Actually a heart murmur is more than just a sound. Many people are born with them, I was premature and had one. It is a defect in the anatomy of your heart, a valve that does not close all the way, sometimes called a hole. People live everyday with them, and are fine. You made it this far right? And EKG/ECG will not show a murmur, but and echocardiogram will. This is simply an ultrasound of your heart. Your doc should order one to make sure the murmur is not too severe ( I am sure it isnt if you have had no symtoms). Usually the only precautions may be taking antibiotics before any dental work or surgery because you may be at greater risk for an infection to affect you heart. Most of the time that is not even required. You can live just fine without any worries, otherwise you doctor would have told you!