Multicenter experience: prevention and management of left ventricular assist device 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.

Ventricular Assist Device Driveline Infections: A Systematic Review

Infection is the most common complication in patients undergoing ventricular assist device (VAD) implantation. Driveline exit site (DLES) infection is the most frequent VAD infection and is a significant cause of adverse events in VAD patients, contributing to morbidity, even mortality, and repetitive hospital readmissions. There are many risk factors for driveline infection (DLI) including younger age, smaller constitution of patients, obesity, exposed velour at the DLES, longer duration of device support, lower cardiac index, higher heart failure score, DLES trauma, and comorbidities such as diabetes mellitus, chronic kidney disease, and depression. The incidence of DLI depends also on the device type. Numerous measures to prevent DLI currently exist. Some of them are proven, whereas the others remain controversial. Current recommendations on DLES care and DLI management are predominantly based on expert consensus and clinical experience of the certain centers. However, careful and uniform DLES care including obligatory driveline immobilization, previously prepared sterile dressing change kits, and continuous patient education are probably crucial for prevention of DLI. Diagnosis and treatment of DLI are often challenging because of certain immunological alterations in VAD patients and microbial biofilm formation on the driveline surface areas. Although there are many conservative and surgical methods described in the DLI treatment, the only possible permanent solution for DLI resolution in VAD patients is heart transplantation. This systematic review brings a comprehensive synthesis of recent data on the prevention, diagnostic workup, and conservative and surgical management of DLI in VAD patients.

Intracranial Mycotic Aneurysm in a Left Ventricular Assist Device Patient: A Complication to Avoid

In the current era of the increasing use of left ventricular assist devices (LVADs) as a bridge to transplant or destination therapy, early diagnosis and therapy of complications are imperative to provide a better quality of life and improve outcomes. This case illustrates how superficial infections can lead to drastic complications in the setting of LVADs. The lack of signs and symptoms of systemic inflammatory response could be explained by cellular immunity impairment in patients on LVAD support. The formation of aneurysms is enhanced in the LVAD population due to altered hemodynamic physiology. It is possible that the combination of impaired cellular immunity and altered hemodynamics of the present-day continuous flow LVADS increases the risk of mycotic aneurysm formation and rupture in patients infected with less virulent organisms.

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.

Feasibility and safety of laparoscopic colorectal surgeries for patients with left ventricular assist device

PURPOSE

There is limited literature regarding the feasibility and safety of laparoscopic procedures in patients having mechanical circulatory support, especially colonic resections.

METHODS

The aim of this study is to present the case of a laparoscopic colectomy for cancer undergone in a 69-year-old patient having a HeartWare II at our institution without any postoperative major complications and to describe the perioperative management and outcome of these patients according to the literature, regarding the hemodynamic, hemorrhagic, and infectious risks and the safety of this procedure.

RESULTS

There was no 90-day postoperative morbidity or death. A total of six patients including ours were identified in the study. This study has a limited number of patients and relatively short follow-up time.

CONCLUSION

Even though the management of patients having a LVAD is challenging and needs a multidisciplinary approach, reported literatures have shown the safety and feasibility of laparoscopic interventions for colorectal surgeries.

Low Incidence of Pump-Related Infections in Jarvik 2000 Ventricular Assist Device Recipients with a Subcostal Driveline Exit Site

Driveline infection has been a persistent problem with mechanical cardiac assist devices. The reported incidence of infection has been low in patients who receive a Jarvik 2000 continuous-flow left ventricular assist device when a skull-pedestal driveline exit site is used. We evaluated whether this is also true when a subcostal driveline exit site is used. We reviewed baseline demographic variables, postimplantation vital signs, laboratory values, and culture results in patients who underwent Jarvik 2000 implantation at our center from April 2000 through October 2009, including follow-up through June 2014. All patients had a subcostal driveline exit site. We defined device-related infection as a positive blood or wound culture associated with a medical or surgical device intervention. Event and time-to-event rates were calculated. Eighty-one patients received 89 Jarvik 2000 devices, all as bridges to transplantation. The median support duration was 69 days (interquartile range, 27-153 d; range, 2-2,249 d). Five superficial driveline infections and one incision-site infection occurred (0.002 events per patient-year of support). The median time from pump implantation to onset of driveline infection was 30 days; the incision-related infection occurred at 44 days. The Jarvik 2000 has a low incidence of infection when implanted with use of a subcostal driveline exit site. The incidence of pump infections is particularly low. Using a subcostal driveline exit site may be as effective in preventing infections as using a skull-pedestal driveline exit site. We detail our findings in this report.

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.

Infection, Oxidative Stress, and Changes in Circulating Regulatory T Cells of Heart Failure Patients Supported by Continuous-Flow Ventricular Assist Devices

The objective of this study was to investigate the changes in oxidative stress (OS) and circulating regulatory T cells (Tregs) of the immune system in patients supported by continuous-flow ventricular assist device (CF-VAD) with or without infection. We recruited 16 CF-VAD patients (5 with infection and 11 without infection) and 7 healthy volunteers. Generation of reactive oxygen species (ROS) from lymphocytes, superoxide dismutase (SOD) in erythrocyte, total antioxidant capacity (TAC), and oxidized low-density lipoprotein (oxLDL) in plasma were measured. Circulating Tregs were evaluated by flow cytometry. Heart failure (HF) patients had elevated OS than healthy volunteers as evident from higher lymphocyte ROS, elevated oxLDL, as well as depleted SOD and TAC levels. At baseline, HF patients had decreased percentage of Tregs (5.12 ± 1.5% vs. 8.14 ± 3.01%, p < 0.01) when compared with healthy volunteers. Postimplant patients with infection illustrated 35% and 44% rise in ROS and oxLDL, respectively, 31% decrease in TAC, and marked rise in percentage of Tregs (14.27 ± 3.17% vs. 9.38 ± 3.41%, p < 0.01) when compared with the patients without infection. Elevated OS and rise in Tregs were more prominent in CF-VAD patients with infection. In conclusion, OS and compromised immune system may be important indicators of systemic response of the body to CF-VAD among HF patients with infection.

Current State and Future Perspectives of Energy Sources for Totally Implantable Cardiac Devices

There is a large population of patients with end-stage congestive heart failure who cannot be treated by means of conventional cardiac surgery, cardiac transplantation, or chronic catecholamine infusions. Implantable cardiac devices, many designated as destination therapy, have revolutionized patient care and outcomes, although infection and complications related to external power sources or routine battery exchange remain a substantial risk. Complications from repeat battery replacement, power failure, and infections ultimately endanger the original objectives of implantable biomedical device therapy - eliminating the intended patient autonomy, affecting patient quality of life and survival. We sought to review the limitations of current cardiac biomedical device energy sources and discuss the current state and trends of future potential energy sources in pursuit of a lifelong fully implantable biomedical device.

Short-Term Experience with Off-Pump Versus On-Pump Implantation of the HeartWare Left Ventricular Assist Device

Implantation of left ventricular assist devices while avoiding cardiopulmonary bypass (CPB) may decrease bleeding and improve postoperative recovery. To understand the effectiveness of this approach, we reviewed the charts of 26 patients who underwent HeartWare left ventricular assist device (HVAD) implantation without use of CPB (off-CPB group) and 22 patients who had HVAD implanted with CPB (CPB group) with an emphasis on the 30 day postoperative period. Preoperatively, both groups had similar demographic, functional, and hemodynamic characteristics. Off-CPB patients had significantly shorter surgery times than CPB patients, 188.5 (161.5-213.3) min versus 265.0 (247.5-299.5) min, respectively; p < 0.001. Blood transfusion requirements during surgery and within the postoperative 48 hour period were significantly lower in the off-CPB group than in the CPB group (odds ratio: 5.9; 95% confidence interval: 1.1-31.1, p = 0.042). Compared with the CPB group, the off-CPB group patients had a shorter intubation time, 21 (17.4-48.5) hours versus 41 (20.6-258.4) hours; p = 0.042. Intensive care unit stay was 7.0 (4.75-13.5) days for off-CPB versus 10.0 (6.0-19.0) days for CPB (p = 0.256). The off-CPB approach allows HVAD to be implanted quickly with significantly less perioperative bleeding and transfusion requirements and facilitates postoperative rehabilitation.

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.

Left Ventricular Assist Device Salvage with Omental Flap

A large number of people are affected with heart failure annually and require left ventricular assist device placement as a bridge to heart transplant or as destination therapy. When these devices become infected, it is a challenge to eradicate the infection. Failure ultimately results in a significant morbidity and mortality. Source control along with debridement and antibiotics can eradicate the infection of the patient, but many times there is a large defect that needs soft-tissue coverage. Many options for soft-tissue coverage have been suggested, but omentum may be an excellent choice due to its vascularity, bulk, and immunological properties. In this case report, the omental flap is employed for salvage of the left ventricular assist device with excellent results.

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.

Challenges faced in long term ventricular assist device support

INTRODUCTION

The development of ventricular assist device (VAD) has been one of the revolutionary advancements in end-stage heart failure management. Although the device has developed and improved significantly over the last few decades, we still face multiple challenges.

AREAS COVERED

This review will discuss quality of life, survival, and clinically encountered complications in patients with VAD support. The literature was extensively reviewed for studies describing the above topic area. We describe the impact of major challenges faced in VAD support and discuss their future and expectations. Expert commentary: The technological advancement of VADs has contributed to major improvement of overall survival, enhancement of quality of life and decrease of incidence of complications. It is expected that technologies will continue to evolve. At the same time, the indications for and timing of device implantation, and selection of device type are continuously important in clinical practice setting.

Left Ventricular Assist Device Driveline Infections

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

Complications of Continuous-Flow Mechanical Circulatory Support Devices

Left ventricular assist devices (LVADs), more importantly the continuous-flow subclass, have revolutionized the medical field by improving New York Heart Association (NYHA) functional class status, quality of life, and survival rates in patients with advanced systolic heart failure. From the first pulsatile device to modern day continuous-flow devices, LVADs have continued to improve, but they are still associated with several complications. These complications include infection, bleeding, thrombosis, hemolysis, aortic valvular dysfunction, right heart failure, and ventricular arrhythmias. In this article, we aim to review these complications to understand the most appropriate approach for their prevention and to discuss the available therapeutic modalities.

Learning self-care after left ventricular assist device implantation

The number of heart failure (HF) patients living with a left ventricular assist device (LVAD) as destination therapy is increasing. Successful long-term LVAD support includes a high degree of self-care by the patient and their caregiver, and also requires long-term support from a multidisciplinary team. All three components of self-care deserve special attention once an HF patient receives an LVAD, including activities regarding self-care maintenance (activities related both to the device and lifestyle), self-care monitoring (e.g., monitoring for complications or distress), and self-care management (e.g., handling alarms or coping with living with the device). For patients to perform optimal self-care once they are discharged, they need optimal education that focuses on knowledge and skills through a collaborative, adult learning approach.

Mechanical circulatory support

The role for temporary and durable mechanical circulatory support is rapidly expanding. As the use of these technologies continues to grow, the emergency physician has an increasing opportunity to participate in the advancement of these potentially life-saving technologies. This review discusses the current role of the intra-aortic balloon pump in cardiogenic shock, describes the complications and management strategies for the critically ill patient with a left ventricular assist device, and explores the emerging role of ECMO in the emergency department for patients presenting in refractory cardiogenic shock and cardiac arrest.

Durable mechanical circulatory support in advanced heart failure: a critical care cardiology perspective

Though cardiac transplantation for advanced heart disease patients remains definitive therapy for patients with advanced heart failure, it is challenged by inadequate donor supply, causing durable mechanical circulatory support (MCS) to slowly become a new primary standard. Selecting appropriate patients for MCS involves meeting a number of prespecifications as is required in evaluation for cardiac transplant candidacy. As technology evolves to bring forth more durable smaller devices, selection criteria for appropriate MCS recipients will likely expand to encompass a broader, less sick population. The "Holy Grail" for MCS will be a focus on clinical recovery and explantation of devices rather than the currently more narrowly defined indications of bridge to transplantation or lifetime device therapy.

Salvage of infected left ventricular assist device with antibiotic beads

BACKGROUND

The use of left ventricular assist devices has become common for the treatment of end-stage heart failure, both as a bridge to transplantation and as destination therapy. The nature of these devices and the comorbid conditions of the patients in whom the devices are implanted lead to high rates of device infection that are related directly to mortality.

METHODS

Over 2 years, the senior author (S.A.I.) treated 26 patients with left ventricular assist device infections, ranging from superficial driveline infections to deeper pocket infections and device infections. An algorithm involving the use of repeated débridement and placement of antibiotic beads was used in treatment of these infections. Once cleared of infection, patients were treated with definitive closure or flap coverage of the formerly infected device component.

RESULTS

Seventeen of 26 patients with left ventricular assist device-related infections were cleared of their infection using this method. Ten of these patients underwent flap coverage of the device after their infection was cleared. In patients that were cleared of infection, mortality was 29 percent, whereas patients with recalcitrant infections had a mortality of 67 percent over the course of the study.

CONCLUSIONS

A systematic approach to treating left ventricular assist device-related infections has the potential to treat and clear these infections, with promising overall survival rates. This proposed algorithm led to high infection clearance rates compared with previously published literature. Infection clearance in patients on left ventricular assist device destination therapy may result in mortality rates approaching those of their uninfected peers.

Ventricular-assist devices for the treatment of chronic heart failure

The role of ventricular-assist devices in the management of end-stage heart failure is growing. Initially developed as a 'bridge to transplantation', they are now implanted permanently in patients who need cardiac replacement but are not candidates for cardiac transplantation ('destination therapy'). Furthermore, observations from expert centers indicate that a significant proportion of patients under long-term mechanical assistance can be weaned from mechanical circulatory support after significant functional recovery of their native heart ('bridge to recovery'). This review discusses the emerging roles of mechanical circulatory support and their direct implications in clinical practice. Evolution of devices, important aspects of candidate selection, challenging issues in the management of ventricular-assist device patients (infection, device malfunction, anticoagulation-thromboembolic complications, psychosocial issues and cost) and ongoing research targeting sustained myocardial recovery are discussed.

Infectious Complications of Mechanical Circulatory Support (MCS) Devices

Left-ventricular assist devices and other forms of mechanical circulatory support are increasingly important in the routine therapy of patients with end-stage congestive heart failure. Technology may help to decrease the rate of infections associated with these devices, but with larger numbers of implants being utilized across the globe, infections overall are becoming more commonplace. Becoming familiar with appropriate techniques for prevention and with the ideal approach to diagnostic and therapeutic strategies is key to managing mechanical circulatory support infections in this unique, but growing, patient population.

Impact of adverse events on ventricular assist device outcomes

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

Variability in infection control measures for the percutaneous lead among programs implanting long-term ventricular assist devices in the United States

Ventricular assist devices (VADs) are a surgical treatment for heart failure. These devices may be implanted as a bridge to transplant or as destination therapy. After surgical recovery and education regarding device care, patients are discharged home. Meticulous care of the driveline must be taken to prevent infection and trauma of the site throughout the perioperative event and for the duration of support. Currently a standardized protocol for care of the driveline and exit site does not exist. VAD coordinators from across the country discussed the variability in care at different centers in the United States through a series of conference calls. A survey consisting of 16 questions was developed. The survey included questions on preoperative antibiotic recommendations, driveline placement and exit site suturing, frequency of dressing changes, and showering practices. VAD coordinators shared center-specific dressing protocols and any driveline success stories. This survey was sent to 73 centers; 38 centers (52%) responded. The purpose of the survey was to define current practice in order to move toward a standard of practice or protocol based on expert opinion for VAD driveline care and to assess the need for future studies.

HeartMate-II left ventricular assist device infections resulting from gastrointestinal-tract fistulas

BACKGROUND

In patients with a left ventricular assist device (LVAD), pump-related infection can cause adverse effects that may result in death.

METHODS

We describe three patients who had infections related to a fistula between the gastrointestinal (GI) tract and the LVAD pocket and who subsequently underwent successful heart transplantation without developing sepsis. In no case did the LVAD-related infection adversely affect the outcome of transplantation.

CONCLUSIONS

For detecting the fistulas, full upper-GI endoscopy and colonoscopy were superior to other types of diagnostic imaging studies.

The pharmacotherapy implications of ventricular assist device in the patient with end-stage heart failure

Advances in mechanical circulatory support, such as the use of ventricular assist devices (VADs), have become a means for prolonging survival in end-stage heart failure (HF). VADs decrease the symptoms of HF and improve quality of life by replacing some of the work of a failing heart. They unload the ventricle to provide improved cardiac output and end-organ perfusion, resulting in improvement in cardiorenal syndromes and New York Heart Association functional class rating. VADs are currently used asa bridge to heart transplantation, a bridge to recovery of cardiac function, or as destination therapy. Complications of VAD include bleeding, infections, arrhythmias, multiple organ failure, right ventricular failure, and neurological dysfunction. Patients with VAD have unique pharmacotherapeutic requirements in terms of anticoagulation, appropriate antibiotic selection, and continuation of HF medications. Pharmacists in acute care and community settings are well prepared to care for the patient with VAD. These patients require thorough counseling and follow-up with regard to prevention and treatment of infections, appropriate levels of anticoagulation, and maintenance of fluid balance. A basic understanding of this unique therapy can assist pharmacists in attending to the needs of patients with VAD.

Risk analysis of bloodstream infection during long-term left ventricular assist device support

BACKGROUND

Infection during left ventricular assist device (LVAD) support is associated with a high mortality. This study investigated the effect of bloodstream infection on survival of patients with LVAD support and assessed risk factors for survival in LVAD patients with bloodstream infection.

METHODS

Between 1999 and 2010, 109 consecutive patients with end-stage heart failure were supported by an LVAD as a bridge to transplantation. Overall survival was compared between those with and without a bloodstream infection. Risk factors for survival of patients with bloodstream infection were analyzed.

RESULTS

A bloodstream infection developed in 65 patients (60%) during 584 ± 389 days of LVAD support. Compared with patients without a bloodstream infection, overall survival was significantly worse in those with bloodstream infection (68% vs 84% at 2 years after LVAD implantation, p = 0.0117). However, of 22 patients bridged to transplantation, none had bloodstream infection recurrence after transplantation, and their 3-year survival rate after transplantation was 100%. Cox multivariate analysis (hazard ratio [95% confidence interval]) identified postoperative right ventricular failure (2.890 [1.238 to 6.757]; p = 0.0141) and bloodstream infection caused by a pathogen other than gram-positive cocci (3.336 [1.390 to 8.006] p = 0.0070) as significant risk factors for death in LVAD patients with a bloodstream infection.

CONCLUSIONS

Bloodstream infection had a significant effect on survival after LVAD implantation. Our results suggest that urgent cardiac transplantation should be considered for LVAD patients with a bloodstream infection based on the causative organism and right ventricular function.

Left ventricular assist device-related infections: past, present and future

Over the last decade, left ventricular assist device (LVAD) implantation has emerged as an alternative treatment strategy in patients with advanced heart failure irrespective of their transplant eligibility. However, success and applicability of this therapy is largely limited by high complication rates associated with these devices. Although superior outcomes have been achieved with the second-generation continuous-flow LVADs, device-related infections continue to be a prevalent complication in this patient population and contribute significantly to the financial burden of this therapy due to an increased need for hospitalizations and surgical interventions. Patient selection, device design and LVAD-induced immune system dysfunction appear to be major risk factors for the development of device-related infections. Improvements in device design and better patient selection strategies, particularly with respect to identifying individuals with genetic susceptibility to device-related infections, may further reduce this prevalent complication and improve outcomes in patients with advanced heart failure.

Flow dynamics of a novel counterpulsation device characterized by CFD and PIV modeling

BACKGROUND

Historically, single port valveless pneumatic blood pumps have had a high incidence of thrombus formation due to areas of blood stagnation and hemolysis due to areas of high shear stress.

METHODS

To ensure minimal hemolysis and favorable blood washing characteristics, particle image velocimetry (PIV) and computational fluid dynamics (CFD) were used to evaluate the design of a new single port, valveless counterpulsation device (Symphony). The Symphony design was tested in 6-h acute (n=8), 5-day (n=8) and 30-day (n=2) chronic experiments in a calf model (Jersey, 76 kg). Venous blood samples were collected during acute (hourly) and chronic (weekly) time courses to analyze for temporal changes in biochemical markers and quantify plasma free hemoglobin. At the end of the study, animals were euthanized and the Symphony and end-organs (brain, liver, kidney, lungs, heart, and spleen) were examined for thrombus formations.

RESULTS

Both the PIV and the CFD showed the development of a strong moving vortex during filling phase and that blood exited the Symphony uniformly from all areas during ejection phase. The laminar shear stresses estimated by CFD remained well below the hemolysis threshold of 400 Pa inside the Symphony throughout filling and ejection phases. No areas of persistent blood stagnation or flow separation were observed. The maximum plasma free hemoglobin (<10mg/dl), average platelet count (pre-implant = 473 ± 56 K/μl and post-implant = 331 ± 62 K/μl), and average hematocrit (pre-implant = 31 ± 2% and post-implant = 29 ± 2%) were normal at all measured time-points for each test animal in acute and chronic experiments. There were no changes in measures of hepatic function (ALP, ALT) or renal function (creatinine) from pre-Symphony implantation values. The necropsy examination showed no signs of thrombus formation in the Symphony or end organs.

CONCLUSIONS

These data suggest that the designed Symphony has good washing characteristics without persistent areas of blood stagnation sites during the entire pump cycle, and has a low risk of hemolysis and thrombus formations.