Each year nearly 1,800 U.S. children under age five die of congenital heart defects, and some 60 die while awaiting a heart transplant. A well-designed, miniaturized heart implant could lower those numbers, but achieving this goal has proven elusive.
Last December, the Food and Drug Administration gave the green light for a clinical trial to test the Jarvik 2015 ventricular assist device (VAD), an implant small enough to be used in infants and children. It is dubbed the PumpKIN trial after the Pumps for Kids, Infants and Neonates program that launched the research.
The PumpKIN program is the creation of the National Heart, Lung, and Blood Institute (NHLBI)—a response to the lack of circulatory support devices that could be used for some of the smallest of children awaiting a transplant because of congenital heart defects or advanced heart failure.
Pediatric VADs are hardly new, and they have been saving lives. Since using them, “we have seen a more than 50 percent reduction in deaths of children on the heart transplant waiting list,” said J. Timothy Baldwin, Ph.D., deputy chief of the Advanced Technologies and Surgery Branch in the NHLBI Division of Cardiovascular Sciences.
However, among children who need a VAD, those with congenital heart disease who weigh less than 20 pounds are at especially high risk due to the complex nature of their heart’s anatomy. The problem, Baldwin said, is the lack of devices to effectively treat such small children.
What was needed, researchers concluded, was more targeted devices that offered circulatory support specifically for these at-risk tiny babies and small toddlers. This was the impetus behind the launch of the PumpKIN program that led to the Jarvik 2015 VAD.
A goal of the program was to develop a fully implantable VAD, like the Jarvik 2015, so that these young patients wouldn’t need to be connected to bulky external systems, which often raises the risk of complications, such as infections, strokes and device failure. These systems also limit their mobility, further taxing families’ and children’s quality of life.
The Jarvik 2015 VAD is not a shrunken version of a VAD for grown-ups. Children are too small for the adult-size models, and need a device that adjusts to their activity levels and rapid growth, and this is particularly so for infants.
“We started with the concept of developing a heart assist device that was small enough to implant inside the natural heart,” said Robert Jarvik, M.D., chairman and CEO of Jarvik Heart, Inc. “This would prevent infection because the device would be surrounded by flowing blood that would constantly wash the pump surfaces with antibodies and blood cells, which are specialized to kill bacteria.”
The Jarvik 2015 VAD is only 15mm wide and is about the size of an AA battery. It attaches to the left ventricle to assist weakened heart muscles and treat heart failure. The researchers engineered a control system that allows clinicians to adjust the speed of the blood flow as the child grows, making it suitable for children up to age ten.
The PumpKIN study, managed by the New England Research Institutes, will compare the Jarvik 2015 VAD System with the Berlin Heart EXCOR Pediatric System, the only other VAD approved for small children in the U.S., to assess the ability of each to provide circulatory support while children wait for a heart transplant.
Patients eligible for the study will be assigned at random to either system and will be assessed over a six-month period. Researchers expect to enroll 88 patients from 20 institutions in the United States and Canada. The first implant procedure is expected in March.
The PumpKIN program researchers look forward to trial with great anticipation—and satisfaction at having reached this milestone.
“The development of the Jarvik 2015 has been unique because the government has taken a lead role and NHLBI funded the entire arc of the device’s development,” said Baldwin. The effort required collaboration with the VAD industry, various medical, engineering, and science academic departments and companies, and small businesses.
According to Jarvik, there is little market incentive to develop a VAD for pediatrics, since the number of infants who need it is small, and the development costs are too high to offer a return on the investment.
“Without the support of NHLBI, the infant pump would not have been developed,” Jarvik said.
Now, he said, even adults with heart problems could reap dividends. In cases where these patients only need partial help with blood flow, for example, Jarvik said the less invasive implant of a tiny pump like the Jarvik 2015 VAD could be the perfect choice.