A team of researchers at The Pennsylvania State University Applied Research Laboratory (ARL) and Materials Science Department, University Park, have seen the Left Ventricular Assist Device (LVAD) minimally invasive heart pump they developed between 2005 and 2011 transitioned to its first successful human testing. LVADs are designed to partially take over the pumping function of a failing heart.
Thoratec Corporation, Pleasanton, CA, a leader in mechanical circulatory support therapies, licensed the technology from Penn State, and in fewer than three years, the preliminary design components, test facilities, and manufacturing techniques developed at Penn State for the prototype device were advanced by Thoratec to where the LVAD could be tested in humans.
“The design goals for the now-termed HeartMate PHP (percutaneous heart pump) were daunting: Develop a blood pump on the end of a long, thin catheter small enough to be inserted through an incision in a patient’s thigh and snaked up through the descending aorta to the left ventricle to be deployed,” said Rob Kunz, ARL researcher and principal investigator on the project. “The PHP has to provide enough blood-pumping capability to support an adult male (approximately 4.5 liters per minute at a 60mmHg pressure head) for several days, without causing undo damage to the heart or the blood itself.”
Many commercially available long-term LVADs require that the chest wall be surgically opened for device insertion, but the design goals for the short-term PHP device were for a rapidly inserted minimally invasive acute support technology. The PHP is designed to be inserted, deployed, and operating within minutes of a patient suffering a heart attack or other acute heart condition.
With these requirements, industry came to Penn State because of the University’s strong capabilities in hydrodynamics (design, testing, and modeling) and materials science.
Developing the turbomachine has required the researchers to overcome multiple challenges. The impeller pumps blood while spinning at 19,000 RPM. But, the blades had to be engineered so that they would only minimally damage red blood cells. In addition, the blade material had to be flexible enough to compress within a 4mm catheter, and be designed to offset deflection while preserving the desired hydrodynamic performance. And, the cannula in which the impeller spins, and which guides the blood flow through the pump, also needed to be collapsible, to fold into a 4mm catheter.
Thoratec intends to continue clinical trials on the use of the HeartMate PHP to support patients undergoing high-risk percutaneous interventions, as well as those in cardiogenic shock, a population with persistently high mortality rates. The company anticipates initiating a European study in the second half of 2013, followed by a US clinical trial in early 2014.