Francis Fynn-Thompson, MD, Surgical Director of the Mechanical Circulatory Support and Heart Transplant Programs; Director of the Cardiovascular Surgery Training Program
As recently as ten years ago, mechanical support devices were designed almost exclusively for adult patients, says Francis Fynn-Thompson, MD, Surgical Director of the Mechanical Circulatory Support Program and Heart Transplant Program at Boston Children’s Hospital. Children with heart failure waiting for a transplant were uniformly treated with ECMO, or extracorporeal membrane oxygenation. But ECMO comes with a strict time limit: it can only keep a patient alive for two to three weeks.
Today, the average wait for a pediatric heart transplant is 2-3 months.
Thankfully, significant advances in mechanical support technology have led to the creation of child-appropriate devices that can keep patients alive longer than ever before. In 2011, the Berlin Heart became the first such device to be approved by the FDA for use in children. (Compassionate use began as early as 2005.) With the Berlin Heart, children could safely endure longer wait periods for a transplant, but they remained confined to a hospital.
Today, wearable ventricular assistive devices (VADs) enable many heart failure patients to leave the hospital and return to their normal daily lives. The most sophisticated product available today, “Heartware,” uses a surgically implanted internal pump with an external battery and controller small enough to fit in a fanny pack or small backpack. Fynn-Thompson says the longest a Boston Children’s patient has used such a device is one year, but “there are reports from other countries of patients using the same device for two, three, even four years.”
Unfortunately, children who weigh less than 33 lbs (15 kg) still cannot safely leave a clinical care setting with a ventricular assist device. One device currently in development, called the Jarvik Heart, is designed to be placed in a child as small as 11 lbs (5 kg). Fynn-Thompson is hopeful that clinical trials for this device will begin within a year.
In the meantime, Boston Children’s cardiologists and cardiac nurses have trained the staff at local rehabilitation centers, so they can admit patients who are too fragile for a portable VAD, but can be kept alive on a Berlin Heart. “We have more options for small children than ever before,” says Fynn-Thompson. He emphasizes that having multiple options is important, because different patients have different needs.
The ultimate goal is to be able to support all children, regardless of the severity of their heart disease. “We want to be involved in every new clinical trial,” he adds. “We want to stay at the cutting edge.”
Boston Children’s has more experience putting mechanical pumps in children with single ventricle defects than anywhere else in the world. In just the past five years, the Heart Failure/Heart Transplant Program has grown into a robust, multi-disciplinary team. It now consists of multiple surgeons, cardiologists, intensivists, nurses, a VAD coordinator (Beth Hawkins, NP) and dedicated administrative staff.
“Our program is receiving more referrals for patients with end stage heart failure,” Fynn-Thompson explains. “This isn’t inherently a bad thing—it is because young patients with increasingly complex heart disease are having better outcomes. But with a fixed organ donor pool, it also means that transplant wait list times have gone up.”
Patients waiting for a transplant need more than just mechanical support for heart function: they also require medical management. Because heart failure increases the risk for blood clotting and stroke, a careful regimen of anticoagulation medications is extremely important. Boston Children’s has a dedicated Cardiac Anticoagulation Monitoring Program (CAMP) with staff specially trained to monitor and regulate anticoagulants in pediatric patients. Children metabolize these medications differently than adults, and every child reacts differently. Diligence and personalized attention are key to this program’s success. A study demonstrating CAMP’s positive impact on patient satisfaction was recently published in Pediatric Cardiology.
While there is still room for advancement in the field of VADs—Heartware only supports the left side of the heart, and some patients need both sides supported—Fynn-Thompson is optimistic about the future. “The total artificial heart, which is now designed for adults, will be adapted for use in children,” he predicts. You can bet that Boston Children’s will be one of the first to utilize this and other new improvements as they arise.