New procedure offers hope in preventing severe heart defect

Feb 25 (HeartCenterOnline) - For the first time, a team of doctors has prevented the development of a serious heart defect by widening a young patient's heart valve before birth. According to an article in today's Boston Globe, Dr. Wayne Tworetzky at Children's Hospital in Boston had discussed "the science fiction procedure" with the baby's parents shortly after prenatal testing revealed that the young patient's aortic valve was dangerously narrowed. The doctor told the parents that if the fetus continued to develop under those conditions, the baby would probably be born with a left ventricle that was underdeveloped and malformed, such that he would essentially be born with only one pumping chamber in the heart. This very serious heart defect is called hypoplastic left heart syndrome (HLHS). By widening the aortic valve when the fetus was young enough for a needle to pierce the ventricle fairly easily, the doctors successfully prevented the child from being born with HLHS.

HLHS is a very serious congenital heart defect in which the chambers, valves and related blood vessels on the left side of the heart are so malformed that they cannot efficiently pump blood to the rest of the body. Before birth, the right ventricle helps the left ventricle to circulate blood throughout the body. Soon after a baby takes his or her first breath, however, certain prenatal heart structures begin to close (a normal process). Following this transition, the left ventricle becomes solely responsible for pumping oxygen-rich blood to the rest of the body, and the right ventricle takes on its new lifelong responsibility of pumping oxygen-poor blood to the lungs. Because the left ventricle cannot accomplish its normal function, the signs of HLHS begin to rapidly appear (e.g., a blue tint to the skin, lips and fingernails). Without a series of open-heart surgeries, the baby will not be able to survive.

HLHS affects about 1,500 to 2,000 babies per year in the United States, accounting for about 1 to 2 percent of all congenital heart defects in American infants. It is responsible for 25 percent of all infant deaths within the first week of life.

As prevention strategies are researched, treatment efforts also continue to evolve. In the past, treatment could not sustain life for more than six weeks. Now, some HLHS babies are able to live into childhood and beyond, and a November 2000 Circulation study found that the survival rates for HLHS patients undergoing multi-stage open-heart surgeries are steadily increasing. Researchers examined records of more than 840 HLHS patients who had been treated with multi-stage surgeries (e.g., the Norwood procedure) over a period of 15 years at a single children's hospital, beginning in 1984. Rates for infants surviving the first stage of surgeries increased from 56 percent (1984-1989) to 71 percent (1995-1998). Unpublished rates for the facility for January 1999 to April 2000 were even better, with a survival rate of 86 percent. Three-year survival rates also improved from 28 percent (1984-1989) to 66 percent (1995-1998). Improved surgical techniques as well as the experience of performing many similar surgeries were credited as factors affecting survival rates.

For additional information about HLHS, click on the following: Hypoplastic Left Heart Syndrome.

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