with the aim to prevent infection, omitting however a thorough look on the implant-skin interactions that govern local tissue reactions. Here, we utilized an integrated approach for the biophysical modification of transdermal implants and their evaluation by chronic sheep implantation in comparison to the standard of care VAD drivelines. We developed a novel method for the transfer of breath topographical features on thin wires with modular size. We examined the impact of implant's diameter, surface topography, and chemistry on macroscopic, histological, and physical markers of inflammation, fibrosis, and mechanical adhesion. All implants demonstrated infection-free performance. The fibrotic response was enhanced by the increasing diameter of implants but not influenced by their surface properties. The implants of small diameter promoted mild inflammatory responses with improved mechanical adhesion and restricted epidermal downgrowth, in both silicone and polyurethane coated transdermal wires. On the contrary, the VAD drivelines with larger diameter triggered severe inflammatory reactions with frequent epidermal downgrowth. We validated these effects by quantifying the infiltration of macrophages and the level of vascularization in the fibrotic zone, highlighting the critical role of size reduction for the benign integration of transdermal implants with skin. This insight on how the biophysical properties of implants impact local tissue reactions could enable new solutions on the transdermal transmission of power, signal, and mass in a broad range of medical devices.

Antimicrobial stewardship in solid organ transplant-Opportunities in the National Health Service

BACKGROUND

Antimicrobial stewardship (AMS) is an intervention, which ensures the appropriateness of antimicrobial use to avoid in part the rising problem of antimicrobial resistance and negative effects of inappropriate antimicrobial use. In the solid organ transplant (SOT) population, which is prone to a particularly high risk of infection resulting from immunosuppression and anatomical issues with each type of SOT, the need for good stewardship has never been more important. This article looks at current AMS practice in SOT units in the United Kingdom and how things could be improved in the future.

METHODS

The current practice of AMS alongside national antimicrobial resistance rates were reviewed using national mandatory reporting data. The background to the current practice and policies in place in the National Health Service (NHS) were also reviewed and possibilities for future approaches explored.

RESULTS

AMS is a requirement within all NHS hospitals in the United Kingdom as per government policy. Mandatory reporting of specific bloodstream infections (BSIs) and antimicrobial consumption alongside financial incentives has been the approach nationwide. Gram-negative resistance rates in BSIs have been increasing prior to the COVID-19 pandemic. Little SOT-specific data on antimicrobial resistance exists, and the general approach to AMS in SOT units has generally modeled the national approach.

CONCLUSION

Although there is a good, standardized approach to AMS in the NHS, there is a need for SOT-specific AMS approaches to be developed in the United Kingdom. More data is required on antimicrobial resistance rates, and studies are needed to investigate optimal antimicrobial prophylaxis regimens for each solid organ group. Tools to aid AMS efforts and novel treatment options for complex multiresistant infection must also be explored amongst transplant centers.

Vancomycin-resistant Enterococcus outbreak in a pre- and post-cardiothoracic transplant population: Impact of discontinuing multidrug-resistant organism surveillance during the coronavirus disease 2019 pandemic

INTRODUCTION

Many institutions suspended surveillance and contact precautions for multidrug-resistant organisms (MDROs) at the outset of the coronavirus disease 2019 (COVID-19) pandemic due to a lack of resources. Once our institution reinstated surveillance in September 2020, a vancomycin-resistant Enterococcus (VRE) faecium outbreak was detected in the cardiothoracic transplant units, a population in which we had not previously detected outbreaks.

METHODS

An outbreak investigation was conducted using pulsed-field gel electrophoresis for strain typing and electronic medical record review to determine the clinical characteristics of involved patients. The infection prevention (IP) team convened a multidisciplinary process improvement team comprised of IP, cardiothoracic transplant nursing and medical leadership, environmental services, and the microbiology laboratory.

RESULTS

Between December 2020 and March 2021, the outbreak involved thirteen patients in the cardiothoracic transplant units, four index cases, and nine transmissions. Of the 13, seven (54%) were on the transplant service, including heart and lung transplant recipients, patients with ventricular assist devices, and a patient on extracorporeal membrane oxygenation as a bridge to lung transplantation. Four of 13 (31%) developed a clinical infection.

DISCUSSION

Cardiothoracic surgery/transplant patients may have a similar risk for VRE-associated morbidity as abdominal solid organ transplant and stem cell transplant patients, highlighting the need for aggressive outbreak management when VRE transmission is detected. Our experience demonstrates an unintended consequence of discontinuing MDRO surveillance in this population and highlights a need for education, monitoring, and reinforcement of foundational infection prevention measures to ensure optimal outcomes.

Driveline Features as Risk Factor for Infection in Left Ventricular Assist Devices: Meta-Analysis and Experimental Tests

Background: Risk factors for driveline infection (DLI) in patients with left ventricular assist devices are multifactorial. The aim of this study was to analyze the correlation between mechanical driveline features and DLI occurrence.

Methods: A meta-analysis was conducted that included studies reporting DLI rates at 6 months after implantation of any of three contemporary devices (HVAD with Pellethane or Carbothane driveline, HeartMate II, and HeartMate 3). Further, outer driveline diameter measurements and ex-vivo experimental three-point bending and torsion tests were performed to compare the stiffness of the four different driveline types.

Results: 21 studies with 5,393 patients were included in the meta-analysis. The mean weighted DLI rates ranged from 7.2% (HeartMate II) to 11.9% (HeartMate 3). The HeartMate II driveline had a significantly lower maximal bending force (Load_max) (4.52 ± 0.19 N) compared to the Carbothane HVAD (8.50 ± 0.08 N), the HeartMate 3 (11.08 ± 0.3 N), and the Pellethane HVAD driveline (15.55 ± 0.14 N) (p < 0.001). The maximal torque (Torque_max) of the HeartMate II [41.44 (12.61) mNm] and the Carbothane HVAD driveline [46.06 (3.78) mNm] were significantly lower than Torque_max of the Pellethane HVAD [46.06 (3.78) mNm] and the HeartMate 3 [95.63 (26.60) mNm] driveline (p < 0.001). The driveline of the HeartMate 3 had the largest outer diameter [6.60 (0.58) mm]. A relationship between the mean weighted DLI rate and mechanical driveline features (Torque_max) was found, as the the HeartMate II driveline had the lowest Torque_max and lowest DLI rate, whereas the HeartMate 3 driveline had the highest Torque_max and highest DLI rate.

Conclusions: Device-specific mechanical driveline features are an additional modifiable risk factor for DLI and may influence clinical outcomes of LVAD patients.

Systems of conductive skin for power transfer in clinical applications

The primary aim of this article is to review the clinical challenges related to the supply of power in implanted left ventricular assist devices (LVADs) by means of transcutaneous drivelines. In effect of that, we present the preventive measures and post-operative protocols that are regularly employed to address the leading problem of driveline infections. Due to the lack of reliable wireless solutions for power transfer in LVADs, the development of new driveline configurations remains at the forefront of different strategies that aim to power LVADs in a less destructive manner. To this end, skin damage and breach formation around transcutaneous LVAD drivelines represent key challenges before improving the current standard of care. For this reason, we assess recent strategies on the surface functionalization of LVAD drivelines, which aim to limit the incidence of driveline infection by directing the responses of the skin tissue. Moreover, we propose a class of power transfer systems that could leverage the ability of skin tissue to effectively heal short diameter wounds. In this direction, we employed a novel method to generate thin conductive wires of controllable surface topography with the potential to minimize skin disruption and eliminate the problem of driveline infections. Our initial results suggest the viability of the small diameter wires for the investigation of new power transfer systems for LVADs. Overall, this review uniquely compiles a diverse number of topics with the aim to instigate new research ventures on the design of power transfer systems for IMDs, and specifically LVADs.