Trial of “Cutting
Balloon” for pulmonary artery stenosis
FDA approves device for children
In February, the Food and Drug Administration gave Children's
Hospital Boston the green light to lead the world's first
randomized, multicenter trial of the “Cutting Balloon”
to treat branch pulmonary artery stenosis in children. The device
has three to four tiny knife blades that create small cuts, spaced
evenly around the inside of the vessel wall. These cuts become
controlled tears that allow a second, low-pressure balloon to
stretch and dilate the vessel.
Pulmonary artery stenosis affects up to 1 in 1,000 newborns,
many of whom also have tetralogy of Fallot. Some children may
have only one or two stenoses, or blockages, while others may
have dozens, sometimes deep inside their lungs. If the obstruction
isn't relieved, the blood doesn't receive enough oxygen,
and high pressures are placed on the heart's right ventricle,
potentially leading to heart failure and death. When the blockages
occur in the major pulmonary arteries, they can be fixed surgically,
but surgery cannot repair the smaller arteries that branch off
inside the lungs without causing extensive lung damage. In such
cases, the current standard of care is balloon angioplasty. However
the blockage persists about 40 to 60 percent of the time, and
the child's only option becomes a lung or a heart-lung transplant.
The Children's-led study will enroll 50 children who have
persistent vessel obstructions after conventional angioplasty.
These patients will be randomized to undergo either “Cutting
Balloon” angioplasty or conventional balloon angioplasty
at high pressures. An ultrasound device will be inserted in the
artery to visualize the degree of artery dilation, and both groups
of patients will be closely monitored for complications, such
as severe vessel tearing and the formation of aneurysm.
Children's has used the smaller diameter “Cutting
Balloons” experimentally for several years. In January 2003,
Lisa Bergersen, MD, a Children's cardiologist
who is conducting this study, and her colleagues reported results
in 12 patients with a total of 38 treated vessels. None of the
patients had been helped by conventional balloon angioplasty,
even at high balloon pressures, but 35 of the 38 vessels were
successfully dilated with the “Cutting Balloon.” Despite
concern that the tiny cuts made by the balloon would cause excessive
scarring, leading to recurrent stenosis, six-month follow-up data
showed restenosis rates similar to balloon angioplasty.
The “Cutting Balloon's” primary use is in adult
coronary arteries, but Children's investigators persuaded
the FDA to allow them to test it in pediatric patients who aren't
helped by conventional balloon angioplasty. Kathy
Jenkins, MD, MPH, the study's principal investigator,
says that this typifies Children's commitment to seeking
interventions for rare pediatric heart conditions with few or
no treatment options. “We're aggressively using technology,
so that no kids are left out,” Jenkins says.
Device companies tend to shy away from testing in children because
of legal concerns and the rarity of many congenital conditions.
Jenkins' team is trying to break through these barriers.
“You need to find right-minded people to help you bring
this research to the pediatric level,” Jenkins says. “What
we're good at doing is finding the good Samaritans.”
Interventional Technologies, Inc., a division of Boston Scientific,
Inc., is funding the study as well as providing all the devices
free of charge.
The six other centers in the study are the University of California
at San Francisco, Children's Hospital of Philadelphia, Stanford
University Medical Center, The Cleveland Clinic, Miami Children's
Hospital, and Duke Medical Center.