Ethan Kung
Ethan Kung, an assistant professor of mechanical engineering, has won a $65,000 grant to support the project “Feasibility of a Novel Fontan Right-Side Assist Device”. This grant will be funded by the Saving tiny Hearts Society (StHS).
He has also won a three year, $231,000 ($77,000 a year) grant to support the project “Design of Fontan Cavopulmonary Assist Using A Novel Combined Experimental-Computational Technology”. This grant will be funded by the American Heart Association (AHA).
Single ventricle patients typically undergo staged palliative surgery, which at the third stage involves a Fontan procedure (total cavo-pulmonary connection). This results in non-pulsatile venous return directly to pulmonary arteries commonly by the way of an extra cardiac Gore-Tex graft. Although the Fontan provides excellent short-term palliation, a large proportion of these children have severe life-threatening sequelae likely from elevated venous pressures and progressive early diastolic and later systolic ventricular dysfunction. Over a period of time all Fontan patients have significantly limited exercise capacities and many need heart transplantation, which is often not a feasible option. While restoring a cavopulmonary power source is an ideal solution which can essentially convert the uni-ventricular system back into a normal bi-ventricular circulation, mechanical support for these patients remains very high risk due to anatomical variability and size constraints in these children.
We propose a novel design for Fontan right-side support that applies the external aortic balloon pump concept to the Fontan extra-cardiac graft. This attractive approach requires no additional thoracotomy for device implementation, and results in no additional blood-contact surface, providing hemodynamic benefits with minimal risk to the patient.
The purpose of this project is to demonstrate the feasibility of this design concept using computational physiology simulations, and a novel framework that provides a physical bench testing environment that is directly coupled to a computational physiology model, which we call “Physiology Modeling Coupled Experiment (PMCE)”. The rationale for this study design is that the computational simulations provide an inexpensive method for quickly narrowing down prototype requirements, and the PMCE confirms the physical operation of the device and is used to concretely characterize its relationship to physiologic outcomes.
Restoring a cavopulmonary power source in the single-ventricle (Fontan) circulation is an ideal solution to convert the uni-ventricular system back into a normal bi-ventricular circulation; however, there is currently no available device suitably designed for this specific application. A lack of understanding in operating requirements, challenges in testing due to the lack of a viable chronic animal model, and limitations in current computational and in-vitro testing methods, has impeded developments in this area of clinical need.
In this work, we will develop and validate a novel technology (which we call “Physio-Exp”) to provide a low-cost, low-risk, and yet highly meaningful and physiologically-realistic testing environment for cavopulmonary assist devices. We will use this technology to identify an optimal surgical configuration for cavopulmonary assist device installation, and to obtain a set of device operation criteria in the context of various metabolic states and pathology. This will mitigate the aforementioned obstacles, and aid the development of this promising therapeutic option for Fontan patients. The “Physio-Exp” technology will couple a physical experiment directly to a computational model of physiology, providing a closed-loop system capable of capturing the dynamic feedback between device operation and physiological responses.
Specifically, we aim to first construct a Physio-Exp system describing the full Fontan circulation, and validate it against corresponding multi-scale computational simulations. Then, we will implement cavopulmonary assist in the system with a physical pump, compare the physiological results of several surgical options of pump installation, and identify the optimal surgical option. Finally, we will correlate assist device operation to physiological improvements for a range of patient body sizes, exercise conditions, and pulmonary hypertension. This will provide concrete design targets for continued device development.
The end point of the project is to investigate a feasible surgical installation of Fontan cavopulmonary assist, and obtain a set of device operation criteria in the context of physiology. A secondary end point is to perform a proof-of-concept application of the Physio-Exp technology. A matured version of this technology has the potential to transform the design and testing processes of a wide variety of other cardiovascular devices and procedures, such as heart valves and bypass surgeries.
