Cardiology and Heart Surgery Research

Managing transposition of the great arteries in the womb

November 15, 2016

Monitoring and managing fetuses’ heart health in the womb can greatly improve their chances of living long and productive lives

Over the 22 years that Mary T. Donofrio, M.D., has been practicing fetal cardiology, the field has changed radically. The goal once had been simply to offer parents an accurate diagnosis and prepare them for sometimes devastating outcomes. Now, Dr. Donofrio, who directs the Fetal Heart Program and Critical Care Delivery Program at Children’s National Health System, says specialists can follow fetuses throughout the pregnancy and manage many conditions in the womb, greatly improving their chances of living long and productive lives.

Case in point: Transposition of the great arteries, a congenital defect characterized by reversal of the heart’s two main arteries—the aorta, which distributes oxygenated blood throughout the body, and the pulmonary artery, which carries deoxygenated blood from the heart to the lungs. The single abnormality means that the oxygenated “red” blood flows back to the lungs while deoxygenated “blue” blood flows out to the body.

After birth, when the cord is clamped and the connection to the placenta severed, the baby’s cardiovascular system must adjust. If the fetal connections between the two sides of the heart no longer remain, the brain and other organs in infants with this defect are severely deprived of oxygen. The condition may be fatal if something is not done immediately to reopen the fetal connections to stabilize the circulation before surgery can be done. But if the fetal cardiologist can keep tabs on what’s happening to the heart over time and prepare a specialty team of cardiologists to treat the problem immediately after birth, chances of survival are significantly improved.

More than a decade ago, as a young attending physician, Dr. Donofrio witnessed a case that has stuck with her to this day. The baby’s diagnosis of transposition of the great arteries was not made until shortly before birth. In addition, the two fetal blood flow connections that allow blood to circulate had closed, causing severe heart failure. Although the care team performed an emergency delivery and immediate cardiac procedure, including initiation of a heart-lung machine in the delivery room to try to stabilize the circulation, the baby ultimately died due to complications from a very low oxygen level. “I always wonder what happened,” Dr. Donofrio says. “Was the baby’s heart always that bad and nobody noticed it, or did it change over time?”

In a paper published recently in the Journal of Neonatal-Perinatal Medicine, she and colleagues illustrate the dramatic transformation in care that has taken place in the 14 years since this unforgettable case. The new publication describes the case of a different fetus diagnosed at 22 weeks gestation with transposition of the great arteries in 2015 at Children’s National. Unlike many congenital heart disorders, the heart’s four chambers appear misleadingly normal at the typical mid-pregnancy ultrasound. Despite the challenging diagnosis for many obstetricians, this fetus’ heart condition was recognized early by looking at the arteries leaving the heart in addition to the chambers.

While such a defect is fatal if left untreated, Dr. Donofrio explains there are two pathways that can allow the blood to get to where it needs to go such that the circulation is stabilized and the damage mitigated. One is the fetal blood vessel known as the ductus arteriosus that typically stays open for a day or two after birth. The second is an opening between the heart’s two upper chambers, known as the foramen ovale, which usually closes upon delivery. By keeping those two pathways open, blood can cross from one side of the heart to the other, buying time in the delivery room so that babies can be stabilized before they receive surgery to permanently move the arteries back to their normal position.

In the 2015 case, Dr. Donofrio and colleagues had the chance to monitor the fetus and the fetal heart at follow-up appointments every four weeks after diagnosis. What they saw completely changed the course of their treatment plan and likely saved the baby’s life. With each ultrasound, they saw that the ductus arteriosus and the foramen ovale—the critical connections needed for survival—were gradually closing.

Dr. Donofrio noted at the fetal evaluation at 38 weeks that the structures had closed, and the heart was showing signs that it was not functioning well. She and her team realized that the only way to save this baby was to deliver earlier than planned and to have cardiac specialists standing by ready to perform a life-saving procedure to open the connections right after the baby was separated from the placenta. The baby was delivered by Cesarean section in the cardiac operating room at Children’s. The cardiac intervention team immediately created a hole where the foramen ovale should have been by using a balloon to open the tissue that had closed. The care team also administered a prostaglandin infusion, a drug that can keep the ductus arteriosis open. This time, however, the medicine did not work. The baby was stabilized with several cardiac medications and, with little time to spare, the cardiac surgeons operated on the one-day-old baby to switch his great arteries back to the normal position, saving his life.

The baby is now 1-year-old, Dr. Donofrio says, and is healthy—a scenario that likely wouldn’t have happened had the fetal team not made the diagnosis and continually monitored the condition in the womb.

“I remember back to that first case when we were really scrambling to do everything we could at the last minute because we didn’t have the information we needed until the very end,” Dr. Donofrio says. “Now, we can spot problems early and do something about it. For me, that’s amazing. We’re making a difference, and that’s a really great thing.”

Newborn pulse oximetry screening: which algorithm is best?

October 14, 2016

Gerard Martin

There’s a consensus that Pulse oximetry screening (POS) is a proven way to find critical congenital heart defects. But, screenings, specifically the algorithm used, vary. Gerard R. Martin, M.D., Medical Director of Global Health at Children’s National Health System, and Andrew K. Ewer, MD, explore which algorithm is best in their just-published article in Pediatrics. Read more.

Getting to the heart of cardiac malposition with fetal MRI

October 7, 2016

Mary T. Donofrio, M.D., Director of the Fetal Heart Program and Critical Care Delivery Program at Children’s National Health System

In a small percentage of pregnancies, the fetuses’ hearts develop in the wrong place. In the congenital anomaly known as heterotaxy syndrome that often includes a severe heart defect, the heart is often displaced from its usual position in the left chest. In other instances, the heart starts out in a normal position; however, it is pushed out of its normal position by a mass that grows in the chest cavity, by abnormal development of the lungs, or due to other causes. Although rare, babies born with cardiac malpositions associated with other congenital defects can be the most serious of all possible birth defects.

Sometimes, fetuses with these congenital problems die in the womb. Others do not survive long after birth. In some pregnancies, surgery is performed shortly after childbirth to stabilize the circulation so newborns even have a chance at life.

Correctly diagnosing these cardiac conditions during pregnancy can help doctors and parents alike make the most informed decisions and plan ahead.

However, the tools now used most often to reveal the overall anatomic details of cardiac malpositions — obstetrical ultrasound and fetal echocardiography — often don’t give a full picture. A clear view of the fetus can be obscured by the position of the fetus, insufficient amniotic fluid, or even a mother’s body habitus. Imaging techniques sometimes also have a hard time distinguishing between liver, bowel, and lung because the echogenicity of these tissues — the signature that sound waves make as they bounce back from their targets — is so similar.

“To be able to offer parents the best and most comprehensive counseling, and to begin planning for the type of intensive and multidisciplinary care that many of these babies will require, we need to have access to as much information as we can about each baby, not only relating to the heart but all the other organs as well,” says Mary T. Donofrio, M.D., a pediatric cardiologist who directs the Children’s National Health System Fetal Heart Program and Critical Care Delivery Program. “Unfortunately in some instances, obstetrical ultrasound and fetal echocardiography, the two diagnostic tools used most often in these cases, can be limited in what they tell us.”

What fetal MRI can show

An underutilized technique that gathers more details about the associated abnormalities that often accompany cardiac malposition during pregnancy is fetal magnetic resonance imaging, or fetal MRI, says Dr. Donofrio. Even though this technique is widely used to diagnose other fetal conditions, such as brain anomalies, it’s rarely used to better define the overall anatomy in cardiac malposition.

To determine whether fetal MRI is effective in complementing obstetrical ultrasound and fetal echocardiography, the current standard of care for this condition, Dr. Donofrio and colleagues took a retrospective look at all cases of cardiac malposition in which fetuses were evaluated using MRI between 2008 to 2013 at Children’s National. Their search turned up 42 cases.

Twenty-three cases had been diagnosed with obstetrical ultrasound and fetal echocardiography as having additional abnormalities beyond the heart’s changed position, and 19 had been given the diagnosis of heterotaxy syndrome. Each patient had been assigned to various known subtypes of these conditions, with some classified as having an unknown etiology for the findings.

After fetal MRI, the diagnoses of nearly one-third changed or were better delineated. Seven of the 23 cases of cardiac malposition attributed to an extra cardiac anomaly were reassigned to a cause different from the original diagnosis based on the new, more detailed information provided by fetal MRI, including three in which a complete diagnosis could not be made due to poor visualization by ultrasound. Five of the 19 cases attributed of heterotaxy were reassigned to different subgroups within this disorder or were given a different diagnosis completely after fetal MRI.

In eight of these 12 diagnoses that changed after fetal MRI, doctors were able to confirm these findings postnatally. Other cases were either lost to follow-up, pregnancy termination, or fetal demise.

The research team led by Dr. Donofrio published these results in the August 2016 issue of Prenatal Diagnosis.

Overall, she says the findings demonstrated the benefits of using fetal MRI as an adjunct to obstetrical ultrasound and fetal echocardiography. MRI offers advantages over ultrasound, she explains, including better spatial resolution, a wider field of view, and a way to see through or around maternal body fat, overlying fetal bone, or a fetus whose position is not optimal.

“Determining the etiology of cardiac malposition remains a challenging diagnosis, and the value of accurate prenatal diagnosis has been long recognized,” Donofrio and colleagues write in the study. “Ultimately, fetal MRI can assist with identifying the etiology of cardiac malposition for informative prenatal counseling and multidisciplinary planning.”

Interventional cardiac magnetic resonance team welcomes new specialist

October 5, 2016

elena-grant-photo

The Interventional Cardiac Magnetic Resonance (ICMR) Program at Children’s National is actively developing newer and safer ways to perform cardiac procedures on young patients, with some of the world’s leading experts in cardiac catheterization and imaging. Elena Grant, M.D., a former pediatric cardiology fellow at Children’s National, is the newest member to join the team that pioneered real-time MRI-guided radiation-free cardiac catheterization for children.

In addition to clinical work as a Children’s National Interventional Cardiologist, Dr. Grant will perform preclinical research at the National Institutes of Health to develop new procedures, techniques, and devices that can be translated to clinical practice to treat children and adults with congenital heart disease.

Dr. Grant specializes in interventional cardiology. She received her medical degree from the University of Dundee Medical School in Dundee, Scotland, followed by Foundation Training in Edinburgh, Scotland. She completed her pediatric residency at Massachusetts General Hospital, her Pediatric Cardiology fellowship at Children’s National, and she recently finished an advanced fellowship in interventional pediatric cardiology at Children’s Healthcare of Atlanta and Emory University.

Advances in interventional cardiovascular MRI

Children’s National is at the forefront of this exciting new field and is currently the only institution in the United States to perform radiation-free MRI-guided cardiac catheterization procedures in children.

ICMR is a partnership with the National Institutes of Health that brings together researchers, clinicians, engineers, and physicists to provide radiation-free, less invasive, and more precise diagnostics and treatment options for pediatric patients and adults with congenital heart disease.

The ICMR approach to heart catheterization uses real-time MRI, instead of X-ray, in pediatric research subjects undergoing medically necessary heart catheterization. This research study is intended as a step toward routine MRI-guided catheterization in children, which attempts to avoid the hazards of ionizing radiation (X-ray).

In 2015, after working with NIH to explore how interventional cardiovascular MRI could be integrated into pediatric practices, the ICMR team, including Dr. Grant, Russell Cross, M.D., Joshua Kanter, M.D., and Laura Olivieri, M.D., performed the first radiation-free MRI-guided right heart catheterization on a 14-year-old girl at Children’s National. Since then, nearly 50 such procedures have been successfully completed, and the team is working to broaden the age range and cardiac disease complexity of patients who can undergo the procedure.

About 1 percent of newborns are born with a heart condition, and the team at Children’s performs more than 450 X-ray guided cardiac catheterizations and over 500 cardiac MRI scans per year.

Rheumatic heart disease is a family affair

September 14, 2016

Parasternal long axis echocardiographic still frames in early systole in black and white and color Doppler of RHD-positive index case, sibling, and mother.

Siblings of children in Northern Uganda with latent rheumatic heart disease (RHD) are more likely to have the disease and would benefit from targeted echocardiographic screening to detect RHD before it causes permanent damage to their heart valves, according to an unprecedented family screening study.

RHD results from a cascade of health conditions that begin with untreated group A β-hemolytic streptococcal infection. In 3 percent to 6 percent of cases, repeat strep throat can lead to acute rheumatic fever. Almost half of children who experience acute rheumatic fever later develop chronic scarring of the heart valves, RHD. RHD affects around 33 million people and occurs most commonly in low-resource environments, thriving in conditions of poverty, poor sanitation, and limited primary healthcare. Treating streptococcal infections can prevent a large percentage of children from developing RHD, but these infections are difficult to diagnose in low-resource settings.

Right now, kids with RHD often are not identified until they reach adolescence, when the damage to their heart valves is advanced and severe cardiac symptoms or complications develop. In such countries, cardiac specialists are rare, and intervention at an advanced stage is typically too expensive or unavailable. Echocardiographic screening can “see” RHD before symptoms develop and allow for earlier, more affordable, and more practical intervention. A team led by Children’s National Health System clinicians and researchers conducted the first-ever family echocardiographic screening study over three months to help identify optimal strategies to pinpoint the families in Northern Uganda at highest RHD risk.

“Echocardiographic screening has the potential to be a powerful public health strategy to lower the burden of RHD around the world,” says Andrea Beaton, M.D., a cardiologist at Children’s National and the study’s senior author. “Finding the 1 percent of vulnerable children who live in regions where RHD is endemic is a challenge. But detecting these silent illnesses would open the possibility of providing these children monthly penicillin shots – which cost pennies and prevent recurrent streptococcal infections, rheumatic fever, and further valve damage.”

The research team leveraged existing school-based screening data in Northern Uganda’s Gulu District and recruited 60 RHD-positive children and matched them with 67 kids attending the same schools who were similar in age and gender but did not have RHD. After screening more than 1,000 parents, guardians, and first-degree family members, they found that children with RHD were 4.5 times as likely to have a sibling who definitely had RHD.

“Definite RHD was more likely to be found in mothers, with 9.3 percent (10/107 screened) having echocardiographic evidence of definite RHD, compared to fathers 0 percent (0/48 screened, p = 0.03), and siblings 3.3 percent (10/300 screened, p = 0.02),” writes lead author Twalib Aliku, School of Medicine, Gulu University, and colleagues. “There was no increased familial, or sibling risk of RHD in the first-degree relatives of RHD-positive cases (borderline & definite RHD) versus RHD-negative cases. However, RHD-positive cases had a 4.5 times greater chance of having a sibling with definite RHD (p = 0.05) and this risk increased to 5.6 times greater chance if you limited the comparison to RHD-positive cases with definite RHD (n = 30, p = 0.03.”

The paper, “Targeted Echocardiographic Screening for Latent Rheumatic Heart Disease in Northern Uganda,” was published recently by PLoS and is among a dozen papers published this year about the group’s work in Africa, done under the aegis of the Children’s Research Institute global health initiative.

The World Health Organization previously has prioritized screening household contacts when an index case of tuberculosis (TB) is identified, the authors note. Like TB, RHD has a strong environmental component in that family members are exposed to the same poverty, overcrowding, and circulating streptococcal strains. In a country where the median age is 15.5, it is not practical to screen youths without a detailed plan, Dr. Beaton says. Additional work would need to be done to determine which tasks to shift to nurses, who are more plentiful, and how to best leverage portable, hand-held screening machines.

“Optimal implementation strategies, the who, when, in what setting, and how often to screen, have received little study to date, yet these details are critical to developing cost-effective and sustainable screening programs,” Aliku and co-authors write. “Our study suggests that siblings of children identified with latent RHD are a high-risk group, and should be prioritized for screening.”

Related resources: Research at a Glance

Targeted echocardiographic screening for latent RHD in Northern Uganda

June 13, 2016

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What’s Known
Echocardiograms use the echoes of sound waves to create “movies” of the beating heart, its valves, and other structures. While rheumatic heart disease (RHD) was prevalent in the United States as late as the 1900s, improved housing conditions and the availability of powerful medicines like antibiotics and penicillin have lowered its incidence to 0.04 to 0.06 cases per 1,000 U.S. children. In regions where streptococcal infections flourish, RHD remains a scourge. Using echocardiographic screening to identify latent RHD— which is apparent on echocardiography before the child has symptoms that can be spotted by clinicians—has the potential to reduce the disease’s global burden.

What’s New
Optimal implementation must account for whom to target, when, in which settings, and how often to screen. The team led by Children’s National Health System researchers and clinicians conducted the first family screening study in Northern Uganda to assess the utility of echocardiographic screening of first-degree relatives of children with latent RHD. They used existing school-based screening data to identify potential participants and invited all first-degree relatives older than 5 years for echocardiography screening. The study recruited 60 RHD-positive schoolchildren and matched them with 67 RHD-negative kids of similar age and gender. Some 1,122 family members were then screened. Children with any RHD were 4.5 times as likely to have a sibling with definite RHD, a risk that increased to 5.6 times if researchers looked solely at index cases with definite RHD. The team, led by Andrea Beaton, MD, a cardiologist at Children’s National, also found that mothers had a 9.3 percent rate of latent RHD—a high rate that was independent of whether their child was RHD-positive.

Questions for Future Research
Q: Many children living in RHD-endemic areas, exposed to the same environmental conditions as RHD-positive kids, are able to fend off disease. Are protective genes to credit for their resilience?
Q: What are the best approaches to train nurses and community workers in how to use lower-cost, handheld echocardiograms to facilitate large-scale screening in countries where healthcare resources are constrained?

Source: “Targeted Echocardiographic Screening for Latent Rheumatic Heart Disease in Northern Uganda: Evaluating Familial Risk Following Identification of an Index Case.” T. Aliku, C. Sable, A. Scheel, A. Tompsett, P. Lwabi, E. Okello, R. McCarter, M. Summar, and A. Beaton. Published online by PLoS June 13, 2016.

Lessons learned from newborn screening for critical congenital heart defects

May 1, 2016

chd_screening

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What’s Known

In 2011, screening for critical congenital heart defects (CCHD) became the second point-of-care newborn screening test added to the Recommended Uniform Screening Panel, and it has since been widely adopted. Heart defects are the primary targets for CCHD screening, which often require evaluation by echocardiogram. An original list of seven conditions represented the most common critical lesions which routinely present with hypoxemia for newborns. Endorsed by the American Academy of Pediatrics and four other professional medical societies, the CCHD screening using pulse oximetry is required by law in all but two states. Remaining challenges include national data collection and outcomes analyses at the population level.

What’s New

An expert panel including Gerard R. Martin, MD, a cardiologist at the Center for Translational Science at Children’s National Health System, reviewed current practices in newborn screening for CCHD and identified opportunities for improvement. The panel’s study expanded the list of core conditions to 12 to emphasize the importance of other potentially critical, yet treatable secondary conditions. Roughly 79 percent of “positive” screens for CCHD identify secondary conditions, such as sepsis and pulmonary diseases. The study found algorithm misinterpretation was common in states collecting outcomes data, emphasizing needs for proper training and quality-assurance feedback mechanisms. Public health surveillance varied dramatically, with nearly one-fifth of states neither actively collecting data nor planning to do so. Additional CCHD screening research in special settings like the NICU, out-of hospital settings, and areas with high altitude may result in adaptations to screening protocol. Future improvements to the current screening algorithm and analyses of the impact on CCHD outcomes will rely on further investment in a national data repository.

Questions for Future Research

Q: What will be the impact on present screening for CCHD on outcomes of non-CCHD secondary conditions?
Q: What is the optimal algorithm for CCHD based on screening and testing ease of use, costs, resource utilization, and sensitivity for different treatment settings?
Q: What will be the impact on present screening for CCHD on outcomes of non-CCHD secondary conditions?

Source: “Lessons Learned From Newborn Screening for Critical Congenital Heart Defects.” M.E. Oster, S.W. Aucott, J. Glidewell, J. Hackell, L. Kochilas, G.R. Martin, J. Phillippi, N.M.Pinto, A. Saarinen, M. Sontag, and A.R. Kemper. Published by Pediatrics May 2016.

Connection between abnormal placenta and impaired growth of fetuses discovered

March 15, 2016

CLimperopoulous

A team of researchers used 3-D volumetric magnetic resonance imaging (MRI) in an innovative study that reported that when the placenta fails to grow adequately in a fetus with congenital heart disease (CHD), it contributes to impaired fetal growth and premature birth. Fetal CHD involves an abnormality of the heart and is associated with increased risk for neurodevelopmental morbidity.Until now, CHD in the fetus and its relationship to placental function has been unknown. But the advanced fetal imaging study has shown for the first time that abnormal growth in the fetus with CHD relates to impaired placental growth over the third trimester of pregnancy. Catherine Limperopoulos, PhD, Director of Children’s National Developing Brain Research Laboratory in the Division of Diagnostic Imaging and Radiology, is the senior author of the study published in the September 2015 issue of the journal Placenta, “3-D Volumetric MRI Evaluation of the Placenta in Fetuses With Complex Heart Disease.”

Specifically, the decreased 3-D volumetric MRI measurements of pregnant women reported in this study suggest placental insufficiency related to CHD. The placenta nourishes and maintains the fetus, through the delivery of food and oxygen. Its volume and weight can determine fetal growth and birth weight.

Abnormality in placental development may contribute to significant morbidity in this high risk-population. This study shows impaired placental growth in CHD fetuses is associated with the length of the pregnancy and weight at birth. Nearly 1 in every 100 babies is born in the United States with a congenital heart defect.

Developing the capacity to examine the placenta non-invasively using advanced MRI is needed to identify early markers of impaired placental structure and function in the high-risk pregnancy. This is a critical first step towards developing strategies for improved fetal monitoring and management, Dr. Limperopoulos says.

“We are trying to develop the earliest and most reliable indicators of placental health and disease in high-risk pregnancies. Our goal is to bring these early biomarkers into clinical practice and improve our ability to identify placental dysfunction,” Dr. Limperopoulos says. “If we can develop the capacity to reliably identify when things begin to veer off course, we then have a window of opportunity to develop therapies to restore function.”

The study used in-vivo 3-D MRI studies and explored placental development and its relationship to neonatal outcomes by comparing placental volumetric growth in healthy pregnancies and pregnancies complicated by CHD.

While mortality rates continue to decrease steadily in newborns diagnosed with complex CHD, long-term neurodevelopmental impairments are recognized with increasing frequency in surviving infants, Dr. Limperopoulos says.

“Our goal is to better support the developing fetus with CHD. We can best accomplish this if we develop technology that can allow us to safely and effectively monitor the fetal-placental unit as a whole throughout pregnancy,” Dr. Limperopoulos says.

“This is the new frontier, not only to ensure survival but to safeguard the fetus and to ensure the best possible quality of life,” she says.