Researchers have found that one third of children with high blood pressure also have an enlarged heart. While the seriousness of this in children is not known, heart enlargement ultimately leads to heart failure in adults.

In a recent issue of the journal Circulation, scientists from Children's Hospital Medical Center in Cincinnati used ultrasound images to study the hearts of 104 children and adolescents, ages 6 to 23, with high blood pressure. They found that in one third, the muscular wall of the heart's main pumping chamber had thickened significantly. While the thickened muscle allows the heart to pump more forcefully, cells deep in the middle of the working muscle may not receive enough blood flow. This could result in a chronic lack of oxygen that one day may cause a heart attack.

But two thirds of children with elevated blood pressure do not develop enlarged hearts, according to Stephen R. Daniels, leader of the study that intends to follow the hypertensive children into adulthood. "We know very little about the early effects of high blood pressure," Daniels said. The children with heart enlargement also tended to be obese and to be especially sensitive to salt, according to Daniels.

The study raises concern because children with high blood pressure tend to carry the problem into adulthood. Some 2.7 million children, ages 6 to 17, have high blood pressure, according to the American Heart Association, as do an estimated 61 million adults. High blood pressure significantly increases an adult's risk of dying from a heart attack or a stroke.

All of the children in the study were being treated for their high blood pressure, primarily with weight loss regimens and by restricting salt consumption, he said. Some of the children also received medication to reduce their blood pressure. Daniels said he believes that lowering a child's excessive blood pressure may help prevent the heart enlargement.