Acquired von Willebrand syndrome in continuous-flow ventricular assist device recipients

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.

Retinal microvascular remodeling associates with adverse events in continuous-flow left ventricular assist device supported patients

BACKGROUND

Continuous-flow left ventricular assist device (cfLVAD) use is effective in supporting patients with end-stage heart failure (ESHF). Reduced flow pulsatility within the systemic circulation in cfLVAD-supported patients may lead to alterations within the microcirculation. Temporal changes in microvasculature in relation to adverse events in cfLVAD supported patients has not been studied. We aimed to profile changes within retinal microvasculature and its association with adverse events.

METHODS

Retinal photography was performed using Topcon TRC-NW8 non-mydriatic fundus camera in cfLVAD supported patients and ESHF control patients. Retinal measurements including arteriolar and venular caliber, fractal dimension, branching angle, and vessel tortuosity were evaluated using a validated semi-automated program. Demographic and adverse event data were documented.

RESULTS

172 images were recorded from 48 patients (n=29 cfLVAD, n=19 ESHF, mean age 54.2 ± 11.9 years). There were significant trends in retinal arteriolar caliber (B = -0.53 µm, 95% CI: -0.96 - -0.10, p = 0.016) and retinal fractal dimension parameters (B = 0.014, 95% CI: 0.001 - 0.002, p = 0.016) in linear mixed model regressions. Amongst cfLVAD patients, there was a significant association between the incidence of gastrointestinal bleeding and stepwise increases in retinal arteriolar-venular caliber ratio (HR: 3.03, 95% CI: 2.06 - 4.45, p = 0.005), a measure of arteriolar narrowing.

CONCLUSIONS

We have observed for the first time that alterations in retinal microvasculature in cfLVAD-supported patients may be associated with gastrointestinal bleeding. While understanding these temporal changes may predict future adverse events in cfLVAD-supported patients, further multi-center studies are required to confirm the associations observed.

Impact of Diabetes Mellitus on Outcomes in Patients with Left Ventricular Assist Devices

Heart failure (HF) represents a significant health burden in the United States, resulting in substantial mortality and healthcare costs. Through the array of treatment options available, including lifestyle modifications, medications, and implantable devices, HF management has evolved. Left ventricular assist devices (LVADs) have emerged as a crucial intervention, particularly in patients with advanced HF. However, the prevalence of comorbidities such as diabetes mellitus (DM) complicates treatment outcomes. By elucidating the impact of DM on LVAD outcomes, this review aims to inform clinical practice and enhance patient care strategies for individuals undergoing LVAD therapy. Patients with DM have higher rates of hypertension, dyslipidemia, peripheral vascular disease, and renal dysfunction, posing challenges to LVAD management. The macro/microvascular changes that occur in DM can lead to cardiomyopathy and HF. Glycemic control post LVAD implantation is a critical factor affecting patient outcomes. The recent literature has shown significant decreases in hemoglobin A1c following LVAD implantation, representing a possible bidirectional relationship between DM and LVADs; however, the clinical significance of this decrease is unclear. Furthermore, while some studies show increased short- and long-term mortality in patients with DM after LVAD implantation, there still is no literature consensus regarding either mortality or major adverse outcomes in DM patients.

The Role of the von Willebrand Factor Collagen-Binding Assay (VWF:CB) in the Diagnosis and Treatment of von Willebrand Disease (VWD) and Way Beyond: A Comprehensive 36-Year History

The von Willebrand factor (VWF) collagen binding (VWF:CB) assay was first reported for use in von Willebrand diagnostics in 1986, by Brown and Bosak. Since then, the VWF:CB has continued to be used to help diagnose von Willebrand disease (VWD) (correctly) and also to help assign the correct subtype, as well as to assist in the monitoring of VWD therapy, especially desmopressin (DDAVP). However, it is important to recognize that the specific value of any VWF:CB is predicated on the use of an optimized VWF:CB, and that not all VWF:CB assays are so optimized. There are some good commercial assays available, but there are also some "not-so-good" commercial assays available, and these may continue to give the VWF:CB "a bad reputation." In addition to VWD diagnosis and management, the VWF:CB found purpose in a variety of other applications, from assessing ADAMTS13 activity, to investigation into acquired von Willebrand syndrome (especially as associated with use of mechanical circulatory support or cardiac assist devices), to assessment of VWF activity in disease states in where an excess of high-molecular-weight VWF may accumulate, and lead to increased (micro)thrombosis risk (e.g., coronavirus disease 2019, thrombotic thrombocytopenic purpura). The VWF:CB turns 37 in 2023. This review is a celebration of the utility of the VWF:CB over this nearly 40-year history.

Impact of Additional Administration of von Willebrand Factor Concentrates to Thrombocyte Transfusion in Perioperative Bleeding in Cardiac Surgery

Background

Von Willebrand factor (vWF) is an important part of blood coagulation since it binds platelets to each other and to endothelial cells. In traumatic and surgical haemorrhage, both blood cells and plasmatic factors are consumed, leading to consumption coagulopathy and fluid resuscitation. This often results in large amounts of crystalloids and blood products being infused. Additional administration of vWF complex and platelets might mitigate this problem. We hypothesize that administration of vWF concentrate additionally to platelet concentrates reduces blood loss and the amount of blood products (platelets, red blood cells [RBC], fresh frozen plasma [FFP]) administered.

Methods

We conducted a monocentric 6-year retrospective data analysis of cardiac surgery patients. Included were all patients receiving platelet concentrates within 48 h postoperatively. Patients who additionally received vWF concentrates were allocated to the intervention group and all others to the control group. Groups were compared in mixed regression models correcting for known confounders, based on nearest neighbour propensity score matching. Primary endpoints were loss of blood (day one and two) and amount of needed blood products on day one and two (platelets, RBC, FFP). Secondary endpoints were intensive care unit (ICU) and in-hospital length of stay, ICU and in-hospital mortality, and absolute difference of platelet counts before and after treatment.

Results

Of 497 patients analysed, 168 (34%) received vWF concentrates. 121 patients in both groups were considered for nearest neighbour matching. Patients receiving additional vWF were more likely to receive more blood products (RBC, FFP, platelets) in the first 24 h after surgery and had around 200 mL more blood loss at the same time.

Conclusion

In this retrospective analysis, no benefit in additional administration of vWF to platelet concentrates on perioperative blood loss, transfusion requirement (platelets, RBC, FFP), length of stay, and mortality could be found. These findings should be verified in a prospective randomized controlled clinical trial (www.clinicaltrials.gov identifier NCT04555785).

Impact of time off anticoagulation in patients with continuous-flow left ventricular assist devices

Patients with left ventricular assist devices (LVADs) receive anticoagulation to decrease the risk of thrombosis. Various circumstances require discontinuing anticoagulation in LVAD patients, but the risks entailed are not well defined. In a retrospective review of LVAD implantation procedures, we examined the effect of time off anticoagulation on thrombosis and mortality rates after implantation. An international normalized ratio ≤ 1.5 was used to screen for patients taken off anticoagulation. Patients were divided into three groups by the cumulative number of days off anticoagulation: no discontinuation, short-term discontinuation (< 30 days), and long-term discontinuation (≥ 30 days). Rates of ischemic stroke, pump thrombosis, and mortality were compared among groups. Of 245 patients who underwent LVAD implantation during the study, 70 (28.6%) were off anticoagulation during follow-up: 37 (15.1%) had short-term discontinuation (median, 11 days), and 33 (13.5%) had long-term discontinuation (median, 124 days). Patients with long-term discontinuation had a higher rate of ischemic stroke (adjusted hazard ratio 8.5, p = 0.001) and death (adjusted hazard ratio 3.9, p = 0.001). The three groups did not differ in pump thrombosis rate. We conclude that after LVAD implantation, discontinuing anticoagulation for ≥ 30 days is independently associated with an increased risk of ischemic stroke and death.

Von Willebrand Factor Multimer Analysis and Classification: A Comprehensive Review and Updates

Von Willebrand factor (VWF) is a multimeric glycoprotein with essential roles in primary hemostasis. Patients with von Willebrand disease (VWD), due to quantitative and/or qualitative defects of VWF usually experience mucocutaneous bleeding. Based on the laboratory results of VWF antigen, various VWF activities, factor VIII activity, and VWF multimer patterns, VWD can be categorized as type 1, 2, and 3 VWD. VWF multimer analysis by either manual or semi-automated electrophoresis and immunoblotting is a critical part of the laboratory testing to differentiate type 1, type 2 VWD, and subtypes of type 1 or 2 VWD. The multimer distribution patterns can also help to understand the underlying molecular mechanism of VWF synthesis, multimerization, and clearance defects in VWD. This review will cover VWF synthesis, multimerization, secretion, VWF multimer analysis, and VWF multimer interpretation of various types and subtypes of VWD.

von Willebrand Factor and Angiopoietin-2 are Sensitive Biomarkers of Pulsatility in Continuous-Flow Ventricular Assist Device Patients

Nonsurgical bleeding occurs in a significant proportion of patients implanted with continuous-flow ventricular assist devices (CF-VADs) and is associated with nonphysiologic flow with diminished pulsatility. An in vitro vascular pulse perfusion model seeded with adult human aortic endothelial cells (HAECs) was used to identify biomarkers sensitive to changes in pulsatility. Diminished pulsatility resulted in an ~45% decrease in von Willebrand factor (vWF) levels from 9.80 to 5.32 ng/ml (n = 5, p < 0.05) and a threefold increase in angiopoietin-2 (ANGPT-2) levels from 775.29 to 2471.93 pg/ml (n = 5, p < 0.05) in cultured HAECs. These changes are in agreement with evaluation of patient blood samples obtained pre-CF-VAD implant and 30-day postimplant: a decrease in plasma vWF level by 50% from ~45.59 to ~22.49 μg/ml (n = 15, p < 0.01) and a 64% increase in plasma ANGPT-2 level from 7,073 to 11,615 pg/ml (n = 8, p < 0.05). This study identified vWF and ANGPT-2 as highly sensitive to changes in pulsatility, in addition to interleukin-6 (IL-6), IL-8, and tumor necrosis-α (TNF-α). These biomarkers may help determine the optimal level of pulsatility and help identify patients at high risk of nonsurgical bleeding.

A sensorless, physiologic feedback control strategy to increase vascular pulsatility for rotary blood pumps

Continuous flow rotary blood pumps (RBP) operating clinically at constant rotational speeds cannot match cardiac demand during varying physical activities, are susceptible to suction, diminish vascular pulsatility, and have an increased risk of adverse events. A sensorless, physiologic feedback control strategy for RBP was developed to mitigate these limitations. The proposed algorithm used intrinsic pump speed to obtain differential pump speed (ΔRPM). The proposed gain-scheduled proportional-integral controller, switching of setpoints between a higher pump speed differential setpoint (ΔRPM Hr ) and a lower pump speed differential setpoint (ΔRPM Lr ), generated pulsatility and physiologic perfusion, while avoiding suction. The switching between ΔRPM Hr and ΔRPM Lr setpoints occurred when the measured ΔRPM reached the pump differential reference setpoint. In-silico tests were implemented to assess the proposed algorithm during rest, exercise, a rapid 3-fold pulmonary vascular resistance increase, rapid change from exercise to rest, and compared with maintaining a constant pump speed setpoint. The proposed control algorithm augmented aortic pressure pulsatility to over 35 mmHg during rest and around 30 mmHg during exercise. Significantly, ventricular suction was avoided, and adequate cardiac output was maintained under all simulated conditions. The performance of the sensorless algorithm using estimation was similar to the performance of sensor-based method. This study demonstrated that augmentation of vascular pulsatility was feasible while avoiding ventricular suction and providing physiological pump outflows. Augmentation of vascular pulsatility can minimize adverse events that have been associated with diminished pulsatility. Mock circulation and animal studies would be conducted to validate these results.

Loss of pulsatility with continuous-flow left ventricular assist devices and the significance of the arterial endothelium in von-Willebrand factor production and degradation

BACKGROUND

Patients on continuous flow ventricular assist devices (CF-VADs) are at high risk for the development of Acquired von-Willebrand Syndrome (AVWS) and non-surgical bleeding. von Willebrand Factor (vWF) plays an essential role in maintaining hemostasis via platelet binding to the damaged endothelium to facilitate coagulation. In CF-VAD patients, degradation of vWF into low MW multimers that are inefficient in facilitating coagulation occurs and has been primarily attributed to the supraphysiological shear stress associated with the CF-VAD impeller.

METHODS

In this review, we evaluate information from the literature regarding the unraveling behavior of surface-immobilized vWF under pulsatile and continuous flow pertaining to: (A) the process of arterial endothelial vWF production and release into circulation, (B) the critical shear stress required to unravel surface bound versus soluble vWF which leads to degradation, and (C) the role of pulsatility in on the production and degradation of vWF.

RESULTS AND CONCLUSION

Taken together, these data suggests that the loss of pulsatility and its impact on arterial endothelial cells plays an important role in the production, release, unraveling, and proteolytic degradation of vWF into low MW multimers, contributing to the development of AVWS. Restoration of pulsatility can potentially mitigate this issue by preventing AVWS and minimizing the risk of non-surgical bleeding.

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.

Mitigation effect of cell exclusion on blood damage in spiral groove bearings

Cell exclusion in spiral groove bearing (SGB) excludes red blood cells from high shear regions in the bearing gaps and potentially reduce haemolysis in rotary blood pumps. However, this mechanobiological phenomenon has been observed in ultra-low blood haematocrit only, whether it can mitigate blood damage in a clinically-relevant blood haematocrit remains unknown. This study examined whether cell exclusion in a SGB alters haemolysis and/or high-molecular-weight von Willebrand factor (HMW vWF) multimer degradation. Citrated human blood was adjusted to 35 % haematocrit and exposed to a SGB (n = 6) and grooveless disc (n = 3, as a non-cell exclusion control) incorporated into a custom-built Couette test rig operating at 2000RPM for an hour; shearing gaps were 20, 30, and 40 μm. Haemolysis was assessed via spectrophotometry and HMW vWF multimer degradation was detected with gel electrophoresis and immunoblotting. Haemolysis caused by the SGB at gaps of 20, 30 and 40 μm were 10.6 ± 3.3, 9.6 ± 2.7 and 10.5 ± 3.9 mg/dL.hr compared to 23.3 ± 2.6, 12.8 ± 3.2, 9.8 ± 1.8 mg/dL.hr by grooveless disc. At the same shearing gap of 20 µm, there was a significant reduced in haemolysis (P = 0.0001) and better preserved in HMW vWF multimers (p < 0.05) when compared SGB to grooveless disc. The reduction in blood damage in the SGB compared to grooveless disc is indicative of cell exclusion occurred at the gap of 20 µm. This is the first experimental study to demonstrate that cell exclusion in a SGB mitigates the shear-induced blood damage in a clinically-relevant blood haematocrit of 35 %, which can be potentially utilised in future blood pump design.

Established Clinical Prediction Rules for Bleeding had Mediocre Discrimination in Left Ventricular Assist Device Recipients

Left ventricular assist devices (LVAD) reduce mortality in patients with end-stage heart failure, but LVAD management is frequently complicated by bleeding. Bleeding prediction post-LVAD implantation is challenging as prediction rules for hemorrhage have not been rigorously studied in this population. We aimed to validate clinical prediction rules for bleeding, derived in the atrial fibrillation and venous thromboembolism populations, in an LVAD cohort. This was a retrospective cohort study of LVAD recipients at an academic center. The primary end-point was time to gastrointestinal bleed or intracranial hemorrhage after implant; the secondary end-point was time to any major hemorrhage after hospital discharge. Four hundred and eighteen patients received an LVAD (135 HeartMate II, 125 HeartMate 3, 158 HVAD) between November 2009 and January 2019. The primary end-point occurred in 169 (40.4%) patients with C-statistics ranging 0.55-0.58 (standard deviation [SD] 0.02 for all models). The secondary end-point occurred in 167 (40.0%) patients with C-statistics ranging 0.53-0.58 (SD 0.02 for all models). Modifying the age and liver function thresholds increased the C-statistic range to 0.56-0.60 for the primary and secondary end-points. In a sensitivity analysis of HeartMate 3 patients, prediction rules performed similarly. Existing prediction rules for major bleeding had mediocre discrimination in an LVAD cohort.

Decreased Platelet Specific Receptor Expression of P-Selectin and GPIIb/IIIa Predict Future Non-Surgical Bleeding in Patients after Left Ventricular Assist Device Implantation

Non-surgical bleeding (NSB) is one of the major clinical complications in patients under continuous-flow left ventricular assist device (LVAD) support. The increased shear stress leads to an altered platelet receptor composition. Whether these changes increase the risk for NSB is unclear. Thus, we compared the platelet receptor composition of patients with (bleeder group, n = 18) and without NSB (non-bleeder group, n = 18) prior to LVAD implantation. Blood samples were obtained prior to LVAD implantation and after bleeding complications in the post-implant period. Platelet receptor expression of GPIbα, GPIIb/IIIa, P-selectin and CD63 as well as intra-platelet oxidative stress levels were quantified by flow cytometry. Bleeders and non-bleeders were comparable regarding clinical characteristics, von Willebrand factor diagnostics and the aggregation capacity before and after LVAD implantation (p > 0.05). LVAD patients in the bleeder group suffered from gastrointestinal bleeding (33%; n = 6), epistaxis (22%; n = 4), hematuria or hematoma (17%; n = 3, respectively) and cerebral bleeding (11%; n = 2). Prior to LVAD implantation, a restricted surface expression of the platelet receptors P-selectin and GPIIb/IIIa was observed in the bleeder group (P-selectin: 7.2 ± 2.6%; GPIIb/IIIa: 26,900 ± 13,608 U) compared to non-bleeders (P-selectin: 12.4 ± 8.1%, p = 0.02; GPIIb/IIIa: 36,259 ± 9914 U; p = 0.02). We hypothesized that the reduced platelet receptor expression of P-selectin and GPIIb/IIIa prior to LVAD implantation may be linked to LVAD-related NSB.

Staphylococcus-induced proliferative glomerulonephritis and cerebral hemorrhage - fatal complications in a young female with postpartum cardiomyopathy and an implanted left ventricular assist device: a case report and review of the literature

Background: The continuous-flow left ventricular assist device (CF-LVAD) is used to save the lives of patients in the final stage of congestive heart failure, replacing the pump function of the left ventricle. Although quality of life increases significantly, CF-LVAD-related complications might prove fatal, as in the case presented in this paper.Methods: A 20-year-old female, during her second pregnancy, presented with signs of heart failure. Emergency caesarean section was necessary to save the baby, but peripartum cardiomyopathy developed in the mother. The use of an implantable cardioverter-defibrillator (ICD) was necessary 5 years later. As the clinical progression was unfavorable under medical treatment, with the patient reaching INTERMACS (Interagency Registry for Mechanically Assisted Circulatory Support) Profile 1 (refractory cardiogenic shock), the treatment of choice was the implantation of a CF-LVAD.Results: After 3 years of follow-up (at the age of 28), the patient presented with a positive hemoculture for Staphylococcus aureus. Prolonged antibiotic therapy and attentive follow-up was prescribed. Although an effective antiplatelet and anticoagulant treatment was applied, and despite therapeutic values of prothrombin time and international normalized ratio (INR), the patient died as result of a fatal cerebral hemorrhage. The autopsy also revealed septic emboli, disseminated intravascular coagulation, and focal proliferative glomerulonephritis.Conclusions: Although the benefits of CF-LVAD are significant, bleeding episodes can be severe and LVAD-associated infection can trigger glomerular injury and increase mortality.

In vitro study of red blood cell and VWF damage in mechanical circulatory support devices based on blood-shearing platform

Blood damage induced by mechanical circulatory support devices (MCSDs) remains a significant challenge to optimal clinical care. Although researchers have been conducting in vitro studies, the major determinant of blood damage is still unclear. An optimized capillary tube blood-shearing platform with custom designed parts was constructed to investigate the influence of two flow-dependent parameters (shear stress and exposure time) on the shear-induced damage of red blood cells and von Willebrand factor (VWF). Blood samples under different high shear stress and instantaneous exposure time were obtained by changing the flow rate and the length of capillary tube. Plasma free hemoglobin assay and immunoblotting of VWF were then performed on the sheared blood samples. The quantitative correlation between the hemolysis index and the two flow-dependent parameters was found following the power law mathematical model under the flow condition with high shear stress and instantaneous exposure time. The degradation of high molecular weight VWF was not obvious under high shear stress factor. However, the degradation of high molecular weight VWF was found as the result of the accumulation over exposure time under non-physiological shear stress, which was consistent with the different mechanism of VWF damage comparing to red blood cell damage. Compared to peak shear stress, exposure time has a greater effect on both red blood cell and VWF damage. To improve the hemocompatibility of MCSDs, it is more important to avoid regions of slow blood flow with non-physiological shear stress under laminar flow conditions.

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.

Hyperadhesive von Willebrand Factor Promotes Extracellular Vesicle-Induced Angiogenesis: Implication for LVAD-Induced Bleeding

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VWF in patients on LVAD supports was hyperadhesive, activated platelets, and generated platelet-derived extracellular vesicles.

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Extracellular vesicles from LVAD patients and those from shear-activated platelets promoted aberrant angiogenesis in a VWF-dependent manner.

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The activated VWF exposed the A1 domain through the synergistic actions of oxidative stress and HSS generated in LVAD-driven circulation.

Bleeding associated with left ventricular assist device (LVAD) implantation has been attributed to the loss of large von Willebrand factor (VWF) multimers to excessive cleavage by ADAMTS-13, but this mechanism is not fully supported by the current evidence. We analyzed VWF reactivity in longitudinal samples from LVAD patients and studied normal VWF and platelets exposed to high shear stress to show that VWF became hyperadhesive in LVAD patients to induce platelet microvesiculation. Platelet microvesicles activated endothelial cells, induced vascular permeability, and promoted angiogenesis in a VWF-dependent manner. Our findings suggest that LVAD-driven high shear stress primarily activates VWF, rather than inducing cleavage in the majority of patients.

Development of Inspired Therapeutics Pediatric VAD: Computational Analysis and Characterization of VAD V3

PURPOSE

Pediatric heart failure patients remain in critical need of a dedicated mechanical circulatory support (MCS) solution as development efforts for specific pediatric devices continue to fall behind those for the adult population. The Inspired Pediatric VAD is being developed as a pediatric specific MCS solution to provide up to 30-days of circulatory or respiratory support in a compact modular package that could allow for patient ambulation during treatment.

METHODS

Hydrodynamic performance (flows, pressures), impeller/rotor mechanical properties (torques, forces), and flow shear stress and residence time distributions of the latest design version, Inspired Pediatric VAD V3, were numerically predicted and investigated using computational fluid dynamics (CFD) software (SolidWorks Flow Simulator).

RESULTS

Hydrodynamic performance was numerically predicted, indicating no change in flow and pressure head compared to the previous device design (V2), while displaying increased impeller/rotor torques and translation forces enabled by improved geometry. Shear stress and flow residence time volumetric distributions are presented over a range of pump rotational speeds and flow rates. At the lowest pump operating point (3000 RPM, 0.50 L/min, 75 mmHg), 79% of the pump volume was in the shear stress range of 0-10 Pa with < 1% of the volume in the critical range of 150-1000 Pa for blood damage. At higher speed and flow (5000 RPM, 3.50 L/min, 176 mmHg), 65% of the volume resided in the 0-10 Pa range compared to 2.3% at 150-1000 Pa.

CONCLUSIONS

The initial computational characterization of the Inspired Pediatric VAD V3 is encouraging and future work will include device prototype testing in a mock circulatory loop and acute large animal model.

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

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

Physiology of Continuous-Flow Left Ventricular Assist Device Therapy

The expanding use of continuous-flow left ventricular assist devices (CF-LVADs) for end-stage heart failure warrants familiarity with the physiologic interaction of the device with the native circulation. Contemporary devices utilize predominantly centrifugal flow and, to a lesser extent, axial flow rotors that vary with respect to their intrinsic flow characteristics. Flow can be manipulated with adjustments to preload and afterload as in the native heart, and ascertainment of the predicted effects is provided by differential pressure-flow (H-Q) curves or loops. Valvular heart disease, especially aortic regurgitation, may significantly affect adequacy of mechanical support. In contrast, atrioventricular and ventriculoventricular timing is of less certain significance. Although beneficial effects of device therapy are typically seen due to enhanced distal perfusion, unloading of the left ventricle and atrium, and amelioration of secondary pulmonary hypertension, negative effects of CF-LVAD therapy on right ventricular filling and function, through right-sided loading and septal interaction, can make optimization challenging. Additionally, a lack of pulsatile energy provided by CF-LVAD therapy has physiologic consequences for end-organ function and may be responsible for a series of adverse effects. Rheological effects of intravascular pumps, especially shear stress exposure, result in platelet activation and hemolysis, which may result in both thrombotic and hemorrhagic consequences. Development of novel solutions for untoward device-circulatory interactions will facilitate hemodynamic support while mitigating adverse events. © 2021 American Physiological Society. Compr Physiol 12:1-37, 2021.

Neurologic Complications of Surgery and Anesthesia

Surgery and anesthesia carry risks of ischemic, hemorrhagic, hypoxic, and metabolic complications, all of which can result in neurologic symptoms and deficits. Patients with underlying cardiovascular and cerebrovascular risk factors are particularly vulnerable. In this article the authors review the neurologic complications of surgery and anesthesia, with a focus on the role of the neurologic consultant in preoperative evaluation and risk stratification and diagnosis and management of postoperative complications.

A data mining-based cross-industry process for predicting major bleeding in mechanical circulatory support

Aims

Over a third of patients, treated with mechanical circulatory support (MCS) for end-stage heart failure, experience major bleeding. Currently, the prediction of a major bleeding in the near future is difficult because of many contributing factors. Predictive analytics using data mining could help calculating the risk of bleeding; however, its application is generally reserved for experienced researchers on this subject. We propose an easily applicable data mining tool to predict major bleeding in MCS patients.

Methods and results

All data of electronic health records of MCS patients in the University Medical Centre Utrecht were included. Based on the cross-industry standard process for data mining (CRISP-DM) methodology, an application named Auto-Crisp was developed. Auto-Crisp was used to evaluate the predictive models for a major bleeding in the next 3, 7, and 30 days after the first 30 days post-operatively following MCS implantation. The performance of the predictive models is investigated by the area under the curve (AUC) evaluation measure. In 25.6% of 273 patients, a total of 142 major bleedings occurred during a median follow-up period of 542 [interquartile range (IQR) 205-1044] days. The best predictive models assessed by Auto-Crisp had AUC values of 0.792, 0.788, and 0.776 for bleedings in the next 3, 7, and 30 days, respectively.

Conclusion

The Auto-Crisp-based predictive model created in this study had an acceptable performance to predict major bleeding in MCS patients in the near future. However, further validation of the application is needed to evaluate Auto-Crisp in other research projects.

HFA of the ESC Position paper on the management of LVAD supported patients for the non LVAD specialist healthcare provider Part 1: Introduction and at the non-hospital settings in the community

The accepted use of left ventricular assist device (LVAD) technology as a good alternative for the treatment of patients with advanced heart failure together with the improved survival of the LVAD‐supported patients on the device and the scarcity of donor hearts has significantly increased the population of LVAD‐supported patients. The expected and non‐expected device‐related and patient–device interaction complications impose a significant burden on the medical system exceeding the capacity of the LVAD implanting centres. The ageing of the LVAD‐supported patients, mainly those supported with the ‘destination therapy’ indication, increases the risk for those patients to experience comorbidities common in the older population. The probability of an LVAD‐supported patient presenting with medical emergency to a local emergency department, internal, or surgical ward of a non‐LVAD implanting centre is increasing. The purpose of this trilogy is to supply the immediate tools needed by the non‐LVAD specialized physician: ambulance clinicians, emergency ward physicians, general cardiologists, internists, anaesthesiologists, and surgeons, to comply with the medical needs of this fast‐growing population of LVAD‐supported patients. The different issues discussed will follow the patient's pathway from the ambulance to the emergency department and from the emergency department to the internal or surgical wards and eventually to the discharge home from the hospital back to the general practitioner. In this first part of the trilogy on the management of LVAD‐supported patients for the non‐LVAD specialist healthcare provider, after the introduction on the assist devices technology in general, definitions and structured approach to the assessment of the LVAD‐supported patient in the ambulance and emergency department is presented including cardiopulmonary resuscitation for LVAD‐supported patients.

Cerebral Microvascular Injury in Patients with Left Ventricular Assist Device: a Neuropathological Study

Strokes are common among patients with left ventricular devices (LVAD). We hypothesize that there is ongoing cerebral microvascular injury with LVAD support and aim to describe this among LVAD-implanted patients through post-mortem neuropathologic evaluation. We identified and reviewed medical records of LVAD patients who underwent brain autopsy between January 2006 and December 2019 at a tertiary center. Cerebral injury was defined as both gross and microscopic injuries within the intracranial space including cerebral infarct (CI), hypoxic-ischemic brain injury (HIBI), intracranial hemorrhage (ICH), and cerebral microvascular injury. Cerebral microvascular injury was defined as microscopic brain intraparenchymal or perivascular hemorrhage, perivascular hemosiderin deposition, and perivascular inflammation. Twenty-one patients (median age = 57 years, 67% male) had autopsy after LVAD support (median LVAD support = 51 days). The median time from death to autopsy was 19 h. All 21 patients had cerebral injuries and 19 (90%) patients had cerebral microvascular injuries. Fourteen patients (78%) harbored more than one type of cerebral injury. On gross examination, 8 patients (38%) had CI, and 6 patients (29%) had ICH. On microscopic exam, 12 patients (57%) had microscopic intraparenchymal hemorrhage, 3 patients (14%) had perivascular hemorrhage, 11 patients (43%) had perivascular hemosiderin deposition, 5 patients (24%) had meningeal hemorrhage, 13 patients had chronic perivascular inflammation (62%), and 2 patients had diffuse HIBI (10%). Among patients with LVAD, there is a high prevalence of subclinical microvascular injuries and cerebral microbleeds (CMBs), which may provide some insights to the cause of frequent cerebral injury in LVAD population.

Uncommon obstacle: management of end-stage heart failure in thrombocytopenia with absent radii (TAR) syndrome

Thrombocytopenia with absent radii (TAR) syndrome is a rare genetic condition causing absent radial bones and thrombocytopenia. Management is generally supportive although there may be a role for platelet-stimulating agents such as romiplostim. In this case, we highlight the obstacles in managing end-stage heart failure in a patient with TAR syndrome.

Cardiac Emergencies in Kids

Encountering a child with congenital heart disease after surgical palliation in the emergency department, specifically the single-ventricle or ventricular assist device, without a basic familiarity of these surgeries can be extremely anxiety provoking. Knowing what common conditions or complications may cause these children to visit the emergency department and how to stabilize will improve the chance for survival and is the premise for this article, regardless of practice setting.

Mathematical models for shear-induced blood damage based on vortex platform

Non-physiological shear stress in Ventricular Assist Device (VAD) is considered to be an important trigger of blood damage, which has become the biggest shackle for clinical application. The researches on blood damage in literature were limited to qualitative but did not make much quantitative analysis. The purpose of this study was to investigate the quantitative influence of two flow-dependent parameters: shear stress (rotational speed) and exposure time on the shear-induced damage of red blood cells and von Willebrand Factor (vWF). A vortex blood-shearing platform was constructed to conduct in vitro experiments. Free hemoglobin assay and vWF molecular weight analysis were then performed on the sheared blood samples. MATLAB was used for regression fitting of original experimental data. The quantitative correlations between the hemolysis index, the degradation of high molecular weight vWF and the two flow-dependent parameters were found both following the power law model. The mathematic models indicated that the sensitivity of blood damage on red blood cells and vWF to exposure time was both greater than that of shear stress. Besides, the damage of vWF was more serious than that of red blood cells at the same flow condition. The models could be used to predict blood damage in blood-contacting medical devices, especially for the slow even stagnant blood flow regions in VAD, thus may provide useful guidance for VAD development and improvement. It also indicated that the vortex platform can be used to study the law of blood damage for the simple structure and easy operation.

Contemporary outcomes of continuous-flow left ventricular assist devices-a systematic review

Background

End stage heart failure is a major cause of morbidity and mortality, and its prevalence is expected to rise with the ageing population. For suitable patients, orthotopic heart transplantation remains the gold standard therapy, however, a paucity of donor organs has led to the development of left ventricular assist devices (LVAD). These devices can be utilized as either a bridge-to-transplant (BTT) or as an alternative to heart transplantation. While these devices can prolong life and improve quality of life, they are associated with a significant number of adverse events. We aim to systematically review the literature to quantify survival and the incidence of adverse events following implantation of continuous-flow LVADs (cf-LVAD).

Methods

A systematic review was performed to determine outcomes following implantation of a cf-LVAD. Primary outcomes were survival and frequency of adverse events (such as bleeding, infection, thrombosis, stroke and right ventricular failure). Secondary outcomes included quality of life and assessment of functional status.

Results

Sixty-three studies reported clinical outcomes of 9,280 patients. Survival after cf-LVAD varied between studies. Industry-funded trials generally reported better overall survival than the single- and multi-center case series, which showed significant variation. The largest registry report documented twelve, twenty-four and forty-eight-month survival rates of 82%, 72% and 57% respectively. The most commonly reported adverse events were gastrointestinal bleeding (GIB), device-related infection, neurological events and right heart failure (RHF). Bleeding, RHF and infection were the most frequent complications experienced by those supported with cf-LVAD, occurring in up to 35%, 40% and 55% of patients, respectively. Quality of life as measured using the Kansas City Cardiomyopathy Questionnaire (KCCQ) and functional status as measured with the 6-minute walk test (6MWT) improved after cf-LVAD implantation with no decline evident two years after implantation.

Conclusions

The paucity of donor hearts has led to the development of left-ventricular assist devices as a BTT or as a destination therapy (DT). Outcomes after cf-LVAD implantation are excellent, with short-term survival comparable to heart transplantation, but long-term survival remains limited due to the incidence of post-implantation adverse events. Despite these complications, quality of life and functional status improve significantly post-implantation and remain improved over the long-term. This study demonstrates the potential benefits of cf-LVAD therapy whilst also identifying adverse events as an area of increased morbidity and mortality.

Turbulence and turbulent flow structures in a ventricular assist device-A numerical study using the large-eddy simulation

Numerical flow simulations that analyze the turbulent flow characteristics within a turbopump are important for optimizing the efficiency of such machines. In the case of ventricular assist devices (VADs), turbulent flow characteristics must be also examined in order to improve hemocompatibility. Turbulence increases the shear stresses in the VAD flow, which can lead to an increased damage to the transported blood components. Therefore, an understanding of the turbulent flow patterns and their significance for the numerical blood damage prediction is particularly important for flow optimizations in VADs in order to identify and thus minimize flow regions where blood could be damaged due to high turbulent stresses. Nevertheless, the turbulence occurring in VADs and the local turbulent structures that lead to increased turbulent stresses have not yet been analyzed in detail in these machines. Therefore, this study aims to investigate the turbulence in an axial VAD in a comprehensive and double tracked way. First, the flow in an axial VAD was computed using the large-eddy simulation method, and it was verified that the majority of the turbulence was directly resolved by the simulation. Then, the turbulent flow state of the VAD was quantified globally. For this purpose, a self-designed evaluation method, the power loss analysis, was used. Subsequently, local flow regions and flow structures were identified where significant turbulent stresses prevail. It will be shown that the identified regions are universal and will also occur in other axial blood pumps as well, for example, in the HeartMate II.

Mechanical circulatory support systems: evolution, the systems and outlook

The joint efforts in the fields of surgery, medicine and biomedical engineering, sponsored by both the government and the industry, have led to the development of mechanical support devices that can provide reliable circulatory support, which can temporarily support a patient's circulation until either the heart recovers or until a new heart can be transplanted or permanently replace a failed heart. Their development has been driven by the shortage of donor organs. Various systems have eventually evolved for short or long-term support of patients suffering from cardiogenic and/or advanced heart failure (HF). Over time, several have been withdrawn from the market due to high rate of thromboembolism and pump-related complications, but many others remained with modern principles of circulatory support proved to be durable and reliable. Hopefully, the ever-evolving technology will yield several devices aimed at their miniaturization, with an energy supply without risk of infection, a system which is simple to implant and to exchange, minimalization of thrombus formation by optimal interior pump design, new antithrombotic medications and a system with demand-based pump activity. It is important to remember that such devices are only implanted to keep a patient alive or in an immediate life-threatening stage. In such circumstances, attribution of aforementioned difficulties to pump limitations or to advanced disease states remains difficult. In the coming years, ventricular assist devices (VADs) could be the most common surgical preference for treating severe HF.

Hemostatic Challenges in Pediatric Critical Care Medicine-Hemostatic Balance in VAD

Ventricular assist devices (VAD) are used more in children. Safe and effective anticoagulation is required for successful management of children supported with ventricular assist devices. Developmental hemostasis, device hemocompatibility, plastic to body ratio, surgical variable techniques, lack of knowledge on pharmacokinetics of anticoagulants, and wide variability in anticoagulation protocols have all contributed to increased incidence of bleeding and thromboembolic complications. New collaborative learning networks, such as the ACTION network, provide opportunities to define best practices, optimize, and reduce anticoagulation related adverse events. ACTION was established Dec 2017. It consists of expert clinicians in heart failure, as well as researchers, parents, and patients, with goals to improve outcomes, share data, improve education and standard practice for children with heart failure (, n.d). Changes in pediatric VAD anticoagulation strategy from using mainly heparin to DTI such as bivalirudin have helped reduce bleeding and clotting complications.

Acquired von Willebrand syndrome in ECMO patients: A 3-year cohort study

BACKGROUND

Bleeding is a common but possibly underreported side effect of Extracorporeal Membrane Oxygenation (ECMO). Impairment of primary hemostasis by acquired von Willebrand syndrome (aVWS) and platelet dysfunction as well as activation and consumption of plasmatic coagulation factors contribute to hemorrhage. The aim of the present cohort study of consecutively enrolled patients admitted to our ECMO center was to collect demographic, medical and laboratory data possibly associated with i) development of clinically relevant bleeding and/or ii) death during a 12-months follow-up.

RESULTS

Within a 3-year period 338 white patients aged 18-89 years (median: 60; male 64.5%) were enrolled. 78 of 338 patients (23%) presented with clinical relevant bleeding symptoms. The overall death rate was 74.6% within a median time of 9 days (1-229) post intervention. Logistic-regression analysis adjusted for age and gender revealed that i) the presence of blood group O versus non-O (Odds ratio (OR)/95%CI: 1.9/1.007-3.41), ECMO duration per day (1.1/1.06-1.14), veno-venous versus veno-arterial ECMO cannulation (2.33/1.2-4.5) and the overall need for blood product administered per unit (1.02/1.016-1.028) was independenly associated with bleeding in patients suffering from aVWS. ii) Older age (increase per year) at ECMO start (1.015/1.012-1.029) and an increasing amount of blood product units were significantly related with death (1.007/1.001-1.013). Patients with veno-venous versus veno-arterial cannulation survived longer (0.48/0.24-0.94).

CONCLUSION

In the present cohort study we found a clinical relevant bleeding rate of 23% in subjects with aVWS associated with blood group O, a longer ECMO duration and veno-venous cannulation.

HFSA/SAEM/ISHLT clinical expert consensus document on the emergency management of patients with ventricular assist devices

Mechanical circulatory support is now widely accepted as a viable long-term treatment option for patients with end-stage heart failure (HF). As the range of indications for the implantation of ventricular assist devices grows, so does the number of patients living in the community with durable support. Because of their underlying disease and comorbidities, in addition to the presence of mechanical support, these patients are at a high risk for medical urgencies and emergencies (Table 1). Thus, it is the responsibility of clinicians to understand the basics of their emergency care. This consensus document represents a collaborative effort by the Heart Failure Society of America, the Society for Academic Emergency Medicine, and the International Society for Heart and Lung Transplantation (ISHLT) to educate practicing clinicians about the emergency management of patients with ventricular assist devices. The target audience includes HF specialists and emergency medicine physicians, as well as general cardiologists and community-based providers.

Management of Intracranial Hemorrhage in Patients with a Left Ventricular Assist Device: A Systematic Review and Meta-Analysis

BACKGROUND

Intracranial hemorrhage (ICH) has been reported to occur in up to 23% of patients with left ventricular assist devices (LVADs). Currently, limited data exists to guide neurosurgical management strategies to optimize outcomes in patients with an LVAD who develop ICH.

METHODS

A systematic review and meta-analysis of the literature was performed to evaluate the mortality rate in these patients following medical and/or surgical management and to evaluate antithrombotic reversal and resumption strategies after hemorrhage.

RESULTS

17 studies reporting on 3869 LVAD patients and 545 intracranial hemorrhages spanning investigative periods from 1996 to 2019 were included. The rate of ICH in LVAD patients was 10.6% (411/3869) with 58.6% (231/394) being intraparenchymal hemorrhage (IPH), 23.6% (93/394) subarachnoid hemorrhage (SAH), and 15.5% (61/394) subdural hemorrhage (SDH). Total mortality rates for surgical management 65.6% (40/61) differed from medical management at 45.2% (109/241). There was an increased relative risk of mortality (RR=1.45, 95% CI: 1.10-1.91, p = 0.01) for ICH patients undergoing surgical intervention. The hemorrhage subtype most frequently managed with anticoagulation reversal was IPH 81.8% (63/77), followed by SDH 52.2% (12/23), and SAH 39.1% (18/46). Mean number of days until antithrombotic resumption ranged from 6 to 10.5 days.

CONCLUSION

Outcomes remain poor, specifically for those undergoing surgery. As experience with this population increases, prospective studies are warranted to contribute to management and prognostication .

Toward a Standard Practice to Quantify von Willebrand Factor Degradation During Left Ventricular Assist Device Support

BACKGROUND

Continuous-flow left ventricular assist devices (LVADs) cause degradation of von Willebrand factor (VWF) multimers and bleeding. Multiple techniques exist to characterize VWF deficiency. However, a standard methodology has not been established in LVAD patients. Toward this goal, we evaluated 4 methods to quantify VWF multimers.

METHODS

We collected paired blood samples from patients (n = 48) before and after 1 week of LVAD support. After 652 ± 59 days of support, patients were classified as bleeders (≥1 bleeding episode) or nonbleeders. VWF multimers were resolved with electrophoresis and immunoblotting, the gold-standard to evaluate VWF multimers. We evaluated 4 quantification methods.

RESULTS

Each method demonstrated significant VWF degradation during LVAD support vs a paired, pre-LVAD sample (method 1, VWF length: 48 of 48 patients, -10% ± 1%, P < .0001; method 2, VWF density: 40 of 48, -34% (interquartile range, -46% to -8%), P < .0001; method 3, pre-LVAD to LVAD ratio: 46 of 48, 17 ± 5: 10 ± 1, P < .0001; method 4, LVAD/pre-LVAD index: 46 of 48, 57% (interquartile range, 50% to 73%), P < .0001). Bleeding occurred in 27 of 48 patients. Method 1 demonstrated significantly fewer VWF multimers in bleeders compared with nonbleeders (-11% ± 1% vs -8% ± 1%; P = .01). Other methods did not demonstrate this potentially important clinical relationship.

CONCLUSIONS

A standardized methodology is needed to quantify VWF multimer degradation with mechanical circulatory support devices. Novel method 1 successfully quantified the patient-specific change in VWF multimer length during LVAD support and demonstrated a difference in VWF multimers between bleeders and nonbleeders. Adoption of consensus methodology will assist to standardize patient-specific bleeding risk, inform anticoagulation and antiplatelet therapy, and evaluate LVAD hemocompatibility.

Evaluating the impact of chronic obstructive pulmonary disease on in-hospital outcomes following left ventricular assist device implantation

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is a cause of ventricular dysfunction. However, in the setting of patients with heart failure undergoing left ventricular assist device (LVAD) implantation, there is a paucity of data on the association between COPD and in-hospital outcomes.

METHODS AND RESULTS

Retrospective cohort study based on the NIS including patients ≥18 years who underwent LVAD implantation from 2011 to 2017. Multivariate regression was used to evaluate the impact of COPD on in-hospital outcomes. A total of 25,503 patients underwent LVAD implantation, of which 13.8% also had COPD. COPD group was older (median 62 vs. 58 years), and more males (82% vs. 76.4%, p < .001 for both). COPD group had more hypertension, diabetes, atrial tachyarrhythmias, dyslipidemia, prior stroke, coronary artery diseases, pulmonary hypertension, and chronic kidney disease (p < .001 for all). No differences in strokes, infections, mechanical circulatory support, and LVAD thrombosis. There was a higher incident of inpatient acute kidney injury, major bleeding, cardiac complications, thromboembolism, and cardiac arrest in patients without COPD (p < .05 for all). Compared with no-COPD group, COPD group had a lower mortality (6.2% vs. 12.4%; odds ratio, 0.59; confidence interval, 0.512-0.685; p < .05).

CONCLUSION

Patients with COPD undergoing LVAD implantation have more comorbidities, without an associated increase mortality.

Decreased RPM reduces von Willebrand factor degradation with the EVAHEART LVAS: implications for device-specific LVAD management

BACKGROUND

Continuous-flow left ventricular assist devices (LVADs) produces supraphysiologic shear stress that causes von Willebrand factor (VWF) degradation and a bleeding diathesis. Reduction of revolutions per minute (RPM) with axial-flow LVADs does not decrease shear stress enough to reduce VWF degradation and bleeding. However, it is unknown if RPM reduction with centrifugal flow LVADs may minimize VWF degradation. We tested the hypothesis that RPM reduction preserves VWF multimers in the centrifugal-flow EVAHEART left ventricular assist system (LVAS), which is designed to minimize shear stress and blood trauma.

METHODS

Whole blood samples were collected from humans (n = 28). Blood was circulated in ex vivo mock circulatory loops for 6 hours with an EVAHEART LVAS at 2300 (n = 12), 2100 (n = 8), or 1800 RPM (n = 8). Immunoblotting was used to resolve and quantify VWF multimers and degradation fragments.

RESULTS

RPM reduction from 2300 to 2100 to 1800 RPM significantly decreased EVAHEART blood flow from 5.8 ± 0.4 to 4.3 ± 0.6 to 4.1 ± 0.5 L/min (analysis of variance [ANOVA], P = .03). RPM reduction protected VWF from pathologic degradation. At lower RPMs, significantly greater levels of VWF multimers were observed (ANOVA, P = .001). Similarly, at lower RPMs, significantly fewer VWF fragments, a product of VWF degradation, were observed (ANOVA, P = .007).

CONCLUSIONS

RPM reduction significantly reduced VWF degradation with the centrifugal-flow EVAHEART LVAS, an LVAD specifically designed with low shear stress. Different LVADs have unique hematologic footprints and should be managed with device-specific protocols. Adjustment of RPM to minimize blood trauma while still maintaining physiologic hemodynamics has the potential to decrease complications related to LVAD-associated von Willebrand's disease, such as gastrointestinal bleeding and hemorrhagic stroke.

An Emergency Medicine-focused Summary of the HFSA/SAEM/ISHLT Clinical Consensus Document on the Emergency Management of Patients With Ventricular Assist Devices

Mechanical circulatory support is increasingly used as a long-term treatment option for patients with end-stage heart failure. Patients with implanted ventricular assist devices are at high risk for a range of diverse medical urgencies and emergencies. Given the increasing prevalence of mechanical circulatory support devices, this expert clinical consensus document seeks to help inform emergency medicine and prehospital providers regarding the approach to acute medical and surgical conditions encountered in these complex patients.

Device-related epistaxis risk: continuous-flow left ventricular assist device-supported patients

BACKGROUND

The aim of this study was to analyze the effect of device-dependent factors on epistaxis episodes comparing patients supported with a continuous-flow left ventricular assist device (CF-LVAD) to patients under the same antithrombotic therapy.

METHODS

Patients who underwent CF-LVAD between 2012 and 2018 were reviewed retrospectively from the institutionally adopted electronic database. Patients who underwent mitral valve replacement (MVR) surgery receiving the same anticoagulant and antiaggregant therapy were included as a control group. Demographics, epistaxis episodes, and nonepistaxis bleeding between the two groups were compared.

RESULTS

A total of 179 patients met the inclusion criteria (61 patients CF-LVAD group, 118 patients MVR group). The median (range) follow-up periods for the study (CF-LVAD) and control (MVR) groups were 370 (2819) and 545.70 (2356) days, respectively. There was a significant difference for frequency of bleeding episodes per month between CF-LVAD and MVR groups (p = 0.003 < 0.05). The most common site of bleeding was the anterior septum in both groups (90.9% for the CF-MVR group and 100% for the MVR group). While 14 patients (23%) had nonepistaxis bleeding in the CF-LVAD group, only two patients (1.7%) had nonepistaxis bleeding in the MVR group. There were significant differences in nonepistaxis bleeding rates between the CF-LVAD and MVR groups (χ²=19.79, p < 0.001).

CONCLUSION

Both epistaxis and nonepistaxis bleeding rates were higher in the CF-LVAD group than in the MVR group. This suggests that the use of CF-LVAD support could directly increase the risk of hemorrhagic complications.

LEVEL OF EVIDENCE

2A (Etiology/Harm).

Platelet Mapping by Thromboelastography and Whole Blood Aggregometry in Adult Patients Supported by Mechanical Circulatory Support Device on Aspirin Therapy

Patients on mechanical circulatory support (MCS) devices are placed on aspirin and may require platelet function testing (PFT) to monitor the adequacy of therapy. Routine laboratory PFT is performed using whole blood aggregation (WBA) which typically has a long turnaround time (4-5 hours) and may not be readily available. By contrast, platelet mapping by thromboelastography (TPM) can provide results within 45 minutes. The objective of this study was to compare the results of TPM with WBA. We compared platelet mapping maximal amplitude (MA) by TPM with that of arachidonic acid (AA) to WBA with AA by impedance. We analyzed paired samples where both TPM and WBA were available. Of 45 paired samples, 34 were from 29 MCS patients and 11 were from non-MCS patients. When applying institutional interpretation guidelines with an MA_Activator cutoff of ≤40 mm, WBA_AA vs TPM MA_AA in non-MCS and MCS patients correlated well with an accuracy of 100 and 94.4%, respectively. MA_Activator >40 had poor correlation with an accuracy of 37.5%. Irrespective of MA_Activator value, TPM AA inhibition expressed in percent of inhibition had poor accuracy. When used with proper guidelines for interpretation, specifically when MA_Activator ≤ 40 mm, TPM is a suitable and reliable test to use for MCS patients on aspirin.

Endoscopic Algorithm for Management of Gastrointestinal Bleeding in Patients With Continuous Flow LVADs: A Prospective Validation Study

BACKGROUND

Gastrointestinal bleeding (GIB) is a common complication of left ventricular assist device (LVAD) therapy accounting for frequent hospitalizations and high resource utilization.

METHODS

We previously developed an endoscopic algorithm emphasizing upfront evaluation of the small bowel and minimizing low-yield procedures in LVAD recipients with GIB. We compared the diagnostic and therapeutic yield of endoscopy, health-care costs, and re-bleeding rates between conventional GIB management and our algorithm using chi-square, Fisher's exact test, Wilcoxon-Mann-Whitney, and Kaplan-Meier analysis.

RESULTS

We identified 33 LVAD patients with GIB. Presentation was consistent with upper GIB in 20 (61%), lower GIB in 5 (15%), and occult GIB in 8 (24%) patients. Forty-one endoscopies localized a source in 23 (56%), resulting in 14 (34%) interventions. Algorithm implementation compared with our conventional cohort was associated with a 68% increase in endoscopic diagnostic yield (P< .01), a 113% increase in therapeutic yield (P= .01), a 27% reduction in the number of procedures per patient (P < .01), a 33% decrease in length of stay (P < .01), and an 18% reduction in estimated costs (P < .01). The same median number of red blood cell transfusions were used in the 2 cohorts, with no increase in re-bleeding events in the algorithm cohort (33.3%) compared with our conventional cohort (43.7%).

CONCLUSIONS

Our endoscopic management algorithm for GIB in LVAD patients proved effective in reducing low-yield procedures, improving the diagnostic and therapeutic yield of endoscopy, and decreasing health-care resource utilization and costs, while not increasing the risk of a re-bleeding event.

Effect of aspirin dose on hemocompatibility-related outcomes with a magnetically levitated left ventricular assist device: An analysis from the MOMENTUM 3 study

BACKGROUND

Aspirin (ASA) anti-platelet therapy is mandated with left ventricular assist devices (LVADs) to prevent hemocompatibility-related adverse events (HRAEs). However, the optimal dose of ASA with HeartMate 3 (HM3) LVAD is unknown.

METHODS

In an exploratory analysis of HM3-supported patients in the MOMENTUM 3 study (NCT02224755), 2 groups were analyzed: usual-dose (325 mg) and low-dose (81 mg) ASA with anti-coagulation targeted to an international normalized ratio of 2.0 to 3.0. Exclusion criteria included patients not receiving either ASA 81 mg or 325 mg, those with HRAEs ≤7 days after device implantation, and those receiving >1 anti-platelet agent. The primary end-point was survival free from HRAEs (non-surgical bleeding, pump thrombosis, stroke, and peripheral arterial thromboembolic events) at 2 years.

RESULTS

Overall, 321 HM3 patients (usual-dose: n = 141, low-dose: n = 180) were included in this analysis. Usual-dose group patients were younger (57 ± 13 vs 60 ± 12 years, p = 0.035) and less often assigned destination therapy (55% vs 67%, p = 0.029) than low-dose ASA. At 2 years, a similar proportion of patients in the usual- and low-dose groups (43.4% vs 45.3%, p = 0.94) met the primary end-point. There were no differences in survival free from hemorrhagic (usual-dose: 54.4% vs low-dose: 51.7%, p = 0.42) or thrombotic (usual-dose: 76.8% vs low-dose: 75.7%, p = 0.92) events.

CONCLUSIONS

Usual- and low-dose ASA revealed similar rates of bleeding and thrombotic events in HM3 LVAD-supported patients within the MOMENTUM 3 trial. Whether ASA therapy provides any meaningful therapeutic effect in patients treated by the HM3 LVAD remains to be determined.

Patients with left ventricle assist devices presenting for thoracic surgery and lung resection: tips, tricks and evidence

PURPOSE OF REVIEW

Over a thousand left ventricular-assist device (LVAD) implants were performed for heart failure destination therapy in 2017. With increasing survival, we are seeing increasing numbers of patients present for noncardiac surgery, including resections for cancer. This article will review the relevant literature and guidelines for patients with LVADs undergoing thoracic surgery, including lung resection.

RECENT FINDINGS

The International Society for Heart and Lung Transplant Mechanically Assisted Circulatory Support Registry has received data on more than 16 000 patients with LVADs. Four-year survival is more than 60% for centrifugal devices. There are increasing case reports, summaries and recommendations for patients with LVADs undergoing noncardiac surgery. However, data on thoracic surgery is restricted to case reports.

SUMMARY

Successful thoracic surgery requires understanding of the LVAD physiology. Modern devices are preload dependent and afterload sensitive. The effects of one-lung ventilation, including hypoxia and hypercapnia, may increase pulmonary vascular resistance and impair the right ventricle. Successful surgery necessitates a multidisciplinary approach, including thorough preoperative assessment; optimization and planning of intraoperative management strategies; and approaches to anticoagulation, right ventricular failure and LVAD flow optimization. This article discusses recent evidence on these topics.