Left Ventricular Assist Device: Indication, Timing, and Management

Long term event-free survival following cell-based therapy in patients with cardiomyopathy: the HYPERION observational cohort

INTRODUCTION

There is limited long-term clinical outcome data supporting the use of cell-based therapy to treat heart failure. The HYPERION study (NCT03071835) followed long-term outcomes of patients with ischemic cardiomyopathy (ICM) and non-ischemic cardiomyopathy (NIDCM) who received mesenchymal stromal cells (MSC). We hypothesized that improved cardiac parameters predict longer event-free survival.

METHODS

We performed a Kaplan-Meier analysis to examine event-free survival as the primary outcome. Time-to-event information was captured from all eligible participants. Endpoint events were defined as death (all-cause), Left Ventricular Assist Device (LVAD) placement, or Heart Transplant. Subjects were categorized based on increase in Left Ventricular Ejection Fraction (LVEF) or decrease in Left Ventricular End Diastolic Volume (LVEDV) for comparisons within disease etiologies.

RESULTS

There were 134 men and 21 women, with mean age 60.0 ± 11.0 years. There were 121 (78%) with ICM and 34 (22%) with NIDCM. By the end of long-term follow-up (~13 years), 38 (24.5%) subjects had deceased, 5 (3.2%) received LVAD, and 8 (5.2%) underwent heart transplantation. Post-therapy increase of ≥5% LVEF was associated with longer event-free survival in NIDCM (HR:0.31; 95%CI, 0.11,0.86; P = .025), but not ICM (HR:1.14; 95%CI, 0.47,2.72; P = .776). Conversely, reduction in left ventricular end-diastolic volume (LVEDV) was associated with longer event-free survival in ICM (HR:0.16; 95%CI, 0.05, 0.55; P = .008) but not NIDCM (HR:0.35; 95%CI, 0.1,1.2; P = .098). ICM improvers had LVEDV of 225.7 ± 95.9 mL at baseline and 209.0 ± 100.6 mL by year 5 (P = .046). NIDCM improvers had LVEF of 27.2 ± 8.9% at baseline and 36.1 ± 11.6% by year 5 (P = .018).

CONCLUSION

In this long-term observational cohort analysis, improvement of LVEF and/or reduction in LVEDV was associated with survival benefits among subjects with NIDCM and ICM, respectively. In both etiologies the respective improvements are sustained for up to 5 years, providing evidence that cell-based therapy may be a promising and durable treatment option for patients with heart failure.

Linking Cardiac Psychology and Cardiovascular Medicine via Self-Determination Theory and Shared Decision-Making

Despite considerable progress in recent years, research in cardiac psychology is not widely translated into routine practice by clinical cardiologists or clinical health psychologists. Self-determination theory (SDT), which addresses how basic psychological needs of autonomy, competence, and relatedness contribute to the internalization of motivation, may help bridge this research-practice gap through its application to shared decision-making (SDM). This narrative review discusses the following: (a) brief background information on SDT and SDM, (b) the application of SDT to health behavior change and cardiology interventions, and (c) how SDT and SDM may be merged using a dissemination and implementation (D&I) framework. We address barriers to implementing SDM in cardiology, how SDM and SDT address the need for respect of patient autonomy, and how SDT can enhance D&I of SDM interventions through its focus on autonomy, competence, and relatedness and its consideration of other constructs that facilitate the internalization of motivation.

Cardiac replacement therapy: Critical issues and future perspectives of heart transplantation and artificial heart

Diagnostic and therapeutic advances in the cardiovascular field have caused a progressive reduction in mortality from acute causes, with an ever-increasing chronicity of cardiovascular pathologies. In recent years, mechanical supports have played a fundamental role, allowing the patient to be stabilized in the most critical phase of acute heart failure (AHF) and acting as a "bridge" for definitive therapies. Heart transplantation (HTx) is the gold-standard treatment for end-stage HF, but it is burdened by a series of critical issues that limit its use, first of all the shortage of grafts. It also requires the patient to take immunosuppressive therapy for life, which exposes him to a greater risk of infectious and oncological diseases. For these reasons, in the last years, mechanical supports are increasingly used as "destination therapy", alternatively to HTx. However, also mechanical supports are not free from critical issues that limit their use. In this review we aim to analyze critical issues and future perspectives of advanced HF therapies.

Effect of Oxidative Stress on Mitochondrial Damage and Repair in Heart Disease and Ischemic Events

The literature analysis conducted in this review discusses the latest achievements in the identification of cardiovascular damage induced by oxidative stress with secondary platelet mitochondrial dysfunction. Damage to the platelets of mitochondria as a result of their interactions with reactive oxygen species (ROS) and reactive nitrogen species (RNS) can lead to their numerous ischemic events associated with hypoxia or hyperoxia processes in the cell. Disturbances in redox reactions in the platelet mitochondrial membrane lead to the direct oxidation of cellular macromolecules, including nucleic acids (DNA base oxidation), membrane lipids (lipid peroxidation process) and cellular proteins (formation of reducing groups in repair proteins and amino acid peroxides). Oxidative changes in biomolecules inducing tissue damage leads to inflammation, initiating pathogenic processes associated with faster cell aging or their apoptosis. The consequence of damage to platelet mitochondria and their excessive activation is the induction of cardiovascular and neurodegenerative diseases (Parkinson's and Alzheimer's), as well as carbohydrate metabolism disorders (diabetes). The oxidation of mitochondrial DNA can lead to modifications in its bases, inducing the formation of exocyclic adducts of the ethano and propano type. As a consequence, it disrupts DNA repair processes and conduces to premature neoplastic transformation in critical genes such as the p53 suppressor gene, which leads to the development of various types of tumors. The topic of new innovative methods and techniques for the analysis of oxidative stress in platelet mitochondria based on methods such as a nicking assay, oxygen consumption assay, Total Thrombus formation Analysis System (T-Tas), and continuous-flow left ventricular assist devices (CF-LVADs) was also discussed. They were put together into one scientific and research platform. This will enable the facilitation of faster diagnostics and the identification of platelet mitochondrial damage by clinicians and scientists in order to implement adequate therapeutic procedures and minimize the risk of the induction of cardiovascular diseases, including ischemic events correlated with them. A quantitative analysis of the processes of thrombus formation in cardiovascular diseases will provide an opportunity to select specific anticoagulant and thrombolytic drugs under conditions of preserved hemostasis.

Left Ventricular Assist Device in Advanced Refractory Heart Failure: A Comprehensive Review of Patient Selection, Surgical Approaches, Complications and Future Perspectives

The management of advanced heart failure (HF) has long posed significant challenges due to its complex and chronic nature. Heart transplantation, while effective, is not always feasible due to the limited availability of donor organs. In this context, long term mechanical circulatory support and mainly left ventricular assist devices (LVADs) have emerged as a vital intervention to fill this gap. LVAD superiority compared to medical therapy for some patients in advanced heart failure has been demonstrated either as a bridge to transplantation or as destination therapy. This literature review provides a comprehensive overview of the effectiveness, challenges, and advancements in the use of LVADs for treating advanced heart failure. It evaluates clinical outcomes associated with LVAD therapy, focusing on survival rates and quality of life improvements. The review synthesizes findings from recent studies, highlighting both the benefits and complications of LVAD implantation, such as infectious risk, thromboembolic events, hemorrhage and device malfunction. Additionally, it explores the latest technological and biomedical advancements in LVAD design, including innovations in biocompatibility, miniaturization, and power management. By examining current research, this review aims to elucidate how LVADs are transforming heart failure treatment and to offer insights into future directions for clinical practice and research.

Left ventricular unloading to facilitate ventricular remodelling in heart failure: A narrative review of mechanical circulatory support

Heart failure represents a dynamic clinical challenge with the continuous rise of a multi-morbid and ageing population. Yet, the evolving nature of mechanical circulatory support offers a variety of means to manage candidates who might benefit from such interventions. This narrative review focuses on the role of the main mechanical circulatory support devices, such as ventricular assist device, extracorporeal membrane oxygenation, Impella and TandemHeart, in the physiological process of ventricular unloading and remodelling in heart failure, highlighting their characteristics, mechanism and clinical outcomes. The outcome measures described include physiological changes (i.e., stroke volume or preload and afterload), intracardiac pressure (i.e., end-diastolic pressure) and extracardiac pressure (i.e., pulmonary capillary wedge pressure). Overall, all the above mechanical circulatory support strategies can facilitate the unloading of the ventricular failure through different mechanisms, which subsequently affects the ventricular remodelling process. These physiological changes start immediately after ventricular assist device implantation. The devices are indicated in different but overlapping populations and operate in distinctive ways; yet, they have evidenced performance to a favourable standard to improve cardiac function in heart failure, although this proved variable for different devices, and further high-quality trials are vital to assess their clinical outcomes further. Both Impella and TandemHeart are indicated mainly in cardiogenic shock and high-risk percutaneous coronary intervention patients; at the time the literature was evaluated, both devices were found to yield a significant improvement in haemodynamics but not in survival. Nevertheless, the choice of device strategy should be based on individual patient factors, including indication, to optimize clinical outcomes.

Outcomes of HeartMate 3 in pediatric patients with end-stage heart failure: a single-center preliminary experience from Turkey

Objectives

We aim to evaluate our initial experience with the HeartMate 3 (HM3) device (Abbott, USA) for palliating pediatric patients with end-stage heart failure (ESHF).

Methods

We conducted a retrospective review of clinical data from pediatric patients (aged 7-18 years) who underwent HM3 implantation for ESHF at our institution between 2022 and 2024. Patient demographics and follow-up data were comprehensively analyzed.

Results

We identified 11 patients (45% males) with a median age of 14 years (IQR 11-17), a median weight of 47 kg (IQR 28-50), a median height of 159 cm (IQR 135-165), and a median body surface area of 1.36 m2 (IQR 1.07-1.53) at the time of the intervention. All patients were diagnosed with dilated cardiomyopathy and categorized with PEDIMACS profiles ranging from one to three. The median ICU stay was 14 days (IQR 6-32), with 11 patients receiving inotropic support for a median of four postoperative days (IQR 3-8). The median follow-up period was 150 days (IQR 90-210). Early complications included two cases of pleural effusion, 1 case of cardiac tamponade, 3 cases of polyuria, and one instance of positive blood cultures. One patient, who was non-compliant with warfarin therapy, developed a thrombus in the right atrium that was resolved with a revision of anticoagulant therapy, and did not experience pump thrombosis. During follow-up, one patient died after 28 days from sepsis, one underwent heart transplantation after 10 days, and nine patients remained alive on the device. Notably, there were no reported cases of pump thrombosis, ischemia, or stroke post- implantation.

Conclusions

The HM3 device appears to be a safe and effective palliative option for pediatric patients with ESHF.

[Patient selection for left ventricular assist device implantation. The main problems]

AIM

To analyze the experience of Chazov National Medical Research Center of Cardiology in patient selection for left ventricular assist device (LVAD) implantation.

MATERIALS AND METHODS

901 patients, whose documents were sent to Chazov National Medical Research Center of Cardiology from regional medical and prophylactic institutions, were screened as selection for LVAD implantation. Firstly, all patients underwent transthoracic echocardiography performed according to the extended protocol with a comprehensive assessment of the left and right ventricle size and function. Patients who underwent the screening procedure underwent further examination including both laboratory and instrumental diagnostic methods. In addition, the polyclinic database of patients diagnosed with chronic heart failure (CHF) and dilated cardiomyopathy was also analyzed.

RESULTS

Among 901 screened patients 7.9% were suitable candidates for LVAD implantation and only 23 (2.6%) patients underwent surgery. Among those not eligible for surgery: 208 (29%) patients were not on optimal medical therapy, 15% of patients had indications for other surgical treatment of CHF, 12% of patients had severe right ventricular failure, 9.8% had severe comorbidities, 6.8% of patients refused surgery.

CONCLUSIONS

The main problems of selection for LVAD implantation were: low awareness of doctors about the introduction of new treatment methods, poor quality of transthoracic echocardiography, a large percentage of patients not receiving basic therapy for CHF, untimely referral of patients for other types of surgical treatment.

Mechanical Circulatory Support in Cardiogenic Shock: A Narrative Review

Cardiogenic shock (CS) remains a critical condition with high mortality rates, often arising from acute myocardial infarction and advanced heart failure. Despite advancements in medical therapy, traditional interventions frequently fall short of reversing the profound hemodynamic instability seen in CS. Mechanical circulatory support (MCS) devices have emerged as crucial therapeutic options, offering temporary stabilization and bridging to recovery, heart transplantation, or long-term ventricular assist device implantation. This narrative review explores the current landscape of MCS in CS, highlighting the various types of support devices, including intra-aortic balloon pumps (IABP), veno-arterial extracorporeal membrane oxygenation (VA-ECMO), and percutaneous ventricular assist devices (pVADs) such as Impella and TandemHeart. We examine their mechanisms of action, clinical indications, and outcomes alongside the challenges and complications associated with their use. Additionally, we discuss the evolving guidelines and the role of MCS in contemporary CS management, emphasizing the need for timely intervention and a multidisciplinary approach. The review underscores the importance of individualized patient selection and device choice to optimize outcomes in this critically ill population.

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.

Back to the basics: The need for an etiological classification of chronic heart failure

The left ventricular (LV) ejection fraction (LVEF), despite its severe limitations, has had an epicentral role in heart failure (HF) classification, management, and risk stratification for decades. The major argument favoring the LVEF based HF classification has been that it defines groups of patients in which treatment is effective. However, this reasoning has recently collapsed, since medical treatment with neurohormonal inhibitors, has proved beneficial in most HF patients regardless of the LVEF. In addition, there has been compelling evidence, that the LVEF provides poor guidance for device treatment of chronic HF (implantation of cardioverter defibrillator, cardiac resynchronization therapy) since sudden cardiac death may occur and cardiac dyssynchronization may be disastrous in all HF patients. The same holds true for LV assist device implantation, in which the LVEF has been used as a surrogate for LV size. In this review article we update the evidence questioning the use of LVEF-based HF classification and argue that guidance of chronic HF treatment should transition to more contemporary concepts. Specifically, we propose an etiologic chronic HF classification predominantly based on epidemiological data, which will be foundational for further higher resolution phenotyping in the emerging era of precision medicine.

Sex-Linked Differences in Cardiac Atrophy After Mechanical Unloading Induced by Heterotopic Heart Transplantation

No information is available about sex-related differences in unloading-induced cardiac atrophy. We aimed to compare the course of unloading-induced cardiac atrophy in intact (without gonadectomy) male and female rats, and in animals after gonadectomy, to obtain insight into the influence of sex hormones on this process. Heterotopic heart transplantation (HT((x)) was used as a model for heart unloading. Cardiac atrophy was assessed as the weight ratio of heterotopically transplanted heart weight (HW) to the native HW on days 7 and 14 after HTx in intact male and female rats. In separate experimental groups, gonadectomy was performed in male and female recipient animals 28 days before HT(x) and the course of cardiac atrophy was again evaluated on days 7 and 14 after HT(x). In intact male rats, HT(x) resulted in significantly greater decreases in whole HW when compared to intact female rats. The dynamics of the left ventricle (LV) and right ventricle (RV) atrophy after HT(x) was quite similar to that of whole hearts. Gonadectomy did not have any significant effect on the decreases in whole HW, LV, and RV weights, with similar results in male and female rats. Our results show that the development of unloading-induced cardiac atrophy is substantially reduced in female rats when compared to male rats. Since gonadectomy did not alter the course of cardiac atrophy after HTx, similarly in both male and female rats, we conclude that sex-linked differences in the development of unloading-induced cardiac atrophy are not caused by the activity of sex hormones.

Cardiac Device Therapy in Patients with Chronic Kidney Disease: An Update

Cardiovascular diseases (CVDs) and chronic kidney disease (CKD) are frequently interconnected and their association leads to an exponential increase in the risk of both fatal and non-fatal events. In addition, the burden of arrhythmias in CKD patients is increased. On the other hand, the presence of CKD is an important factor that influences the decision to pursue cardiac device therapy. Data on CKD patients with device therapy are scarce and mostly derives from observational studies and case reports. Cardiac resynchronization therapy (CRT) is associated with decreased mortality, reduced heart failure symptoms, and improved renal function in early stages of CKD. Implantable cardioverter defibrillators (ICDs) are associated with a significant reduction in the mortality of CKD patients only for the secondary prevention of sudden cardiac death. Cardiac resynchronization therapy with defibrillator (CRT-D) is preferred in patients who meet the established criteria. The need for cardiac pacing is increased three-fold in dialysis patients. CKD is an independent risk factor for infections associated with cardiac devices.

Heart Transplantation and Thromboembolic Risk In Patients With Percutaneous Aortic Valve Prosthesis and Left Ventricular Assist Device: A Case Report

Transcatheter aortic valve replacements have become a good option for patients with aortic valve disease and high surgical risk. Thromboembolism is reported as a relatively common complication of Transcatheter aortic valve replacement. This risk may be increased in patients who have left ventricular assist devices, as valve motion is drastically reduced. We present the case of a 65-year-old man with a history of alcoholism and valvular cardiomyopathy (severe chronic aortic insufficiency) with severe left ventricular dysfunction. Improvement in ventricular function followed the cessation of alcohol consumption, but still in poor clinical condition. Due to his high surgical risk, it was decided to implant a percutaneous aortic valve to treat the valve deficiency. Two months later, he suffered from a first episode of embolic stroke, which he successfully recovered. Despite the treatment, his clinical status did not improve (INTERMACS 3-4), and he was referred for heart transplantation. A left ventricular assist device was implanted as a bridge to the transplant. While on the waiting list, he suffered from other 3 episodes of stroke, 2 of them requiring mechanical thrombectomy. Finally, his transplant was performed with a favorable postoperative clinical course. Heart transplantation may be feasible in patients with multiple intracardiac devices in left chambers, although we must be aware of the increased thromboembolic risk, especially when used in combination.

Kidney health and function with left ventricular assist devices

PURPOSE OF REVIEW

Mechanical circulatory support (MCS) is a group of evolving therapies used for indications ranging from temporary support during a cardiac procedure to permanent treatment of advanced heart failure. MCS is primarily used to support left ventricle function, in which case the devices are termed left ventricular assist devices (LVADs). Kidney dysfunction is common in patients requiring these devices, yet the impact of MCS itself on kidney health in many settings remains uncertain.

RECENT FINDINGS

Kidney dysfunction can manifest in many different forms in patients requiring MCS. It can be because of preexisting systemic disorders, acute illness, procedural complications, device complications, and long-term LVAD support. After durable LVAD implantation, most persons have improvement in kidney function; however, individuals can have markedly different kidney outcomes, and novel phenotypes of kidney outcomes have been identified.

SUMMARY

MCS is a rapidly evolving field. Kidney health and function before, during, and after MCS is relevant to outcomes from an epidemiologic perspective, yet the pathophysiology underlying this is uncertain. Improved understanding of the relationship between MCS use and kidney health is important to improving patient outcomes.

How to Select Patients for Left Ventricular Assist Devices? A Guide for Clinical Practice

In recent years, a significant improvement in left ventricular assist device (LVAD) technology has occurred, and the continuous-flow devices currently used can last more than 10 years in a patient. Current studies report that the 5-year survival rate after LVAD implantation approaches that after a heart transplant. However, the outcome is influenced by the correct selection of the patients, as well as the choice of the optimal time for implantation. This review summarizes the indications, the red flags for prompt initiation of LVAD evaluation, and the principles for appropriate patient screening.

Durable left ventricular assist device implant-how I teach it

Left ventricular assist devices (LVADs) have become a mainstay of advanced heart failure therapy. The technical aspects of performing a device implant are nuanced and attention to these details allows for successful therapy with good outcomes. As more patient with heart failure are expected to benefit from mechanical circulatory support, the need for a concise and consistent technique for LVAD implantation is needed. Teaching this procedure is most comprehensible when broken down into separate steps, as with many other procedures. Here, we describe our standard protocol for LVAD implantation, as well as rudimentary outcomes of 6-year experience in our center. We hope this will provide some insight and guidance to centers who are expanding into the field of mechanical circulatory support and can help them form a foundation with which to build their own experience and success.

Successful Bacteriophage-Antibiotic Combination Therapy against Multidrug-Resistant Pseudomonas aeruginosa Left Ventricular Assist Device Driveline Infection

There is considerable interest in the use of bacteriophages (phages) to treat Pseudomonas aeruginosa infections associated with left ventricular assist devices (LVADs). These infections are often challenging to manage due to high rates of multidrug resistance and biofilm formation, which could potentially be overcome with the use of phages. We report a case of a 54-year-old man with relapsing multidrug-resistant P. aeruginosa LVAD driveline infection, who was treated with a combination of two lytic antipseudomonal phages administered intravenously and locally. Treatment was combined with LVAD driveline repositioning and systemic antibiotic administration, resulting in a successful outcome with clinical cure and eradication of the targeted bacteria. However, laboratory in vitro models showed that phages alone could not eradicate biofilms but could prevent biofilm formation. Phage-resistant bacterial strains evolved in biofilm models and showed decreased susceptibility to the phages used. Further studies are needed to understand the complexity of phage resistance and the interaction of phages and antibiotics. Our results indicate that the combination of phages, antibiotics, and surgical intervention can have great potential in treating LVAD-associated infections. More than 21 months post-treatment, our patient remains cured of the infection.

Daptomycin Pharmacokinetics in Blood and Wound Fluid in Critical Ill Patients with Left Ventricle Assist Devices

Daptomycin is a cyclic lipopeptide antibiotic with bactericidal effects against multidrug-resistant Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecalis (VRE). For critically ill patients, especially in the presence of implants, daptomycin is an important therapeutic option. Left ventricle assist devices (LVADs) can be utilized for intensive care patients with end-stage heart failure as a bridge to transplant. We conducted a single-center prospective trial with critically ill adults with LVAD who received prophylactic anti-infective therapy with daptomycin. Our study aimed to evaluate the pharmacokinetics of daptomycin in the blood serum and wound fluids after LVAD implantation. Daptomycin concentration were assessed over three days using high-performance liquid chromatography (HPLC). We detected a high correlation between blood serum and wound fluid daptomycin concentration at 12 h (IC95%: 0.64 to 0.95; r = 0.86; p < 0.001) and 24 h (IC95%: -0.38 to 0.92; r = 0.76; p < 0.001) after antibiotic administration. Our pilot clinical study provides new insights into the pharmacokinetics of daptomycin from the blood into wound fluids of critically ill patients with LVADs.

A mathematical model for assessing shear induced bleeding risk

PURPOSE

The objective of this study is to develop a bleeding risk model for assessing device-induced bleeding risk in patients supported with blood contact medical devices (BCMDs).

METHODS

The mathematical model for evaluating bleeding risk considers the effects of shear stress on von Willebrand factor (vWF) unfolding, high molecular weight multimers-vWF (HMWM-vWF) degradation, platelet activation and receptor shedding and platelet-vWF binding ability. Functions of the effect of shear stress on the above factors are fitted/employed and solved by the Eulerian transport equation. An axial flow-through Couette device and two clinical VADs which are HeartWare Ventricular Assist Device (HVAD) and HeartMate II (HM II) blood pump were employed to perform the simulation to evaluate platelet receptor shedding (GPIbα and GPIIb/IIIa), loss of HWMW-vWF, platelet-vWF binding ability and bleeding risk for validating the accuracy of our model.

RESULTS

The platelet-vWF binding ability after being subjected to high shear region in the axial flow-through Couette device predicted by our bleeding model was highly consistent with reported experimental data. As indicated by our CFD simulation results in the axial flow-through Couette device, it can find that an increase in shear stress led to a decrease in the adhesion ability of platelets on vWF, while the binding ability of vWF with platelets first increase and then decrease as shear stress elevates gradually beyond a threshold. The factor of exposure time can enhance the effect of shear stress. Additionally, the shear-induced bleeding risk predicted by our model increases with increasing shear stress and exposure time in an axial flow-through Couette device. As indicated by our numerical model, the bleeding risk in HVAD was higher than HMII, which is highly consistent with the meta-analysis based on clinical statistics. Our simulation investigations in these two clinical VADs also found that HVAD caused a higher rate of platelet receptor shedding and lower damage to HWMW-vWF than HeartMate II. The high shear stress generated in the narrow and turbulent regions of both VADs was the underlying cause of device-induced bleeding.

CONCLUSION

In this study, the shear-induced bleeding risk predicted by our bleeding model in axial flow-through Couette device and two clinical VADs is consistent or highly correlated with experimental and clinical findings, which proves the accuracy of our bleeding model. Our bleeding model can be used to aid the development of new BCMDs with improved functional characteristics and biocompatibility, and help to reduce risk of device-induced adverse events in patients.

A Holistic View of Advanced Heart Failure

Advanced heart failure (HF) may occur at any level of left ventricular (LV) ejection fraction (LVEF). The latter, which is widely utilized for the evaluation of LV systolic performance and treatment guidance of HF patients, is heavily influenced by LV size and geometry. As the accurate evaluation of ventricular systolic function and size is crucial in patients with advanced HF, the LVEF should be supplemented or even replaced by more specific indices of LV function such as the systolic strain and cardiac power output and size such as the LV diastolic diameters and volumes. Conventional treatment (cause eradication, medications, devices) is often poorly tolerated and fails and advanced treatment (mechanical circulatory support [MCS], heart transplantation [HTx]) is required. The effectiveness of MCS is heavily dependent on heart size, whereas HTx which is effective in the vast majority of the cases is limited by the small donor pool. Expanding the MCS indications to include patients with small ventricles as well as the HTx donor pool are major challenges in the management of advanced HF.

Altered mRNA Expression of Interleukin-1 Receptors in Myocardial Tissue of Patients with Left Ventricular Assist Device Support

Serum levels of cytokines interleukin 1 beta ( IL-1β) and interleukin 33 (IL-33) are highly abnormal in heart failure and remain elevated after mechanical circulatory support (MCS). However, local cytokine signaling induction remains elusive. Left (LV) and right ventricular (RV) myocardial tissue specimens of end-stage heart failure (HF) patients without (n = 24) and with MCS (n = 39; 594 ± 57 days) were analyzed for cytokine mRNA expression level of IL-1B, interleukin 1 receptor 1/2 (IL-1R1/2), interleukin 1 receptor-like 1 (IL-1RL1), IL-33 and interleukin-1 receptor accessory protein (IL-1RaP). MCS patients showed significantly elevated IL-1B expression levels (LV: 2.0 fold, p = 0.0058; RV: 3.3 fold, p < 0.0001). Moreover, IL-1R1, IL-1RaP and IL-33 expression levels strongly correlated with each other. IL-1RL1 and IL-1R2 expression levels were significantly higher in RV myocardial tissue (RV/LV ratio IL-1R2 HF: 4.400 ± 1.359; MCS: 4.657 ± 0.655; IL-1RL1 HF: 3.697 ± 0.876; MCS: 4.529 ± 0.5839). In addition, IL1-RaP and IL-33 RV expression levels were significantly elevated in MCS. Furthermore, IL-33 expression correlates with C-reactive protein (CRP) plasma levels in HF, but not in MCS patients. Increased expression of IL-1B and altered correlation patterns of IL-1 receptors indicate enhanced IL-1β signaling in MCS patients. Correlation of IL-1 receptor expression with IL-33 may hint towards a link between both pathways. Moreover, diverging expression in LV and RV suggests specific regulation of local cytokine signaling.