Left ventricular assist devices-current state and perspectives

Economic aspects of long-term left ventricular assist device treatment for chronic heart failure

AIMS

Technological advances and the current shortage of donor organs have contributed to an increase in the number of left ventricular assist device (LVAD) implantations in patients with end-stage heart failure. Demographic change and medical progress might raise the number of these patients, resulting in a further increase in the number of LVAD implantations. The aim of this study was to evaluate the long-term costs of LVAD therapy and identify diagnoses resulting in expensive stays.

METHODS AND RESULTS

In this retrospective analysis of prospectively collected data, all patients after implantation of a second- or third-generation LVAD by 31 March 2022 were included. In addition to demographic and survival data, revenues and case mix points were determined for each patient. Of the 163 patients included, 75.5% were male. The mean age at LVAD implantation was 52 ± 14 years. The mean survival was 1458 ± 127 days. During follow-up, the total inpatient treatment time per patient was 70 ± 87 days. The average duration of outpatient treatment was 55.1%, based on the total duration of support. The average revenue per patient for the implant stay was $193 192.35 ± $111 801.29, for inpatient readmissions $52 068.96 ± $116 630.00, and for outpatient care $53 195.94 ± $62 363.53.

CONCLUSIONS

LVAD implantation in patients with end-stage heart failure leads to improved survival but a significant increase in treatment costs. Further multi-centre studies are necessary in order to be able to assess the effects of long-term LVAD treatment on the healthcare system.

Pharmacologic targeting of coagulation factors XII and XI by monoclonal antibodies reduces thrombosis in nitinol stents under flow

BACKGROUND

Cardiovascular implantable devices, such as vascular stents, are critical for the treatment of cardiovascular diseases. However, their success is dependent on robust and often long-term antithrombotic therapies. Yet, the current standard-of-care therapies often pose significant bleeding risks to patients. Coagulation factor (F)XI and FXII have emerged as potentially safe and efficacious targets to safely reduce pathologic thrombin generation in medical devices.

OBJECTIVES

To study the efficacy of monoclonal antibody-targeting FXII and FXI of the contact pathway in preventing vascular device-related thrombosis.

METHODS

The effects of inhibition of FXII and FXI using function-blocking monoclonal antibodies were examined in a nonhuman primate model of nitinol stent-related thrombosis under arterial and venous flow conditions.

RESULTS

We found that function-blocking antibodies of FXII and FXI reduced markers of stent-induced thrombosis in vitro and ex vivo. However, FXI inhibition resulted in more effective mitigation of thrombosis markers under varied flow conditions.

CONCLUSION

This work provides further support for the translation of contact pathway of coagulation inhibitors for their adjunctive clinical use with cardiovascular devices.

LVAD as a Bridge to Transplantation-Current Status and Future Perspectives

Heart failure (HF) is a common disease associated with high morbidity and mortality rates despite advanced pharmacological therapies. Heart transplantation remains the gold standard therapy for end-stage heart failure; however, its application is curtailed by the persistent shortage of donor organs. Over the past two decades, mechanical circulatory support, notably Left Ventricular Assist Devices (LVADs), have been established as an option for patients waiting for a donor organ. This comprehensive review focuses on elucidating the benefits and barriers associated with this application. We provide an overview of landmark clinical trials that have evaluated the use of LVADs as a bridge to transplantation therapy, with a particular focus on post-transplant outcomes. We discuss the benefits of stabilizing patients with these systems, weighing associated complications and limitations. Further technical advancements and research on optimal implantation timing are critical to ultimately improve outcomes and securing quality of life. In a world where the availability of donor organs remains constrained, LVADs are an increasingly important piece of patient care, bridging the critical gap to transplantation in advanced heart failure management.

Percutaneous intravascular micro-axial blood pump: current state and perspective from engineering view

The utilization of a minimally invasively placed catheter-mounted intravascular micro-axial flow blood pump (IMFBP) is increasing in the population with advanced heart failure. The current development of IMFBPs dates back around the 1990s, namely the Hemopump with a wire-drive system and the Valvopump with a direct-drive system. The wire-drive IMFBPs can use a brushless motor in an external console unit to transmit rotational force through the drive wire rotating the impeller inside the body. The direct-drive IMFBPs require an ultra-miniature and high-power brushless motor. Additionally, the direct-drive system necessitates a mechanism to protect against blood immersion into the motor. Therefore, the direct-drive IMFBPs can be categorized into two types of devices: those with seal mechanisms or those with sealless mechanisms using magnetically coupling. The IMFBPs can be classified into two groups depending on their purpose. One group is for cardiogenic shock following a heart attack or for use in high-risk percutaneous coronary intervention (PCI), and the other group serves the purpose of acute decompensated heart failure. Both direct-drive IMFBPs and wire-drive IMFBPs have their own advantages and disadvantages, and efforts are being made to develop and improve, and clinically implement them, leveraging their own strengths. In addition, there is a possibility that innovative new devices may be invented. For researchers in the field of artificial heart development, IMFBPs offer a new area of research and development, providing a novel treatment option for severe heart failure.

Epistaxis Rates and Health Care Utilization in Patients With a Ventricular Assist Device

Objective

Identify baseline epistaxis rates and epistaxis-related health care utilization trends in the ventricular assist device (VAD) population.

Methods

Single center, retrospective cohort study consisting of chart review of adult VAD patients. Analysis of descriptive statistics was assessed using χ 2 tests, independent sample t tests, or Fisher's exact when expected counts were low. Logistic regression was used to assess associations between epistaxis and variables of interest.

Results

Two hundred ninety patients were included in the analysis. Ninety-eight (33.8%) patients developed epistaxis and 84 (29.0%) received medical attention. Patients with gastrointestinal (GI) bleeding had increased rates of epistaxis (42.4% vs 29.0%). Logistic regression analysis found GI bleeding to have an adjusted odds of developing epistaxis of 1.94 (95% confidence interval [CI]: 1.12-3.37) and kidney disease to have an adjusted odds of 1.83 (95% CI: 1.06, 3.13).

Discussion

VAD implantation improves survival and quality of life but also carries significant bleeding risks. At our institution, 29% of VAD patients received medical attention for epistaxis. GI bleeding and kidney disease were found to have increased adjusted odds of developing epistaxis. Fifty-nine percent of epistaxis events occurred while inpatient and 32.8% of events were seen in the emergency department.

Implications for Practice

VAD patients are an at-risk group that could potentially benefit from preventative nasal hydration regimen.

Urgent Spinal Surgery in a Lateral Decubitus on a Patient with a Left Ventricular Assist Device on Full Anticoagulation: A Case Report

This case report aims to demonstrate the feasibility of performing spinal surgery in patients with a left ventricular assist device (LVAD), who are traditionally considered unsuitable candidates due to the need for anticoagulation and the challenges associated with the prone position. A case of a patient with an LVAD undergoing microdiscectomy in the left lateral decubitus position is presented. The procedure was carried out by a specialized interdisciplinary team with appropriate monitoring. The patient underwent the procedure safely, demonstrating that spinal surgery can be performed in patients with LVAD without reversing anticoagulation or resorting to the prone position. This approach mitigates the risk of thrombotic events and hemodynamic instability. This case study suggests that spinal surgery, specifically microdiscectomy, can be safely performed in patients with LVAD using the left lateral decubitus position. This finding has significant implications for patients who are unable to ambulate and therefore struggle to qualify for a heart transplant.

Transcatheter Aortic Valve Embolization in a Patient With a Left Ventricular Assist Device

•LVAD patients commonly develop AR. •TAVI is one option for improving AR. •Valve embolization and migration is possible in these patients. •TEE imaging is critical in attempting to resolve valve embolization.

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

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

Computational analysis of thrombosis risk with variations in left ventricular assist device inflow cannula design in a multi-patient model

BACKGROUND AND OBJECTIVES

Left ventricular assist devices (LVADs) are mechanical pumps used to support patients with end-stage heart failure. The inflow cannula is a critical component of the LVAD as it connects the pump to the left ventricle, allowing blood to be drawn from the heart. However, the design of the cannula can significantly impact LV hemodynamics and cause complications, including thrombosis. Therefore, this study aimed to analyze the numerical effects of left ventricle (LV) size on cannula design in order to enhance hemodynamic performance using post-operative left ventricular assist device (LVAD) models.

METHODS

A parametric design evaluation of two different inflow cannulas were carried out on left ventricles (LV) of varying sizes (ranging from 154 to 430 ml) constructed from computerized tomography (CT) data from VAD patients using computational fluid dynamics (CFD) simulations. The study analyzed three key factors contributing to thrombosis formation: blood residence time, blood stagnation ratio, and wall shear stress.

RESULTS

Results showed higher blood residence time and stagnation ratio for larger left ventricular sizes. In addition, increasing the insertion length of the cannula reduced the average wall shear stress.

CONCLUSION

Overall, the study's findings suggest that the optimal cannula shape for LVADs varies with left ventricular size.

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.

Titanium is a potent inducer of contact activation: implications for intravascular devices

BACKGROUND

Titanium (Ti) and its alloys are widely used in manufacturing medical devices because of their strength and resistance to corrosion. Although Ti compounds are considered compatible with blood, they appear to support plasma contact activation and may be thrombogenic.

OBJECTIVES

The objective of this study was to compare Ti and titanium nitride (TiN) with known activators of contact activation (kaolin and silica) in plasma-clotting assays and to assess binding and activation of factor XII, (FXII), factor XI (FXI), prekallikrein, and high-molecular-weight kininogen (HK) with Ti/TiN.

METHODS

Ti-based nanospheres and foils were compared with kaolin, silica, and aluminum in plasma-clotting assays. Binding and activation of FXII, prekallikrein, HK, and FXI to surfaces was assessed with western blots and chromogenic assays.

RESULTS

Using equivalent surface amounts, Ti and TiN were comparable with kaolin and superior to silica, for inducing coagulation and FXII autoactivation. Similar to many inducers of contact activation, Ti and TiN are negatively charged; however, their effects on FXII are not neutralized by the polycation polybrene. Antibodies to FXII, prekallikrein, or FXI or coating Ti with poly-L-arginine blocked Ti-induced coagulation. An antibody to FXII reduced FXII and PK binding to Ti, kallikrein generation, and HK cleavage.

CONCLUSION

Titanium compounds induce contact activation with a potency comparable with that of kaolin. Binding of FXII with Ti shares some features with FXII binding to soluble polyanions but may have unique features. Inhibitors targeting FXII or FXI may be useful in mitigating Ti-induced contact activation in patients with titanium-based implants that are exposed to blood.

Transcutaneous Pulsed RF Energy Transfer Mitigates Tissue Heating in High Power Demand Implanted Device Applications: In Vivo and In Silico Models Results

This article presents the development of a power loss emulation (PLE) system device to study and find ways of mitigating skin tissue heating effects in transcutaneous energy transmission systems (TETS) for existing and next generation left ventricular assist devices (LVADs). Skin thermal profile measurements were made using the PLE system prototype and also separately with a TETS in a porcine model. Subsequent data analysis and separate computer modelling studies permit understanding of the contribution of tissue blood perfusion towards cooling of the subcutaneous tissue around the electromagnetic coupling area. A 2-channel PLE system prototype and a 2-channel TETS prototype were implemented for this study. The heating effects resulting from power transmission inefficiency were investigated under varying conditions of power delivery levels for an implanted device. In the part of the study using the PLE setup, the implanted heating element was placed subcutaneously 6-8 mm below the body surface of in vivo porcine model skin. Two operating modes of transmission coupling power losses were emulated: (a) conventional continuous transmission, and (b) using our proposed pulsed transmission waveform protocols. Experimental skin tissue thermal profiles were studied for various levels of LVAD power. The heating coefficient was estimated from the porcine model measurements (an in vivo living model and a euthanised cadaver model without blood circulation at the end of the experiment). An in silico model to support data interpretation provided reliable experimental and numerical methods for effective wireless transdermal LVAD energization advanced solutions. In the separate second part of the study conducted with a separate set of pigs, a two-channel inductively coupled RF driving system implemented wireless power transfer (WPT) to a resistive LVAD model (50 Ω) to explore continuous versus pulsed RF transmission modes. The RF-transmission pulse duration ranged from 30 ms to 480 ms, and the idle time (no-transmission) from 5 s to 120 s. The results revealed that blood perfusion plays an important cooling role in reducing thermal tissue damage from TETS applications. In addition, the results analysis of the in vivo, cadaver (R1Sp2) model, and in silico studies confirmed that the tissue heating effect was significantly lower in the living model versus the cadaver model due to the presence of blood perfusion cooling effects.

Living with a left ventricular assist device: Capturing recipients experiences using group concept mapping software

Background

Left ventricular assist device (LVAD) implantation significantly impacts on a recipient’s symptoms and quality of life. Capturing their experiences and post implant journey is an important part of clinical practice, research and device design evolution. Patient reported outcome measures (PROMs) are a useful tool for capturing that experience. However, patient reported outcome measures need to reflect recipients’ experiences. Discussions with a patient partner group found that none of the frequently used cardiology PROMs captured their unique experiences.

Aims

To capture the experiences and important issues for LVAD recipients. Develop a conceptual map of domains and items that should be reflected in patient reported outcomes.

Methods

Group concept mapping (GCM) web-based software was used to remotely capture and structure recipients’ experiences across a wide geographical area. GCM is a semi-quantitative mixed method consisting of 3 stages: item generation, item sorting and rating (importance, relevance and frequency). Patient partners were involved in all aspects of the study design and development.

Results

18 LVAD recipients consented to take part. 101 statements were generated and multi-dimensional scaling, and hierarchical cluster analysis identified 9 clusters. Cluster themes included: Activities, Partner/family support, Travel, Mental wellbeing, Equipment and clothing, Physical and cognitive limitations, LVAD Restrictions, LVAD Challenges and positive impact of the LVAD (LVAD Positives). LVAD Positives were scored highest across all the rating variables, e.g., frequency (2.85), relevance (2.44) and importance (2.21). Other domains rated high for importance included physical and cognitive limitations (2.19), LVAD restrictions (2.11), Partner/family support (2.02), and Equipment and clothing (2.01).

Conclusion

Online GCM software facilitated the inclusion of geographically dispersed recipients and provided useful insights into the experiences of LVAD recipients. The conceptual framework identifies important domains and items that should be prioritised and included in patient reported outcomes in future research, LVAD design evolution, and clinical practice.

Lived experiences of patients implanted with left ventricular assist devices

BACKGROUND

Besides survival, improvement in quality of life (QoL) is a major aim of left ventricular assist device (LVAD) implantation. QoL assessment tools in current use are effective in the gathering of standardized metrics but are limited in their ability to elucidate everyday lived patient experiences that also affect overall patient wellbeing.

OBJECTIVE

To describe and understand the lived experiences of patients undergoing long-term circulatory support with LVAD.

METHODS

A phenomenological approach was used. Purposive sampling of consecutive willing inpatients and outpatients living with an LVAD for longer than 6 months was conducted until theme saturation. There were a total of 21 patients interviewed and this was then recorded and transcribed.

RESULTS

A total of eight themes emerged from the data. Overall, the patients' quality of life was affected by: (1) whether they had experienced improvements or setbacks in their recent health condition, (2) experiencing burdens from their device such as weight and handling, (3) limitations in their physical ability such as participating in sports, their inability to work; or reduced sleep, (4) reduced social interactions; (5) reduction in sexual activity and performance; (6) experiencing emotional and psychological problems and experiencing anxiety. Patients highlighted the value of obtaining (7) support from family and friends. The interviews also revealed that some patients experienced the feeling of (8) optimism and obtaining "a second chance" at life.

CONCLUSIONS

LVAD patients have unique concerns and lived experiences. Some themes emerging from this interview series such as having to give up work, having reduced social contact, reduced sexual activity and emotional problems, family support structures demand careful attention during the pre-implantation counselling and post implantation ongoing care. These aspects also deserve more attention in quality of life studies among LVAD patients. Patients with recent improvements in health reported a more positive outlook. Overall the majority of patients reported feeling that they obtained a second chance at life.

Advancements in left ventricular assist devices to prevent pump thrombosis and blood coagulopathy

Mechanical circulatory support (MCS) devices, such as left ventricular assist devices (LVADs) are very useful in improving outcomes in patients with advanced-stage heart failure. Despite recent advances in LVAD development, pump thrombosis is one of the most severe adverse events caused by LVADs. The contact of blood with artificial materials of LVAD pumps and cannulas triggers the coagulation cascade. Heat spots, for example, produced by mechanical bearings are often subjected to thrombus build-up when low-flow situations impair washout and thus the necessary cooling does not happen. The formation of thrombus in an LVAD may compromise its function, causing a drop in flow and pumping power leading to failure of the LVAD, if left unattended. If a clot becomes dislodged and circulates in the bloodstream, it may disturb the flow or occlude the blood vessels in vital organs and cause internal damage that could be fatal, for example, ischemic stroke. That is why patients with LVADs are on anti-coagulant medication. However, the anti-coagulants can cause a set of issues for the patient-an example of gastrointestinal (GI) bleeding is given in illustration. On account of this, these devices are only used as a last resort in clinical practice. It is, therefore, necessary to develop devices with better mechanics of blood flow, performance and hemocompatibility. This paper discusses the development of LVADs through landmark clinical trials in detail and describes the evolution of device design to reduce the risk of pump thrombosis and achieve better hemocompatibility. Whilst driveline infection, right heart failure and arrhythmias have been recognised as LVAD-related complications, this paper focuses on complications related to pump thrombosis, especially blood coagulopathy in detail and potential strategies to mitigate this complication. Furthermore, it also discusses the LVAD implantation techniques and their anatomical challenges.

Point-of-Care Ultrasound in the Evaluation of Patients with Left Ventricular Assist Devices at the Emergency Department

BACKGROUND

Left ventricular assist devices (LVADs) can be used as a bridging therapy for myocardial recovery or cardiac transplant, as well as a destination therapy for long-term support in patients with advanced heart failure. Patients with LVADs can present to the emergency department (ED) for acute deterioration and emergency physicians (EPs) must be equipped with the necessary knowledge and skill to treat this unique population.

OBJECTIVE

This review describes the role of point-of-care ultrasound (POCUS) in the evaluation of patients with LVADs and illustrates how EPs can incorporate POCUS into the evaluation of these patients in the ED.

DISCUSSION

The clinical applications for which POCUS may be useful in patients with LVADs include hypotension or shock, dyspnea, cardiac failure, dysrhythmia, syncope, and cardiac arrest. The normal features of POCUS in patients with LVADs and the features of POCUS associated with diseased states are presented.

CONCLUSIONS

Patients with LVADs have altered anatomy and physiology. Therefore, an understanding of key modifications to standard POCUS views is necessary so that EPs can use POCUS effectively in their evaluation of these patients.

Flow assessment as a function of pump timing of tubular pulsatile pump for use as a ventricular assist device in a left heart simulator

INTRODUCTION

Although mechanical circulatory support saved many lives during the last decade, clinical observations have shown that the continuous flow pumps are associated with a much higher incidence of gastrointestinal bleeding and kidney problems, among others, compared with the earlier generation pulsatile pumps. However, the presence of several moving mechanical components made pulsatile pumps less durable, bulky, and prone to malfunction, ultimately leading to bias in favor of continuous flow designs.

OBJECTIVE

The aim of the current work is to create a prototype tubular pulsatile pump and to test the timing of the pump in a left heart simulator.

METHODS

A left heart simulator to mimic pumping from a failing heart was created. This was used to experimentally test the output of a prototype ventricular assist device relative to a failing heart in the form of flow and pressure. The effect of pulsation timing was quantified.

RESULTS

A failing heart was simulated with an average flow rate of 1.1 L/min and a systolic pressure of 47 mmHg. With the pump, the flow rate increases to 4.8 L/min and a systolic pressure of 110mmHg, in a copulsation mode, while activating for 300-400 ms. If the activation time is reduced, or increased, the pump becomes less effective. Load on the heart is reduced when the pump operates in a counterpulsation mode.

CONCLUSION

A pulsatile pump, like the one proposed, provides adequate output for mechanical circulatory support, while minimizing the number of moving parts that could otherwise lead to tribological wear.

Parameter Identification of Cardiovascular System Model Used for Left Ventricular Assist Device Algorithms

Advancement of implanted left ventricular assist device (LVAD) technology includes modern sensing and control methods to enable online diagnostics and monitoring of patients using on-board sensors. These methods often rely on a cardiovascular system (CVS) model, the parameters of which must be identified for the specific patient. Some of these, such as the systemic vascular resistance (SVR), can be estimated online while others must be identified separately. This paper describes a three-staged approach for designing a parameter identification algorithm (PIA) for this problem. The approach is demonstrated using a two-element Windkessel model of the systemic circulation (SC) with a time-varying elastance for the left ventricle (LV). A parameter identifiability stage is followed by identification using an unscented Kalman filter (UKF), which uses measurements of LV pressure (P_lv), aortic pressure (P_ao), aortic flow (Q_a), and known input measurement of LVAD flowrate (Q_vad). Both simulation and experimental data from animal experiments were used to evaluate the presented methods. By bounding the initial guess for left ventricular volume, the identified CVS model is able to reproduce signals of P_lv, P_ao, and Q_a within a normalized root mean squared error (nRMSE) of 5.1%, 19%, and 11%, respectively, during simulations. Experimentally, the identified model is able to estimate SVR with an accuracy of 3.4% compared with values from invasive measurements. Diagnostics and physiological control algorithms on-board modern LVADs could use CVS models other than those shown here, and the presented approach is easily adaptable to them. The methods also demonstrate how to test the robustness and accuracy of the identification algorithm.

Development of Mechanical Circulatory Support Devices: 55 Years and Counting

Heart failure is a leading cause of morbidity and mortality in the United States. Treatment of this condition increasingly involves mechanical circulatory support devices. Even with optimal medical therapy and use of simple cardiac devices, heart failure often leads to reduced quality of life and a shortened life span, prompting exploration of more advanced treatment approaches. Left ventricular assist devices constitute an effective alternative to cardiac transplantation. These devices are not without complications, however, and their use requires careful cooperative management by the patient's cardiology team and primary care provider. Left ventricular assist devices have undergone many technological advancements since they were first introduced, and they will continue to evolve. This article reviews the history of different types of left ventricular assist devices, appropriate patient selection, and common complications in order to increase health professionals' familiarity with these treatment options.

Body Piercing with a Metallic Tongue Stud Resulting in Ineffective Implantable Cardioverter-defibrillator Shocks: "Heart to Mouth"

Left ventricular assist devices (LVADs) provide circulatory support to patients with severe left ventricular systolic dysfunction. Many such patients have a pre-existing implantable cardioverter-defibrillator (ICD) at the time of their LVAD surgery. LVAD implantation can alter the ICD lead parameters, including R-wave sensing, right ventricular capture threshold, and impedance. These changes can in turn affect the ability of the ICD to successfully treat malignant ventricular arrhythmias. In most patients who present with ineffective ICD shocks, the failed shock is assumed to be secondary to the patient’s severe cardiomyopathy. Especially, the role of physical examination in such patients is often minimized. In our patient, a thorough history-taking and history-guided physical examination led us to the root cause of the failed ICD shocks. Our patient was noted to have a metal tongue piercing, which was the likely cause of his ineffective ICD shocks. Our case highlights the importance of a comprehensive history-taking and physical examination.

Stroke in Patients with Left Ventricular Assist Devices

BACKGROUND

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

SUMMARY

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

Five-year outcomes following left ventricular assist device implantation in England

Objective

Implant rates of mechanical circulatory supports such as left ventricular assist devices (LVAD) have steadily increased in the last decade. We assessed the utility of administrative data to provide information on hospital use and outcomes.

Methods

Using 2 years of national hospital administrative data for England linked to the death register, we identified all patients with an LVAD and extracted hospital activity for 5 years before and after the LVAD implantation date.

Results

In the two index years April 2011 to March 2013, 157 patients had an LVAD implanted. The mean age was 50.9 (SD 15.4), and 78.3% were men. After 5 years, 92 (58.6%) had died; the recorded cause of death was noncardiovascular in 67.4%. 42 (26.8%) patients received a heart±lung transplantation. Compared with the 12 months before implantation, the 12 months after but not including the month of implantation saw falls in total inpatient and day case admissions, a fall in admissions for heart failure (HF), a rise in non-HF admissions, a fall in emergency department visits not ending in admission and a rise in outpatient appointments (all per patient at risk). Postimplantation complications were common in the subsequent 5 years: 26.1% had a stroke, 23.6% had a device infection and 13.4% had a new LVAD implanted.

Conclusions

Despite patients’ young age, their mortality is high and their hospital use and complications are common in the 5 years following LVAD implantation. Administrative data provide important information on resource use in this patient group.

Coil Design of a Wireless Power-Transfer Receiver Integrated into a Left Ventricular Assist Device

This study deals with the design of a near-field wireless power transfer (WPT) system applied to a left ventricular assist device (LVAD) to treat patients with heart-failure problems. An LVAD is an implanted electrically driven pump connected to the heart and is traditionally powered by batteries external to the human body via a percutaneous driveline cable. The main challenge of wirelessly powering an LVAD implanted deep in the human body is to transfer relatively high power with high efficiency levels. Here the optimal design of the primary and secondary WPT coils is proposed to improve the performance of the WPT, avoiding possible safety problems of electromagnetic fields (EMF). As a main result, an average power of 5 W is continuously delivered to the LVAD by the WPT system working at 6.78 MHz with a total (DC–to–DC) efficiency of approximately 65% for the worst-case configuration.

Longest reported support (7.5 years) with postauricular type of Jarvik 2000 axial-flow left ventricular assist device

Mechanical circulatory supports with left ventricular assist devices (LVAD) are nowadays an established treatment in end-stage heart failure for those patients who are waiting for an organ donation or are unsuitable for transplantation. The duration of LVAD support is variable, depending on the device, the intention to treat and the issues occurring during treatment, which can change the purpose treatment or accelerate the transplantation. Moreover, length of reported supports in the literature is heterogenous. In here, we present the clinical and surgical case of the longest LVAD support reported in the literature, as a bridge to transplantation, with axial pump Jarvik 2000 (Jarvik Heart, Inc, New York, NY).

Ventricular fibrillation in a left ventricular assist device patient: Can the echocardiogram be misleading?

Sustained ventricular tachycardia and ventricular fibrillation (VF) are life-threatening arrhythmias which remain highly prevalent in patients with advanced heart failure. These ventricular arrhythmias may impair the support provided by continuous-flow left ventricular assist devices (CF-LVADs) and lead to frequent hospitalizations, antiarrhythmic medication use, external defibrillations, and need for heart transplantation. We report a case in which a patient with a CF-LVAD and an implantable cardioverter defibrillator at end of life presented with asymptomatic low-flow alarms and was found to have VF of unknown duration. Unique in our case was the presence of apparent organized contractility and rhythmic opening of the mitral valve on echocardiogram despite VF on electrocardiogram.

Preoperative Treatment of Malnutrition and Sarcopenia in Cardiac Surgery: New Frontiers

Cardiac surgery is performed more often in a population with an increasing number of comorbidities. Although these surgeries can be lifesaving, they disturb homeostasis and may induce a temporary overall loss of physiologic function. The required postoperative intensive care unit and hospital stay often lead to a mid- to long-term decline of nutritional and physical status, mental health, and health-related quality of life. Prehabilitation before elective surgery might be an opportunity to optimize the state of the patient. This article discusses current evidence and potential effects of preoperative optimization of nutrition and physical status before cardiac surgery.

Noninvasive measurement of arterial blood pressure in patients with continuous-flow left ventricular assist devices: a systematic review

Accurate mean blood pressure determination is essential to prevent adverse events in patients with continuous-flow left ventricular assist devices (CFLVAD). We sought to evaluate the accuracy of noninvasive methods of blood pressure measurement compared with invasive intra-arterial recordings in patients with CFLVAD. Systematic electronic search was performed on four online databases (PubMed, Scopus, Embase, and Web of Knowledge) for the terms "Blood Pressure" AND ("Heart-Assist Devices" OR "Left ventricular Assist Devices"). Only studies that compared an intra-arterial and noninvasive blood pressure measurement were included. Electronic search of scientific literature identified 5968 articles. After deduplication, screening of titles and abstracts, full-text review, and excluding incorrect populations and comparator, a total of 12 studies with 502 participants were included, of those 402 participants who had intra-arterial blood pressure measurement. Doppler mean arterial blood pressure showed a very high correlation with mean intra-arterial blood pressure (r = 0.97, r = 0.87) in low pulsatility situations. When the pulsatility was not evaluated, the correlation was high moderate (r = 0.63, r = 0.741). In low pulsatility situations, the correlation was moderate to high moderate (r = 0.42 to r = 0.65). Oscillometer automatic blood pressure cuff showed a moderate to very high correlation with intra-arterial mean arterial blood pressure (r = 0.42, r = 0.86) but also could be low in the context of low pulsatility associated with inconsistent success in noninvasive measurement (r = 0.25). Studies correlating intra-arterial with noninvasive techniques were performed in the context of routine clinical care using fluid-filled catheters. The degree of correlation between both methods is at least moderate.

Application of a likelihood ratio test based method for safety signal detection to left ventricular assist devices

Effective post-market safety surveillance of medical devices is critical for public health. However, many current statistical methods for safety signal detection do not control for type I error when assessing multiple device and adverse event (AE) combinations. This can result in increased false signals, underscoring the need for more robust statistical methods. Moreover, the duration of medical device use can be an important factor to consider in safety surveillance. In this study, we adapted a likelihood ratio test (LRT) based method, which was initially developed and applied to drugs, to identify safety signals for left ventricular assist devices (LVAD). Among patients with chronic, advanced left ventricular failure, we analyzed AE data for HeartWare and HeartMate II patients during a two-year period and further incorporated person-years (henceforth exposure-time). The novel modified LRT and conventional Z-test with p-values adjusted by the Benjamini-Hochberg (BH) procedure were used to explore safety signals by comparing HeartWare and HeartMate II patients in the presence of multiple adverse events. Both methods identified greater incidence of stroke among HeartWare as compared to HeartMate II patients without exposure-time (p = .025 for LRT and p = .027 for Z-test with BH) and with exposure-time (p = .002 for LRT and p = .005 for Z-test with BH). By using improved statistical methods for safety signal detection, potential safety issues can be identified and addressed in a more timely manner to enhance public safety.

Ventricular Fibrillation 7 Years After Left Ventricular Assist Device Implantation

Patient: Male, 74-year-old

Final Diagnosis: Ventricular fibrillation

Symptoms: Altered mental status • slurred speech • somnolence

Medication:—

Clinical Procedure: Left ventricular assist device placement

Specialty: Cardiology • Critical Care Medicine • General and Internal Medicine

A Comparative Content Analysis of Digital Channels for Ventricular Assist Device Patients, Caregivers, and Healthcare Practitioners

This article seeks to review and analyze the emergence of digital channels designed for ventricular assist device (VAD) patients, caregivers, and practitioners and to understand how such digital channels support the user experience of VAD implantation. Following a content analysis methodology, the authors investigated 16 digital channels designed for VAD patients, caregivers, and practitioners, with data being analyzed thematically. Competitor Positioning Matrix diagrams were created to visually represent the landscape of digital channels that support VAD stakeholders. These matrices identified opportunities and potential areas for improvement in future VAD digital channel design, with an emphasis on interactivity coupled with intelligence and focus along the various stages of the VAD patient journey. Innovation in digital channels has the potential to reduce burden on all users by enabling communication, self-management, and remote monitoring. Digital channels can be information enhanced for point of care, function as a decision support tools or be used to empower patient-caregiver pairs to be more sufficient with self-management, while enabling communication with their practitioner.

The analysis of unplanned readmissions after left ventricular assist device implantation as bridge-to-transplant

Background

In this study, we aimed to investigate frequency, patterns, etiologies, and costs of unplanned readmissions after left ventricular assist device implantation.

Methods

Between April 2012 and September 2016, 99 unplanned readmissions of a total of 50 consecutive bridge-to-transplant patients (45 males, 5 females; mean age 46.9±10.3 years; range, 19 to 67 years) who were successfully discharged after left ventricular assist device implantation were retrospectively analyzed. Patient demographic data, hemodynamic measurements before implantation, and readmissions after discharge were recorded. Hospitalizations due to major problems which were unable to be managed in routine outpatient clinic were accepted as unplanned readmissions. Survival analysis was performed.

Results

The readmission rate was 1.7 per year after discharge. Survival of patients who were readmitted within the first 90 days was found to be significantly lower than those without early readmission. The most common reasons of readmissions during follow-up were major infection (23.2%), neurological dysfunction (22.2%), cardiac causes (12.1%), bleeding (11.1%), and device malfunction (10.1%). Neurological dysfunctions (82,005 USD) and device malfunctions (73,300 USD) caused the highest economic burden.

Conclusion

Among patients with a left ventricular assist device, hospital readmissions are common. Development of preventive strategies as well as effective treatment methods focused on longterm adverse events is critical to reduce the frequency and costs of hospital readmissions.

Oral health and dental behaviour of patients with left ventricular assist device: a cross-sectional study

Aims

The aim of this cross‐sectional study was the assessment of dental behaviour, oral health, as well as oral health‐related quality of life of patients with left ventricular assist device (LVAD).

Methods and results

Patients (128) with LVAD were recruited from the University Department for Cardiac Surgery at Heart Center, Leipzig, Germany. A healthy control group (HC, n = 113) was included. Dental behaviour was assessed with a standardized questionnaire, and to evaluate oral health‐related quality of life, the German short form of oral health impact profile was applied. The presence of decayed, missing, and filled teeth; dental treatment need; periodontitis severity; and periodontal treatment need were assessed. These findings were correlated to disease‐related and device‐related factors. The minority of patients used aids for interdental hygiene (16.4%). For the LVAD patients, a German short form of oral health impact profile sum score of 4.96 ± 8.67 [0.5; 0–6] was assessed. The LVAD group suffered from more missing teeth (11.91 ± 9.13 vs. 3.70 ± 3.77; P < 0.01) than HC. More severe periodontitis was found in LVAD group (LVAD = 41.4% and HC = 27.4%; P < 0.01). Periodontal treatment need was high in both groups, without a significant difference (LVAD = 84.4% vs. HC = 86.7%; P = 0.71). LVAD therapy as bridge to transplantation was correlated with periodontal treatment need (odds ratio = 11.48 [1.27; 103.86]; P = 0.03). Further correlations between treatment need and disease specific factors were not detected.

Conclusions

Patients with LVAD suffer from a high periodontal treatment need and a lack in oral behaviour. Interdisciplinary special care concepts appear recommendable to improve oral health in LVAD patients.

Lack in Periodontal Care of Patients Suffering from Severe Heart Diseases-Results after 12 Months Follow-Up

BACKGROUND

To assess whether the standardized recommendation of patients with heart failure (HF), left-ventricular assist device (LVAD) and heart transplantation (HTx) to visit their dentist leads to improved oral conditions after 12 months.

METHODS

Patients from the Department of Cardiothoracic Surgery, Leipzig Heart Centre, Germany were examined at baseline and after 12 months. A dental (decayed-, missing-, and filled-teeth index (DMF-T)) and periodontal examination (periodontal probing depth, clinical attachment loss) was performed. At baseline, patients received a standardized recommendation to visit their dentist. At follow-up, a standardized questionnaire regarding the dental consultation was applied.

RESULTS

Eighty-eight participants (HTx: 31, LVAD: 43, HF: 14) were included. The majority of patients (79.5%) followed the recommendation to visit their dentist. Within the total cohort, periodontal treatment need was significantly reduced from 91% (baseline) to 75% (follow-up; p < 0.01). Only 10% of total cohort stated that they received periodontal treatment. The outcome in periodontal and dental treatment need at follow-up appointment revealed no statistically significant associations to the questionnaire regarding dentist consultation (p > 0.05). Conclusions: The simple recommendation to visit the dentist appears not enough to obtain sufficient dental and periodontal conditions in patients with severe heart diseases. Thereby, a lack in periodontal treatment of patients with HF, HTx and LVAD was identified, making interdisciplinary dental special care programs recommendable.

Cavitation in left ventricular assist device patients: a potential early sign of pump thrombosis

Mechanical ventricular support with left ventricular assist device (LVAD) has emerged as a durable and safe therapy, both as bridge-to-transplant (BTT) or destination therapy (DT), in patients with advanced heart failure (HF). However, the occurrence of pump thrombosis (PT) still represents a serious complication, especially when LVADs of first or second generation are implanted. During the latest years, some investigations have recognized the occurrence of cavitation, evidenced through transthoracic echocardiography (TTE), as a potential early and indirect sign of PT. In the present manuscript, we reviewed the available data on the occurrence of cavitation in LVAD patients as an early potential marker of PT, also presenting the hemodynamic mechanisms involved.

Approaches to improving exercise capacity in patients with left ventricular assist devices: an area requiring further investigation

Introduction: Left ventricular assist device (LVAD) implantation has become a well-established treatment option for patients with end stage heart failure (HF) who are refractory to medical therapy. While LVADs implantation does effectively improve hemodynamic performance many patients still possess peripheral pathological adaptations often present in end-stage HF. Therefore, increased attention has been placed on investigating the effects of exercise training for patients with LVADs to improve clinical outcomes. However, the available evidence on exercise training for patients with LVADs is limited. Areas covered: The purpose of this narrative review is to summarize: 1) The evolution of LVAD technology and usage; 2) The physiological responses to exercise in patients with LVADs; 3) The available evidence regarding exercise training; 4) Potential strategies to implement exercise training programs for this patient population. Expert opinion: The available evidence for exercise training to improve physical function and clinical outcomes for patients with LVADs is promising but limited. Future research is needed to further elucidate the ideal exercise training parameters, method of delivery for exercise training, and unique barriers and facilitators to exercise training for patients receiving LVAD implantation.

18F-FDG PET/CT-imaging of left ventricular assist device infection: a retrospective quantitative intrapatient analysis

BACKGROUND

Despite the use of 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT), diagnosis of a driveline infection in ventricular assist device (LVAD) recipients remains challenging. Our aim was to evaluate the potential of a baseline 18F-FDG PET/CT (prior to an infection) for the diagnosis of an LVAD-related infection.

METHODS

We retrospectively selected all LVAD recipients who had undergone two consecutive whole-body 18F-FDG PET/CT examinations between January 2010 and December 2016. PET/CT was analyzed qualitatively (uptake pattern) and semi-quantitatively (SUVmax and ∆SUVmax). SUVmax was measured and compared in five distinctive volumes of interest along the LVAD driveline. An SUVmax threshold was calculated. Final diagnosis was made by clinical examination, microbiological parameters, and molecular imaging.

RESULTS

Thirty patients were enrolled (mean age 54 ± 12 years; 26 male). Mean difference in SUVmax for all five positions between the first and the second PET/CT along the driveline was significantly higher in patients with an LVAD-related infection (mean ∆SUVmax = 4.38 ± 1.44) compared to those without a driveline infection (mean ∆SUVmax = 0.03 ± 0.43), P < 0.05. Applying ROC analysis, an SUVmax threshold of 3.88 resulted in a sensitivity and specificity of 100%, respectively. There were three distinctive uptake patterns in patients with a driveline infection.

CONCLUSION

PET/CT diagnosis in the context of an LVAD-related infection can be improved by comparison to a baseline examination using a distinctive SUVmax threshold.

Human Factors and User Experience Issues with Ventricular Assist Device Wearable Components: A Systematic Review

Ventricular Assist Devices (VADs) provide continuous mechanical circulatory support during in- and out-of-hospital care. However, limitations of the external wearable components influence patient quality of life. There is insufficient understanding of the issues with such components that combines a holistic viewpoint from both human factors and user (including patient and caregiver) experience perspectives. This paper comprehensively details the issues with VAD wearable systems and proposes a way for human-centered design to bridge the gap, addressing such issues synergistically. Through the review the authors investigated: the user issues caused by wearable components of VADs, and how human factors issues correlate to the VAD user experience. A Boolean search ("ventricular assist" AND "human factors" AND "experience") for peer-reviewed studies published between 2008 and 2018 returned 338 titles, with 35 relevant studies selected using a PRISMA process for inclusion in cross-study analysis and synthesis. This paper provides design recommendations for the issues found in the literature. Four key focus areas to inform the future design of VAD wearable components were identified-'Power Supply', 'Wearability and Travel Freedom', 'The Female Experience' and 'Intuitive Handling'. Using design to drive innovation could result in VAD wearable components which better meet or exceed users' quality of life goals.

Impact of preoperative atrial fibrillation in patients with left ventricular assist device: A systematic review and meta-analysis

Atrial fibrillation (AF) is a common finding in patients evaluated for left ventricular assist device (LVAD). There is conflicting data regarding the mortality risk as well as the thromboembolic risk in patients with preoperative AF who undergo LVAD implantation. We examined these risks by performing a meta-analysis. We performed a literature search of Pubmed, EMBASE, SCOPUS, and Cochrane from inception to February 2018. The eligible studies were used to compare mortality rate and thromboembolic risk between AF and Non-AF (NAF) groups after LVAD implantation. We obtained 391 articles from our search strategy. Seven retrospective studies were included and accounted for 5823 LVAD patients (AF 1589; NAF 4234). The median follow-up duration ranged from 7-24 months. The pooled analysis revealed a significantly increased risk of mortality in preoperative AF patients who underwent LVAD operation compared to those with NAF (Risk Ratio [RR] 1.16, 95% CI 1.05-1.28, I2 = 0%). Five studies reported thromboembolism events involving 1359 preoperative AF and 3893 NAF patients. The pooled analysis did not show a statistically significant association between risk of thromboembolic event and preoperative AF (Risk Ratio [RR] 1.08, 95% CI 0.86-1.36, I2 = 76.2%). Our study shows that preoperative AF may be associated with a higher mortality rate. This study is limited by the fact that the data are pooled from retrospective studies. Further prospective studies are warranted in order to validate these results.

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.

Cardiac Assist Devices: Early Concepts, Current Technologies, and Future Innovations

Congestive heart failure (CHF) is a debilitating condition that afflicts tens of millions of people worldwide and is responsible for more deaths each year than all cancers combined. Because donor hearts for transplantation are in short supply, a safe and durable means of mechanical circulatory support could extend the lives and reduce the suffering of millions. But while the profusion of blood pumps available to clinicians in 2019 tend to work extremely well in the short term (hours to weeks/months), every long-term cardiac assist device on the market today is limited by the same two problems: infections caused by percutaneous drivelines and thrombotic events associated with the use of blood-contacting surfaces. A fundamental change in device design is needed to address both these problems and ultimately make a device that can support the heart indefinitely. Toward that end, several groups are currently developing devices without blood-contacting surfaces and/or extracorporeal power sources with the aim of providing a safe, tether-free means to support the failing heart over extended periods of time.