The HVAD Left Ventricular Assist Device: Risk Factors for Neurological Events and Risk Mitigation Strategies

An ISHLT consensus statement on strategies to prevent and manage hemocompatibility related adverse events in patients with a durable, continuous-flow ventricular assist device

Life expectancy of patients with a durable, continuous-flow left ventricular assist device (CF-LVAD) continues to increase. Despite significant improvements in the delivery of care for patients with these devices, hemocompatability-related adverse events (HRAEs) are still a concern and contribute to significant morbility and mortality when they occur. As such, dissemination of current best evidence and practices is of critical importance. This ISHLT Consensus Statement is a summative assessment of the current literature on prevention and management of HRAEs through optimal management of oral anticoagulant and antiplatelet medications, parenteral anticoagulant medications, management of patients at high risk for HRAEs and those experiencing thrombotic or bleeding events, and device management outside of antithrombotic medications. This document is intended to assist clinicians caring for patients with a CF-LVAD provide the best care possible with respect to prevention and management of these events.

Developments and Challenges in Durable Ventricular Assist Device Technology: A Comprehensive Review with a Focus on Advancements in China

Heart transplantation is currently the most effective treatment for end-stage heart failure; however, the shortage in donor hearts constrains the undertaking of transplantation. Mechanical circulatory support (MCS) technology has made rapid progress in recent years, providing diverse therapeutic options and alleviating the dilemma of donor heart shortage. The ventricular assist device (VAD), as an important category of MCS, demonstrates promising applications in bridging heart transplantation, destination therapy, and bridge-to-decision. VADs can be categorized as durable VADs (dVADs) and temporary VADs (tVADs), according to the duration of assistance. With the technological advancement and clinical application experience accumulated, VADs have been developed in biocompatible, lightweight, bionic, and intelligent ways. In this review, we summarize the development history of VADs, focusing on the mechanism and application status of dVADs in detail, and further discuss the research progress and use of VADs in China.

Stroke and Mechanical Circulatory Support in Adults

PURPOSE OF THE REVIEW

Short-term and durable mechanical circulatory support (MCS) devices represent life-saving interventions for patients with cardiogenic shock and end-stage heart failure. This review will cover the epidemiology, risk factors, and treatment of stroke in this patient population.

RECENT FINDINGS

Short-term devices such as intra-aortic balloon pump, Impella, TandemHeart, and Venoatrial Extracorporal Membrane Oxygenation, as well as durable continuous-flow left ventricular assist devices (LVADs), improve cardiac output and blood flow to the vital organs. However, MCS use is associated with high rates of complications, including ischemic and hemorrhagic strokes which carry a high risk for death and disability. Improvements in MCS technology have reduced but not eliminated the risk of stroke. Mitigation strategies focus on careful management of anti-thrombotic therapies. While data on therapeutic options for stroke are limited, several case series reported favorable outcomes with thrombectomy for ischemic stroke patients with large vessel occlusions, as well as with reversal of anticoagulation for those with hemorrhagic stroke. Stroke in patients treated with MCS is associated with high morbidity and mortality. Preventive strategies are targeted based on the specific form of MCS. Improvements in the design of the newest generation device have reduced the risk of ischemic stroke, though hemorrhagic stroke remains a serious complication.

When all Else Fails, Try This: The HeartMate III Left Ventricle Assist Device

Heart failure (HF) is a progressive disease. It is estimated that more than 250,000 patients suffer from advanced HF with reduced ejection fraction refractory to medical therapy. With limited donor pool for heart transplant, continue flow left ventricle assist device (LVAD) is a lifesaving treatment option for patients with advanced HF. This review will provide an update on indications, contraindications, and associated adverse events for LVAD support with a summary of the current outcomes data.

Depression among Patients with an Implanted Left Ventricular Assist Device: Uncovering Pathophysiological Mechanisms and Implications for Patient Care

Depression is a common and devastating mental illness associated with increased morbidity and mortality, partially due to elevated rates of suicidal attempts and death. Select patients with end-stage heart failure on a waiting-list for a donor heart undergo left ventricular assist device (LVAD) implantation. The LVAD provides a circulatory flow of oxygenated blood to the body, mimicking heart functionality by operating on a mechanical technique. LVAD improves functional capacity and survivability among patients with end-stage heart failure. However, accumulating data suggests that LVAD recipients suffer from an increased incidence of depression and suicide attempts. There is scarce knowledge regarding the pathological mechanism and appropriate treatment approach for depressed LVAD patients. This article summarizes the current evidence on the association between LVAD implantation and occurrence of depression, suggesting possible pathological mechanisms underlying the device-associated depression and reviewing the current treatment strategies. The summarized data underscores the need for a rigorous pre-(LVAD)-implantation psychiatric evaluation, continued post-implantation mental health assessment, and administration of antidepressant treatment as necessary.

Management of hypertension in patients supported with continuous flow left ventricular assist devices

PURPOSE OF REVIEW

Hypertension remains one of the most common clinical problems leading to devastating postleft ventricular assist device (LVAD) implant complications. This study reviews the pathophysiology of hypertension in the setting of continuous flow LVAD support and provides an update on currently available antihypertensive therapies for LVAD patients.

RECENT FINDINGS

The true prevalence of hypertension in the LVAD population remains unknown. Effective blood pressure (BP) control and standardization of BP measurement are key to prevent suboptimal left ventricular unloading, pump malfunction and worsening aortic regurgitation. Angiotensin-converting enzyme inhibitors (ACEI), angiotensin receptor blockers (ARB), beta blockers and mineralocorticoid receptor antagonists (MRA) are the preferred antihypertensive agents because of their additional potential benefits, including optimization of haemodynamics, prevention of stroke, gastrointestinal bleed and in some patients myocardial recovery. Angiotensin receptor-neprilysin inhibition (ARNI) may be a well tolerated and effective therapy for BP control especially among CF-LVAD patients with resistant hypertension. Similarly, sodium glucose co-transporter 2 inhibitors (SGLT2i) should be considered in the absence of contraindications.

SUMMARY

Hypertension is very common post-LVAD implant. Heart failure guideline directed medical therapies, including ACEI, ARB, beta blockers and MRA, are the preferred antihypertensive agents to improve post-LVAD outcomes.

A novel metrics to predict right heart failure after left ventricular assist device implantation

BACKGROUND

Right Heart Failure (RHF) is a severe complication that can occur after left ventricular assist device (LVAD) implantation, increasing early and late mortality. Although numerous RHF predictive scores have been developed, limited data exist on the external validation of these models. We therefore aimed at comparing existent risk score models and identifying predictors of severe RHF at our center.

METHODS

In this retrospective, single-center analysis, clinical, biological and functional data were collected in patients implanted with a LVAD between 2011 and 2020. Early severe RHF was defined as the use of inotropes for ≥ 14 days, nitric oxide use for ≥ 48 h or unplanned right-sided circulatory support. Risk models were evaluated for the primary outcome of RHF or RVAD implantation by means of logistic regression and receiver operating characteristic curves.

RESULTS

Among 92 patients implanted, 24 (26%) developed early severe RHF. The EUROMACS-RHF risk score performed the best in predicting RHF (C = 0.82-95% CI: 0.68-0.90), compared with the other scores (Michigan, CRITT). In addition, we developed a new model, based on four variables selected for the best reduced logistic model: the INTERMACS level, the number of inotropes used, the ratio of right atrial/pulmonary capillary wedge pressure and the ratio of right ventricle/left ventricle diameters by echocardiography. This model demonstrated significant discrimination of RHF (C = 0.9-95% CI: 0.76-0.96).

CONCLUSION

Amongst available risk scores, EUROMACS-RHF performs best to predict the occurrence of RHF after LVAD implantation. Our model's performance compares well to the EUROMACS-RHF score, adding a more objective parameter to RV function evaluation.

HFSA Expert Consensus Statement on the Medical Management of Patients on Durable Mechanical Circulatory Support

The medical management of patients supported with durable continuous flow left ventricular assist device (LVAD) support encompasses pharmacologic therapies administered in the preoperative, intraoperative, postoperative and chronic LVAD support stages. As patients live longer on LVAD support, the risks of LVAD-related complications and progression of cardiovascular and other diseases increase. Using existing data from cohort studies, registries, randomized trials and expert opinion, this Heart Failure Society of America Consensus Document on the Medical Management of Patients on Durable Mechanical Circulatory Support offers best practices on the management of patients on durable MCS, focusing on pharmacological therapies administered to patients on continuous flow LVADs. While quality data in the LVAD population are few, the utilization of guideline directed heart failure medical therapies (GDMT) and the importance of blood pressure management, right ventricular preload and afterload optimization, and antiplatelet and anticoagulation regimens are discussed. Recommended pharmacologic regimens used to mitigate or treat common complications encountered during LVAD support, including arrhythmias, vasoplegia, mucocutaneous bleeding, and infectious complications are addressed. Finally, this document touches on important potential pharmacological interactions from anti-depressants, herbal and nutritional supplements of relevance to providers of patients on LVAD support.

Stroke Complications in Patients Requiring Durable Mechanical Circulatory Support Systems After Extracorporeal Life Support

Stroke is one of the leading complications following durable mechanical circulatory support (MCS) implantation. The aim of this multicenter study was to investigate stroke complications in patients requiring durable MCS following extracorporeal life support (ECLS). Data of 11 high volume MCS centers were collected and evaluated to identify patients who underwent durable MCS implantation after ECLS support between January 2010 and August 2018. The primary outcome was stroke following durable MCS implantation. Univariate and multivariate logistic regression analyses were performed to determine predictors of stroke. Overall, 531 patients met the inclusion criteria. Only patients who were supported with continuous flow pumps were included in this study accounting for 495 patients (median age 54 years old [interquartile range 47-60]). A total of 136 patients (27%) developed postoperative stroke on device during the follow-up (48% ischemic and 52% hemorrhagic) after a median durable MCS support of 320 [32-1,000] days, accounting for 0.17 events per patient-year. Of 133 patients with known date of stroke, a total of 47 (10%) developed stroke during the first 30 days (64% ischemic and 36% hemorrhagic), and 86 patients developed stroke after 30 days (38% ischemic and 62% hemorrhagic) of durable MCS support (late stroke). Survival rate was significantly lower in patients with hemorrhagic stroke ( p = 0.00091). Stroke appears to be a common complication in patients transitioned to durable MCS support after ECLS. Hemorrhagic stroke is a more common type of late stroke and is associated with inferior outcomes.

Neurologic Complications in Patients With Left Ventricular Assist Devices

Left ventricular assist device (LVAD) use has revolutionised the care of patients with advanced heart failure, allowing more patients to survive until heart transplantation and providing improved quality for patients unable to undergo transplantation. Despite these benefits, improvements in device technology, and better clinical care and experience, LVADs are associated with neurologic complications. This review provides information on the incidence, risk factors, and management of neurologic complications among LVAD patients. Although scant guidelines exist for the evaluation and management of neurologic complications in LVAD patients, a high index of suspicion can prompt early detection of neurologic complications which may improve overall neurologic outcomes. A better understanding of the implications of continuous circulatory flow on systemic and cerebral vasculature is necessary to reduce the common occurrence of neurologic complications in this population.

Microembolic signal monitoring in patients with HeartMate 3 and HeartWare left ventricular assist devices: Association with antithrombotic treatment and cerebrovascular events

BACKGROUND

In patients with left ventricular assist devices (LVADs), ischemic and hemorrhagic stroke are dreaded complications. Predictive markers for these events are lacking. This study aimed to investigate the prevalence and predictive value of microembolic signals (MES) for stroke, detected by Transcranial Doppler sonography (TCD) in patients with HeartMate 3 (HM 3) or HeartWare (HW).

METHODS

A thirty-minute bilateral TCD monitoring of the middle cerebral artery (MCA) was performed in 62 outpatients with LVAD (HM 3 N = 31, HW N = 31) and 31 healthy controls. Prevalence and quantity of MES were investigated regarding clinical and laboratory parameters. Cerebrovascular events (CVE) were recorded on follow-up at 90 and 180 days.

RESULTS

MES were detected in six patients with HM 3, three patients with HW, and three controls. Within the LVAD groups, patients on monotherapy with vitamin-K-antagonist (VKA) without antiplatelet therapy were at risk for a higher count of MES (negative binomial regression: VKA: 1; VKA + ASA: Exp(B) = 0.005, 95%CI 0.001-0.044; VKA + clopidogrel: Exp(B) = 0.012, 95%CI 0.002-0.056). There was no association between the presence of MES and CVE or death on follow-up (p > 0.05).

CONCLUSION

For the first time, the prevalence of MES was prospectively investigated in a notable outpatient cohort of patients with HM 3 and HW. Despite optimized properties of the latest LVAD, MES remain detectable depending on antithrombotic therapy. No association between MES and CVE could be detected.

Left Ventricular Assist Devices: A Primer For the General Cardiologist

Durable implantable left ventricular assist devices (LVADs) have been shown to improve survival and quality of life for patients with stage D heart failure. Even though LVADs remain underused overall, the number of patients with heart failure supported with LVADs is steadily increasing. Therefore, general cardiologists will increasingly encounter these patients. In this review, we provide an overview of the field of durable LVADs. We discuss which patients should be referred for consideration of advanced heart failure therapies. We summarize the basic principles of LVAD care, including medical and surgical considerations. We also discuss the common complications associated with LVAD therapy, including bleeding, infections, thrombotic issues, and neurologic events. Our goal is to provide a primer for the general cardiologist in the recognition of patients who could benefit from LVADs and in the principles of managing patients with LVAD. Our hope is to "demystify" LVADs for the general cardiologist.

Predictors of gastrointestinal bleeding in patients following left ventricular assist device implantation: a systematic review and meta-analysis

Aim: Our study aims to provide a more holistic understanding of the available data and predictive risk factors for gastrointestinal bleed (GIB). Materials & methods: We searched MEDLINE, Embase, Cochrane Central Register of Controlled Trials and Web of Science Core Collection and calculated relative risk and meta-regression was utilized to evaluate for risk factors in order to assess the effect of covariates. Results: Our meta-analysis reported a pooled prevalence rate of GIB of 24.4%. Meta-regression analysis did not yield a statistically significant association between GIB and risk factors, including age, gender, hypertension, chronic kidney disease and diabetes. Conclusion: Studies investigating larger sample sizes are required for conclusive findings.

Arterial Compliance and Continuous-Flow Left Ventricular Assist Device Pump Function

Durable continuous-flow left ventricular assist devices (cfLVADs) demonstrate superior survival, cardiac functional status, and overall quality of life compared to medical therapy alone in advanced heart failure. Previous studies have not considered the impact arterial compliance may have on pump performance or developed arterial pressure. This study assessed the impact of alterations in arterial compliance, preload, and afterload on continuous-flow pump function and measured hemodynamics using an in-vitro pulsatile mock circulatory loop. Decreased arterial compliance was associated with a significant increase in arterial pressure pulsatility which was not evident in the flow pulsatility, as displayed in pump flow waveforms. There were marked changes in the pump flow waveforms due to the significant alteration in the aortoventricular gradient during diastole according to the changes in compliance. This study demonstrates that changes in systemic blood pressure, afterload, and left ventricular contractility each significantly affects the flow waveform. The association of hypertension with lower aortic compliance results in markedly decreased diastolic flow rates which may be important in contributing to a greater risk of adverse events under cfLVAD support.

HVAD to HeartMate 3 Left Ventricular Assist Device Exchange: Best Practices Recommendations

The HeartWare HVAD System (Medtronic) is a durable implantable left ventricular assist device that has been implanted in approximately 20,000 patients worldwide for bridge to transplant and destination therapy indications. In December 2020, Medtronic issued an Urgent Medical Device Communication informing clinicians of a critical device malfunction in which the HVAD may experience a delay or failure to restart after elective or accidental discontinuation of pump operation. Moreover, evolving retrospective comparative effectiveness studies of patients supported with the HVAD demonstrated a significantly higher risk of stroke and all-cause mortality when compared with a newer generation of a commercially available durable left ventricular assist device. Considering the totality of this new information on HVAD performance and the availability of an alternate commercially available device, Medtronic halted the sale and distribution of the HVAD System in June 2021. The decision to remove the HVAD from commercial distribution now requires the use of the HeartMate 3 left ventricular assist system (Abbott, Inc) if a patient previously implanted with an HVAD requires a pump exchange. The goal of this document is to review important differences in the design of the HVAD and HeartMate 3 that are relevant to the medical management of patients supported with these devices, and to assess the technical aspects of an HVAD-to-HeartMate 3 exchange. This document provides the best available evidence that supports best practices.

Twenty-four-hour blood pressure and heart rate variability are reduced in patients on left ventricular assist device support

BACKGROUND

Limited data exist on the circadian blood pressure (BP) and heart rate (HR) variations that occur in heart failure (HF) patients on left ventricular assist device (LVAD) support.

METHODS

We prospectively recorded clinic and 24-hour ambulatory BP and HR data in patients on HeartMate II LVAD support. Results were compared to HF patients with ejection fraction ≤30% and controls with no history of cardiovascular disease. Physiologic nocturnal BP and HR dipping was defined as a ≥10% decline compared to daytime values.

RESULT

Twenty-nine LVAD patients (age 59 ± 15 years, 76% male, 38% ischemic etiology), 25 HF patients (age 64 ± 13 years, 84% male, 32% ischemic etiology) and 26 controls (age 56 ± 9 years, 62% male) were studied. Normal nocturnal BP dipping was less frequent in LVAD patients (10%) than in HF patients (28%) and controls (62%) and reversed BP dipping (BP increase at night) was more common in LVAD patients (24%), compared to HF (16%) and controls (8%), (p < 0.001, for all comparisons). Physiologic HR reduction was less frequent in LVAD patients (14%), compared to HF (16%) and controls (59%) (p < 0.001, for all comparisons). Among LVAD patients, 36% exhibited sustained hypertension over the 24-hours and 25% had white-coat hypertension.

CONCLUSIONS

Treatment of advanced HF with an LVAD does not restore physiologic circadian variability of BP and HR; additionally, BP was not adequately controlled in more than a third of LVAD patients, and a quarter of them exhibited white-coat hypertension. Future studies are warranted to confirm these findings and investigate prognostic and management implications in this population.

Left Ventricular Assist Devices: A Primer for the Non-Mechanical Circulatory Support Provider

Survival after implant of a left ventricular assist device (LVAD) continues to improve for patients with end-stage heart failure. Meanwhile, more patients are implanted with a destination therapy, rather than bridge-to-transplant, indication, meaning the population of patients living long-term on LVADs will continue to grow. Non-LVAD healthcare providers will encounter such patients in their scope of practice, and familiarity and comfort with the physiology and operation of these devices and common problems is essential. This review article describes the history, development, and operation of the modern LVAD. Common LVAD-related complications such as bleeding, infection, stroke, and right heart failure are reviewed and an approach to the patient with an LVAD is suggested. Nominal operating parameters and device response to various physiologic conditions, including hypo- and hypervolemia, hypertension, and device failure, are reviewed.

Management of Hypertension in Patients With Ventricular Assist Devices: A Scientific Statement From the American Heart Association

Mechanical circulatory support with durable continuous-flow ventricular assist devices has become an important therapeutic management strategy for patients with advanced heart failure. As more patients have received these devices and the duration of support per patient has increased, the postimplantation complications have become more apparent, and the need for approaches to manage these complications has become more compelling. Continuous-flow ventricular assist devices, including axial-flow and centrifugal-flow pumps, are the most commonly used mechanical circulatory support devices. Continuous-flow ventricular assist devices and the native heart have a constant physiological interplay dependent on pump speed that affects pressure-flow relationships and patient hemodynamics. A major postimplantation complication is cerebrovascular vascular accidents. The causes of cerebrovascular vascular accidents in ventricular assist device recipients may be related to hypertension, thromboembolic events, bleeding from anticoagulation, or some combination of these. The most readily identifiable and preventable cause is hypertension. Hypertension management in these patients has been hampered by the fact that it is difficult to accurately measure blood pressure because these ventricular assist devices have continuous flow and are often not pulsatile. Mean arterial pressures have to be identified by Doppler or oscillometric cuff and treated. Although guidelines for hypertension management after ventricular assist device implantation are based largely on expert consensus and conventional wisdom, the mainstay of treatment for hypertension includes guideline-directed medical therapy for heart failure with reduced ejection fraction because this may reduce adverse effects associated with hypertension and increase the likelihood of favorable ventricular remodeling. The use of systemic anticoagulation in ventricular assist device recipients may at a given blood pressure increase the risk of stroke.

Low Blood Pressure Threshold for Adverse Outcomes During Left Ventricular Assist Device Support

It has been suggested that maintaining low mean arterial pressure (MAP) in left ventricular assist device (LVAD) recipients is associated with a reduced risk of stroke/death. However, the lower limit of the optimal MAP range has not been established. We aimed to identify this lower limit in a contemporary cohort of LVAD recipients with frequent longitudinal MAP measurements. We analyzed 86,651 MAP measurements in 309 patients with an LVAD (32% LVADs with full magnetic levitation of the impeller) at a tertiary medical center during a mean follow-up of 1.7 ± 1.1 years. Cox proportional hazards regression modeling was used to study the association of serial MAP measurements with stroke/death within 3 years after index discharge. Multivariate analysis identified MAP ≤75 mm Hg, compared with MAP >75 mm Hg, as the low MAP threshold associated with increased risk of death (hazard ratio [HR] 4.74, 95% confidence interval [CI] 2.85 to 7.87, p <0.001), stroke (HR 2.72;, 95% CI 1.39 to 5.33, p = 0.01), and stroke/death (HR 4.45, 95% CI 2.83 to 6.99, p <0.001). The risk associated with MAP ≤75 mm Hg was consistent in subgroups categorized by age, gender, race, device type, renal function, right-sided heart failure, and blood pressure medications. In conclusion, our findings suggest that maintaining MAP ≤75 mm Hg during long-term follow-up in LVAD recipients is associated with increased risk of stroke/death regardless of risk factors or medical management.

Implications of Causes of Intracranial Hemorrhage During Left Ventricular Assist Device Support

BACKGROUND

Intracranial hemorrhage (ICH) is a frequent complication in patients with an implanted left ventricular assist device (LVAD) for advanced heart failure. Bloodstream infection is known to be associated with ICH in patients with LVAD, but its effects on ICH-associated mortality are unknown. We compared characteristics and mortality of infection-associated, traumatic, and spontaneous hemorrhages.

METHODS

Patients in an LVAD registry at a tertiary care center were reviewed for this cohort study. ICH included intraparenchymal hemorrhage, subarachnoid hemorrhage, and subdural hemorrhage. Hemorrhages were categorized into infectious, traumatic, and spontaneous by the presence or absence of concurrent device-associated infection or antecedent trauma.

RESULTS

Of 683 patients with an LVAD, 73 experienced ICH (10.7%). Intraparenchymal hemorrhage was the most prevalent (72%), followed by subarachnoid hemorrhage (27%) and subdural hemorrhage (23%), with multiple concurrent hemorrhage subtypes in 16 patients (22%). Median time from implantation to ICH was shorter in spontaneous ICH than in infection-associated ICH (100 days vs. 252 days, p = 0.048). The prevalence of the different subtypes of ICH were similar between spontaneous and infection-associated ICH, and no differences were seen in mortality between the different causes of ICH.

CONCLUSIONS

Although spontaneous ICH occurred earlier after LVAD implantation than infection-associated ICH, no difference in mortality was seen between the different causes of ICH.

HVAD to HeartMate 3 left ventricular assist device exchange: Best practices recommendations

The HeartWare HVAD System (Medtronic) is a durable implantable left ventricular assist device that has been implanted in approximately 20,000 patients worldwide for bridge to transplant and destination therapy indications. In December 2020, Medtronic issued an Urgent Medical Device Communication informing clinicians of a critical device malfunction in which the HVAD may experience a delay or failure to restart after elective or accidental discontinuation of pump operation. Moreover, evolving retrospective comparative effectiveness studies of patients supported with the HVAD demonstrated a significantly higher risk of stroke and all-cause mortality when compared with a newer generation of a commercially available durable left ventricular assist device. Considering the totality of this new information on HVAD performance and the availability of an alternate commercially available device, Medtronic halted the sale and distribution of the HVAD System in June 2021. The decision to remove the HVAD from commercial distribution now requires the use of the HeartMate 3 left ventricular assist system (Abbott, Inc) if a patient previously implanted with an HVAD requires a pump exchange. The goal of this document is to review important differences in the design of the HVAD and HeartMate 3 that are relevant to the medical management of patients supported with these devices, and to assess the technical aspects of an HVAD-to-HeartMate 3 exchange. This document provides the best available evidence that supports best practices.

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.

A Case Report of Ventricular Fibrillation Survival by Left Ventricular Assist Device for Hours

In recent years, the population of patients implanted with a left ventricular assist device has been increasing. Ventricular arrhythmias are the most interesting and most deadly complications among patients with these implants. Ventricular arrhythmias may cause cardiovascular collapse and death in some cases, whereas they may be asymptomatic or less symptomatic in others. In the case described here, we present the therapeutic approach to a patient with a left ventricular assist device who had ventricular fibrillation and the pathophysiology of his clinical condition.

Time in Therapeutic Range Significantly Impacts Survival and Adverse Events in Destination Therapy Patients

The study aim was to examine the impact time in therapeutic range (TTR, International Normalized Ratio [INR] 2.0-3.0) has on survival and adverse events in patients receiving the HeartWare HVAD System in the ENDURANCE and ENDURANCE Supplemental Trials. Evaluable subjects (n = 495) had >1 INR value recorded 1-24 months postimplant and were categorized as: low TTR (10-39%), moderate TTR (40-69%), and high TTR (≥70%). Baseline characteristics, adverse events, and survival were analyzed. Low TTR patients experienced higher rates of major bleeding (1.69 vs. 0.54 events per patient year [EPPY]; p < 0.001), GI bleeding (1.22 vs. 0.38 EPPY; p < 0.001), stroke (0.47 vs. 0.17 EPPY; p < 0.001), thrombus requiring exchange (0.05 vs. 0.01 EPPY; p = 0.02), infection (1.44 vs. 0.69 EPPY; p < 0.001), and renal dysfunction (0.23 vs. 0.05 EPPY; p < 0.001) compared with high TTR. Moderate TTR had higher rates of major bleeding (0.75 vs. 0.54 EPPY; p < 0.001), thrombus requiring exchange (0.05 vs. 0.01 EPPY; p = 0.007), cardiac arrhythmia (0.32 vs. 0.24 EPPY; p = 0.04), and infection (0.90 vs. 0.69 EPPY; p = 0.001) compared with high TTR. Two year survival was greater among moderate and high versus low cohorts (Log-rank p = 0.001). The significant reduction in morbidity and mortality in destination therapy (DT) HVAD patients with well-controlled TTR (≥70%) emphasizes the importance of vigilant anticoagulation management.

Neutrophil dysfunction due to continuous mechanical shear exposure in mechanically assisted circulation in vitro

OBJECTIVE

Leukocytes play an important role in the body's immune system. The aim of this study was to assess alterations in neutrophil phenotype and function in pump-assisted circulation in vitro.

METHODS

Human blood was circulated for four hours in three circulatory flow loops with a CentriMag blood pump operated at a flow of 4.5 L/min at three rotational speeds (2100, 2800, and 4000 rpm), against three pressure heads (75, 150, and 350 mm Hg), respectively. Blood samples were collected hourly for analyses of neutrophil activation state (Mac-1, CD62L, CD162), neutrophil reactive oxygen species (ROS) production, apoptosis, and neutrophil phagocytosis.

RESULTS

Activated neutrophils indicated by both Mac-1 expression and decreased surface expression of CD62L and CD162 receptors increased with time in three loops. The highest level of neutrophil activation was observed in the loop with the highest rotational speed. Platelet-neutrophil aggregates (PNAs) progressively increased in two loops with lower rotational speeds. PNAs peaked at one hour after circulation and decreased subsequently in the loop with the highest rotational speed. Neutrophil ROS production dramatically increased at one hour after circulation and decreased subsequently in all three loops with similar levels and trends. Apoptotic neutrophils increased with time in all three loops. Neutrophil phagocytosis capacity in three loops initially elevated at one hour after circulation and decreased subsequently. Apoptosis and altered phagocytosis were dependent on rotational speed.

CONCLUSIONS

Our study revealed that the pump-assisted circulation induced neutrophil activation, apoptosis, and functional impairment. The alterations were strongly associated with pump operating condition and duration.

Clinical considerations for the evaluation of patients with left ventricular assist devices

ABSTRACT

A left ventricular assist device (LVAD) provides mechanical circulatory support for patients with end-stage heart failure. As these devices become more prevalent, clinicians must be familiar with the device's function, common complications, and management strategies when evaluating this patient population.

Physiology and Clinical Utility of HeartMate Pump Parameters

The HeartMate 3 left ventricular assist device (LVAD) is now the only centrifugal pump intended for durable support being actively manufactured and implanted for adults in the United States. The changes in preload and afterload that accompany common clinical scenarios experienced by patients with an LVAD will cause specific changes to the LVAD pump parameters, namely, the pump power, pulsatility index, and flow. Appropriate care of this unique, and growing, population requires a full understanding of these variables as well as the underlying physiologic principles governing their derivation. The aim of this review is to focus on the updated functionality of the HeartMate 3, specifically in comparison to the HeartMate II, as well as the application of pump parameter interpretation to common clinical scenarios.

Angiotensin Receptor-Neprilysin Inhibition Improves Blood Pressure and Heart Failure Control in Left Ventricular Assist Device Patients

Angiotensin receptor-neprilysin inhibitors (ARNIs) greatly benefit functional capacity and longevity in heart failure with reduced ejection fraction (HFrEF). Angiotensin receptor-neprilysin inhibitors remain underutilized and unstudied, however, in left ventricular assist device (LVAD) recipients, in spite of their underlying HFrEF. In this case series, we studied the feasibility and short-term efficacy of ARNI utilization in 21 LVAD patients. Angiotensin receptor-neprilysin inhibitor initiation was successful in most, resulting in significant consolidation of blood pressure (BP) medical management and marked improvements in both functional capacity and diuretic requirements. Angiotensin receptor-neprilysin inhibitors are safe, feasible, and within a short timeframe benefit BP and heart failure control in LVAD recipients.

Alarms and Their Outcomes in Left Ventricular Assist Device Patients

Low flow and suction alarms are provided to alert caregivers of changes in left ventricular assist device pump function but may be reset in clinical practice. We investigated the incidence and underlying causes of these alarms as well as their prognostic significance. HeartWare ventricular assist device patients (n = 113) were divided into quartiles based on their frequency of low flow and suction alarms. Survival and adverse events (thrombus, stroke, bleeding, and right heart failure) were compared between quartiles. Low flow alarms peaked in the first few months of pump support before dropping down to near negligible levels. Suction alarm frequency remained relatively constant throughout pump support. Although pump speeds (p < 0.001) and flow (p = 0.01) decreased over time, there was an increase in suction alarm frequency (p = 0.018), with no changes in low flow alarms. Patients with smaller body size (p = 0.016) and lower pump flows (p = 0.008) had higher frequencies of low flow alarms on multiple regression (p < 0.001). Patients with the highest low flow alarm frequency demonstrated poorer survival (p = 0.026). There was no relationship between suction alarm frequency and survival. There was also no relationship between either low flow or suction alarm frequency with strokes, gastrointestinal bleeds, pump thrombus, or right ventricular failure. Duration of alarm and intervention in response to the alarm was not assessed in this study. Further studies examining alarm duration and responses may inform future pump alarm algorithms.

Left Ventricular Flow Dynamics with the HeartMate3 Left Ventricular Assist Device: Effect of Inflow Cannula Position and Speed Modulation

Improper left ventricular assist device (LVAD) inflow cannula (IC) positioning creates areas of stasis and low pulsatility that predispose thromboembolism, but may be mitigated with LVAD speed modulation. A mock loop study was performed to assess the sensitivity of left ventricle (LV) flow architecture to IC position and speed modulation during HeartMate3 support. System pressure, flow, and the time-resolved velocity field were measured within a transparent silicone LV for three IC angles and three IC insertion depths at matched levels of cardiac function and LVAD speed. Inflow cannula angulation towards the septum increased the resistance to LVAD flow as well as increasing the size and energy of the counter-clockwise (CCW) vortex. Apical velocity was reduced compared to IC angulation towards the mitral valve, but regional pulsatility was maintained across all angles and LVAD speeds. Increased IC protrusion decreased LVAD flow resistance, increasing velocity within the IC but reducing flow and pulsatility in the adjacent apical region. Increasing LVAD flow resistance improves aortic valve opening and strengthens the CCW vortex which directs inflow towards the septum, producing higher blood residence time and shear activation potential. Despite this impact on flow architecture, pulsatility reduction with increased LVAD speed was minimal with the HeartMate3 speed modulation feature.

Impact of renin-angiotensin-aldosterone system inhibition on morbidity and mortality during long-term continuous-flow left ventricular assist device support: An IMACS report

BACKGROUND

Inhibition of the renin angiotensin aldosterone system (RAAS) improves survival and reduces adverse cardiac events in heart failure with reduced ejection fraction, but the benefit is not well-defined following left ventricular assist device (LVAD).

METHODS

We analyzed the ISHLT IMACS registry for adults with a primary, continuous-flow LVAD from January 2013 to September 2017 who were alive at postoperative month 3 without a major adverse event, and categorized patients according to treatment an angiotensin converting enzyme inhibitor (ACEI/ARB) or mineralocorticoid receptor antagonist (MRA). Propensity score matching was performed separately for ACEI/ARB vs none (n = 4,118 each) and MRA vs none (n = 3,892 each).

RESULTS

Of 11,494 patients included, 50% were treated with ACEI/ARB and 38% with MRA. Kaplan-Meier survival was significantly better for patients receiving ACEI/ARB (p < 0.001) but not MRA (p = 0.31). In Cox proportional hazards analyses adjusted for known predictors of mortality following LVAD, ACEI/ARB use (hazard ratio 0.81 [95% confidence interval 0.71-0.93], p < 0.0001) but not MRA use (hazard ratio 1.03 [95% confidence interval 0.88-1.21], p = 0.69) was independently associated with lower mortality. Among patients treated with an ACEI/ARB, there was a significantly lower unadjusted risk of cardiovascular death (p < 0.001), risk of gastrointestinal bleeding (p = 0.01), and creatinine level (p < 0.001). MRA therapy was associated with lower risk of gastrointestinal bleeding (p = 0.01) but higher risk of hemolysis (p < 0.01). Potential limitations include residual confounding and therapy crossover.

CONCLUSION

These findings suggest a benefit for ACEI/ARB therapy in patients with heart failure after LVAD implantation.

Heart Failure Association of the European Society of Cardiology position paper on the management of left ventricular assist device-supported patients for the non-left ventricular assist device specialist healthcare provider: Part 2: at the emergency department

The improvement in left ventricular assist device (LVAD) technology and scarcity of donor hearts have increased dramatically the population of the LVAD‐supported patients and the probability of those patients to present to the emergency department with expected and non‐expected device‐related and patient–device interaction complications. The ageing of the LVAD‐supported patients, mainly those supported with the ‘destination therapy’ indication, increases the risk for those patients to suffer from other co‐morbidities common in the older population. In this second part of the trilogy on the management of LVAD‐supported patients for the non‐LVAD specialist healthcare provider, definitions and structured approach to the LVAD‐supported patient presenting to the emergency department with bleeding, neurological event, pump thrombosis, chest pain, syncope, and other events are presented. The very challenging issue of declaring death in an LVAD‐supported patient, as the circulation is artificially preserved by the device despite no other signs of life, is also discussed in detail.

The dominant left ventricular assist device: lessons from an era

The production and distribution of the HeartWare ventricular assist device has come to an abrupt end, but with this end comes the opportunity to reflect upon lessons learned from its lifespan. Running counter to the standard of evidence-based practice, the era of the HeartWare ventricular assist device was marred with fragmented data in relation to its primary counterpart, the HeartMate III. This created an incomplete understanding of devices, limited individualized patient care, and effectively positioned providers to make inferences regarding device superiority. We briefly review pertinent literature on this topic among the most commonly implanted durable devices from the era, detail the inherent limitations of this data, and argue the necessity of randomized clinical trials among novel devices towards the optimization of patient care.

Stroke in Patients with Left Ventricular Assist Devices

BACKGROUND

Left ventricular assist devices (LVADs) are artificial pumps used in end-stage heart failure to support the circulatory system. These cardiac assist devices work in parallel to the heart, diverting blood from the left ventricle through an outflow graft and into the ascending aorta. LVADs have allowed patients with end-stage heart failure to live longer and with improved quality of life compared to best medical therapy alone. However, they are associated with significant risks related to both thrombosis and bleeding in this medically complex patient population. As LVADs continue to be used more widely, stroke neurologists need to become familiar with the unique physical exam and vascular imaging findings associated with this population.

SUMMARY

Reported rates of LVAD-associated stroke at 2 years post-implantation range from 10 to 30%, which is significantly higher than in age-matched controls. There are approximately equal rates of ischemic and hemorrhagic strokes, and rates are highest during the peri-implantation period and in the first year of therapy. Risk factors associated with ischemic and hemorrhagic stroke in this cohort can be grouped into treatment-related factors, including specific devices and antithrombotic/anticoagulation strategy, and patient-related factors. Evidence for reperfusion therapy for acute stroke in this population is limited. Intravenous tissue plasminogen activator (IV-tPA) is often contraindicated as events may occur in the perioperative setting, or in the context of therapeutic anticoagulation. Endovascular therapy with successful recanalization is reported, but there is little experience documented in the published literature. Key messages: LVAD use is increasingly common. Given the high associated risks of stroke, neurologists will need to become increasingly familiar with an approach to assessment and therapy for LVAD patients with cerebrovascular issues.

Gastrointestinal Bleeding Rates in Left Ventricular Assist Device Population Reduced with Octreotide Utilization

Patients with continuous-flow left ventricular assist devices have a high risk of gastrointestinal bleeding (GIB) and recurrent bleeding. Studies have shown octreotide can reduce the risk of GIB. This retrospective, case-crossover study, evaluated the efficacy of octreotide for the prevention of recurrent GIB in patients with left ventricular assist devices between August 2008 and October 2018. A total of 32 patients received octreotide and were included in the study. Hospital admission for GIB was evaluated before and after the initiation of octreotide. Each case served as his/her own control. Most patients were on a reduced aspirin dose (56.2%) and had a reduced international normalized ratio goal (59.4%) before starting monthly octreotide. The most common dose of long-acting octreotide was 30 mg every 28 days. Overall, octreotide decreased the frequency of GIB (4.3 vs. 0.9 events/year, p < 0.001). Nineteen (59.4%) patients did not have a subsequent gastrointestinal bleed. Of the 13 patients who rebled after initiation of octreotide, the frequency of events decreased by 2.6 bleeds per patient per year (4.8 vs. 2.2; p = 0.043). In high-risk patients who have failed conventional therapy, octreotide can be useful for the prevention of recurrent GIB.

Comparison of two individualized antithrombotic protocols in HeartWare HVAD recipients

We previously reported low rates of pump thrombosis and hemorrhagic stroke, but increased bleeding, under our original antithrombosis protocol (P1) in HeartWare recipients. We designed and implemented a revised protocol (P2) to reduce complexity and bleeding. Thrombelastography and PFA-100 guide antiplatelet titration. Goals for P2 were altered to decrease antiplatelet use and anticoagulation intensity. We compared the incidence and rates of gastrointestinal bleeding (GIB), embolic (eCVA) and hemorrhagic (hCVA) stroke, pump thrombosis (PT), and total bleeding (GIB+hCVA), total thrombosis (eCVA+PT), and total events between P1 and P2. Laboratory and medication data were assessed. Patients with and without hemocompatibility-related adverse events (HRAEs) were compared. The study included 123 patients (P1: 65; P2: 58). GIB rate decreased (P1: 0.66; P2 0.30 EPPY, P = .003). CVA rates and incidence were statistically similar, although hCVA incidence increased (P1: 3%; P2: 12%, P = .06). Incidence (P1: 3%; P2: 16%, P = .02) and rate (P1: 0.03; P2: 0.12 EPPY, P = .08) of PT increased. Incidence and rate of overall HRAEs and thrombotic events were similar, while bleeding rate decreased (P1: 0.69; P2: 0.40 EPPY, P = .02). Twelve-month medication burden decreased. Compared to non-HRAE patients, patients with bleeding HRAEs had more antiplatelet and pentoxifylline use, but less statin use; and lower PFAs. Patients with thrombotic HRAEs had less dual antiplatelet use, lower INRs, R-times, and PFA-ADP values. A revised antithrombotic protocol decreased GIB and overall hemorrhagic HRAE rate and medication burden. Unfortunately, PT increased. Non-HRAE and HRAE patients differed in anticoagulation and antiplatelet intensity. These differences will guide the revision of P2.

The evolution of long-term pediatric ventricular assistance devices: a critical review

Introduction: The gap between the number of heart failure patients and the number of potential heart donors has never been larger than today, especially among the pediatric population. The use of mechanical circulatory support is seen as a potential alternative for clinicians to treat more patients. This treatment has proven its efficiency on short-term use. However, in order to replace heart transplant, the techniques should be used over longer periods of time.Areas covered: This review aims at furnishing an engineering vision of the evolution of ventricular assistance devices used in pediatrics. A critical analysis of the clinical complications related to devices generation is made to give an overview of the design improvements made since their inception.Expert opinion: The long-term use of a foreign device in the body is not without consequences, especially among fragile pediatric patients. Moreover, the size of their body parts increases the technical difficulties of such procedure. The balance between the living cells of the body is disturbed by the devices, mostly by the shear stress generated. To provide a safe mechanical circulatory support for long-term use, the devices should be more hemocompatible, preserving blood cells, adapted to the patient's systemic grid and miniaturized for pediatric use.