MONDAY, Oct. 25, 2004 (HealthDayNews) -- A measure of blood vessel capacity called endothelial function could be an early predictor of heart problems, a Finnish study finds.
Endothelial function is the ability of the inner layer of blood vessels to widen when more blood flow is needed. Using ultrasound to assess blood vessels in a group of relatively young people, researchers at the University of Turku found that children who had risk factors for heart disease such as obesity and high cholesterol have impaired endothelial function in their 20s and 30s.
The finding appears in the Oct. 26 issue of Circulation.
The research promises to be one of the longest-running studies in medical history, said study author Dr. Olli T. Raitakari, an assistant professor of clinical physiology at the university.
The first measurements of the 2,109 people in the study were made in 1980, when they were children and adolescents, and the plan is to continue for "at least another 30 years" to see the effect of childhood risk factors on illness and death from heart attack, stroke and other cardiovascular conditions later in life, he said.
So far, no such problems have been detected in the participants. But the subtle signs of trouble ahead in terms of flawed blood vessels can be seen in those people who scored high on risk factors earlier in life and have impaired endothelial function, Raitakari said.
The Finnish researchers are using ultrasound to assess endothelial function and the thickness of walls of the carotid arteries, the two main vessels carrying blood to the brain. If artery walls become thicker, the result is atherosclerosis, a hardening of the arteries that is a hallmark of cardiovascular trouble.
"We believe that atherosclerosis is a diffuse disease that affects arteries universally," Raitakari said. "Therefore, by measuring arterial wall thickness in carotid arteries it is possible to get a general idea of the atherosclerotic involvement in the whole arterial tree."
The measurements showed a direct relationship between risk factors in the early years of life and artery wall thickening decades later for people with diminished endothelial function, but not for those with normal endothelial function, the study found. The greater the number of risk factors detected in childhood, the greater the thickening of the artery walls for people with reduced endothelial function.
The finding is far from conclusive, but it indicates that "in adolescence, risk factors start to have a meaning," Raitakari said. "Our goal is to get enough information to start looking at their effect on cardiovascular morbidity [illness] and mortality in 20 or 30 years."
Dr. Alan T. Hirsch is an associate professor of epidemiology at the University of Minnesota School of Public Health and a spokesman for the American Heart Association. He said the Finnish trial is "an imperfect study, but the best that anyone has done."
It is imperfect because the researchers did not follow the participants individually, linking early risk factors to later problems person by person, Hirsch said. Instead, they lumped together readings on the group as a whole.
"The study implies that risk factors present in youth lead to changes in blood vessels, but it does not prove it," he said.
Nevertheless, Hirsch said, the report "strengthens the case that classic risk factors cause harm by doing direct damage to the endothelium. It reinforces what we already know very well, that exposure to risk factors is damaging and that we should do everything we can to prevent such exposure."
Raitakari agreed more work is needed to determine whether poor endothelial function is an independent risk factor for cardiovascular disease.
The Federation of American Societies for Experimental Biology offers a detailed discussion on the role of the endothelium in blood vessels.