The American Heart Association is recommending that children undergo a heart exam before they're prescribed ADHD drugs.

Stimulant drugs like Ritalin that are used to treat hyperactivity and attention-deficit disorder can increase blood pressure and heart rate. For kids with heart conditions, the drugs could make them more vulnerable to a heart attack and other problems.

The heart group now wants children to have a thorough exam, including a family history and an EKG, before they're put on the drugs to make sure that they don't have any undiagnosed heart issues.

The government estimates about 2.5 million American children and 1.5 million adults take medication for ADHD. A screening of about 1,100 children found that about 2 percent of them had some kind of heart problem.