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Fresh Wind Cross Shore

Evgenij Potapov, MD, PhD
Deutsches Herzzentrum
Berlin, Germany

M. Schmid Daners, PhD
ETH Zurich
Zurich, Switzerland

Today, there is only a small number of main players who dominate the LVAD market and develop new devices, or rather improve existing devices, and promote their implementation in clinical practice. The most important papers in the area of LVAD research are comparisons of the two main types of devices from studies supported by larger companies. However, no breakthrough devices have been presented for a long time and the clinical results of the new devices are not remarkably better than those of the previous models. We are sure that the companies are interested in new developments, but such changes only slowly find their way into clinical practice, as we see in the example of transcutaneous energy transfer.

How can we improve this situation? In the pediatric VAD field, a solution envisaged was the Pumpkin project supported by the US government. So far, after over 10 years, no real clinical results have been presented.

Now the Zurich Heart Project offers a different approach to overcome the current problems and creates an environment for young researchers in the VAD field. The Zurich Heart Project was born in 2012. The initiative, started by University Medicine Zurich (www.hochschulmedizin.uzh.ch/en/projekte/zurichheart), has brought together up to 20 research groups with over 75 researchers. Novel and unconventional ideas are pursued in close collaboration among the University of Zurich, the associated hospitals in Zurich and the Swiss Federal Institute of Technology Zurich (ETH Zurich) as well as the German Heart Center Berlin (DHZB) and the Swiss Federal Laboratories for Materials Science and Technology. This large consortium aims to revolutionize mechanical circulatory support therapy, and address the drawbacks of current devices and challenges of long-term VAD therapy per se.

The research topics range from pump flow adaption, entire device implantability and transcutaneous energy supply to membrane development, pump geometry improvements and surface structure. It is expected that the increased hemocompatibility will result in a decrease in the number of thromboembolic and bleeding events. Further, the need for freedom of movement and continuous support adjustments are accounted for. Not only left ventricular support is in focus, but also heart valves, Mechanical Fontan Assist and total artificial hearts. Synergies among the groups help to foster new and creative ideas, such as combustion-powered actuation for a soft total artificial heart.

One of the projects is the development of physiological pump adaptation. The physiological controller envisaged will work collaboratively with biocompatible pressure and/or volume sensor devices that are under development in the consortium and are intended to be integrated into the novel pump. In-vitro and in-vivo tests have shown that the developed physiological controllers reliably avoided suction and ventricular overload conditions caused by pre- or afterload changes.

To reach the goal of a fully implantable mechanical circulatory support device, the pump geometry, the rotor design, the actuation and the bearing principle need to be reconsidered, beside the need for a transcutaneous energy transmission system. The latter development has already demonstrated very promising results. Pump geometry adjustments and rotor configuration changes have shown great influence on the hydraulic pump efficiency and hemocompatibility.

Additionally, the high risk of thromboembolic and bleeding events can be addressed by novel surface structures that allow cell adhesion to be promoted or demoted at the luminal pump-to-blood surface. The microstructuring at the interface with specifically engineered gratings enables endothelial cell migration and adhesion under flow, and yields full coverage by a differentiated and functional endothelium. The same is true for a structured hyperelastic hybrid membrane that guarantees full hemocompatibility when entirely covered by endothelium. In a bioreactor, the endothelial cell layer was tested under a variety of flow conditions and membrane deformations that correspond to representative loads that are present in a pulsatile pump. This approach may foster the development of pulsatile devices again.

We believe that the Zurich Heart Project, with its constructive and ambitious spirit, has the know-how and financial potential to create novel ideas that will dramatically change mechanical circulatory support therapy in the future as well as lead a cohort of talented young scientists for biomedical engineering and in particular, future VAD technology. ■

Disclosure Statement: The authors have no conflicts of interest to disclose.

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