Hybrid Continuous Flow Dual-Support Pediatric Artificial Heart
Thursday, March 5, 2020
10:30 AM-12:30 PM
BIOMED PhD Research Proposal
Title:
Hybrid Continuous Flow Dual-Support Pediatric Artificial Heart
Speaker:
Matthew Hirschhorn, PhD Candidate
School of Biomedical Engineering, Science and Health Systems
Drexel University
Advisor:
Amy Throckmorton, PhD
Associate Professor
School of Biomedical Engineering, Science and Health Systems
Drexel University
Details:
Four million live births occur in the US each year, and 25% of those babies are born with a congenital heart defect requiring treatment. Of that cohort, approximately 40,000 are born with significant heart malformations necessitating surgical intervention within the first days to years of life. Patients receiving early surgical intervention frequently require multiple open-heart surgeries and develop premature heart failure (HF). A growing number of patients with complex congenital heart disease are also developing cardiomyopathies (ventricular dysfunction), due to inherited muscle disorders, metabolic and mitochondrial defects, exposure to bacteria and viruses that attack the myocardium, and arrhythmias. The gold standard treatment for end-stage HF is heart transplantation, and there are a limited number of donor organs, especially for children. More than 15% of transplant eligible patients will die before a heart becomes available. Thus, there continues to be a significant clinical need for alternative solutions for pediatric HF, such as the use of mechanical circulatory assist devices.
Ventricular assist device (VAD) or blood pump technology for adults has achieved significant milestones in recent years by a demonstrated improvement in clinical outcomes due to design innovation. These devices leverage contact, surface free magnetic levitation and eliminate thrombosis-inducing mechanical or polymeric valves. However, VAD technologies for children significantly lag behind those for adults. While adult devices have been used in children, the operation of these pumps at off-design conditions increases the risk for irregular blood flow, contributing to blood cell damage (hemolysis) and dangerous clotting (thrombosis). High-risk pediatric patients also have limited options due to their size and require devices for a range of physiological heterogeneity due to childhood heart disease and the changing cardiovascular demands of physical growth.
Thus, there is a substantial unmet clinical need, and the purpose of this dissertation research is to advance a breakthrough innovation of a high-impact, hybrid-design, magnetically levitated, medical device that uniquely integrates two blood pumps for supporting pediatric patients. This new device (Dragon Hatchling Heart) has only 2 moving parts - an axial pump impeller for the pulmonary circulation and a centrifugal pump impeller for the systemic circulation. As a hybrid dual design, the centrifugal pump rotates around the separate axial pump domain. This device utilizes the latest generation of bearings to levitate the rotating impellers in a magnetic field, thus facilitating a long operational lifespan and wider clearances between the rotating and stationary surfaces. Wider clearances lower fluid stresses, hence reducing the risk of thrombosis and hemolysis. This design avoids the use of mechanical or biologic valves, thus further minimizing the thrombosis risk. It will maintain pulse pressure by being able to produce continuous or pulsatile flow, thus mitigating neurologic impairment. The Dragon Hatchling Heart is also compact (60mm x 50mm) and delivers physiologic pressures and blood flows for high-risk pediatric with various degrees of heart failure, anatomic defects, and sizes/ages.
In strong support of our approach, we have generated substantial preliminary data of the pump designs (axial and centrifugal) and motor/magnetic suspension by performing in silico modeling and in vitro hydraulic and hemolytic testing. These prior studies demonstrated that the initial pumps deliver flows of 1-5 L/min and pressure rises of 15-30 mmHg (pulmonary circulation) and 60-140 mmHg (systemic circulation) for a range of rotational speeds. Our central hypothesis is that the innovative, hybrid integration of an axial flow pump within a centrifugal flow blood pump will successfully provide pediatric cardiac support.
Contact Information
Ken Barbee
215-895-1335
barbee@drexel.edu