New findings on the typical teen athlete's heart may help doctors weed out those few with a potentially fatal heart condition, according to researchers.
Hypertrophic cardiomyopathy is a relatively uncommon disorder in which the heart muscle becomes enlarged and interferes with normal cardiac function. Thickening in muscle fibers is usually greatest in the walls of the left ventricle, the heart's main pumping chamber. This thickening reduces the size of the pumping chamber itself, which in turn hinders blood flow.
Often, the first and only symptom of hypertrophic cardiomyopathy is sudden death from cardiac arrest, and the condition is responsible for about one third of all sudden deaths among young athletes.
Yet, the upper limit for normal heart-muscle enlargement due to regular exercise--a benign characteristic known as "athlete's heart"--is based on studies of adult athletes, the authors of the new study explain.
To determine the normal upper limits for teenage athletes' hearts, the UK and US investigators performed cardiac tests on 720 UK teens participating in sports such as tennis, soccer, cycling, rugby and swimming. They compared the athletes with 250 healthy but relatively sedentary teens.
Ultrasounds revealed that, overall, the athletes had a "significantly greater" maximum thickness in the left ventricular wall than their sedentary peers. But only three athletes, all male, showed an enlargement consistent with hypertrophic cardiomyopathy, according to findings published in the October 16th issue of the Journal of the American College of Cardiology.
And in all 38 athletes who showed a potentially concerning wall thickness, there was also an enlargement in the left ventricular chamber itself, report Dr. Sanjay Sharma, of University Hospital Lewisham in London, and his colleagues.
In contrast, Sharma's team notes, teens with hypertrophic cardiomyopathy would show a small or average-size left ventricle.
They recommend that the heart disorder "be considered strongly" in trained male adolescent athletes when the left ventricular wall thickness is greater than 12 millimeters and there is no dilation in the pumping chamber itself. For female athletes, the upper limit should be 11 millimeters, according to the researchers.
The hope, Sharma and his colleagues write, is that this study will help doctors separate hypertrophic cardiomyopathy from normal athlete's heart in teenagers--"ultimately avoiding sudden deaths."
However, they add, since the study population was largely white, the findings may not extend to other racial groups. And some sports common in the US, such as basketball and American football, were not included.
SOURCE: Journal of the American College of Cardiology 2002;40:1431-1436. | |
