Foundation for poor heart health laid early in life

Jun 9 2004

Heart disease - long viewed as a scourge of adulthood - is a growing threat to children because of soaring rates of obesity and related problems, such as diabetes. At the very least, studies are showing, the foundation for poor heart health is laid much earlier in life than previously thought, with high blood pressure, high cholesterol and fluctuating blood sugar levels initiating physical changes that can have devastating consequences years later.

University of Florida Health Science Center researchers have added to that expanding body of evidence, with a study that shows children with diabetes are more likely to have stiff blood vessels that fail to function properly. That’s a deadly combination, as prolonged high blood sugar levels mingle with inflammatory factors, family history and other medical concerns to undermine vessel health over a period of years, says pediatrician Dr. Michael Haller, a postdoctoral fellow at UF who will describe the team’s findings Saturday at the annual scientific sessions of the American Diabetes Association in Orlando.

UF scientists used a novel technique designed to measure the pressure waves created in vessels when the heart pumps blood into the arteries. Healthy children’s vessels responded to blood flow by distending, much like a balloon filled with a small amount of water. But those with diabetes had vessels that acted more like rigid garden hoses, Haller said.

“In today’s society, obviously, cardiovascular disease is one of the No. 1 causes of death, and as a pediatrician I’m interested in trying to come up with ways to provide primary prevention for people who are at higher risk of developing cardiovascular disease as they get older,” Haller said. “On the basis of epidemiologic studies we know that diabetes confers a significant increased risk of dying from a cardiovascular event when you compare that to the risk for those people who don’t have diabetes.

“Most physicians treating children with type 1 diabetes tend to underestimate the significant risk for future cardiovascular disease, or at least they think the risk doesn’t start to increase until these children reach their late teen years,” he added. “The problem still remains: Does the metabolic derangement of having diabetes in and of itself affect blood vessels early on in life, causing permanent damage at an early age? Some studies suggest that is the case. Studies looked at autopsies of kids killed in car accidents or from trauma looked at coronary vessels and aortas, and they could see fatty streaks by 3 years of age and plaques in kids as young as 8 years of age.”

That, Haller said, suggests health practitioners need to encourage children - especially those with diabetes - to adopt heart-healthy habits now, including eating a well-balanced diet and getting regular exercise.

“It is well-known that optimal control of blood sugar and blood pressure are vital to reducing risk,” he said. “At the same time, family history and exercise play an important role, and there are potential things we could do to further reduce risk, such as aggressively lowering cholesterol, lowering our accepted ranges for blood sugar control and improving blood pressure control. Using noninvasive techniques to help predict a person’s risk may help guide us in terms of how aggressively we decide to treat at-risk children.”

In the United States, about 1 in every 300 children has type 1 diabetes. All told, about 17 million adults and children have type 2 diabetes in this country. In adults, type 1 diabetes is associated with a five- to seven-fold risk of death from cardiovascular disease, due in part to damage that develops in the lining of blood vessels and eventually promotes formation of fatty obstructions.

For the UF study, funded by the Diabetes Action Research and Education Foundation, the Children’s Miracle Network and the UF Clinical Research Center, researchers evaluated nearly 100 children with type 1 diabetes and 57 healthy children, all 10 to 18 years of age. They then matched a total of 44 pairs of children on the basis of age, sex, race and body mass index. They used a method called radial artery tonometry, which involves placing a pencil-sized probe on the pulse point at the wrist to calculate the pressures generated by flowing blood.

“The pressure wave there gives us the information as to how flexible or stiff the vessels are,” said Haller, who collaborated on the study with Dr. Janet Silverstein, a professor and chief of the division of endocrinology at UF.

The scientists also measured study participants’ cholesterol and blood glucose levels and blood pressure, took a detailed family history and inquired about their exercise regimens.

“Regardless of the values for glucose levels, blood pressure and cholesterol, children with type1 diabetes had stiffer vessels than controls,” Haller said. “That’s been confirmed in a couple of other recent studies using different noninvasive techniques. The advantage of our technique is it’s very easy to reproduce, and it’s a portable system that can be learned by almost anybody. That has potential implications for its future use as a clinical tool.”

Researchers still don’t know what the real risk of heart disease is over time for children whose vessels were stiffer; long-term studies will need to be conducted to assess that.

“For the study we did, we couldn’t say that because a child had stiffer vessels their risk of heart disease was X percent higher,” Haller said. “But you’d assume that risk is higher.”

If the technique proves valuable, radial artery tonometry could easily be incorporated into routine evaluations of patients with diabetes, or who are otherwise at risk for heart disease because of family history or other factors, he said.

“The long preclinical phase of atherosclerotic diseases provides a window for the early identification of high-risk individuals with asymptomatic arterial changes in childhood using noninvasive techniques,” said Dr. Mikko Järvisalo, of Turku University Hospital in Turku, Finland. “Extensive prospective studies are needed before these methods can be accepted as tools for routine clinical practice, but hopefully the techniques will in the future help physicians in risk stratification of young patients with cardiovascular risk factors, including children with diabetes.”

http://www.ufl.edu/