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

Epidemiology and impact of device-specific infections on patients receiving left ventricular assist devices

Background

Left ventricular assist device-specific infections (LSIs) remain a persistent problem facing patients with durable left-ventricular assist devices (LVADs). However, the infectious agents and associated morbidity remained poorly defined. We sought to evaluate the incidence, epidemiology, and morbidity associated with LSIs in patients receiving modern centrifugal LVADs at 2 tertiary care centers.

Methods

Retrospective analysis was performed of adult patients receiving HeartMate 3 implants at the University of Pennsylvania and Mount Sinai Health Systems from January 1, 2015 to March 31, 2021, with follow-up until March 31, 2022. Patients were grouped by history of LSI, defined as culture-positive infections and/or those requiring medical or surgical intervention. Demographic data, available culture data, medical interventions, and surgical interventions were queried. Survival analysis was censored at 4 years and landmarked according to 25th percentile time-to-infection.

Results

Among 206 LVAD recipients, 71 (34.5%) developed an LSI. Predominant organisms were Staphylococcus (47.9%), Pseudomonas (15.5%), and Serratia (8.5%). Predictors of infection included Black race (LSI vs No LSI: 46.2% vs 29.2%, p = 0.021) and body mass index (median 29.7 vs 26.2 kg/m2, p = 0.007). Median time to infection was 231 days (112-423), with 19 (26.8%) patients requiring surgical debridement. Landmarked survival did not differ (log-rank p = 0.830). LSI patients were hospitalized an extra 8 (0-28) days for infection-related reasons.

Conclusion

LSIs remain pervasive, with most related to Staphylococcus, Pseudomonas, and Serratia, and are associated with significantly increased rehospitalization burden. Surgical interventions were utilized in 26.8% of patients. Continued efforts to understand and prevent LSIs are necessary to improve care for LVAD patients.

Design and rationale for the clinical investigation of a novel, magnetically levitated left ventricular assist device for the treatment of refractory heart failure

BACKGROUND

Contemporary durable left ventricular assist devices (LVAD) have established current benchmarks for patient outcomes, but introduction of more novel technology is lacking. The BrioVAD System (BrioHealth Solutions, Burlington, MA) is an innovative, fully magnetically levitated pump intended to provide short-term (ST) and long-term (LT) mechanical circulatory support.

METHODS

The Investigation of a Novel, MagNetically Levitated VAD for the Treatment of RefractOry Left Ventricular HeArT FailurE Clinical Trial (INNOVATE) is designed to evaluate safety and efficacy of the BrioVAD by demonstrating non-inferiority to the HeartMate 3 (HM3; Abbott Labs, Chicago, IL). INNOVATE is a multi-center, prospective, non-blinded, randomized (2 BrioVAD: 1 HM3), controlled, non-inferiority study designed as a staged pivotal study with a pre-defined safety phase. Exclusion criteria are designed to enroll a patient population that aligns with contemporary clinical practice. Primary endpoints include a composite of survival to transplant, cardiac recovery, or 6 months (ST) or 24 months (LT) of LVAD support free from debilitating stroke (modified Rankin Scale > 3), or reoperation to replace the pump. A powered secondary outcome evaluates days spent in hospital, skilled nursing facility, or inpatient rehabilitation.

RESULTS

INNOVATE study screening and enrollment began in 2024. Completed enrollment of the safety cohort (n = 45) is projected in early 2025. Completion of the ST cohort (n = 237) and LT cohort (n = 402) is projected for 2026 and 2027, respectively.

CONCLUSIONS

INNOVATE represents a contemporary clinical trial design evaluating unique design features of the BrioVAD System with the expectation to improve patient outcomes.

Recent Developments in Ventricular Assist Device Therapy

The evolution of left ventricular assist devices (LVADs) from large, pulsatile systems to compact, continuous-flow pumps has significantly improved implantation outcomes and patient mobility. Minimally invasive surgical techniques have emerged that offer reduced morbidity and enhanced recovery for LVAD recipients. Innovations in wireless power transfer technologies aim to mitigate driveline-related complications, enhancing patient safety and quality of life. Pediatric ventricular assist devices (VADs) remain a critical unmet need; challenges in developing pediatric VADs include device sizing and managing congenital heart disease. Advances in LVAD technology adapted for use in right ventricular assist devices (RVADs) make possible the effective management of right ventricular failure in patients with acute cardiac conditions or congenital heart defects. To address disparities in mechanical circulatory support (MCS) access, cost-effective VAD designs have been developed internationally. The Vitalmex device from Mexico City combines pulsatile-flow technology with a paracorporeal design, utilizing cost-effective materials like silicone-elastic and titanium, and features a reusable pump housing to minimize manufacturing and operational costs. Romanian researchers have used advanced mathematical modeling and three-dimensional (3D) printing to produce a rim-driven, hubless axial-flow pump, achieving efficient blood flow with a compact design that includes a wireless power supply to reduce infection risk. In conclusion, MCS continues to advance with technological innovation and global collaboration. Ongoing efforts are essential to optimize outcomes, expand indications, and improve access to life-saving therapies worldwide.

Feasibility Testing of the Bionet Sonar Ultrasound Transcutaneous Energy Transmission (UTET) System for Wireless Power and Communication of a LVAD

PURPOSE

To address the clinical need for totally implantable mechanical circulatory support devices, Bionet Sonar is developing a novel Ultrasonic Transcutaneous Energy Transmission (UTET) system that is designed to eliminate external power and/or data communication drivelines.

METHODS

UTET systems were designed, fabricated, and pre-clinically tested using a non-clinical HeartWare HVAD in static and dynamic mock flow loop and acute animal models over a range of pump speeds (1800, 2400, 3000 RPM) and tissue analogue thicknesses (5, 10, 15 mm).

RESULTS

The prototypes demonstrated feasibility as evidenced by meeting/exceeding function, operation, and performance metrics with no system failures, including achieving receiver (harvested) power exceeding HVAD power requirements and data communication rates of 10kB/s and pump speed control (> 95% sensitivity and specificity) for all experimental test conditions, and within healthy tissue temperature range with no acute tissue damage.

CONCLUSION

During early-stage development and testing, engineering challenges for UTET size reduction and stable and safe operation were identified, with solutions and plans to address the limitations in future design iterations also presented.

Long-term outcomes of a novel fully magnetically levitated ventricular assist device for the treatment of advanced heart failure in China

BACKGROUND

Left ventricular assist devices (LVADs) are well-established for treating end-stage heart failure, but this therapy is only available to Chinese patients in recent years. The CH-VAD is the first used fully magnetically levitated pump in China. This study reports the long-term outcomes of a cohort supported by the CH-VAD for the first time.

METHODS

From June 2017 to August 2023, 50 consecutive patients received CH-VAD implantation in Fuwai Hospital. Clinical data were collected and retrospectively analyzed.

RESULTS

Baseline characteristics included a mean age of 47.9 ± 13.9 years, 90% male, and 26% ischemic etiology. The Interagency Registry for Mechanically Assisted Circulatory Support profile revealed 12% profile 1, 56% profile 2, 26% profile 3, and 6% profile 4. The mean support duration was 868 ± 630 days (range 33 days-6.4 years). Kaplan-Meier survival rate was 93% (95% CI, 79-98) at 1 year, 93% (95% CI, 79-98) at 2 years, and 89% (95% CI, 71-96) at 3 years. Forty patients (80%) currently remain on support, 3 were bridged to recovery, 2 received transplants, and 5 expired during support. Major adverse events (AEs) included right heart failure (10%), surgical-related bleeding (8%), arrhythmia (8%), and driveline infection (16%). Major hemocompatibility-related AEs were limited to 3 nondisabling strokes and 1 gastrointestinal bleeding. No major device malfunction occurred during the follow-up period.

CONCLUSIONS

The largest single-center experience with the leading LVAD in China shows high survival with low complication rates, demonstrating that CH-VAD is safe and efficient in providing long-term support for patients with end-stage heart failure.

Mechanical Characterization of Anchoring Devices for the Prevention of Driveline Infection in Left Ventricular Assist Device Patients

Driveline infection (DLI) is associated with increased mortality and morbidity in left ventricular assist device (LVAD) patients. Because trauma to the driveline exit-site (DLES) is a risk factor for DLI, adhesive anchoring devices are used to immobilize the DL. In this study, commonly used products (identified through literature review and contact with nine international VAD implantation centers) were mechanically characterized to evaluate their effectiveness in preventing DLES trauma. Eight devices were tested in an in vitro abdominal model of the DLES, where a tensile force (10 N) was applied to a HeartMate 3 DL, whereas the resulting force ( FTotal ) on the DLES was recorded using a three-axis load cell. Four devices (CathGrip: FTotal = 2.1 ± 0.4 N, Secutape: FTotal = 2.6 ± 0.3 N, Hollister: FTotal = 2.7 ± 0.5 N, Tubimed: FTotal = 2.9 ± 0.2 N) were significantly ( p < 0.05) better at preventing tensile forces at the DLES compared to the other four devices (Main-Lock: FTotal = 3.7 [0.7] N, Secutape sensitive: FTotal = 3.9 ± 0.4 N, Foley Anchor: FTotal = 4.3 ± 0.5 N, Grip-Lok: FTotal = 5.4 ± 0.8 N). Immobilization of the DL with each anchoring device resulted in lower tensile force on the DLES than without an anchor ( FTotal = 8.2 ± 0.3 N). In conclusion, the appropriate selection of anchoring devices plays a critical role in reducing the risk of DLI, whereas the CathGrip, Secutape, Hollister, or Tubimed were superior in preventing trauma to the DLES in this study.

Driveline infection according to driveline positioning in left ventricular assist device implant recipients

We conducted a prospective, open-labeled, clinical trial, with a two-by-two factorial design, of argon cold plasma application and two different types of driveline positioning for the prevention of driveline infection (DLI) in 80 patients with a left ventricular assist device (LVAD) implant. Here, we present the results of intracorporeal loop positioning (n = 40) versus no intracorporeal loop positioning (n = 40). Patients were followed up for 1 year. According to the Driveline Expert STagINg and carE grading (DESTINE) system, a DLI was considered in case of a stage 2 or higher graded infection. During follow-up, 29 (36%) patients experienced a DLI, 16 in the group with intracorporeal loop positioning and 13 in the group with no intracorporeal loop positioning. Kaplan-Meier estimates of freedom from DLI showed no statistically significant difference between study groups during follow-up (p = 0.33). In detail, 30-day freedom from DLI was for the groups with and without intracorporeal loop positioning 92 and 92%, respectively, and 1-year freedom from DLI was 51 and 62%, respectively. In conclusion, this controlled clinical trial was unable to show a statistically significant difference in freedom from DLI during one year of follow-up in groups with or without intracorporeal loop positioning. However, larger trials have to confirm these results.

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.

Infections in Patients With Left Ventricular Assist Devices: Current State and Future Perspectives

Mechanical circulatory support is increasingly being used as bridge-to-transplant and destination therapy in patients with advanced heart failure. Technologic improvements have led to increased patient survival and quality of life, but infection remains one of the leading adverse events following ventricular assist device (VAD) implantation. Infections can be classified as VAD-specific, VAD-related, and non-VAD infections. Risk of VAD-specific infections, such as driveline, pump pocket, and pump infections, remains for the duration of implantation. While adverse events are typically most common early (within 90 days of implantation), device-specific infection (primarily driveline) is a notable exception. No diminishment over time is seen, with event rates of 0.16 events per patient-year in both the early and late periods postimplantation. Management of VAD-specific infections requires aggressive treatment and chronic suppressive antimicrobial therapy is indicated when there is concern for seeding of the device. While surgical intervention/hardware removal is often necessary in prosthesis-related infections, this is not so easily accomplished with VADs. This review outlines the current state of infections in patients supported with VAD therapy and discusses future directions, including possibilities with fully implantable devices and novel approaches to treatment.

Optimal timing of heart transplantation in patients with an implantable left ventricular assist device

Heart transplantation (HTPL) has been established as the gold-standard surgical treatment for end-stage heart failure. However, the use of a left ventricular assist device (LVAD) as a bridge to HTPL has been increasing due to the limited availability of HTPL donors. Currently, more than half of HTPL patients have a durable LVAD. Advances in LVAD technology have provided many benefits for patients on the waiting list for HTPL. Despite their advantages, LVADs also have limitations such as loss of pulsatility, thromboembolism, bleeding, and infection. In this narrative review, the benefits and shortcomings of LVADs as a bridge to HTPL are summarized, and the available literature evaluating the optimal timing of HTPL after LVAD implantation is reviewed. Because only a few studies have been published on this issue in the current era of third-generation LVADs, future studies are needed to draw a definite conclusion.