Treating heart defects

Heart defects are among the most common birth defects, affecting about 1 in 100 babies in the United States. Advances in diagnosis and surgical treatment have led to dramatic increases in survival for children with serious heart defects. March of Dimes grantees have contributed to these advances. For example, in the 1970s, grantees Abraham M. Rudolph, MD, and Michael A. Heyman, MD, at the University of California at San Francisco, discovered a drug treatment for patent ductus arteriosus, a heart defect that is common in premature infants. The ductus arteriosus is a large artery that lets the blood bypass the baby's lungs before birth because the fetus gets oxygen through the placenta. If the ductus does not close properly soon after birth, the baby may develop heart failure. Treatment with indomethacin often closes the ductus, sparing many babies from the risks of surgery.

But babies with certain other life-threatening heart defects may require the opposite treatment. Drs. Rudolph and Heyman also discovered that the same drug can keep the ductus open, helping to restore some blood flow through the heart until the newborn is strong enough to survive lifesaving heart surgery. In the 1980s, a grantee at Yale University in New Haven, Connecticut, Charles Kleinman, MD, helped pioneer the use of echocardiography, a specialized form of ultrasound, to diagnose heart defects before birth. This test shows details of the heart's structure, blood flow and even the motions of its tiny valves. If the baby has a heart defect, doctors can plan for any special treatment the baby may need soon after delivery. The test also can show if the baby has an arrhythmia (a heart that beats too fast, too slowly or erratically), which can sometimes lead to heart failure and death. Drug treatment before birth often can correct the arrhythmia and save the baby.

In spite of many advances in treatment, heart defects remain the leading cause of birth defect-related infant deaths. Today's March of Dimes grantees are pursuing a variety of approaches aimed at preventing heart defects and improving their treatment. Many grantees are seeking to identify genes that contribute to heart defects, as a basis for developing novel treatments. For example, Caroline Erter Burns, PhD, of Massachusetts General Hospital in Charlestown, Massachusetts, aims to identify genes that regulate the development of certain immature cells destined to form the right side of the heart. Abnormalities in these cells can result in serious heart defects, such as tetralogy of Fallot, that require surgical correction soon after birth.

Others are studying a specific heart defect, in order to develop new treatments. Seok-Yong Lee, PhD, of Duke University School of Medicine in Durham, North Carolina, is investigating a life-threatening heart rhythm disturbance called congenital long QT syndrome, which may cause some cases of sudden infant death syndrome (SIDS). Dr. Lee is studying the structure of proteins that make up channels (openings) that allow potassium to pass in and out of heart muscle cells, helping maintain normal heart rhythm. Abnormal versions of these proteins may result in faulty channels and congenital long QT syndrome. Understanding the underlying protein abnormality may lead to drug treatments to help prevent sudden deaths in infants and people of all ages