Adapting Heart-Assist Technology to Younger, Smaller Patients

Bridge to a New Life

We’re helping usher in a new generation of child-sized heart pumps designed to save kids whose hearts are failing.

Julie Kobayashi

Hospital services like the school room helped Julie Kobayashi, 12, (pictured here with teacher Lisa Schab) maintain some of the normal rhythms of life – like keeping current with her studies – during her five-month stay in Seattle when a heart-assist pump kept her failing heart going until she had a successful transplant.

It all started on a Thursday evening in November 2013.

Julie Kobayashi had a stomach ache and threw up. Feeling better on Monday morning – and not wanting to miss clarinet practice before an upcoming concert – the active 12-year-old went to school, but was puzzled when she couldn’t keep up with the others during gym class. Days went by in this curious up and down cycle. She’d feel better in the morning, insist on going to school and then find herself breathing hard during the day. By nightfall, the color would drain from her face and she’d feel nauseous and vomit right around 8 p.m.

Stomach flu was the family doctor’s initial diagnosis. But when Julie’s symptoms didn’t subside, mom Lori Kobayashi pulled her daughter out of a coveted field trip to the only ice rink on their home island of Oahu, Hawaii, and asked her husband, Dave Kobayashi, to take Julie to the doctor. When her pediatrician saw Julie’s ashen coloring and heard only a weak heartbeat, he sent her to the lab where she fainted after the tech had no luck drawing blood. From there, Julie was transported to the children’s hospital in Honolulu where she was diagnosed with myocarditis – a viral infection that weakens the heart and prevents it from pumping enough blood to the rest of the body.

350 each year: Number of U.S. children who develop heart disease

Dr. Mike McMullan

Heart surgeon Dr. Mike McMullan is helping bring implantable ventricular-assist technology to smaller children and infants through research testing new devices.

“Dave and I were totally in shock,” recalls Kobayashi. “We didn’t see anything like that coming.”

After three weeks in the intensive care unit in Honolulu, Julie’s heart was deteriorating. By the time she was airlifted to Seattle Children’s, she was in advanced heart failure and time was running out.

“We knew Julie would need a new heart, but she was so sick we were concerned she wouldn’t make it to transplant,” explains veteran cardiac surgeon Dr. Mike McMullan.

That’s when McMullan, an expert on keeping failing hearts beating, offered the family a relatively new option for adolescents and teens in Julie’s situation: an implantable mechanical pump that would take over the work of her heart while she waited for a new one.

New for kids

HeartMate II

The Thoratec HeartMate II is a mechanical pump that connects to the left ventricle of the heart and circulates oxygenated blood when the heart is too weak to work on its own. It is now being used to treat teens – an advance that buys bigger kids with heart failure the freedom to continue daily activities for months or even years while they wait for a new heart.

Mechanical heart pumps aren’t new – for adults. The first ventricular assist device (VAD) was introduced in 1988. Since then, the technology has improved dramatically from stationary bedside consoles with tubes implanted in the patient’s heart to completely portable, fanny pack–sized VADs that allow patients to go about their daily lives. Yet it’s only been in the last few years that the hardware for these portable, adult-sized devices has been engineered, small enough to fit inside the chest cavities of adolescents and teens.

Julie was lucky.

She was the third patient at Seattle Children’s (and any pediatric hospital in the Pacific Northwest, Alaska and Hawaii) to receive a Thoratec HeartMate II – a newly designed pump that’s 60% smaller than other portable VADs manufactured for adults. The HeartMate II’s palm-sized pump – implanted in Julie’s chest and powered by a small controller and two rechargeable batteries – gave her the mobility she needed to leave the hospital and stay active prior to transplant.

“There’s been a real progression in VAD technology for adults,” explains McMullan. “We’re bringing these advances to teens, and we’re part of a national research team working to bring these same advances to smaller children and infants.”

“I got to go outside and see snow for the first time.”

— Julie Kobayashi, 12

The HeartMate restored blood flow to Julie’s body, which helped her breathe easier and feel more energetic. And because she could move around normally, her organ function improved. All of these factors contribute to better outcomes after transplant.

Right after the VAD surgery, Julie started eating more and enjoying life – a sign that heart failure wasn’t controlling her entire life. “I got to go outside and see snow for the first time,” she says. “My parents didn’t always need to be by my side. I felt like my old self.”

Different technologies, similar skills

AJ and Dr. Chen

AJ Hwangbo, 6, (pictured with heart surgeon Dr. Jonathan Chen) arrived at Seattle Children’s with his heart so inflamed it filled half his chest cavity and so weak it couldn’t pump enough blood to his other organs. He would have suffered permanent damage or died without the help of an external heart pump. After eight days connected to the pump, he spent a month recuperating and is expected to make a full recovery.

Seattle Children’s Heart Center is one of an elite group with the expertise to implant smaller VADs like the HeartMate II into teens, either as abridge to transplant or as a therapeutic tool to allow the heart muscle to rest and recover from injury.

Over the last seven years, the Heart Center has performed 14 implants using VADs from several different manufacturers. It’s a success due in part to the substantial amount of information available on VADs in adults and in part to the team’s expertise. Seattle Children’s is nationally recognized as a center of excellence for heart-lung bypass machines – devices that do the work of the heart and lungs when the heart must be stopped for a surgical procedure or short-term rest.

“The team at Children’s has spent two decades troubleshooting heart-lung bypass systems, and that’s the same think-outside-the-box mindset you need to fine-tune a VAD,” explains Dr. Jonathan Chen. Chen joined Seattle Children’s as surgical director of the Heart Center in 2013 from Columbia University Medical Center, which has one of the largest VAD programs in the nation.

“VADs are the future of our field, and the depth of experience across every cardiology subspecialty at Seattle Children’s puts us at the forefront of becoming a center of excellence for children who may need to be on a heart pump for weeks or months.”

Finding a tot-sized solution

Dr. Rob Mazor

It takes a highly trained team with specialized skills and the most advanced technology to keep failing hearts beating. Dr. Rob Mazor leads the ventricular assist device program in our cardiac intensive care unit that keeps kids as healthy as possible while they recover or await a new heart.

Although there are now many mechanical pump options for teens with chest cavities big enough to fit an adult-sized device, VADs for smaller children and infants are still very new. Approximately 60 infants and children under age 5 die in the U.S. each year while on the heart transplant waiting list, illustrating why smaller heart pumps are needed.

The first VAD made specifically for little kids (known as the Berlin Heart) is small enough for children under age 5, but there are drawbacks with the device. “Even though the pump is small, it sits outside the body on top of the abdomen and it’s connected to a large console that controls the pump,” notes McMullan. “Children with a Berlin Heart can’t leave the hospital, and being in a bed tethered to a machine or dragging the machine around the hospital for weeks or months is hard on the body and mind.”

Seattle Children’s is one of two sites on the West Coast to participate in the National Heart, Lung, and Blood Institute’s “Pumps for Kids, Infants, and Neonates (PumpKIN)” trial. The study is slated to begin this fall and will focus on finding the best device for infants and young children who weigh as little as 7 pounds. McMullan will lead Seattle Children’s part of the trial.

The Heart Center team is also one of the first in the nation authorized to use the new SynCardia Total Artificial Heart – an implantable mechanical replacement heart made in different pediatric sizes and used to bridge patients to transplant when both ventricles of the heart can’t pump enough blood to the body.

“We’re proud to be the only pediatric heart center in our region to offer every type of therapy for heart failure, including VAD technology,” says Chen. “We want to give our patients the very best quality of life and our families the greatest amount of hope for a healthy child.”

“Our decades of experience treating children with heart failure make us a key player in the emerging field of heart-assist devices for the tiniest hearts.”

— Dr. Jonathan Chen

Published in Connection magazine, September 2014