NEW ORLEANS - Using a speckle tracking-based analysis tool that can analyze 2D data from ultrasound scanners, Australian researchers have shown that overweight and obese children have worse left ventricular function than their normal-weight counterparts, according to research presented at this week's American Heart Association (AHA) meeting.
"With the increasing prevalence of obesity among children, we are concerned about the development of heart disease risk factors at a young age," said Dr. Walter Abhayaratna, of the Australian National University in Canberra. "We are also concerned that the development of these risk factors is associated with premature cardiovascular disease in adulthood."
The researchers looked at the effect of body mass index (BMI) on left ventricular untwisting velocity -- a sensitive marker of left ventricular function that reflects the heart rebounding from wringing as it pumps out blood. The community-based study involved 150 healthy children with a mean age of 10 years and a mean BMI of 18.2 kg/m².
Cardiac structure and function were assessed by transthoracic echocardiography. Left ventricular twist mechanics were quantitated using 2D speckle-tracking imaging of the left ventricular base and apex in short axis.
In univariate analysis, untwisting velocity was inversely related to BMI, left ventricular end-diastolic diameter, and left ventricular end-systolic diameter. There was a positive correlation with traditional measures of left ventricular function, including ejection fraction and early diastolic annular velocity; novel measures of left ventricular mechanics, including torsion and twisting velocity; and heart rate.
"Interestingly, there was no correlation with left ventricular relative wall thickness or mass index," Abhayaratna said.
In multivariate analysis, the strength of the relationship between higher body mass index and slower untwisting velocity increased, and the correlation persisted after adjustment for heart rate and torsion, he said.
"What this means is that there is worse relaxation of the heart even at this young age in healthy children who are obese," Abhayaratna said.
Additional studies are needed to evaluate whether lifestyle measures to reduce body mass will attenuate further deterioration in left ventricular mechanics and function, he said.
By Charlene Laino
AuntMinnie.com contributing writer
November 13, 2008
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