PHILADELPHIA (WPVI) -- A program is helping children with a silent and potentially dangerous heart defect in Philadelphia.
N'Hoj Lindsay who is 6-years-old really loves soccer, but he can't play it right now.
He was born with a heart defect which could be life-threatening if he over-exerts himself.
It's called a coronary artery anomaly, and that's when a heart artery comes off the aorta in the wrong place.
The arteries can either be too close together or one can run along inside the aorta, with an opening too small to move blood freely.
"There may not be enough blood flow through it to actually give enough blood to the heart, especially during exercise," said Dr. Julie Brothers, a cardiologist at Children's Hospital.
Dr. Brothers has accumulated over 450 cases in years of studying these defects.
She says boys outnumber girls about 3 to 1. And, many kids show no signs until the problem shows on other medical tests.
For N'Hoj, the defect was found shortly after birth, during checks for a different heart defect.
These days, he sometimes has symptoms.
N'Hoj's mother, Tychelle Rossmiller says, "He gets weak, sometimes he gets pain in his chest."
And, it's hard on the family.
"He doesn't understand that he cannot play sports, and that he can't run and be as active as other children," said Rossmiller.
Dizziness or fainting, especially with strenuous exercise, can be a sign, too.
Dr. Brothers says there's no way yet to tell whose high or low risk, so treatment is individual.
N'Hoj will likely have surgery to relocate his arteries.
Then maybe he'll get onto the soccer field! But, his mom will always have help watching over him.
"We want to follow these kids as they become adults, and follow them over a long period of time," said Dr. Brothers.
Dr. Brothers also says these defects can run in families, so siblings and close relatives of kids with them need to be screened, too.
Healthy Kids: Helping kids with heart defects