New Continuous-Flow Total Artificial Heart For Use in Smaller Sized Adults & Pediatric Patients
Authors:   , Fox Carson Solon , Throckmorton Amy 
Published: July 2021

Congestive heart failure (CHF) is a progressive and debilitating disease that affects millions of people worldwide. Hundreds of thousands of new cases of CHF are diagnosed each year in the U.S., and this high volume of patients costs the healthcare industry tens of billions annually. The limited number of donor hearts and limited long-term effectiveness of pharmacologic treatment necessitate the use of mechanical circulatory support (MCS) alternatives. Clinical trials of MCS devices have demonstrated that patients derive substantial survival and quality of life benefits from long-term MCS. Only two total artificial hearts (TAHs) are approved for clinical implantation in the U.S., and the implementation of TAHs in the treatment of patients with CHF has increased more than 3 fold in 6 years. These devices and other new TAHs that are under development, however, have several design limitations and challenges, such as thromboembolic events, neurologic impairment, risk of infection due to large size, and infection at the abdominal site of the percutaneous driveline. Additional design limitations include lack of ambulation due to a sizeable drive console or a heavy portable unit, non-pulsatile blood flow conditions, and the use of polyurethane membranes and valves which risks rupture or failure after repetitive flexions or openings. To address these limitations and to provide a new therapeutic solution, we seek to develop an innovative therapeutic alternative: a unique hybrid-design, continuous flow, implantable, magnetically levitated TAH (Dragon Heart). The Dragon Heart is designed to support pediatric and adult patients (BSA > 0.95 sq. meters) with CHF. This TAH has only 2 moving parts - an axial impeller for the pulmonary circulation and a centrifugal impeller for the systemic circulation. This device utilizes the latest generation of magnetic bearing technology to levitate the impellers, thus enabling a longer operational lifespan of 15-20 years and larger clearances between the rotating impellers and pump housing. Larger clearances lead to lower fluid shear stresses, hence mitigating the risk of thrombosis and hemolysis. This design avoids the use of mechanical or biologic valves and will have an antithrombogenic coating applied to blood-contacting surfaces, thus further reducing the risk of thrombosis. It will incorporate state-of-theart monitoring with Wifi-based sensors to report operational status and will be able to produce both continuous and pulsatile blood flow. A transcutaneous energy transfer system using wireless technology will be incorporated to eliminate the percutaneous driveline. The compact Dragon TAH, which has a target diameter and height of 60 mm by 50 mm, will produce the physiologic pressures and flows necessary to support CHF patients. This thesis project involved the initial steps in the design and development of the Dragon Heart. The pump geometries (axial and centrifugal) were established using standard pump design equations and available literature on similar pumps. Computational modeling using ANSYS CFX 15.0 was performed to gain insight into the performance of the pump geometries. The axial and centrifugal pump designs were optimized twice to reduce the outer diameter without compromising pump performance. These computational models served as the foundation by which prototype manufacturing was completed for hydraulic testing. Two hydraulic test rigs were constructed to evaluate the performance of the axial and centrifugal pump prototypes. A blood analog solution of water and glycerin was utilized for the experiments. The computational studies and prototype testing revealed that the Dragon Heart is capable of delivering the target blood flows of 1-6.5 L/min and pressure rises of 15-25 mmHg for the pulmonary circulation and 80-140 mmHg for the systemic circulation at rotational speeds of 2,000-12,000 RPM with power consumptions of 3-6 watts. This work successfully reflects the first design phase of the Dragon Heart and represents the foundation by which to begin Phase II optimization and development. The long-term goal of this research is to commercialize a novel, less expensive, more compact, low thrombus, and effective therapeutic alternative for adult and pediatric patients with CHF, thereby saving thousands of lives annually.