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Competing Flow Between Partial Circulatory Support and Native Cardiac Output: A Clinical Computational Fluid Dynamics Study

Engelke, Jennifer*; Karmonik, Christof; Rengier, Fabian; Partovi, Sasan§; Popov, Aron-Frederik; Osswald, Anja*; Arif, Rawa*; Schmack, Bastian*; Raake, Philip; Simon, André R#; Doesch, Andreas; Weymann, Alexander*; Lotz, Joachim**; Karck, Matthias*; Ruhparwar, Arjang*

doi: 10.1097/MAT.0000000000000701
Adult Circulatory Support

Partial circulatory support is a promising concept for the treatment of heart failure patients. A better understanding of induced hemodynamic changes is essential for optimizing treatment efficacy. Computational fluid dynamics (CFD) is an alternative method to gain insight into flow phenomena difficult to obtain in vivo. In 10 patients implanted with a Circulite Synergy Micro-pump (HeartWare, Framingham, Massachusetts) (a continuous flow partial circulatory assist device connecting the left atrium to the right subclavian artery), transient CFD simulations were performed. Patients were divided into two groups depending on their cardiac output (CO; high CO group: 5.5 ± 1.1 L/min, low CO group: 1.7 ± 0.7 L/min). The partial assist device provided a supporting flow of 1.5 ± 0.8 L/min. Support was highest at diastole and decreased during systole because of a collision of the blood flows from the partial assist device and the CO. Reversed flow counteracting the flow of the device was significantly higher for the high CO group (mean flow in peak systole: −2.18 ± 1.08 vs. 0.23 ± 0.59 L/min; p = 0.002) showing an inverse correlation between CO and amount of reversed flow during peak systole (R = −0.7; p < 0.02). The flow collision lead to higher total pressures at the point of collision and consequently in the Circulite outflow graft. The CFD simulations allow quantifying hemodynamic alterations in patients with partial support consisting of a flow collision, thereby reducing effectiveness of the circulatory support. Partial support in heart failure patients alternates their hemodynamics not only in providing support for the circulation but also inducing unfavorable changes in flow patterns.

From the *Department of Cardiac Surgery

Department of Radiology

Department of Cardiology, Angiology and Pneumology, University Hospital Heidelberg, Heidelberg, Germany

Houston Methodist Research Institute, Houston, Texas

§Department of Radiology, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, Ohio

Department of Cardiac Surgery, Royal Brompton & Harefield NHS Foundation Trust, Harefield, UK

#Department of Cardiothoracic Transplantation and Mechanical Circulatory Support, Harefield Hospital, Royal Brompton and Harefield NHS Foundation Trust, London, UK

**Department of Diagnostic and Interventional Radiology, University Hospital Goettingen, Goettingen, Germany.

Submitted for consideration April 2017; accepted for publication in revised form September 2017.

Funding was provided by institutional research grants.

Disclosure: The authors have no conflicts of interest to report.

Correspondence: Arjang Ruhparwar, Department of Cardiac Surgery, University Hospital Heidelberg, Im Neuenheimer Feld 110, 69120 Heidelberg, Germany. Email: Arjang.Ruhparwar@med.uni-heidelberg.de.

Copyright © 2018 by the American Society for Artificial Internal Organs