HeartWare left ventricular assist device for the treatment of advanced heart failure

Steps Toward Recapitulating Endothelium: A Perspective on the Next Generation of Hemocompatible Coatings

Endothelium, the lining in this blood vessel, orchestrates three main critical functions such as protecting blood components, modulating of hemostasis by secreting various inhibitors, and directing clot digestion (fibrinolysis) by activating tissue plasminogen activator. No other surface can perform these tasks; thus, the contact of blood and blood-contacting medical devices inevitably leads to the activation of coagulation, often causing device failure, and thromboembolic complications. This perspective, first, discusses the biological mechanisms of activation of coagulation and highlights the efforts of advanced coatings to recapitulate one characteristic of endothelium, hereafter single functions of endothelium and noting necessity of the synergistic integration of its three main functions. Subsequently, it is emphasized that to overcome the challenges of blood compatibility an endothelium-mimicking system is needed, proposing a synergy of bottom-up synthetic biology, particularly synthetic cells, with passive- and bioactive surface coatings. Such integration holds promise for developing advanced biomaterials capable of recapitulating endothelial functions, thereby enhancing the hemocompatibility and performance of blood-contacting medical devices.

Vascular procedures in patients with left ventricular assist devices: single-center experience

Objective

A growing number of patients suffering from heart failure is living with a left ventricular assist device (LVAD) and is in the need for non-cardiac surgery. Vascular procedures due to ischemia, bleeding, or other device-related complications may be required and pose a challenge to the caregivers in terms of monitoring and management of these patients. Therefore, we reviewed our experience with LVAD patients undergoing vascular surgery.

Methods

From January 2010 until March 2017, a total of 54 vascular procedures were performed on 41 LVAD patients at our institution. Patient records were reviewed retrospectively in terms of incidence of LVAD-related complications, including thrombosis, stroke, bleeding, wound healing, and survival associated with vascular surgery. The type of surgery was recorded, as well as various clinical demographic variables.

Results

Vascular procedures were performed in 35 men (85.4%) and 6 women (14.6%) with LVADs. There were no perioperative strokes, device thromboses, or device malfunctions. Thirty-day mortality overall was 26.8% (eleven patients), with most patients dying within 30 days after LVAD implantation due to multi-organ failure. In 25 procedures (46.3%), a blood transfusion was necessary.

Conclusion

Patients on LVAD support are a complex cohort with a high risk for perioperative complications. In a setting where device function and anticoagulation are monitored closely, vascular surgery in these patients is feasible with an acceptable perioperative risk.

Preclinical Device Thrombogenicity Assessments: Key Messages From the 2018 FDA, Industry, and Academia Forum

Device-related thrombosis and thromboembolic complications remain a major clinical concern and often impact patient morbidity and mortality. Thus, improved preclinical thrombogenicity assessment methods that better predict clinical outcomes and enhance patient safety are needed. However, there are several challenges and limitations associated with developing and performing preclinical thrombogenicity assessments on the bench and in animals (e.g., the clinical relevance of most in vitro tests has not been established, animal studies may not accurately predict clinical thrombotic events). To facilitate a discussion on how to overcome some of these challenges and to promote collaboration between the Food and Drug Administration (FDA), industry, and academia for the development of more reliable test methods, a scientific forum was organized by FDA and held in Washington, DC, on June 15, 2018 at the ASAIO 64th Annual Conference. Three subject matter experts from the medical device industry and FDA presented their perspectives at this forum, and several audience experts provided input during the open dialogue session. This article summarizes the key messages from the forum regarding the current status and challenges of preclinical thrombogenicity testing, important areas of needed research, and mechanisms for working with FDA to further improve thrombogenicity evaluations of medical devices.

In Vitro Study on the Dynamics of Blood Flow Impelled by an Alternating Current Magnetohydrodynamic Blood Pump

Artificial hearts are effective devices to treat heart failure in clinical practice and can be divided into two categories: artificial hearts and ventricular assist devices. The goal of this work was to investigate the fluidity and biological changes of in vitro sheep blood using a novel alternating current (AC) magnetohydrodynamic blood pump (central magnetic intensity: 0.9 T, alternating current frequency of the electric motor: 0-80 Hz). Blood samples were collected from five sheep and were divided into two groups: the control group (no exposure to an external magnetic field) and the exposed group (3 h of exposure to an alternating magnetic field). The blood cell counts, changes in blood viscosity, and ultrastructural changes of the blood cells under transmission electron microscopy were investigated. This study demonstrated several findings: (i) Continuous sheep blood flow can be achieved; (ii) The blood cell counts remained unchanged after 3 h of exposure to an alternating magnetic field; (iii) Compared with the control group, the high- and low-shear viscosities of the whole blood from the sheep significantly decreased after 3 h of exposure to an alternating magnetic field (P < 0.05 and P < 0.01, respectively). Plasma viscosity was significantly reduced after exposure to high-intensity alternating magnetic fields (P < 0.001); (iv) The cytoplasm of blood cells (especially erythrocytes) became lighter in color in the exposure group compared to the control group, and "beads-on-string" aggregations of black particles appeared. This work provides detailed and reliable scientific research data for the development of this type of blood pump, which may serve as a transition to the clinical artificial heart.

Left ventricular assist device (LVAD) program in Chile: first successful experience in South America

Background

The need to have a variety of tools to deal with end-stage heart failure (ES-HF), along with the limited heart transplantation availability encouraged us to create a pilot Left ventricular assist device (LVAD) program in a public health care system hospital in Chile.

Methods

A retrospective analysis of the first nine patients of an ongoing LVAD program initiated on August 2013 was performed, completing an average of 30 months of follow-up. The most important events regarding to morbidity and mortality are described.

Results

Nine patients with ES-HF underwent LVAD implantation surgery; one of them died 23 days after surgery and another died after 11 months. One patient successfully underwent heart transplantation after 16 months of HeartWare ventricular assist device (HVAD) support; the other six patients remain in the program and have an average follow-up of 846 days at the time of this study (range, 23-1,481 days). The survival rate at 6, 12 and 18 months follow-up was 89%, 78% and 78% respectively.

Conclusions

This new pioneering LVAD program in Chile has been successful and now constitutes a vital adjunct to all who work in heart transplantation and ES-HF programs. It offers an effective therapeutic alternative when there is a severe donor shortage, in cases of atypical blood types, emergencies, exceptional cases with contraindication for heart transplantation or when there is important donor-receiver size mismatch.

MitraClip procedure prior to left ventricular assist device implantation

Background

Functional mitral valve regurgitation is a frequent consequence of left ventricular dysfunction in patients with severe heart failure and is associated with a poor prognosis. It is hypothesized that in this patient group the mitral valve repair, respectively replacement, improves hemodynamics and clinical symptoms. As operative interventions with the help of heart-lung-machine are high risk procedures in these cases, the transcatheter mitral repair with MitraClip^® (Abbott Vascular, IL, USA) has recently become frequently used. Most of these cases experience a progress in left ventricular dysfunction, which finally leads to in an implantation of a left ventricular assist device. In this report, we describe a series of six cases in which patients with end stage heart failure and consecutive functional mitral valve regurgitation were supported with a left ventricular assist device after MitraClip implantation. We aimed to investigate, whether the MitraClip implantation leads to an improvement of the hemodynamic prior left ventricular assist device (LVAD)-implantation.

Methods

We retrospectively analyzed the data of 6 patients (5 males, 1 female) with severe heart failure, who underwent LVAD implantation after the MitraClip procedure. The mean age at MitraClip procedure was 64.6 years, mean age at time of LVAD implantation was 65.5 years. The parameters examined were cardiac index (CI), left ventricular ejection fraction (LVEF), left ventricular end-diastolic diameter (LVEDD) and the pulmonary capillary wedge pressure (PCWP).

Results

All patients had functional mitral regurgitation (MR). Severity of MR was reduced successfully in all treated patients. All patients were discharged with MR I-II and NYHA functional class III or IV after MitraClip procedure. The mean CI was 2.93 before MitraClip procedure and 2.36 before LVAD-Implantation. Mean LVEDD was 71 mm before MitraClip, mean LVEDD was 70.6 mm before LVAD, and 63.2mm after LVAD implantation respectively. The mean PCWP was 21.5 mmHg before MitraClip and 19.8 mmHg before LVAD implantation respectively. The mean left ventricular ejection fraction (LVEF) was 19.2% before MitraClip, the mean LVEF was 17.6% before LVAD and 15% after LVAD implantation. Two of the LVAD implanted patients died due to post-operative complications. There were no complications after MitraClip procedure.

Conclusions

Our presented patient cohort presented little hemodynamic improvement after the MitraClip procedure. There was no clinical benefit for the patients after MitraClip procedure, progressing left ventricular dysfunction could not be prevented and resulted in subsequent LVAD implantation.