Ventricular Assist Device Infections

Current status and future directions in pediatric ventricular assist device

A ventricular assist device (VAD) is a form of mechanical circulatory support that uses a mechanical pump to partially or fully take over the function of a failed heart. In recent decades, the VAD has become a crucial option in the treatment of end-stage heart failure in adult patients. However, due to the lack of suitable devices and more complicated patient profiles, this therapeutic approach is still not widely used for pediatric populations. This article reviews the clinically available devices, adverse events, and future directions of design and implementation in pediatric VADs.

The International Society for Heart and Lung Transplantation (ISHLT): 2024 infection definitions for durable and acute mechanical circulatory support devices

Infections remain a significant concern in patients receiving mechanical circulatory support (MCS), encompassing both durable and acute devices. This consensus manuscript provides updated definitions for infections associated with durable MCS devices and new definitions for infections in acute MCS, integrating a comprehensive review of existing literature and collaborative discussions among multidisciplinary specialists. By establishing consensus definitions, we seek to enhance clinical care, facilitate consistent reporting in research studies, and ultimately improve outcomes for patients receiving MCS.

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.

Continuous-flow left ventricular assist device: Current knowledge, complications, and future directions

Long-term continuous-flow left ventricular assist devices have become a real alternative to heart transplantation in patients with advanced heart failure, achieving a promising 2-year event-free survival rate with new-generation devices. Currently, this technology has spread throughout the world, and any cardiologist or cardiac surgeon should be familiar with its fundamentals and its possible complications as well as the advances made in recent years. The aim of this review is to describe current knowledge, management of complications, and future directions of this novel heart-failure therapy.

Successful Use of Arteriovenous Graft for Hemodialysis Access After Left Ventricular Assist Device Placement

Kidney replacement therapy is required in up to one-third of patients after left ventricular assist device (LVAD) placement. A subset of these patients requires long-term maintenance hemodialysis and therefore needs durable vascular access but the ideal access in such patients has not been established. We present a series of 3 patients in whom arteriovenous grafts (AVGs) were successfully used for long-term kidney replacement therapy after LVAD placement. The maximum time from AVG placement to first successful AVG use was 40 days, and the longest AVG use duration was more than 2 years. 2 patients required AVG excision due to infection but both had successful placement of a second AVG. Total time on kidney replacement therapy was 993, 1,055, and 956 days for the 3 cases, of which dialysis catheter use was required for only 23%, 6.5%, and 27%, respectively. These cases suggest that AVG placement is a viable option for dialysis access in patients with LVADs.

Identifying Causative Microorganisms in Left Ventricular Assist Device Infections as a Guide for Developing Bacteriophage Therapy

BACKGROUND

As more left ventricular-assist devices (LVADs) are implanted, multidrug-resistant LVAD infections are becoming increasingly common, partly due to bacterial biofilm production. To aid in developing bacteriophage therapy for LVAD infections, we have identified the most common bacterial pathogens that cause LVAD driveline infections (DLIs) in our heart transplant referral center.

MATERIALS AND METHODS

We studied a retrospective cohort of patients who received LVADs from November 2003 to August 2017 to identify the common causative organisms of LVAD infection. We also studied a prospective cohort of patients diagnosed with DLIs from October 2018 to May 2019 to collect bacterial strains from DLIs for developing bacteriophages to lyse causative pathogens. LVAD infections were classified as DLI, bacteremia, and pump/device infections in the retrospective cohort.

RESULTS

In the retrospective cohort of 582 patients, 186 (32.0%) developed an LVAD infection, with 372 microbial isolates identified. In the prospective cohort, 96 bacterial strains were isolated from 54 DLIs. The microorganisms causing DLIs were similar in the two cohorts; the most common isolate was Staphylococcus aureus. We identified 6 prospective S. aureus strains capable of biofilm formation. We developed 3 bacteriophages that were able to lyse 5 of 6 of the biofilm-forming S. aureus strains.

CONCLUSIONS

Similar pathogens caused LVAD DLIs in our retrospective and prospective cohorts, indicating our bacterial strain bank will be representative of future DLIs. Our banked bacterial strains will be useful in developing phage cocktails that can lyse ≥80% of the bacteria causing LVAD infections at our institution.

Pharmacotherapy for durable left ventricular assist devices

Left ventricular assist devices (LVADs) have revolutionized the care of patients with advanced heart failure, yet still require concomitant medications in order to achieve the best possible clinical outcomes. Since the outset of routine placement of durable, continuous-flow LVADs, much of the medication management of these patients to date has been based on International Society of Heart and Lung Transplantation (ISHLT) guidance, most recently published in 2013. Since 2013, numerous multidisciplinary pharmacotherapy publications have increased the LVAD community's understanding of best practices with respect to medications. We identified the major domains of LVAD medication management and conducted a comprehensive search of US National Library of Medicine MEDLINE^® database using keywords chosen to identify medication-related publications of significance dated 2013 or later. Trials pertaining to the HeartMate II™ and the HeartMate™ 3 LVADs (Abbott, Chicago, IL) and the HeartWare™ HVAD™ System (Medtronic, Minneapolis, MN) were chosen for inclusion. Highest priority for inclusion was given to prospective, randomized, controlled studies. Absent these, controlled trials (retrospective or prospective observational) were given next-highest consideration, followed by retrospective uncontrolled studies, and finally case series. Reference lists of qualified publications were reviewed to find any other publications of interest that were not discovered on initial search. Case reports were generally excluded, except where the insight gained was deemed to be uniquely pertinent. This document serves to provide a comprehensive review of the current understanding of optimal medication management in patients with durable, continuous-flow LVADs.

Surgical infection prophylaxis prior to left ventricular assist device implantation: A survey of clinical practice

BACKGROUND

Short duration, antimicrobial prophylaxis that includes antistaphylococcal activity is recommended at the time of left ventricular assist device (LVAD) implantation to reduce infection-related complications. There continues to be wide variability in surgical infection prophylaxis (SIP) regimens among implantation centers. The aim of this study is to characterize current SIP regimens at different LVAD centers.

METHODS

A survey study was conducted from 26 September 2017 to 25 October 2017. Surveys were distributed electronically to LVAD coordinators and infectious diseases specialists at 75 US medical centers identified as having an LVAD program. Data collection included information about antimicrobial selection, duration, Staphylococcus aureus screening, and decolonization procedures.

RESULTS

We received 29 survey responses. The majority of surveys were completed by infectious diseases physicians (72.4% [21 out of 29]). Most responding centers reported LVAD programs established for greater than 10 years (20 out of 29 [69%]). Cardiac transplantation was performed in 28 out of 29 (96%) centers. Of centers reporting a defined SIP regimen for non-penicillin allergic patients (96% [28 out of 29]), 17.9% (5 out of 28) reported a four-drug regimen, 35.7% (10 out of 28) reported a three-drug regimen, and 46.4% (13 out of 28) reported a two-drug regimen, while no centers reported a single-drug regimen. Empiric fluconazole was common (50% [14 out of 28]) and 96.4% (27 out of 28) of regimens included vancomycin. Duration of antimicrobial prophylaxis (24 hours to 5 days), S. aureus screening, decolonization procedures, and alterations due to drug allergies varied across participating centers.

CONCLUSIONS

Our survey results indicate wide variation in SIP regimens among participating LVAD centers. These results highlight the need for studies evaluating the implications of SIP regimens, and whether clinical factors that prolong antimicrobial duration impact postoperative infection rates.

Left ventricular assist devices and their complications: A review for emergency clinicians

INTRODUCTION

End stage heart failure is associated with high mortality. However, recent developments such as the ventricular assist device (VAD) have improved patient outcomes, with left ventricular assist devices (LVAD) most commonly implanted.

OBJECTIVE

This narrative review evaluates LVAD epidemiology, indications, normal function and components, and the assessment and management of complications in the emergency department (ED).

DISCUSSION

The LVAD is a life-saving device in patients with severe heart failure. While first generation devices provided pulsatile flow, current LVAD devices produce continuous flow. Normal components include the pump, inflow and outflow cannulas, driveline, and external controller. Complications related to the LVAD can be divided into those that are LVAD-specific and LVAD-associated, and many of these complications can result in severe patient morbidity and mortality. LVAD-specific complications include device malfunction/failure, pump thrombosis, and suction event, while LVAD-associated complications include bleeding, cerebrovascular event, infection, right ventricular failure, dysrhythmia, and aortic regurgitation. Assessment of LVAD function, patient perfusion, and mean arterial pressure is needed upon presentation. Electrocardiogram and bedside ultrasound are key evaluations in the ED. LVAD evaluation and management require a team-based approach, and consultation with the LVAD specialist is recommended.

CONCLUSION

Emergency clinician knowledge of LVAD function, components, and complications is integral in optimizing care of these patients.