First clinical experience with the double cuff tipless inflow cannula in the EVAHEART left ventricular assist system: Case report

Stable and Thin-Polymer-Based Modification of Neurovascular Stents with 2-Methacryloyloxyethyl Phosphorylcholine Polymer for Antithrombogenicity

The advent of intracranial stents has revolutionized the endovascular treatment of cerebral aneurysms. The utilization of stents has rendered numerous cerebral aneurysm amenable to endovascular treatment, thereby obviating the need for otherwise invasive open surgical options. Stent placement has become a mainstream approach because of its safety and efficacy. However, further improvements are required for clinically approved devices to avoid the frequent occurrence of thrombotic complications. Therefore, controlling the thrombotic complications associated with the use of devices is of significant importance. Our group has developed a unique stent coated with a 2-methacryloyloxyethyl phosphorylcholine (MPC)-based polymer. In this study, the surface characteristics of the polymer coating were verified using X-ray photoelectron spectroscopy and atomic force microscopy. Subsequently, the antithrombotic properties of the coating were evaluated by measuring platelet count and thrombin-antithrombin complex levels of whole human blood after 3 h of incubation in a Chandler loop model. Scanning electron microscopy was utilized to examine thrombus formation on the stent surface. We observed that MPC polymer-coated stents significantly reduced thrombus formation as compared to bare stents and several clinically approved devices. Finally, the coated stents were further analyzed by implanting them in the internal thoracic arteries of pigs. Angiographic imaging and histopathological examinations that were performed one week after implantation revealed that the vascular lumen was well maintained and coated stents were integrated within the vascular endothelium without inducing adverse effects. Thus, we demonstrated the efficacy of MPC polymer coating as a viable strategy for avoiding the thrombotic risks associated with neurovascular stents.

Left ventricular assist devices: yesterday, today, and tomorrow

The shortcomings of expense, power requirements, infection, durability, size, and blood trauma of current durable LVADs have been recognized for many years. The LVADs of tomorrow aspire to be fully implantable, durable, mitigate infectious risk, mimic the pulsatile nature of the native cardiac cycle, as well as minimize bleeding and thrombosis. Power draw, battery cycle lifespan and trans-cutaneous energy transmission remain barriers to completely implantable systems. Potential solutions include decreases in pump electrical draw, improving battery lifecycle technology and better trans-cutaneous energy transmission, potentially from Free-range Resonant Electrical Energy Delivery. In this review, we briefly discuss the history of LVADs and summarize the LVAD devices in the development pipeline seeking to address these issues.

Review of Implantable Left Ventricular Assist Devices

Mechanical circulatory support has been an indispensable treatment for severe heart failure. While the development of a total artificial heart has failed, left ventricular assist devices (LVAD) have evolved from extracorporeal to implantable types. The first generation implantable LVAD (pulsatile device) was used as a bridge to transplantation, and demonstrated improvement in survival rate and activity of daily living. The evolution from the first-generation (pulsatile device) to the second-generation (continuous flow device: axial flow pump and centrifugal pump) has resulted in many clinical benefits by reducing mechanical failures and minimizing device size. Furthermore, third-generation devices, which use a moving impeller suspended by magnetic and/or hydrodynamic forces, have improved overall device reliability and durability. Unfortunately, there are still many device-related complications, and further device development and improvement of patient management methods are required. However, we expect to see further development of implantable VADs, including for destination therapy, in future.

Potential of the EVAHEART 2 Double-Cuff Tipless Inflow Cannula for Prevention of Thromboembolic Events

A 32-year-old man, who had developed fulminant myocarditis leading to asystole, underwent implantation of an EVAHEART 2 left ventricular assist system with a double-cuff tipless inflow cannula and a concurrent Fontan operation. Approximately 2 years after the simultaneous EVAHEART 2 implantation and the Fontan operation, the patient underwent heart transplantation. There was no device-related thromboembolism or pump malfunction under adequate antithrombotic management during the postoperative support period. Computed tomography showed no malposition of the inflow cannula irrespective of the left ventricular chamber size. Macroscopically, the left ventricular cavity of the excised heart revealed a smooth inflow ostium with appropriate intimal proliferation and without pannus or wedge thrombus formation. These findings suggest the utility of the double-cuff tipless inflow cannula for long-term clinical applications, which may lead to favorable outcomes during long-term patient management. The double-cuff tipless inflow cannula, which does not protrude into the left ventricular cavity, potentially contributes to the prevention of suction events and the collision of the inflow cannula with the interventricular septum and left ventricular free wall. Further investigation is required to confirm the role of the unique EVAHEART 2 inflow cannula in reducing thromboembolic events.