McGowan Institute for Regenerative Medicine
faculty member Peter Wearden, MD, PhD, pediatric cardiothoracic surgeon and director of Pediatric Mechanical Cardiopulmonary Support, Children’s Hospital of Pittsburgh of UPMC, and assistant professor of Cardiothoracic Surgery, University of Pittsburgh School of Medicine, is part of a team of medical professionals at Children’s who are using advanced and innovative technologies to perform life-saving procedures on children in need of cardiac support. The Berlin Heart, an experimental, child-size artificial heart pump, is currently the only ventricular assist device (VAD) available for use in children waiting for a heart transplant. However, another device option may become available to the tiniest-of-patients population. Dr. Wearden has a leadership role in an on-going research study to develop a miniaturized heart pump for children—the implantable pediatric VAD known as the PediaFlow.
The Berlin Heart
In adults, when supplemental cardiac support is needed as an interim measure, surgeons may elect to implant an artificial heart pump. The pumps that work for adults are not suitable for infants and children. Dr. Wearden has successfully used a pediatric heart pump, the Berlin Heart, which is undergoing a U.S. Food and Drug Administration (FDA) evaluation trial at Children’s and 14 other hospitals nationwide. Currently, the Berlin Heart is the only heart-assist device currently available for babies and children. Because it does not have FDA approval for routine use, it must be approved on a case-by-case “compassionate use” basis for cases that are outside of the clinical trial parameters.
The Berlin Heart is an experimental, child-size artificial heart pump, or VAD, that keeps children with life-threatening heart failure alive while awaiting a heart transplant. The device has also been used effectively as a bridge to recovery. Mark Roth,
recently reported the story of 2-year-old Ethan Gradowski who was placed on the heart transplant list in early November 2008 due to narrowing of his arteries as a result of acute inflammation or a reaction to medications following a routine repair of an atrial septal defect (a hole in the wall that divides the heart’s two upper chambers). He was placed on the Berlin Heart shortly thereafter to wait for a donor heart. As Ethan waited and with the help of the Berlin Heart his tiny body slowly began to heal itself. The Berlin Heart gave his arteries the rest they needed to recover, and in late December Ethan was successfully weaned from the device.
Not all pediatric patients on the waiting list for a heart transplant are as fortunate as Ethan. There are 240 children waiting for heart transplants in the United States today, according to the United Network for Organ Sharing. If current trends continue, more than a fifth of them will die before they get a transplant, and those deaths will not be just a personal tragedy for their families, but the loss of decades of productive years that the child could have contributed to society.
The PediaFlow is designed for children from birth to 2 years. The heart pump, the size of a AA battery, will use a magnetically levitated impeller, technology that increases the life span of the pump, reduces the electrical power and cooling requirements, and drastically reduces blood damage and clotting. PediaFlow is designed to go inside a child’s body to minimize the risks of infection from tubes piercing the skin. It is now in a preclinical trial and the availability for human trials is subject to the results of the current studies.
In addition to children on the heart transplant list, other pediatric patients could be helped with an effective heart mini-pump. They include children whose hearts have been attacked by viruses or weakened by other causes, children who have chronically weak hearts, and children who are born with only one pumping chamber instead of the normal two. Once grouped together, the need for this advanced technology could be tens of thousands of children who could benefit from a pediatric VAD each year.
There is one other potential spillover benefit, Dr. Wearden said. "I think just the process of making things smaller will allow us to have smaller, less [injurious] devices for adults."
The PediaFlow Team and Its Current Research Efforts
Since 2004, faculty members of the McGowan Institute have been in pursuit of the successful development of PediaFlow. Once ready for manufacture and commercialization, this device will have features designed to meet the special needs of patients with congenital and acquired heart defects who are as young or as small as a newborn baby. Along with Dr. Wearden, the leaders of the development team are—
James Antaki, PhD, professor of biomedical engineering, Carnegie Mellon University, and
University of Pittsburgh adjunct professor, Departments of Surgery and Bioengineering, and
Harvey Borovetz, PhD, deputy director - Artificial Organs and Medical Devices, McGowan Institute, chair, Bioengineering Department, University of Pittsburgh, Robert L. Hardesty Professor, Department of Surgery, University of Pittsburgh School of Medicine, and senior lecturer of engineering in medicine at Carnegie Mellon University.
The team, comprised of over 30 members, is diligently working to bring to fruition their solution to fill a current technology void in the field of medical devices now available to the tiniest of patients in need of heart surgery.
"Historically, infants and toddlers have been overlooked by technology development. Yet the smallest of our patients have the greatest need because the only means of support available to them is ECMO [extracorporeal membrane oxygenation], which has unacceptably high mortality and complication rates. We hope to be able to develop a device that will allow more babies with congenital heart defects or end-stage heart disease to survive to transplantation, or perhaps even recover cardiac function and avoid the need for transplantation," said Dr. Borovetz, the team’s lead and the co-principal investigator on a 5-year $4.5 million NIH grant.
Since 1986, Dr. Borovetz has headed the UPMC/University of Pittsburgh Clinical Bioengineering Program in Mechanical Circulatory Support. This is a one-of-a-kind program that supports patients who are implanted with a left ventricular assist device, or a total artificial heart, as a bridge to cardiac transplantation. This work in mechanical circulatory support followed Dr. Borovetz's early efforts in which he helped cardiac surgeons apply ECMO to successfully treat a large series of neonates in respiratory distress.
To develop the PediaFlow, Dr. Borovetz assembled a multidisciplinary team of bioengineers, surgeons, and researchers from the University of Pittsburgh’s schools of Engineering and Medicine and the McGowan Institute. Working also as part of the team are pediatric cardiologists from Children's Hospital of Pittsburgh, bioengineers from Carnegie Mellon University, and research teams from MedQuest Products, Inc., of Salt Lake City (which hopes to manufacture and commercialize the device), and LaunchPoint Technologies of Goleta, California. Researchers from Primary Children's Medical Center and LDS Hospital, both in Salt Lake City, also are involved.
The technology being applied to the development of the pediatric VAD builds on the innovative work of Dr. Antaki who is a co-investigator and the project director for the NIH grant. The goal of the project is to develop a miniature centrifugal pump utilizing suspended magnetic levitation technology for use in babies between 5 and 35 pounds. It's conceived that the device could be used for up to 6 months as a bridge to heart transplantation. In some babies, the device may allow the heart to recover. As such, the team plans to develop a smart control system that will indicate patterns consistent with a recovering heart. Since the device will be fully implantable with a small lead to an external power supply, children supported by the device will be able to be mobile and active.
Dr. Antaki has received numerous awards in recognition of his applications of systems engineering to the design and optimization of medical devices in general, and cardiovascular devices in particular. Professor Antaki is responsible for a paradigm shift in the design of blood pumps by replacing trial-and-error approaches with rigorous systems engineering that integrates biomedical engineering, computational fluid dynamics, electromagnetics, control system design, and software engineering. He is a world leader in systems engineering of medical devices, and his contributions have led to life-extending artificial hearts and left ventricular assist devices for adults, toddlers, and infants with cardiac deficiencies.
Currently, PediaFlow is in pre-clinical trials. Offering both a medical research and a clinical support interest, the congenital cardiothoracic surgical expertise of Dr. Wearden is a key component in the success of PediaFlow. Dr. Wearden has helped the Children’s Hospital of Pittsburgh of UPMC Heart Center to establish itself as one of the most active and innovative centers in the care of children in heart failure in the country over the last two decades. He has also contributed to making it one of the world’s most experienced centers in the use of technology to support pediatric patients in heart failure and in need of a transplant. As an advocate for the 1,000 children per year who could benefit from the PediaFlow, Dr. Wearden has spearheaded the on-going clinical efforts to develop this first totally implantable pediatric VAD in the United States.
“Our dream for the PediaFlow — which is about the size of a walnut — is that it could be totally implanted into a child to support his or her heart until a donor could be located or until the heart function recovers,” Dr. Wearden said. “The PediaFlow would be magnetically powered and potentially could support a child for as long as 6 months.”
The availability of VADs for use in infants and young children is extremely limited, with no device specifically approved for use in this age group in the United States. Until such time as a pediatric VAD is developed and approved for use, the pediatric medical staff at Children’s will request on a case-by-case basis approval from the FDA to implant the Berlin Heart for compassionate use. Getting approval to use a Berlin Heart can be a complicated process, especially when a young child’s survival is dependent on it. The research and development challenge is to develop a pediatric VAD for use here in the United States. Realizing this opportunity, Drs. Antaki, Borovetz, and Wearden move towards the crucial success of the PediaFlow—an additional life-saving medical device option for the hundreds of kids who suffer heart failure each year.
Illustration: McGowan Institute for Regenerative Medicine.
Pittsburgh Post-Gazette (02/04/09)
Pittsburgh Post-Gazette (02/01/09)
The Berlin Heart
Mechanical Support for a Child's Failing Heart: Past, Present and Future (webcast) (04/10/08)
Children’s Hospital of Pittsburgh of UPMC News Release (04/03/08)
Regenerative Medicine Podcast—Dr. Peter Wearden (12/24/07)
McGowan Institute In the News: Institute Receives NIH Funding to Develop Heart Assist Device For Infants
McGowan Institute In the News-- Development of Pediatric Artificial Heart
McGowan Institute In the News-- Regenerative Medicine: Pediatric Ventricular Assist Device
Bio: Dr. James Antaki
Bio: Dr. Harvey Borovetz
Bio: Dr. Peter Wearden
Podcast: Dr. Peter Wearden