Karen May-Newman, PhD, director of the Bioengineering program and the Cardiovascular Bioengineering and Medical Device Lab at San Diego State University (SDSU), was recently featured in a Qmed article on The Forces Behind Cardiovascular Device Innovation. Here’s an update on her work and how she uses ViVitro Labs equipment at the university.
What are you working on at SDSU?
My lab focuses on testing the delivery and performance of novel cardiovascular medical devices, as well as studying the response of the native biomechanics and heart valve function. This work utilizes a variety of customized bench-top systems to simulate the native cardiovascular system during device use.
What type of devices do you test?
For several years I’ve been working with cardiothoracic surgeons at Sharp Memorial Hospital on Left Ventricular Assist Devices (LVADs). The LVAD is a large pumps attached directly to the heart and aorta that is implanted in heart failure patients to boost systemic blood flow. These devices are invasive, involving a large amount of foreign material and interfacing with the blood and soft tissue of the heart. Initially, the LVAD recipients see improvement due to increase of blood flow to body tissues. The LVAD reduces LV pressure and cardiac work, but also changes the flow path through the ventricle and the cyclic opening of the aortic valve. These two alterations result in long-term consequences for these patients including thrombus (blood clot) formation and aortic valve dysfunction.
These clinical problems are related to altered fluid and solid biomechanics in the LVAD-supported heart, which we study in the SDSU Cardiac Simulator. We can use flow and pressure sensors, as well as imaging of valve and flow dynamics as our system is entirely transparent. Our studies are used to evaluate new surgical attachment configurations, control algorithms to optimize aortic valve opening, and techniques to normalize intraventricular vortex flow. Our work with ViVitro Labs equipment enables our experimental studies to most closely simulate the human cardiovascular system, which is essential for translating the results to aid clinical practice.
How do you assess the performance of these devices in your Cardiac Simulator?
We have a LaVision Particle Image Velocimetry (PIV) system for flow visualization studies. We use this system to measure flow patterns in the ventricle during different levels of LVAD support, to look for areas of thrombosis formation. (Ed. Note: PIV is an integral laboratory service that ViVitro Labs provides for labs that do not have the equipment or expertise.)
How do you use ViVitro Labs equipment?
The ViVitro Labs SuperPump supplies a realistic left heart waveform and impedance simulator that optimizes conditions for our experimental studies. We use our circulatory loops to evaluate design change in the LVAD or control system that will improve the performance of these devices in vivo. Our original SDSU cardiac simulator was a student-designed and built system that functioned but did not have the degree of flexibility, control and accuracy enabled by the ViVitro components.
What advice do you have for start-ups unfamiliar with the testing needs?
It is critical to understand your regulatory testing and documentation needs. I teach my students to embrace FDA Design Control and begin their experience in my classes by requiring assignments that use this documentation structure.
Any guidance for designing a novel device?
Pay close attention to what the physician needs and try not to diverge with too many features that are outside those needs. Don’t build something fantastic in your mind without talking to the end users, the physicians. They may need a design that is cheap and reliable instead of a fantastic new idea. Be thorough about gathering this background before you begin creating your products.
Use a design control framework and appreciate the need for good documentation from the beginning. Because all of your documentation is subject to FDA scrutiny, it is best to demonstrate adherence to the recommended format from the very beginning. I also emphasize this lesson with my students.
Engineers and physicians need to learn each other’s language. They need to learn how to communicate well with each other. Sometimes they use the same terms, but with different meanings. Engineers need to understand physicians’ ideas and physicians need to understand what engineers are doing with their ideas. That’s the way to make good devices.