Children’s fetal cardiac center
Fetal intervention established as viable treatment for defects
Children’s cardiologists and fetal care specialists performed the first fetal cardiac intervention for a hypoplastic left heart patient with an intact atrial septum. Doctors created an atrial septal defect (fig. 1) to open bloodflow within the heart (fig. 2), improving the infant’s outlook.
Children’s Hospital Boston has been a leader in pediatric cardiac care since 1938, when Robert Gross, MD, performed the world’s first successful surgical repair of a congenital cardiovascular defect, a patent ductus arteriosus. Today, that tradition is upheld by Children’s cardiologists, led by Cardiologist-in-Chief Jim Lock, MD, and clinicians from the Advanced Fetal Care Center (AFCC), led by pediatric and fetal surgeon Rusty Jennings, MD. Over the last 18 months, these teams have established fetal cardiac intervention as a viable treatment for fetuses with life-threatening cardiac defects.
In Sept. 2001, Children’s interventional cardiologists, echocardiographers and fetal surgeons teamed with high-risk obstetricians and fetal ultrasonographers from Boston’s Brigham and Women’s Hospital (BWH) to perform the world’s first successful intervention in a fetus with critical aortic stenosis and early signs of left ventricular hypoplasia.
Based on experience with other fetuses, all indications were that the baby, now named Jack, would go on to develop full blown hypoplastic left heart syndrome (HLHS). At 23 weeks, Jack’s mother underwent a percutaneous procedure in which Jack’s severely narrowed aortic valve was opened with a balloon catheter.
The needle that delivered the catheter was introduced through the mother’s abdomen and into her uterus, and was then slipped between Jack’s ribs and into his heart. The 3-mm balloon was inflated, increasing blood flow through the valve and enabling the ventricle to develop and grow. Ten weeks later when Jack was born, he required no additional cardiac intervention, although according to echocardiographer Wayne Tworetzky, MD, who follows Jack in the cardiology clinic, Jack may require another aortic valve dilation when he gets older.
Since March 2000, Children’s has performed 12 fetal cardiac catheterizations to address a number of serious congenital heart defects, including aortic valve stenosis and atresia, pulmonary valve atresia with hypoplastic right heart syndrome, and HLHS with an intact atrial septum. These advances complement Children’s rapidly growing Advanced Fetal Care Center, one of only four comprehensive fetal care centers in the United States and the only one in New England.
The AFCC brings together specialists in fetal surgery, fetal imaging and diagnosis, neonatal care, genetics, anesthesiology, cardiology and cardiovascular surgery, otolaryngology, urology, and neurology to provide services ranging from state-of-the-art fetal diagnosis to fetal catheter interventions to fetal surgery and exit-to-ECMO procedures.
In the fetal cardiac procedures performed to date, Children’s has partnered with neighboring BWH, where a high-risk obstetrical team headed by Louise Wilkins-Haug, MD, director of Maternal and Fetal Medicine, manages the mother’s care. During the fetal procedures Dr. Wilkins-Haug’s role as the obstetrician includes rotating the fetus into position—either by massaging the mother’s abdomen or massaging the uterus directly—so that Children’s cardiologists can access the tiny target in the fetus’s heart. Under the guidance of Carol Benson, MD, a specialist in obstetrical ultrasound, Dr. Wilkins-Huag then places the needle through the uterus and into the fetus’s chest and heart, where Children’s cardiologists take over.
In Sept. 2002, Dr. Lock and the team performed a fetal cardiac catheterization to create an atrial septal defect (ASD) in a 31-week fetus with HLHS (figures 1 and 2). While HLHS diagnosis carries a mortality risk below 15 percent at Children’s, babies born with HLHS and an intact septum—where there is no route for pulmonary venous return to leave the left atrium—are at the highest risk, with a survival rate around 40 percent. At 31 weeks, the development of the baby’s heart was too adced for cardiologists to improve left ventricular size, but Lock and Mary van der Velde, MD, director of the Fetal Echocardiography Program, believed an ASD would improve the baby’s lung development during his remaining weeks in utero, making him less cyanotic at birth and improving his long term outcome.
The baby, now named Jacob, was stable when he was born at 39 weeks and underwent a Norwood procedure at 2 days of age. His surgery and recovery were uneventful, and his family returned to their home outside Philadelphia just days later with their healthy baby.
Screening Babies for Broken Hearts
When his own children were born, pediatric cardiologist Darshak Sanghavi asked for a simple screening test for heart defects. But the test isn’t widely used.
By Darshak Sanghavi, M.D.
In the middle of one night in August, a seemingly healthy 1-week-old infant named Ryan Olson suddenly began gasping for breath at home in Massachusetts, and his frantic parents rushed him to the hospital. There, emergency room doctors noted the critically ill baby had bluish feet and — even more worrisome — no pulse in his lower body. That almost certainly meant the boy had a “coarctation,” or blockage of his aorta, which is the key pipeline supplying oxygen-rich blood to the body. As the on-call pediatric cardiologist, I was urgently called in to help out.
Ryan’s story isn’t that unusual, and I’ve seen half a dozen similar children recently. A few months ago, the Centers for Disease Control and Prevention reported that the infant mortality rate in the United States was 6.71 per 1,000 live births, which was widely reported as being higher than other developed countries. Birth defects, especially involving the heart, are an important cause of these deaths. In October, researchers studying infant deaths over the past 16 years in California reported that hundreds of American infants like my patient probably die each year due to missed — but treatable — congenital heart defects.
How can we identify these normal-appearing newborns before they leave the hospital, become critically ill like my patient and perhaps die?
Traditionally, prospective mothers have prenatal sonograms to look for birth defects. But the quality of these scans varies widely, depending on the skill of the technician and the supervising doctor. In addition, current guidelines supported by the American College of Obstetricians and Gynecologists mandate only a limited “four-chamber view” of the heart. As a result, a 1998 study from Southwestern Medical School in Texas reported that only one-quarter of major heart defects are identified prenatally.
Unfortunately, when heart defects are missed by prenatal ultrasounds, pediatricians also have a hard time telling if critical cardiac problems are present. Normally, doctors examining newborns suspect heart defects if they hear a loud rushing noise (a “murmur”) with a stethoscope, notice the child has a bluish color, or lacks a pulse in the lower extremities. But in 1999, British researchers found that half of serious heart defects were missed by routine exams after birth. If sent home, these newborns become seriously ill.
Folic acid can prevent up to 50 percent of many heart defects, but only if taken for about two months prior to conception. Because most pregnancies are unplanned, the C.D.C. recommends that all menstruating women should take a daily multivitamin.
What’s needed is a large-scale formal screening program, similar to mammography or colonoscopy to identify at-risk individuals. We already do this to identify newborns with certain hidden but deadly conditions. For example, most state health departments currently analyze a few blood drops taken from a baby’s foot and check for certain genetic problems like phenylketonuria (PKU) and galactosemia, which are treated with special diets to prevent developmental problems.
Recently, researchers have identified a promising new method called pulse oximetry to screen all babies for heart defects. Taped briefly to a newborn’s foot, a small sensor painlessly beams red light through the foot and measures how much oxygen is in the blood. It takes about a minute. (Picture E.T. the extra-terrestrial’s finger lighting up, and you get the idea.) If the screening test is abnormal, doctors perform a confirmatory ultrasound of the heart. Last year, Norwegian doctors published one of the largest clinical trials of this strategy, and checked half of all babies born in the country.
The results were impressive. Within a few hours of birth, pulse oximetry detected three-quarters of critical heart defects that had been previously missed. For every 2,000 newborns screened with the toe light, roughly one with a critical heart defect might have been prevented from going home. The cost-benefit ratio compares favorably to current practices of newborn screening for PKU and hypothyroidism. In January, Swedish doctors published an even more methodical study of almost 40,000 newborns, and showed that oximetry entirely eliminated death from missed critical cardiac defects.
Of course, as with any screening, the technique may miss some defects and also involves some unnecessary, though benign, testing of normal children. But these false positive rates were low (only about one in 1,000 in the Swedish study) and triggered only about two instances of extra, noninvasive testing for every serious heart defect that was picked up. Many parents and doctors caring for children with critical heart defects subscribe to some variant of the “1 percent doctrine.” If there is even a small chance of catastrophe — like the sudden death of a newborn — they feel justified to push for preemptive action, especially when it’s a harmless and inexpensive screening test.
While the screening test is not done routinely in the United States, some hospitals have adopted it, mostly in Texas and Florida, where some small trials have been conducted. But parents can ask doctors to screen their babies for heart defects using pulse oximetry. It’s essentially free since it needs no specialized equipment other than the oximeter, which is present in every hospital already. A specialized doctor isn’t needed; the test is quite simple, and a nurse can do it if the pediatrician orders it anytime after birth, but before discharge from the hospital. Hopefully they won’t mind doing it. Personally, I do think parents should request it. I did for my kids.
Fortunately, Ryan, the baby I was urgently called to treat, had his heart surgery last summer and is doing well now. I see him every few months in clinic.
Dr. Darshak Sanghavi is the chief of pediatric cardiology and assistant professor of pediatrics at the University of Massachusetts Medical School. He is the author of “A Map of the Child: A Pediatrician’s Tour of the Body,” and his Web site is www.darshaksanghavi.com.
(Article appeared in the New York Times Tuesday April 14, 2009)
One of the newest areas of Pediatric Cardiology is Fetal Cardiology. The newest Echocardiographic equipment allows imaging of the fetal heart by 18 to 20 weeks gestational age. We are now able to accurately diagnose most complex congenital heart problems with this technology. This has allowed Pediatric Cardiologists and Maternal-Fetal Medicine specialists to relieve the family’s anxiety if the baby’s heart appears normal, or to counsel families with a baby with a heart problem as to what to expect when the new baby arrives. We are also able to plan for delivery of an infant with a congenital heart problem, at a center that is equipped to deal with the new baby’s problem in a timely and appropriate fashion. There are also some centers in the US which are beginning to experiment with prenatal treatment of some of these problems, such as dilating valves which are too tight, using special balloons. Although the success rates are mixed, this is a very exciting development.
The incidence of congenital heart problems in the general population is about 6 to 8/1000 live births. In families where one parent has a congenital heart problem, the recurrence rate is about 3 to 5%. As patients with congenital heart problems grow to child bearing age, the importance of this testing will increase. It is a test that all patients with congenital heart disease will undoubtedly wish to have done.
Dr. Marc Levine