Continuous-Flow LVAD Support Causes a Distinct Form of Intestinal Angiodysplasia

The influence of arterial stenosis on blood damage under continuous flow

Arterial stenosis, resulting from plaque accumulation, can lead to serious conditions such as thrombosis and von Willebrand syndrome. This study investigates how variations in stenosis shape and severity affect red blood cell (RBC) and von Willebrand factor (VWF) damage through simulations and experimental approaches. A continuous flow generation device was utilized to create a blood circulation platform. The effects of different stenosis shapes and severities under continuous flow conditions on RBC damage and VWF degradation were examined. Blood samples were then analyzed for plasma-free hemoglobin concentration and VWF degradation. The results indicated that increased stenosis severity correlated with elevated hemolysis and a higher degradation rate of high molecular weight VWF (HMW-VWF). Rectangular stenosis induced more severe hemolysis and VWF degradation compared to elliptical stenosis at equivalent stenosis degrees. Both stenosis types demonstrated varying VWF degradation rates at low and medium/high stenosis levels, with elliptical stenosis showing particularly low VWF degradation at lower stenosis levels. The study highlights that different stenosis shapes and severities significantly affect blood damage under continuous flow. Greater stenosis severity resulted in increased blood flow velocity and wall shear stress (WSS), leading to enhanced hemolysis and VWF degradation, with rectangular stenosis showing more pronounced effects.

Impact of Digoxin Utilization on Gastrointestinal Bleeding in Patients With Continuous-Flow Left Ventricular Assist Devices: A Systematic Review and Meta-Analysis

Continuous-flow left ventricular assist devices (CF-LVADs) improve quality of life and survival in patients with advanced heart failure but are frequently complicated by gastrointestinal bleeding (GIB). Reduced pulsatile flow may induce mucosal hypoxia, upregulating factors such as hypoxia-inducible factor (HIF)-1α and triggering neo-angiogenesis, leading to the development of gastrointestinal angiodysplasias (GIADs), a common cause of GIB. Digoxin inhibits HIF-1α and may prevent GIAD development, although its impact on the incidence of GIB remains uncertain. This meta-analysis (PROSPERO ID: CRD42024626222) evaluated the association between digoxin use and GIB occurrence (primary outcome) in patients with CF-LVADs. Research articles including adults with CF-LVADs, comparing digoxin users versus nonusers were included. Overall, four studies were included (n = 14,917; age 55 ± 13 years, 21% female) with 2,742 patients in the digoxin group and 12,175 in the no-digoxin group. Continuous-flow left ventricular assist device was axial (HeartMate II) in 78% of cases and centrifugal (HeartMate 3/HeartWare) in 22%. Digoxin use was associated with a nonsignificant lower risk of GIB (hazard ratio [HR]: 0.70; 95% confidence interval [CI]: 0.49-1.01). However, regarding GIAD-related GIB, digoxin was associated with a significantly lower risk (HR: 0.33; 95% CI: 0.13-0.82). Among 14,917 patients with CF-LVADs, digoxin use was associated with a trend toward a lower risk of GIB and a lower risk of GIAD-related GIB.

Clinical approach to the diagnosis and management of small bowel bleeding

The diagnosis and management of small bowel bleeding (SBB) can be a clinical challenge. Advances in video capsule endoscopy, balloon-assisted enteroscopy, and multiphasic computed tomography allow for localization and therapeutic intervention. Etiologies of SBB including vascular, neoplastic, and inflammatory conditions are associated with age and comorbidities. The present review highlights terminologies that describe SBB, provides a differential diagnosis for bleeding etiologies, and summarizes a clinical approach to managing this condition.

Antithrombotic Treatment for Left Ventricular Assist Devices: One Does Not Fit All

As the prevalence of heart failure is increasing globally, left ventricular assist devices (LVADs) have become essential therapeutic options in managing advanced heart failure. This review explores the development of LVAD technology, with a focus on the shift from pulsatile to continuous-flow devices, particularly the HeartMate 3, the most advanced generation of LVADs. The evolution in design has significantly enhanced patient survival and quality of life. However, hemocompatibility-related adverse events (HRAEs)-such as pump thrombosis, ischemic and hemorrhagic strokes, and gastrointestinal bleeding-remain major clinical challenges. Striking the delicate balance between preventing thromboembolic events and minimizing hemorrhagic risks remains critical in LVAD patient management. Current therapeutic strategies typically involve long-term anticoagulation with vitamin K antagonists and antiplatelet therapy, though optimal management must be individualized based on patient-specific factors and device characteristics. Emerging alternatives, including low-dose anticoagulation, direct oral anticoagulants such as apixaban, and aspirin-free regimens, offer promising potential to reduce adverse outcomes. This review also highlights the role of innovative mechanical designs in minimizing shear stress and alternative treatments in preventing complications like gastrointestinal bleeding. Despite these advancements, personalized treatment strategies are critical, as no single therapeutic regimen fits all LVAD recipients. Ongoing research into both device technology and pharmacological therapies is essential to further reduce HRAEs and improve long-term outcomes for LVAD patients.

The Impact of Acute Exercise on Hemostasis and Angiogenesis Mediators in Patients With Continuous-Flow Left Ventricular Assist Devices: A Prospective Observational Pilot Study

Impaired primary hemostasis and dysregulated angiogenesis, known as a two-hit hypothesis, are associated with gastrointestinal (GI) bleeding in patients with continuous-flow left ventricular assist devices (CF-LVADs). Exercise is known to influence hemostasis and angiogenesis in healthy individuals; however, little is known about the effect in patients with CF-LVADs. The objective of this prospective observational study was to determine whether acute exercise modulates two-hit hypothesis mediators associated with GI bleeding in patients with a CF-LVAD. Twenty-two patients with CF-LVADs performed acute exercise either on a cycle ergometer for approximately 10 minutes or on a treadmill for 30 minutes. Blood samples were taken pre- and post-exercise to analyze hemostatic and angiogenic biomarkers. Acute exercise resulted in an increased platelet count ( p < 0.00001) and platelet function (induced by adenosine diphosphate, p = 0.0087; TRAP-6, p = 0.0005; ristocetin, p = 0.0009). Additionally, high-molecular-weight vWF multimers ( p < 0.00001), vWF collagen-binding activity ( p = 0.0012), factor VIII ( p = 0.034), angiopoietin-1 ( p = 0.0026), and vascular endothelial growth factor ( p = 0.0041) all increased after acute exercise. This pilot work demonstrates that acute exercise modulated two-hit hypothesis mediators associated with GI bleeding in patients with CF-LVADs.

Higher soluble thrombomodulin and angiogenic markers in continuous flow left ventricular assist device-supported patients associated with arteriovenous malformation and nonsurgical bleeding

Bleeding complications are a bane of continuous flow left ventricular assist devices (cfLVAD); gastrointestinal bleeding (GIB) from arteriovenous malformation (AVM) predominating. We hypothesized that shear stress disrupts vascular endothelium altering angiogenesis and contributing to bleeding. We profiled markers of endothelial dysfunction (soluble thrombomodulin [sTM]) and angiogenesis (angiopoietin-1 [Ang-1], angiopoietin-2 [Ang-2]) in 21 patients implanted with a centrifugal cfLVAD. Bleeding episodes were documented in 11 patients, 8 had GIB, 4 of whom had AVMs. We observed a dynamic change in sTM and Ang-2/Ang-1 ratio following cfLVAD support (p = 0.030 and p = 0.025, respectively). Bleeding patients had higher sTM and Ang-2/Ang-1 ratios than patients with no bleeding (p = 0.04 and p = 0.06, respectively). At D180, patients with AVMs had significantly higher Ang-2/Ang-1 ratios vs patients without proven AVMs (p = 0.006). We conclude that bleeding in cfLVAD-supported patients is associated with alteration in endothelial/vascular homeostasis, possibly contributing to AVM formation.

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.

Reduced Rate of Anemia after Transcatheter Aortic Valve Replacement

Background/Objectives: We sought to evaluate changes in hemoglobin level and renal function in patients 5-12 months after transcatheter aortic valve replacement (TAVR), and to examine possible relationships between these changes. Anemia is common in older people with severe aortic stenosis (AS). The two most common etiologies for anemia in this population are iron deficiency due to gastrointestinal blood loss and renal failure. Angiodysplasia in the gastrointestinal system is a feature of AS syndrome. Methods: We collected clinical data, including hemoglobin level and renal function before and 5-12 months after TAVR in 315 consecutive patients. To examine whether calculated clinical predictors such as EuroScore 2 are associated with the persistence of anemia after TAVR, we performed multivariable correlation analysis with post-TAVR anemia as the dependent variable. Results: The mean hemoglobin level increased significantly (from 11.76 to 12.16 g/dL, p < 0.0001) 5-12 months after TAVR, and the number of patients with anemia decreased significantly (from 67.5% to 53.9%, p < 0.0001). At 5-12 months following TAVR, a small reduction in estimated glomerular filtration rate was observed (from 60.05 ± 24.1 to 58.30 ± 24.50 mL/min, p = 0.024). The multivariable correlation analysis did not identify clinical predictors of persistent anemia. Conclusions: A significant increase in hemoglobin was observed 5-12 months after TAVR, despite a reduction in renal function. Our findings imply that gastrointestinal blood loss, which occurs in patients with severe AS, is significantly reduced following TAVR.

Preservation of von Willebrand Factor Activity With the ModulHeart Device

von Willebrand Factor (VWF) destruction is common with current heart pumps. This study evaluates VWF activity with ModulHeart, a novel device using 3 micropumps in parallel. In model 1, ModulHeart was compared with Impella devices in vitro. In model 2, 3 healthy swine received ModulHeart. Model 3 includes VWF data from patients who underwent protected percutaneous coronary intervention with ModulHeart. In models 1, 2, and 3, ModulHeart resulted in preservation of VWF, whereas there was a 27% and 19% reduction in VWF activity with the Impella CP and 5.0, respectively. ModulHeart features a unique design and demonstrated preservation of VWF activity.

Patient-specific severity of von Willebrand factor degradation identifies patients with a left ventricular assist device at high risk for bleeding

BACKGROUND

Continuous-flow left ventricular assist devices (LVADs) cause an acquired von Willebrand factor (VWF) deficiency and bleeding. Models to risk-stratify for bleeding are urgently needed. We developed a model of continuous-flow LVAD bleeding risk from patient-specific severity of VWF degradation.

METHODS

In a prospective, longitudinal cohort study, paired blood samples were obtained from patients (n = 67) with a continuous-flow LVAD before and during support. After 640 ± 395 days, patients were categorized as all-cause bleeders, gastrointestinal (GI) bleeders, or nonbleeders. VWF multimers and VWF clotting function were evaluated to determine bleeding risk.

RESULTS

Of 67 patients, 34 (51%) experienced bleeding, 26 (39%) experienced GI bleeding, and 33 (49%) did not bleed. In all patients, LVAD support significantly reduced high-molecular-weight VWF multimers (P < .001). Bleeders exhibited greater loss of high-molecular-weight VWF multimers (mean ± standard deviation, -10 ± 5% vs -7 ± 4%, P = .008) and reduced VWF clotting function versus nonbleeders (median [interquartile range], -12% [-31% to 4%] vs 0% [-9 to 26%], P = .01). A combined metric of VWF multimers and VWF function generated the All-Cause Bleeding Risk Score, which stratified bleeders versus nonbleeders (86 ± 56% vs 41 ± 48%, P < .001) with a positive predictive value of 86% (95% confidence interval, 66%-95%) and diagnostic odds ratio of 11 (95% confidence interval, 2.9-44). A separate GI Bleeding Risk Score stratified GI bleeders versus nonbleeders (202 ± 114 vs 120 ± 86, P = .003) with a positive predictive value of 88% (64%-97%) and diagnostic odds ratio of 18 (3.1-140).

CONCLUSIONS

The severity of loss of VWF multimers and VWF clotting function generated Bleeding Risk Scores with high predictive value for LVAD-associated bleeding. This model may guide personalized antithrombotic therapy and patient surveillance.

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.

Gastrointestinal bleeding and pro-angiogenic shift in the angiopoietin axis with continuous flow left ventricular assist device implantation

BACKGROUND

Gastrointestinal bleeding (GIB) affects up to 40% of continuous-flow left ventricular assist device (CF-LVAD) recipients. A higher risk of GIB is seen in CF-LVAD recipients with lower device pulsatility without a known mechanism. One hypothesis is that the novel hemodynamics in CF-LVAD recipients affect angiogenesis signaling. We aimed to (1) measure serum levels of angiopoietin (Ang)-1, Ang-2, and VEGF-A in CF-LVAD recipients with and without GIB and in healthy controls and (2) evaluate correlations of those levels with hemodynamics.

METHODS

We recruited 12 patients with CF-LVADs (six who developed GIB after device implantation) along with 12 age-matched controls without heart failure or GIB and measured Ang-1, Ang-2, and VEGF-A levels in serum samples from each patient.

RESULTS

CF-LVAD recipients had significantly higher Ang-2 and lower Ang-1 levels compared to controls with no difference in VEGF-A levels. CF-LVAD recipients with GIB had lower Ang-1 levels than those without GIB. There were trends for pulse pressure to be positively correlated with Ang-1 levels and negatively correlated with Ang-2 levels in CF-LVAD recipients with no correlation observed in healthy controls.

CONCLUSION

CF-LVAD recipients demonstrated a shift toward a pro-angiogenic phenotype in the angiopoietin axis that is significantly associated with GIB and may be linked to low pulse pressure.

The Global Burden of Vascular Intestinal Disorders in 204 Countries and Territories From 1990 to 2019: Global Burden of Diseases Study

Objectives: Assess the prevalence, mortality, and disability-adjusted life years (DALYs) of vascular intestinal disorders (VID) from 1990 to 2019. Methods: This study conducted a secondary data analysis utilizing the Global Burden of Diseases Study 2019. The prevalence, mortality and DALYs of VID were analyzed by sex, age and socio-demographic index (SDI), respectively. Analyses were performed by using R software. Results: Globally, the number of prevalent VID cases increased from 100,158 (95% uncertainty interval: 89,428-114,013) in 1,990-175,740 (157,941-198,969) in 2019. However, the age-standardized rates (ASR) of VID prevalence declined from 2.47 (95% uncertainty interval: 2.24-2.76) per 100,000 population to 2.21 (1.98-2.48) per 100,000 population between 1990 and 2019. Furthermore, the ASR of mortality also decreased from 1990 to 2019. Between 1990 and 2019, the regions with high and high-middle level exhibited the highest diseases burden. Conclusion: Globally, the diseases burden associated with VID demonstrated a decline from 1990 to 2019. However, concerted efforts are still required to enhance measures to combat VID within countries categorized as high and high-middle SDI.

HeartMate-3 Ventricular Assist Devices Versus the Total Artificial Heart for Biventricular Support: A Single-Center Series

INTRODUCTION

The SynCardia total artificial heart (TAH) is the only device approved for biventricular support. Continuous flow ventricular assist devices (VAD) in a biventricular configuration (BiVAD) have been used with variable results. The purpose of this report was to examine differences in patient characteristics and outcomes between two HeartMate-3 (HM-3) VADs in comparison with TAH support.

METHODS

All patients who received durable biventricular mechanical support from November 2018 to May 2022 at The Mount Sinai Hospital (New York) were considered. Baseline clinical, echocardiographic, hemodynamic, and outcome data were extracted. Primary outcomes were postoperative survival and successful bridge-to-transplant (BTT).

RESULTS

A total of 16 patients received durable biventricular mechanical support during the study period, of which 6 (38%) patients received two HM-3 VAD pumps as BiVAD support and 10 (62%) patients received a TAH. Overall, TAH patients had a lower median lactate ( p < 0.05) at baseline compared to those on HM-3 BiVAD support yet had higher operative morbidity, lower 6-month survival ( p < 0.05), and a higher rate of renal failure (80 vs . 17%; p = 0.03). However, survival declined to the same rate at 1 year (50%) and was largely because of extracardiac adverse events related to underlying comorbidities (particularly, renal failure and diabetes, p < 0.05). Successful BTT was achieved in 3 out of 6 HM-3 BiVAD patients and in 5 out of 10 TAH patients.

CONCLUSION

In our single center experience, similar outcomes were observed among patients BTT with HM-3 BiVAD compared to those BTT on TAH support despite lower Interagency Registry for Mechanically Assisted Circulatory Support level.

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.

Kinetic and Dynamic Effects on Degradation of von Willebrand Factor

The loss of high molecular weight multimers (HMWM) of von Willebrand factor (vWF) in aortic stenosis (AS) and continuous-flow left ventricular assist devices (cf-LVADs) is believed to be associated with high turbulent blood shear. The objective of this study is to understand the degradation mechanism of HMWM in terms of exposure time (kinetic) and flow regime (dynamics) within clinically relevant pathophysiologic conditions. A custom high-shear rotary device capable of creating fully controlled exposure times and flows was used. The system was set so that human platelet-poor plasma flowed through at 1.75 ml/sec, 0.76 ml/sec, or 0.38 ml/sec resulting in the exposure time ( texp ) of 22, 50, or 100 ms, respectively. The flow was characterized by the Reynolds number (Re). The device was run under laminar (Re = 1,500), transitional (Re = 3,000; Re = 3,500), and turbulent (Re = 4,500) conditions at a given texp followed by multimer analysis. No degradation was observed at laminar flow at all given texp . Degradation of HMWM at a given texp increases with the Re. Re ( p < 0.0001) and texp ( p = 0.0034) are significant factors in the degradation of HMWM. Interaction between Re and texp , however, is not always significant ( p = 0.73).

Vascular Function in Continuous Flow LVADs: Implications for Clinical Practice

Left ventricular assist devices (LVADs) have been increasingly used in patients with advanced heart failure, either as a destination therapy or as a bridge to heart transplant. Continuous flow (CF) LVADs have revolutionized advanced heart failure treatment. However, significant vascular pathology and complications have been linked to their use. While the newer CF-LVAD generations have led to a reduction in some vascular complications such as stroke, no major improvement was noticed in the rate of other vascular complications such as gastrointestinal bleeding. This review attempts to provide a comprehensive summary of the effects of CF-LVAD on vasculature, including pathophysiology, clinical implications, and future directions.

Gastrointestinal bleeding in patients with continuous-flow left ventricular assist devices: A comprehensive review

BACKGROUND

Gastrointestinal bleeding is a major cause of morbidity that plagues the quality of life of patients supported on contemporary continuous-flow left ventricular assist devices (CF-LVADs). Despite benefits in survival and the nearly 50% reduction in complications provided by CF-LVADs, bleeding remains one of the most frequent adverse events with CF-LVAD implants. The CF-LVADs cause an increased risk of bleeding mainly due to the activation of the coagulation cascade.

METHODS

A literature search was done using PubMed and Google Scholar from Inception to February 2022. Qualitative analyses of the articles retrieved were used to construct this review. This review attempts to provide a comprehensive summary of the epidemiology, pathophysiology, risk stratification, and management of gastrointestinal bleeding as a complication of CF-LVAD as well as propose an algorithm for diagnosis and treatment.

RESULTS

Bleeding can occur at different sites in the gastrointestinal tract, the most common underlying pathology being arteriovenous malformations located in the upper gastrointestinal tract The increased prevalence of gastrointestinal (GI) bleeding in CF-LVAD patients has been attributed to the physiology of the LVAD itself, the use of anticoagulants, as well as patient comorbidities. Management involves pharmacologic and nonpharmacologic strategies.

CONCLUSIONS

CF-LVAD-supported patients have a significant risk of GI bleeding that is mainly caused by arteriovenous malformations located in the upper GI tract. The increased prevalence of GI bleeding in CF-LVAD patients is attributed to several etiologies that include factors attributed to the device itself and extrinsic factors such as the use of anticoagulation.

Impact of hepatopulmonary syndrome in liver transplantation candidates and the role of angiogenesis

BACKGROUND

Hepatopulmonary syndrome affects 10-30% of patients with cirrhosis and portal hypertension. We evaluated the serum angiogenic profile of hepatopulmonary syndrome and assessed the clinical impact of hepatopulmonary syndrome in patients evaluated for liver transplantation.

METHODS

The Pulmonary Vascular Complications of Liver Disease 2 study was a multicentre, prospective cohort study of adults undergoing their first liver transplantation evaluation. Hepatopulmonary syndrome was defined as an alveolar-arterial oxygen gradient ≥15 mmHg (≥20 mmHg if age >64 years), positive contrast-enhanced transthoracic echocardiography and absence of lung disease.

RESULTS

We included 85 patients with hepatopulmonary syndrome and 146 patients without hepatopulmonary syndrome. Patients with hepatopulmonary syndrome had more complications of portal hypertension and slightly higher Model for End-Stage Liver Disease-Na score compared to those without hepatopulmonary syndrome (median (interquartile range) 15 (12-19) versus 14 (10-17), p=0.006). Hepatopulmonary syndrome patients had significantly lower 6-min walk distance and worse functional class. Hepatopulmonary syndrome patients had higher circulating angiopoietin 2, Tie2, tenascin C, tyrosine protein kinase Kit (c-Kit), vascular cell adhesion molecule 1 and von Willebrand factor levels, and lower E-selectin levels. Patients with hepatopulmonary syndrome had an increased risk of death (hazard ratio 1.80, 95% CI 1.03-3.16, p=0.04), which persisted despite adjustment for covariates (hazard ratio 1.79, 95% CI 1.02-3.15, p=0.04). This association did not vary based on levels of oxygenation, reflecting the severity of hepatopulmonary syndrome.

CONCLUSION

Hepatopulmonary syndrome was associated with a profile of abnormal systemic angiogenesis, worse exercise and functional capacity, and an overall increased risk of death.

Biomarkers in Patients with Left Ventricular Assist Device: An Insight on Current Evidence

Left ventricular assist devices (LVADs) have been representing a cornerstone therapy for patients with end-stage heart failure during the last decades. However, their use induces several pathophysiological modifications which are partially responsible for the complications that typically characterize these patients, such as right ventricular failure, thromboembolic events, as well as bleedings. During the last years, biomarkers involved in the pathways of neurohormonal activation, myocardial injury, adverse remodeling, oxidative stress and systemic inflammation have raised attention. The search and analysis of potential biomarkers in LVAD patients could lead to the identification of a subset of patients with an increased risk of developing these adverse events. This could then promote a closer follow-up as well as therapeutic modifications. Furthermore, it might highlight some new therapeutic pharmacological targets that could lead to improved long-term survival. The aim of this review is to provide current evidence on the role of different biomarkers in patients with LVAD, in particular highlighting their possible implications in clinical practice.

Left Ventricular End-Diastolic Dimension and Clinical Outcomes After Centrifugal Flow Left Ventricular Assist Device Implantation

The impact of preoperative end-diastolic left ventricular dimension (preLVEDD) on long-term outcomes with centrifugal continuous-flow left ventricular assist device (CF-LVAD) is not well established. Accordingly, we performed an analysis of the Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) registry to study this relationship. All patients with centrifugal CF-LVAD in the INTERMACS registry from June 2006 to December 2017 were screened. The final study group consisted of 3,304 patients. After a median follow-up of 9.0 months (interquartile range [IQR], 4.2-18.8 months), 2,596 (79%) patients were alive. After adjusting for significant covariates, increased preLVEDD was associated with lower mortality (hazard ratio [HR], 0.91; 95% confidence interval [CI], 0.84-0.98; p = 0.01), stroke (HR, 0.85; 95% CI, 0.77-0.93; p < 0.001), and gastrointestinal bleeding (HR, 0.88; 95% CI, 0.80-0.97; p = 0.01), although there were more arrhythmias (HR, 1.14; 95% CI, 1.05-1.24; p = 0.003). Our study suggests that preLVEDD is an independent predictor of mortality and adverse events in patients treated with centrifugal CF-LVAD. preLVEDD should be considered an important preimplant variable for risk stratification when considering a CF-LVAD.

Characteristics and Outcomes of Pediatric Patients With a Ventricular Assist Device Presenting to the Emergency Department

OBJECTIVES

A growing number of children receive support from left ventricular assist devices (LVADs) in the outpatient setting. Unexpected complications of LVAD support occur that require emergent management, and no studies examine how pediatric LVAD patients present to the emergency department (ED). The goals of this study were (1) to describe frequency of visits, clinical characteristics, adverse events, and outcomes of LVAD-supported children treated in ED settings and (2) to evaluate for associations between specified patient outcomes and ED care location.

METHODS

This was a retrospective cohort study of children in a single-center outpatient VAD program who presented to several EDs during a 10-year period. We defined adverse events according to the Advanced Cardiac Therapies Improving Outcomes Network registry guidelines. Secondary analysis evaluated for associations between specified patient outcomes (adverse events, hospitalizations, intensive care unit admissions) and ED care location (institutional vs other ED).

RESULTS

Of 104 subjects with LVAD implantations during the study period, 30 (28.8%) transitioned to outpatient care. Among subjects in the outpatient VAD program, 24 (80%) of 30 had 54 visits to various EDs over 141.9 patient-months. The median age at time of ED visit was 13.5 years (range, 7.2-17.9 years). The median number of visits per subject was 1 (range, 0-6). The most common complaints on arrival to the ED were vomiting or abdominal pain (16.7%), fever (15.3%), and headache (13.9%). Seventeen adverse events occurred during 14 (25.9%) of 54 ED visits. The most common adverse events were major infection (33.3%) and right heart failure (16.7%). Hospital admission resulted from 41 (75.9%) of 54 ED visits, including 17 (41.5%) of 41 to a cardiovascular intensive care unit. Care at a nonspecialty ED was associated with a higher rate of hospitalization (93.8% vs 68.4%, P = 0.049). During the study period, 4 subjects (13.3%) died, including 1 patient on destination therapy, 1 with multisystem organ failure due to cardiogenic shock, and 2 with hemorrhagic stroke. No patient died while in the ED.

CONCLUSIONS

Among subjects in a single outpatient pediatric VAD program presenting to the ED, the most common complaints were abdominal pain/vomiting, fever, and headache. The most common adverse events were major infection and right heart failure. Subjects had a high rate of ED utilization and hospital admission.

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.

Gastrointestinal angiodysplasia in heart failure and during CF LVAD support

Angiodysplasias (AGD) are common sites of bleeding in the gastrointestinal (GI) tract after Continuous Flow Left Ventricular Assist Device (CF-LVAD) implantation. We sought to investigate whether AGDs are formed as a result of LVAD physiology or preexist as a consequence of heart failure. Thirty-six subjects with HF reduced EF (HFrEF) underwent video capsule endoscopy (VCE) to assess for the presence of AGD. Fifty-three subjects without HF who underwent VCE for a nonbleeding indication formed a control group. The prevalence of AGD was significantly higher in the HFrEF compared to the non-HF controls (50% vs 13%, p = 0.0002). This association persisted after controlling for age and comorbidities. Within the HFrEF cohort, higher Ang2, NT-proBNP and BUN were associated with the presence of AGD. AGD in the GI tract are associated with HFrEF. This is the first description of a new pathology associated with HFrEF and adds to our understanding of CF LVAD associated GI bleeding.

Association of bleeding with serotonergic antidepressants in patients receiving left ventricular assist device support

STUDY OBJECTIVE

This study sought to determine whether SA use is associated with bleeding in patients receiving CF-LVAD support.

DESIGN

A retrospective cohort analysis was conducted of all adult patients who received CF-LVAD implantation at our institution.

SETTING

Barnes-Jewish Hospital between July 1, 2009, and October 1, 2018.

PATIENTS

Patients at least 18 years of age who received a HVAD™ (HeartWare Corp.), HeartMate II™ (St. Jude Medical), or HeartMate 3™ (St. Jude Medical) CF-LVAD and survived for at least 30 days postoperatively were included.

INTERVENTION

Patients who received SAs (n = 203) were compared to those who did not (n = 391) from 30 days to 18 months following implantation. The primary outcome was the incidence of first bleeding events including gastrointestinal bleed (GIB), epistaxis, or intracerebral hemorrhage (ICH).

MEASUREMENTS AND MAIN RESULTS

During follow-up, 219 patients had bleeding events: 93 of 203 (45.8%) in the SA group versus 126 of 391 (32.2%) in the control group (p = 0.001). After adjustment for age, angiotensin-converting enzyme (ACE) inhibitor and angiotensin receptor blocker (ARB) use, history of bleeding events, history of smoking, and CF-LVAD type, SA use remained associated with bleeding (adjusted odds ratio: 1.75, 95% confidence interval: 1.22-2.51, p = 0.002). HeartMate 3™ patients experienced less bleeding than HeartMate II™ patients (adjusted odds ratio 0.46, 95% confidence interval: 0.23-0.90, p = 0.024).

CONCLUSIONS

In this single-center, retrospective cohort of patients supported with CF-LVADs, SA use was associated with the incidence of first bleeding events, primarily driven by GIB. Further studies are needed to assess any differential risk of bleeding among SA agents and to assess the utility of altering antithrombotic strategies.

Endothelial Dysfunction-related Neurological Bleeds with Continuous Flow-Left Ventricular Assist Devices Measured by Digital Thermal Monitor

Endothelial dysfunction has been demonstrated in patients with Continuous Flow-Left Ventricular Assist Devices (CF-LVADs) but association with adverse events has not been shown. We used a noninvasive, operator-independent device called VENDYS® to assess vasodilatory function based on digital thermal measurements postrelease of a brachial artery occlusion in ambulatory patients with CF-LVAD (n = 56). Aortic valve opening and pulse perception were also documented before the test. Median duration of CF-LVAD support was 438 days. The VENDYS® test generates a vascular reactivity index (VRI). Outcomes for the CF-LVAD patients were compared between VRI < 1 and VRI ≥ 1. The bleeding events were driven primarily by a difference in neurologic bleeds. Multivariate analysis showed that VRI < 1 correlated with future bleeding events (HR: 5.56; P = 0.01). The C-statistic with the VRI dichotomized as above was 0.82. There was a trend toward a worse survival in patients with poor endothelial function. Endothelial vasodilatory dysfunction measured by a simple test utilizing digital thermal monitoring can predict adverse bleeding events in patients with CF-LVADs.

Abnormalities in the Von Willebrand-Angiopoietin Axis Contribute to Dysregulated Angiogenesis and Angiodysplasia in Children With a Glenn Circulation

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Children with a bidirectional superior cavopulmonary connection (Glenn circulation) develop dysregulated angiogenesis and pulmonary angiodysplasia in the form of arteriovenous malformations (AVMs). No targeted therapy exists.

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The von Willebrand factor (vWF)–angiopoietin axis plays a major role in normal angiogenesis, angiodysplasia, and AVM formation in multiple diseases.

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vWF and angiopoietin-2 (which destabilizes vessel formation) were abnormal in children with a Glenn circulation versus control children. Within Glenn patients, angiopoietin-1 (which stabilizes vessel formation) and angiogenesis were different in the systemic versus pulmonary circulation. Plasma angiopoietin-1 was lower in the pulmonary circulation of Glenn patients with pulmonary AVMs than Glenn patients without AVMs.

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In parallel, differences in multiple angiogenic and inflammatory signaling peptides were observed between Glenn patients and controls, which indicated derangements in multiple angiogenic pathways in Glenn patients.

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These findings support the novel hypothesis that abnormal vWF metabolism and angiopoietin signaling dysregulate angiogenesis and contribute to pulmonary AVM formation in children with a Glenn circulation.

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The vWF-angiopoietin axis may be a target to correct angiogenic imbalance and reduce pulmonary angiodysplasia in Glenn patients.

Children with a bidirectional superior cavopulmonary (Glenn) circulation develop angiodysplasia and pulmonary arteriovenous malformations (AVMs). The von Willebrand factor (vWF)–angiopoietin axis plays a major role in AVM formation in multiple diseases. We observed derangements in global angiogenic signaling, vWF metabolism, angiopoietins, and in vitro angiogenesis in children with a Glenn circulation versus controls and within Glenn pulmonary versus systemic circulations. These findings support the novel hypothesis that abnormalities in the vWF-angiopoietin axis may dysregulate angiogenesis and contribute to Glenn pulmonary AVMs. The vWF-angiopoietin axis may be a target to correct angiogenic imbalance in Glenn patients, for whom no targeted therapy exists.

How I treat gastrointestinal bleeding in congenital and acquired von Willebrand disease

Gastrointestinal (GI) bleeding is distinctive of severe von Willebrand disease (VWD), generally arising in older patients; in most cases, blood transfusion and hospitalization are required. The presence of arteriovenous malformations is often described when endoscopic examinations are performed. Patients with congenital type 3, 2A, and 2B are those most frequently affected by this symptom, possibly due to the loss of high-molecular-weight multimers of von Willebrand factor (VWF). GI bleeding can also occur in patients affected by acquired von Willebrand syndrome. Endoscopic examination of the GI tract is necessary to exclude ulcers and polyps or cancer as possible causes of GI bleeding. In congenital VWD, prophylaxis with VWF/factor VIII concentrates is generally started after GI-bleeding events, but this therapy is not always successful. Iron supplementation must be prescribed to avoid chronic iron deficiency. Possible rescue therapies (high-dose statins, octreotide, thalidomide, lenalidomide, and tamoxifen) were described in a few case reports and series; however, surgery may be necessary in emergency situations or if medical treatment fails to stop bleeding. In this article, we present several clinical cases that highlight the clinical challenges of these patients and possible strategies for their long-term management.

Association between digoxin use and gastrointestinal bleeding in contemporary continuous flow left ventricular assist device support

BACKGROUND

Assess the association between digoxin use and gastrointestinal bleeding (GIB) in a multicenter continuous flow left ventricular assist device (LVAD) cohort.

METHODS

Patients implanted with continuous flow LVADs with data on GIB and digoxin use from two centers were included in the analysis (n = 649). GIB events were captured up to 2 years of follow-up. Digoxin use was defined as digoxin prescribed at discharge or within the first 3 months after LVAD implantation. A negative binomial regression model was performed to determine the association between digoxin use and number of GIB events over the follow-up period.

RESULTS

Mean age of the cohort was 57 years (±14) and 45% (293/649) were bridge to transplant (BTT). Digoxin was prescribed in 33% of patients. Digoxin use was associated with an unadjusted 32% reduction in the incidence of rate of all cause GIB (IRR 0.68, 95% CI 0.46-0.99, p = 0.049). After adjusting for age, sex, Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) profile, renal function, and implanting center there was still a 34% reduction in the incidence rate (IRR 0.67, 95% CI 0.45-0.99, p = 0.048). When limiting the analysis to those with likely arteriovenous malformation associated GIB, the association strengthened (unadjusted: IRR 0.48, 95 % CI 0.26-0.89, p = 0.02, adjusted: IRR 0.47, 95 % CI 0.25-0.9, p = 0.022).

CONCLUSIONS

In this multicenter study, inclusive of contemporary devices, digoxin use was associated with reduced GIB events. Prospective data will be required to confirm this association.

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.

Clinical Impact of Hematoma Expansion in Left Ventricular Assist Device Patients

BACKGROUND

Hematoma expansion (HE) is associated with poor outcome in patients with intracerebral hemorrhage (ICH), but the impact on patients with an left ventricular assist device (LVAD) is unknown. We aimed to define the occurrence of HE in the LVAD population and to determine the association between HE and mortality.

METHODS

We performed a retrospective cohort study of LVAD patients and intentionally matched anticoagulated controls without LVAD admitted to Columbia University Irving Medical Center with ICH between 2008 and 2019. We compared HE occurrence between patients with an LVAD and those without an LVAD using regression modeling, adjusting for factors known to influence HE. We evaluated pump thrombosis following anticoagulation reversal. We examined the association between HE and hospital mortality using Poisson regression modeling adjusting for factors associated with poor outcome.

RESULTS

Among 605 patients with an LVAD, we identified 28 patients with ICH meeting the study's inclusion criteria. Our LVAD ICH cohort was predominantly male (71%), with a mean age of 56 ± 10 years. The median baseline hematoma size was 20.1 mL³ (interquartile range [IQR], 8.6-46.9 mL³), and the median ICH score was 1 (IQR, 1-2). There was no significant difference in occurrence of HE in LVAD patients and matched non-LVAD patients (adjusted odds ratio [OR], 1.3; 95% confidence interval [CI], 0.4-4.2). There was an association between HE and in-hospital mortality in LVAD patients (adjusted OR, 4.8; 95% CI, 1.4-6.2).

CONCLUSIONS

HE occurrence appears to be similar in LVAD and non-LVAD patients. HE has a significant impact on LVAD ICH mortality, underscoring the importance of adequate coagulopathy reversal and blood pressure management in these patients.

Autoregulation of Pulsatile Bioprosthetic Total Artificial Heart is Involved in Endothelial Homeostasis Preservation

Pulsatile Carmat bioprosthetic total artificial heart (C-TAH) is designed to be implanted in patients with biventricular end-stage heart failure. Since flow variation might contribute to endothelial dysfunction, we explored circulating endothelial biomarkers after C-TAH implantation in seven patients and compared the manual and autoregulated mode. Markers of endothelial dysfunction and regeneration were compared before and during a 6- to 9-month follow-up after implantation. The follow-up was divided into three periods (< 3, 3-6, and > 6 months) and used to estimate the temporal trends during the study period. A linear mixed model was used to analyze repeated measures and association between tested parameters according to the mode of C-TAH and the time. Relevance of soluble endoglin (sEndoglin) level increase has been tested on differentiation and migration potential of human vasculogenic progenitor cells (endothelial colony forming cells [ECFCs]). Normal sEndoglin and soluble endothelial protein C receptor (sEPCR) levels were found in patients after implantation with autoregulated C-TAH, whereas they significantly increased in the manual mode, as compared with pretransplant values (p = 0.005 and 0.001, respectively). In the autoregulated mode, a significant increase in the mobilization of cytokine stromal cell-derived factor 1 was found (p = 0.03). After adjustment on the mode of C-TAH, creatinine or C-reactive protein level, sEndoglin, and sEPCR, were found significantly associated with plasma total protein levels. Moreover, a significant decrease in pseudotubes formation and migration ability was observed in vitro in ECFCs receiving sEndoglin activation. Our combined analysis of endothelial biomarkers confirms the favorable impact of blood flow variation achieved with autoregulation in patients implanted with the bioprosthetic total artificial heart.

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.

Cardiac Emergencies in Patients with Left Ventricular Assist Devices

Continuous-flow left ventricular assist devices are frequently used for management of patients with advanced heart failure with reduced ejection fraction. Although technologic advancements have contributed to improved outcomes, several complications arise over time. These complications result from several factors, including medication effects, physiologic responses to chronic exposure to circulatory support that is minimally/entirely nonpulsatile, and dysfunction of the device itself. Clinical presentation can range from chronic and indolent to acute, life-threatening emergencies. Several areas of uncertainty exist regarding best practices for managing complications; however, growing awareness has led to development of new guidelines to reduce risk and improve outcomes.

Anaerobic Bacteremias in Left Ventricular Assist Devices and Advanced Heart Failure

Left ventricular assisted devices (LVADs) have revolutionized the treatment of advanced heart failure, providing meaningful increases in survival, functional capacity, and quality of life. There are two categories of LVADs patients: (1) bridge-to-transplant and (2) destination therapy. Advanced heart failure and destination LVADs often carry a poor prognosis. The overall 1-year mortality rate remains as high as 30%. LVAD-specific infections, LVAD-related infections, and non-LVAD-related infections represent important emerging clinical problems in this setting. With an incidence ranging from 30 to 50%, these lead to high rates of hospitalization, morbidity, and mortality. Bacteremias caused by anaerobic pathogens in patients with LVAD are underreported. Herein, we describe the microbiological findings, treatment, and clinical outcome of four patients with LVADs and advanced heart failure with anaerobic bacteremias. Fusobacterium species was the most frequent etiological agent. Most patients had a relatively favorable short-term outcome with survival rates of 100% at 30 days and of 50% at 90 days. However, due to other multiple long-term complications, overall mortality remains at 50% during the first year and increases to 75% beyond the first year. Anaerobic bacteremia sources included the oral cavity from odontogenic infections and aspiration pneumonia. Anaerobic bacteremia constitutes an unfavorable mortality prognostic factor in patients with destination LVADs. We recommend implementing preventive strategies with a comprehensive dental care evaluation in patients with LVADs and advanced heart failure.

von Willebrand Factor and Management of Heart Valve Disease: JACC Review Topic of the Week

For decades, numerous observations have shown an intimate relationship between von Willebrand factor (VWF) multimer profile and heart valve diseases (HVD). The current knowledge of the unique biophysical properties of VWF helps us to understand the longstanding observations concerning the bleeding complications in patients with severe HVD. Not only does the analysis of the VWF multimer profile provide an excellent evaluation of HVD severity, it is also a strong predictor of clinical events. Also of importance, VWF responds within minutes to any significant change in hemodynamic valve status, making it an accurate marker of the quality of surgical and transcatheter therapeutic interventions. The authors provide in this review a practical, comprehensive, and evidence-based framework of the concept of VWF as a biomarker in HVD, advocating for its implementation into the clinical decision-making process besides usual clinical and imaging evaluation. They also delineate critical knowledge gaps and research priorities to definitely validate this concept.

The Predicament of Gastrointestinal Bleeding in Patients With a Continuous-Flow Left Ventricular Assist Device: Pathophysiology, Evaluation, and Management

Heart failure affects over 5 million Americans, with numbers expected to rise. While heart transplantation is the most effective long-term strategy for end-stage heart failure, there is a limited cardiac donor pool, and these organs are often unavailable at the time of need. Left ventricular assist devices, therefore, continue to be used to bridge this gap. Originally implanted as a bridge to transplant, these devices are now additionally utilized as destination therapy for patients ineligible for transplant. With the widespread applicability of these devices for not just temporary measures, but also for prolonged use, the short- and long-term impact on other organ systems has become more evident. For example, gastrointestinal (GI) bleeding, with an incidence approaching 30%, is one such complication post-continuous-flow left ventricular assist device implantation. This high incidence of GI bleeding is thought to stem from a combination of factors, including the need for concomitant anticoagulant and antiplatelet therapy, and intrinsic device-related properties resulting in acquired Von Willebrand disease and arteriovenous malformations. Due to the significant morbidity associated with these GI bleeding events, a standardized protocol optimizing medical and endoscopic management, alongside close coordination between the gastroenterology and cardiology services, should be advocated for and ultimately employed.

Noncardiac surgery in patients with a left ventricular assist device

Left ventricular assist devices are implanted in patients with chronic left heart failure refractory to maximal medical therapy. These devices were initially meant as bridge-to-transplant therapy, but with technological advances they are now also used as destination therapy. With improved survival, many patients with implanted devices need noncardiac surgery. We present three representative cases of noncardiac surgery in such patients to highlight the issues involved in their management. We also review the contemporary literature on various aspects of perioperative management. Anesthesia for noncardiac surgery in these patients was initially the domain of cardiac anesthesiologists, but with an increasing number of such patients needing surgery, general anesthesiologists are frequently tasked to provide anesthetic care. An understanding of left ventricular assist device physiology and issues unique to these patients is essential for safe management of these cases.

Outcomes of patients with continuous flow left ventricular assist device undergoing emergency endovascular treatment for atraumatic bleeding

Introduction

Severe spontaneous bleeding is a significant complication in patients with continuous flow left ventricular assist devices; there is little evidence on endovascular treatment to support its use.

Materials and methods

We observed seven patients (five men, two women, age 43–67 years) with continuous flow left ventricular assist devices on antiaggregant/coagulant therapy, admitted to our hospital for uncorrectable symptomatic anemia; CT-angiography and diagnostic angiography confirmed the presence of atraumatic arterious bleeding from the gastrointestinal tract (six patients), from the intercostal artery and from the bronchial tree (one patient).

Results

All patients where successfully treated via an endovascular approach with superselective embolization of the involved arterial branches with coils and particles.

Conclusion

Spontaneous atraumatic bleeding is a frequent complication in patients with continuous flow left ventricular assist devices; endovascular treatment represents a promising alternative to the surgical approach as it is less invasive, easily repeatable and associated to a reduced procedural risk.

Primary Hemostatic Disorders and Late Major Bleeding After Transcatheter Aortic Valve Replacement

BACKGROUND

Periprocedural and late (>30 days) bleedings represent major complications after transcatheter aortic valve replacement and have been identified as potential areas for improved patient care.

OBJECTIVES

The authors sought to evaluate the impact of ongoing primary hemostasis disorders on late major/life-threatening bleeding complications (MLBCs).

METHODS

Bleedings were assessed according to the VARC-2 (Valve Academic Research Consortium-2) criteria. Closure time of adenosine diphosphate (CT-ADP), a surrogate marker of high molecular weight von Willebrand multimers proteolysis was assessed 24 h after the procedure. Ongoing primary hemostasis disorder was defined by a CT-ADP >180 s.

RESULTS

Among 372 patients who survived at 30 days, MLBCs occurred in 42 patients (11.3%) at a median follow-up of 383 days (interquartile range: 188 to 574 days). MLBCs were mainly of gastrointestinal origin (42.8%) and were associated with increased overall mortality (hazard ratio [HR]: 5.66; 95% confidence interval [CI]: 3.10 to 10.31; p < 0.001) and cardiac mortality (HR: 11.62; 95% CI: 4.59 to 29.37; p < 0.001). A 2.5-fold elevation of MLBCs could be evidenced in patients with a CT-ADP > 180 s (27.4% vs. 11.5%; p < 0.001). Multivariate regression analysis identified paravalvular leak (PVL) (HR: 6.31; 95% CI: 3.43 to 11.60; p < 0.0001) and CT-ADP > 180 s (HR: 3.08; 95% CI: 1.62 to 5.81; p = 0.0005) as predictor of MLBCs.

CONCLUSIONS

MLBCs after transcatheter aortic valve replacement are frequent and associated with an increased morbidity and mortality. PVL and CT-ADP >180 s were identified as strong predictors for MLBCs. These findings strongly suggest that persistent HMW defects contribute to enhanced bleeding risk in patients with residual PVL.

Clinical and In Vitro Evidence That Left Ventricular Assist Device-Induced von Willebrand Factor Degradation Alters Angiogenesis

Background Gastrointestinal bleeding from angiodysplasia is a major problem in continuous-flow left ventricular assist device (LVAD) patients. LVAD shear stress causes pathologic degradation of VWF (von Willebrand factor). A mechanistic relationship between VWF degradation and angiodysplasia has not been explored. We tested 2 novel hypotheses: (1) clinical hypothesis: VWF fragments are elevated in LVAD patients that develop angiodysplasia and (2) in vitro hypothesis: VWF fragments generated during LVAD support alter angiogenesis, which may contribute to angiodysplasia. Methods and Results Clinical study: Paired blood samples were collected from continuous-flow LVAD patients (n=35). VWF was quantified with immunoblotting. In vitro experiments: (1) To investigate whether LVAD support alters angiogenesis, human endothelial cells were cultured with LVAD patient plasma (n=11). To investigate mechanism, endothelial cells were cultured with VWF fragments produced by exposing human VWF and ADAMTS-13 (VWF protease) to LVAD-like shear stress (175 dyne/cm², n=8). Clinical study results: in all patients (n=35, mean support 666±430 days), LVAD support degraded high-molecular-weight VWF multimers ( P<0.0001) into low-molecular-weight VWF multimers ( P<0.0001) and VWF fragments ( P<0.0001). In patients with gastrointestinal bleeding from angiodysplasia (n=7), VWF fragments were elevated ( P=0.02) versus nonbleeders. In contrast, in patients with gastrointestinal bleeding without angiodysplasia, VWF fragments were not elevated versus nonbleeders ( P=0.96). In vitro experiments results: LVAD patient plasma caused abnormal angiogenesis with reduced tubule length ( P=0.04) and migration ( P=0.05). Similarly, endothelial cells grown with VWF degradation fragments exhibited reduced tubule length ( P<0.001) and migration ( P=0.01). Conclusions LVAD patients who bled from angiodysplasia had higher levels of VWF fragments than nonbleeders and gastrointestinal bleeders without angiodysplasia. VWF fragments caused abnormal angiogenesis in vitro. These findings suggest that VWF fragments may be a mechanistic link between LVAD support, abnormal angiogenesis, angiodysplasia, and gastrointestinal bleeding.

Innovative Modeling Techniques and 3D Printing in Patients with Left Ventricular Assist Devices: A Bridge from Bench to Clinical Practice

Left ventricular assist devices (LVAD) cause altered flow dynamics that may result in complications such as stroke, pump thrombosis, bleeding, or aortic regurgitation. Understanding altered flow dynamics is important in order to develop more efficient and durable pump configurations. In patients with LVAD, hemodynamic assessment is limited to imaging techniques such as echocardiography which precludes detailed assessment of fluid dynamics. In this review article, we present some innovative modeling techniques that are often used in device development or for research purposes, but have not been utilized clinically. Computational fluid dynamic (CFD) modeling is based on computer simulations and particle image velocimetry (PIV) employs ex vivo models that helps study fluid characteristics such as pressure, shear stress, and velocity. Both techniques may help elaborate our understanding of complications that occur with LVAD and could be potentially used in the future to troubleshoot LVAD-related alarms. These techniques coupled with 3D printing may also allow for patient-specific device implants, lowering the risk of complications increasing device durability.

Outcomes and Predictors of Readmissions with GI Bleeding in Patients with Left Ventricular Assist Devices

OBJECTIVES

Gastrointestinal (GI) bleeding is a major comorbidity in patients with left ventricular assist devices (LVADs). The study aim was to estimate the rate of hospital readmissions for GI bleeding in patients with LVADs using a nationally representative database. Additionally, we evaluated the etiologies, costs, endoscopy utilization, mortality, and predictors of GI bleeding readmissions in these patients.

METHODS

We analyzed data from the National Readmissions Database (NRD) from 2010 through 2014. We compared hospitalized adult patients with congestive heart failure (CHF) who underwent LVAD implantation (cases) with CHF patients without LVAD or heart transplant (controls). Three age- and sex-matched controls were randomly selected per single case. A multivariate Cox regression model was used to compare the hazards of 60-day all-cause and GI bleeding readmission between the groups, controlling for significant confounders.

RESULTS

A total of 3293 hospitalized patients with CHF who had LVAD placement (cases) and 9879 who did not have LVADs (controls) were included in the study. At 60 days, patients with LVAD had a significantly higher readmission rate with GI bleeding (8.7% vs 2.3%, adjusted hazard ratio [aHR] 4.45, 95% confidence interval 3.71-5.33, P < 0.0001). The all-cause readmission rate also was higher (43.3% vs 35.7%, aHR 1.23, 95% confidence interval 1.12-1.34, P < 0.0001). The most common etiologies of bleeding in patients with LVADs were gastroduodenal and small intestinal arteriovenous malformations (28.6%). During bleeding readmissions, patients with LVAD were more likely to undergo endoscopy (72.1% vs 33.5%, P < 0.0001) and receive packed red blood cell transfusions (62% vs 36.6%, P< 0.0001) compared with controls. GI bleeding readmissions were more costly ($40,936 vs $35,313, P< 0.0001), and longer (12 vs 10.9 days, P< 0.0001) in patients with LVADs compared with controls. Independent risk factors for 60-day GI bleeding readmission were increasing age (aHR 1.04, P< 0.0001) and GI bleeding during index admission (aHR 2.68, P< 0.0001). In those without bleeding during index admission, increasing age and chronic anemia were associated with 60-day GI bleeding readmission. Mortality during bleeding readmission was similarly low in patients with LVADs compared with CHF controls (0.2% vs 0.3%, P = 0.14).

CONCLUSIONS

After LVAD implantation, there is a fivefold increased risk of readmission with GI bleeding within 60 days. Gastroduodenal and small intestinal arteriovenous malformations are the most common culprit lesions. These findings suggest that small bowel enteroscopy should be considered as the initial test of choice in patients with suspected upper gastroduodenal bleeding. Readmissions with bleeding in patients with LVADs increase morbidity and cost of care but not mortality. Older patients and those with a history of bleeding during LVAD implantation are at higher risk of bleeding readmission and may benefit from close monitoring and cautious anticoagulation to prevent rebleeding.

Acquired von Willebrand Syndrome Associated with Cardiovascular Diseases

The blood glycoprotein von Willebrand factor (VWF) plays an important role in hemostasis and thrombosis. VWF is produced and secreted as large multimers by endothelial cells and megakaryocytes. It is then cleaved in a sheer-stress dependent manner by a specific protease, ADAMTS13, into multimers consisting of 2–80 subunits. Among VWF multimers, high molecular weight (HMW) multimers play important roles in platelet aggregation. Therefore, their loss induces a hemostatic disorder known as von Willebrand disease (VWD) type 2A. Various cardiovascular diseases, such as aortic stenosis, hypertrophic obstructive cardiomyopathy (HOCM), and several congenital structural diseases, as well as mechanical circulatory support systems, generate excessive high shear stress in the bloodstream. These cause excessive cleavage of VWF multimers resulting in a loss of HMW multimers, known as acquired von Willebrand syndrome (AVWS), a hemostatic disorder similar to VWD type 2A. Bleeding often occurs in the gastrointestinal tract since a fragile angiodysplasia develops associated with these diseases. Radical treatment for AVWS is to remove the pathological high shear causing AVWS.

Acquired von Willebrand Syndrome in Patients With Ventricular Assist Device

During the last decade the use of ventricular assist devices (VADs) for patients with severe heart failure has increased tremendously. However, flow disturbances, mainly high shear induced by the device is associated with bleeding complications. Shear stress-induced changes in VWF conformation are associated with a loss of high molecular weight multimers (HMW) of VWF and an increased risk of bleeding. This phenomenon and its cause will be elaborated and reviewed in the following.

Design and rationale of haemodynamic guidance with CardioMEMS in patients with a left ventricular assist device: the HEMO-VAD pilot study

AIMS

We aim to study the feasibility and clinical value of pulmonary artery pressure monitoring with the CardioMEMS™ device in order to optimize and guide treatment in patients with a HeartMate 3 left ventricular assist device (LVAD).

METHODS AND RESULTS

In this single-centre, prospective pilot study, we will include 10 consecutive patients with New York Heart Association Class IIIb or IV with Interagency Registry for Mechanically Assisted Circulatory Support Classes 2-5 scheduled for implantation of a HeartMate 3 LVAD. Prior to LVAD implantation, patients will receive a CardioMEMS sensor, for daily pulmonary pressure readings. The haemodynamic information provided by the CardioMEMS will be used to improve haemodynamic status prior to LVAD surgery and optimize the timing of LVAD implantation. Post-LVAD implantation, the haemodynamic changes will be assessed for additive value in detecting potential complications in an earlier stage (bleeding and tamponade). During the outpatient clinic phase, we will assess whether the haemodynamic feedback can optimize pump settings, detect potential complications, and further tailor the clinical management of these patients.

CONCLUSIONS

The HEMO-VAD study is the first prospective pilot study to explore the safety and feasibility of using CardioMEMS for optimization of LVAD therapy with additional (remote) haemodynamic information.