Turbodynamic left ventricular assist devices (LVADs) provide a continuous flow depending on the speed at which the pump is set, and do not adapt to the changing requirements of the patient. The limited adaptation of the pump flow (PF) to the amount of venous return can lead to ventricular suction or overload. Physiologic control may compensate such situations by an automatic adaptation of the PF to the volume status of the left ventricle. We evaluated two physiologic control algorithms in an acute study with eight healthy pigs. Both controllers imitate the Frank–Starling law of the heart and are based on a measurement of the left ventricular volume (LVV) or pressure (LVP), respectively. After implantation of a modified Deltastream DP2 blood pump as an LVAD, we tested the responses of the physiologic controllers to hemodynamic changes and compared them with the response of the constant speed (CS) mode. Both physiologic controllers adapted the pump speed (PS) such that the flow was more sensitive to preload and less sensitive to afterload, as compared with the CS mode. As a result, the risk for suction was strongly reduced. Five suction events were observed in the CS mode, one with the volume-based controller and none with the pressure-based controller. The results suggest that both physiologic controllers have the potential to reduce the number of adverse events when used in the clinical setting.
From the *pd|z Product Development Group Zurich, Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Switzerland; †Department of Cardiovascular Surgery, University Hospital Zurich and University of Zurich, Zurich, Switzerland; ‡Wyss Translational Center Zurich, ETH Zurich and University of Zurich, Zurich, Switzerland; §Division for Surgical Research, University Hospital Zurich and University of Zurich, Zurich, Switzerland; and ¶Micro- and Nanosystems Group, Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Switzerland.
Submitted for consideration september 2016; accepted for publication in revised form january 2017.
Ochsner and Wilhelm are the co-first authors.
Disclosures: The authors have no conflicts of interest to disclose.
Petrou and Staufert have received funding from the Stavros Niarchos Foundation. The study was financially supported by the Institute for Dynamic Systems and Control, ETH Zurich.
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Correspondence: Marianne Schmid Daners, pd|z Product Development Group Zurich, Department of Mechanical and Process Engineering, ETH Zurich, CLA G21.1, Tannenstrasse 3, 8092 Zürich, Switzerland. Email: email@example.com.