Alternatives for Vitamin K Antagonists as Thromboprophylaxis for Mechanical Heart Valves and Mechanical Circulatory Support Devices: A Systematic Review.

The holy grail of anticoagulation in patients with intracardiac devices, such as mechanical heart valves (MHVs) and left ventricular assist devices (LVADs), comprises safe prevention of thrombosis without interrupting normal hemostasis. Device-induced thrombosis and anticoagulant-related bleeding problems are dreaded complications that may cause a significantly reduced quality of life and increased morbidity and mortality. Vitamin K antagonists are the current standard for oral anticoagulation therapy in patients with MHVs and LVADs. Even within the therapeutic range, hemorrhage is the primary complication of these drugs, which emphasizes the need for safer anticoagulants for the prevention of device-induced thrombosis. Device-induced thrombosis is a complex multifactorial phenomenon that likely requires anticoagulant therapy targeting multiple pathways. Here, we review the preclinical and clinical data describing the efficacy of a variety of anticoagulants as thromboprophylaxis after implantation of intracardiac devices.

Acquired blood platelet disorder in patients with end-stage heart failure after implantation of a continuous centrifugal-flow left ventricular assist device: A prospective cohort study.

Background: Continuous-flow left ventricular assist devices (CF-LVADs) are an established therapy for advanced heart failure. Thrombosis and hemorrhage are common complications after CF-LVAD implantation, which may be explained by device-induced platelet activation. Few data on the effect of CF-LVAD implantation on platelets are available to date. Objectives: The aim of this study was to characterize the change in the platelet activation status after CF-LVAD. Methods: Platelet phenotype and reactivity were determined with flow cytometry in 32 adults with end-stage heart failure before and 4 to 6 weeks after CF-LVAD implantation. Sixteen adults with a biological aortic valve prosthesis (AVP) using the same antiplatelet regimen were included to discriminate between the effects of CF-LVAD and the antiplatelet regimen. Plasma markers for platelet activation were determined with enzyme-linked immunosorbent assay. Results: Median (IQR) plasma levels of soluble P-selectin increased from 115.6 (79.1-142.7) ng/mL to 144.5 (100.4-197.5) ng/mL after CF-LVAD implantation (P < .001). Median (IQR) ß-thromboglobulin levels were 60.5 (37.8-81.5) ng/mL before implantation and remained high after LVAD implantation [60.0 (42.0-69.5) ng/mL]. The platelet P-selectin expression after stimulation with ADP (30 and 60 µM) or PAR1-activating peptide (12.5 and 25 µM) was reduced by 17% to 21%, and fibrinogen binding was reduced by 37% to 86%. Platelet responses to agonists were similar in patients with a CF-LVAD and patients with an AVP, except for fibrinogen binding in response to 12.5 µM PAR1-AP, which was lower in patients with a CF-LVAD (P < .001). Conclusions: Combined, these data provide evidence for systemic platelet activation and an acquired platelet disorder after CF-LVAD implantation. This might contribute to the risk of both hemorrhage and thrombosis associated with CF-LVADs.

MarioHeart: Novel In-Vitro Flow Model for Testing Heart Valve Prostheses and Anticoagulant Therapies.

Mechanical heart valve (MHV) prostheses present a risk of thromboembolic complications despite antithrombotic therapy. Further steps in the development of more hemocompatible MHVs and new anticoagulants are impeded due to the lack of adequate in-vitro models. With the development of a novel in-vitro model (MarioHeart), a pulsatile flow similar to the arterial circulation is emulated. The MarioHeart design owns unique features as 1) a single MHV within a torus with low surface/volume ratio, 2) a closed loop system, and 3) a dedicated external control system driving the oscillating rotational motion of the torus. For verification purposes, a blood analog fluid seeded with particles was used to assess fluid velocity and flow rate using a speckle tracking method on high-speed video recordings of the rotating model. The flow rate resembled the physiological flow rate in the aortic root, in both shape and amplitude. Additional in-vitro runs with porcine blood showed thrombi on the MHV associated with the suture ring, which is similar to the in-vivo situation. MarioHeart is a simple design which induces well-defined fluid dynamics resulting in physiologically nonturbulent flow without stasis of the blood. MarioHeart seems suitable for testing the thrombogenicity of MHVs and the potential of new anticoagulants.

Insights in the Prothrombotic Changes After Implantation of a Left Ventricular Assist Device in Patients With End-Stage Heart Failure: A Longitudinal Observational Study.

Thrombus formation is a common complication during left ventricular assist device (LVAD) therapy, despite anticoagulation with vitamin K antagonists (VKA) and a platelet inhibitor. Plasma levels of markers for primary and secondary hemostasis and contact activation were determined before LVAD implantation and 6 and 12 months thereafter in 37 adults with end-stage heart failure. Twelve patients received a HeartMate 3, 7 patients received a HeartWare, and 18 patients received a HeartMate II. At baseline, patients had elevated plasma levels of the platelet protein upon activation, ß-thromboglobulin, and active von Willebrand factor in thrombogenic state (VWFa), which remained high after LVAD implantation. Von Willebrand factor levels and VWF activity were elevated at baseline but normalized 12 months after LVAD implantation. High D -dimer plasma levels, at baseline, remained elevated after 12 months. This was associated with an increase in plasma thrombin-antithrombin-complex levels and plasma levels of contact activation marker-cleaved H-kininogen after LVAD implantation. Considering these results it could be concluded that LVAD patients show significant coagulation activation despite antithrombotic therapy, which could explain why patients are at high risk for LVAD-induced thrombosis. Continuous low-grade systemic platelet activation and contact activation may contribute to prothrombotic effects of LVAD.

The use of virtual reality in patient education related to medical somatic treatment: A scoping review.

OBJECTIVE: To map the available evidence on the context, content and outcome of VR in patient education in situations related to preparation for medical somatic treatment. METHODS: A Scoping review. In October 2020, the Embase, CINAHL, MEDLINE and PsycINFO databases were searched with the terms 'Virtual Reality' and 'Patient Education'. The literature was synthesised and mapped with a narrative approach. RESULTS: 17 studies published between 2015 and 2020 were included in the qualitative synthesis. VR was applied in (paediatric) surgery and radiation therapy treatment. VR interventions were heterogeneous regarding technical applications, context of implementation, guidance by healthcare professionals and integration in education sessions. Anxiety reduction was demonstrated significantly in some studies. Patients experienced VR education useful; it enhanced understanding, improved communication with healthcare professionals and encouraged treatment compliance. CONCLUSIONS: The application of VR in patient education is a promising technology. Patients are highly satisfied and experience enhanced understanding. VR education was not effective in reducing all anxiety, pain and stress and improving preparedness for treatment. Practice implications It is important to develop VR interventions profoundly. The application of a methodological framework for VR development is recommended. Involve patients, educationalists and technology professionals in the development of technology interventions.

Patients' voices in the development of pre-surgical patient education using virtual reality: A qualitative study.

Objective: To identify the information needs and perceptions of patients regarding the application of virtual reality in pre-surgical patient education. Methods: A qualitative study was conducted between March and July 2020. The study population consisted of a purposive sample of patients scheduled for cardiac surgery from a single institution. Semi-structured individual interviews (n=19) were conducted and analysed using thematic analysis. Results: Patient perceptions regarding virtual reality and information needs related to hospitalisation and surgery could be categorised into three themes: Creating familiarity, contents to explore and challenges and preconditions. Conclusions: Virtual reality technology is a promising tool that can enhance conventional patient education to improve understanding and to potentially reduce concerns and anxieties. The virtual reality environment creates an opportunity for patients to be in control of the timing, quantity, depth and frequency of patient education. A virtual reality education tool should not be a substitute for personal contact with the physician. Innovation: Patient information needs were identified profoundly to the further development of a virtual reality intervention. This intervention aims to educate patients prior to elective cardiac surgery.

Surgical Treatment of Acute Thoracic Stent Graft Occlusion.

A 24-year-old man presented with acute onset paraplegia related to complete occlusion of a thoracic stent graft placed 2 years prior for repair of traumatic type B aortic dissection. Following emergency surgery comprising reestablishment of aortic flow by stent removal and aortic reconstruction, the paraplegia started to resolve partly, despite an estimated 5-hour interval of preoperative myelum ischemia. Anatomical characteristics of the stent graft placement appear to have played a role in causing this rare complication. Six months later, the patient could walk again with a stick. This case shows that early intervention in cases of full paraplegia may be considered.