Four-month-old Damaris Ochoa was near death, born with an enlarged heart that was quickly giving out. Obtaining a transplant in time was a long shot. Then Dr. Edward Rhee attached a souped-up adult pacemaker to her tiny heart, and six months later Damaris is thriving.
The Missouri tot is among the youngest of just a few dozen children to try an experiment in which doctors are adapting a new technology for adults’ failing hearts to the special needs of their smallest patients.
It’s too early to know how well the therapy, called cardiac resynchronization, will work. But so far, a handful of youngsters are doing so well they’ve been taken off the heart transplant waiting list, and the hope is that others improve enough to postpone that operation.
“At least in the short term, we can improve their symptoms and quality of life,” predicts Rhee, the electrophysiology chief at St. Louis Children’s Hospital.
Cardiac resynchronizers
Cardiac resynchronizers, which hit the market three years ago, can dramatically help many adults with heart failure. Their hearts are weakened by age, a survived heart attack or some other disease, and get flabbier as they struggle to pump blood through the body.
Pacemakers are best known for speeding up a sluggish heartbeat. The resynchronizers are souped-up pacemakers that work differently — because in heart failure, the struggling heart beats too fast. Instead, three wires that deliver electricity are threaded deep into various parts of the heart to make the pumping chambers, called ventricles, move together in rhythm, thus increasing their power.
Children’s heart failure has very different causes. Some are born with an enlarged heart or suffer a heart-damaging viral infection. Others are born with structurally abnormal hearts, and surgeries to correct those birth defects can hurt the heart’s electrical system in ways that, years later, show up as weakened pumping action.
Implanting the pacemaker can be very different, too. Very young children’s blood vessels are too small to thread the wires through, requiring open surgery to put the pacemaker “leads” on the outside of the heart instead of the inside. Some hearts are so small they can handle only one wire.
'We have to bend the rules a little bit'
“We have to bend the rules a little bit and come up with new ways to use this very powerful technique,” says Dr. Anne M. Dubin, a pediatric electrophysiologist at Stanford University Medical Center.
Dubin tracked about 60 cases of cardiac resynchronization performed in U.S. children at 16 hospitals, the first attempt to count. Rhee’s hospital has performed 12 more.
On average, resynchronization substantially improved the heart’s pumping ability, called the ejection fraction, Dubin reported at a major heart meeting in May. Rhee reports a doubling of that crucial measure.
But about 15 percent of the child patients suffer complications at the time of the pacemaker implant, Dubin found, ranging from wires slipping out of place to infection, a stroke and a death.
“We really don’t know who to do this in yet,” she cautions. Still, “it’s very exciting because there are so many possibilities.”
Patients like Damaris Ochoa are fueling supporters’ drive to improve study of the experimental option.
Her sponge-like newborn heart never properly hardened into smooth muscle, and by age 4 months Damaris had only 10 percent heart function. On a ventilator awaiting a transplant, Rhee says the baby likely had weeks to live, and infant donor hearts are rare.
Transplant candidates require a laboratory heart test that lets Rhee take the extra step of mapping spots where electrical conduction seems abnormal. The test itself can be somewhat risky — a catheter poked a hole in Damaris’ soft heart and she had to be resuscitated.
But Rhee found what he thought was the right spot, and implanted a resynchronizer lead through a small cut under her left arm. Another cut near the navel holds the device’s battery.
Damaris was home in Kansas City a week later, and now at age 10 months has doubled her weight to 18 pounds and crawls around the house chasing her four siblings. “It’s like nothing was ever wrong,” says her father, Oscar Ochoa.
“To reverse somebody who is that far gone is pretty much unheard of,” says Rhee. “It’s pretty gratifying.”