(HealthDay News) -- A heart murmur is an extra or unusual sound made by the heart as it beats.

The U.S. National Heart, Lung, and Blood Institute says some cases have no obvious warning signs. In other cases, symptoms may include:

• Feeling short of breath.
• Sweating excessively, despite little physical activity.
• Having chest pain or a chronic cough.
• Fainting or feeling dizzy.
• Having a blue tint to the skin.
• Suddenly gaining weight or swelling.
• Having an enlarged liver or enlarged neck veins.
• Among infants, showing poor development or lack of appetite.