Over the past fifteen years, I have been part of a team dedicated to developing a new class of implantable left-ventricular assist device (or LVAD) by Windmill Cardiovascular Systems, Inc., a UT-system startup I co-founded and based in Austin, Texas. This work arose from a collaboration with Dr. Richard Smalling, UTHealth (Houston), and is sponsored through WCS via funding from NIH-NLBHI and private investment.
I manage collaborative academic research in support of the research and development efforts at WCS, with our on-campus efforts focusing on methods for modeling, simulation, control, and estimation. We are developing hybrid mock circulatory loop experimental setups for hardware-in-the-loop (HIL) evaluation of LVAD systems, as well as techniques for online estimation of device and human cardiovascular system parameters to support diagnostics of patients as well as for LVAD control.
- Ethan Rapp (PhD, expected August 2021)
- Suraj Pawar (PhD, expected 2023)
Development of Electromechanical Hybrid Mock Circulatory Loop Systems for LVAD Testing and Evaluation
This research focuses on the evaluation of nominal and enhanced LVAD function using a hybrid mock circulation loop (hMCL) as a HIL test platform. The research can be split into three major aims: (1) hMCL construction and performance characterization for nominal VAD testing, (2) hMCL based evaluation of enhanced VAD onboard estimation algorithms, (3) HIL requirements for cardiac event generation in hMCL.
The figures below (from Rapp, et al 2020) illustrate the working principle and current laboratory realization of this electromechanical hMCL.
Estimation of Cardiovascular System Parameters using LVAD-based Sensing
See Rapp, et al 2019 below for preliminary work and results on estimation of systemic vascular resistance (SVR). This is ongoing work by Suraj Pawar, wich will make us of the hMCL shown above as well as the one shown in the insert below.
Publications / Products
- Rapp, E.S., Pawar, S.R., Gohean, J.R., Larson, E., and Longoria, R.G., Evaluating a hardware-in-the-loop system intended for testing ventricular-assist device control and sensing algorithms,” 2020 American Control Conference (ACC), Denver, CO, July 1-3, 2020 (invited session)
- Rapp, E., Pawar, S., Gohean, J., Larson, E., Smalling, R., Longoria, R. Estimation of Systemic Vascular Resistance Using Built-In Sensing from an Implanted Left Ventricular Assist Device, ASME Journal of Engineering and Science in Medical Diagnostics and Therapy, Special Issue on Novel and Emergent Personalized Cardiovascular Medicine, Accepted, September 2019
- Gohean, J.R., E.R. Larson, R.G. Longoria, M. Kurusz, and R.W. Smalling, Physiological Preload Sensitivity with TORVAD Counterpulse Support, Cardiovascular Engineering and Technology, 10(3):520-530. doi: 10.1007/s13239-019-00419-0. Epub 2019 Jun 11
- Bartoli, C., S. Hennessy-Strahs, J.R. Gohean, M. Villeda, E. R. Larson, R.G. Longoria, M. Kurusz, M. Acker, R. Smalling, The TORVAD, A Novel Toroidal-Flow LVAD Minimizes Blood Trauma versus the HeartMate II: Implications of Improved LVAD Hemocompatibility, The Annals of Thoracic Surgery, 107(6):1761-1767, 2019
- Gohean, J.R., E.R. Larson, B.H. Hsi, M. Kurusz, M., R.W. Smalling, and R.G. Longoria, Scaling the low-shear pulsatile TORVAD for pediatric heart failure, ASAIO Journal, Mar/Apr; Vol. 63, No. 2, pp. 198-206, Mar-Apr 2017
- Gohean, J.R., M.J. George, K.W. Chang, E.R. Larson, T.D. Pate, M. Kurusz, R.G. Longoria, and R.W. Smalling, Preservation Of Native Aortic Valve Flow And Full Hemodynamic Support With The TORVAD Using A Computational Model Of The Cardiovascular System, ASAIO Journal, Vol. 61, No. 3, pp. 259-265, May-Jun, 2015
- Gohean, J.R., M.J. George, T.D. Pate, M. Kurusz, R.G. Longoria, and R.W. Smalling RW, Verification of a computational cardiovascular system model comparing the hemodynamics of a continuous flow to a synchronous valveless pulsatile flow left ventricular assist device, ASAIO Journal, Vol. 59,No. 2, pp. 107-116, March/April 2013
- Letsou, G.V., Pate, T.D., Gohean, J.R., Kurusz, M., Longoria, R.G., Kaiser, L., Smalling, R.W., Improved left ventricular unloading and circulatory support with synchronized pulsatile left ventricular assistance compared with continuous-flow left ventricular assistance in an acute porcine left ventricular failure model, Journal Of Thoracic And Cardiovascular Surgery, Vol. 140, No. 5, pp. 1181-1188, 2010
- Five issued patents developed with Windmill Cardiovascular with UT-System as assignee
- Thomas D. Pate, Design and Development of a Circular Left-Ventricular Assist Device, MS Thesis, August 2005
- Jeffrey Krol , Design and Implementation of a Mock Circulatory System for the Evaluation of LVADs, MS Thesis, December 2007
- Djordje Adnadjevic, Suction Detection in a Motor-Driven Pulsatile Blood Pump, MS Thesis, August 2010
- Ethan S. Rapp, Brushless DC Motor Modeling and Optimal Control: A Cardiovascular Application, MS Thesis August 2016
- Suraj R. Pawar, Recursive Estimation of Systemic Vascular Resistance Using Measurements from a Left Ventricular Assist Device, MS Thesis August 2019.
- Jeffrey R. Gohean, Hierarchical Control of a Two-Piston Toroidal Pump, PhD Dissertation, May 2019