By Kathryn Doyle
There are noticeable differences in the shape and function of hearts among obese and normal-weight adolescents, researchers say.
“We do not know if (these changes) are clinically meaningful or necessarily dangerous,” said Dr. Norman Mangner of the University of Leipzig Heart Center in Germany. “This is a cross-sectional study and, therefore, we cannot answer this question.”
Still, some of the heart characteristics of obese adolescents were similar to those of children with leukemia after chemotherapy, he wrote in an email to Reuters Health.
The researchers write in JACC: Cardiovascular Imaging, a journal of the American College of Cardiology, that obesity is tied to changes in heart [functioning] in adults. However, those changes may occur even earlier among obese children.
For the new study, Mangner and his colleagues took blood samples from 101 adolescents between ages 9 to 16 years, including 61 who were obese. They also took sonograms, known as two-dimensional echocardiograms, of the adolescents’ hearts to watch their beats.
The obese youngsters had enlarged chambers on both sides of their hearts. They also had thicker walls in the left chamber, which pumps oxygen-rich blood to the rest of the body.
The obese adolescents’ hearts also appeared to be working harder by pumping a higher volume of blood with each beat, compared to thinner participants, according to the researchers.
Obese adolescents had higher blood pressure readings than thinner participants. The blood pressure readings were still within normal limits, however. Obese participants also had more “bad” LDL cholesterol and less “good” HDL cholesterol than the non-obese kids.
“I think this was already pretty well-known,” said Dr. Sheldon E. Litwin, a cardiologist and cardiac imaging specialist at the Medical University of South Carolina in Charleston.
Left ventricular hypertrophy, which is an increase in mass of the heart’s walls, is known to be a risk factor for heart disease, said Litwin, who was not involved in the new study.
“When it’s longstanding it can become problematic,” he told Reuters Health by phone. “The heart muscle can become stiff if it’s too thick and that can lead to congestive heart failure.”
He added that enlarging of the left chamber’s walls typically takes decades to develop, however. Usually, it affects people in their 70s and 80s.
Another recent study published in the Journal of the American College of Cardiology found people who were obese and had high blood pressure were more likely to grow up to have thicker walls in the left chambers of the hearts.
Litwin wrote an editorial accompanying that study in the Journal of the American College of Cardiology. The study was published by researchers at Tulane University in New Orleans and three medical institutions in China.
“The fact that these children today are starting to get high blood pressure, maybe these people will be getting heart disease 20 to 30 years earlier,” Litwin said.
The changes in the heart do improve if people are able to lose weight — particularly for adults who have bariatric or weight-reduction surgery, he said, adding that those types of surgeries are becoming more common for younger people.
“But there’s some other data that suggest that once someone has been obese, they may carry some risk forward once they lose weight,” he said. “There is a cumulative burden of high blood pressure and cholesterol.”
Litwin said diet and exercise are involved with the types of heart changes found in these studies.
“Certainly physical activity and fitness are associated with good longevity,” he said. “Getting them to occur on a society wide basis, that’s the challenge.”