When i walk up a flight of stairs,breathe heavy and hr is 155. i'm a high trained athlete so unusual to be tired doing this.doesn't occur all the time?

Tachycardia at 18 yr: Intermittent tachycardia at 18 yrs could have myriad causes. You should see a pediatric cardiologist who will get a thorough history and physical on you. The appropriate test would be a Holter Monitor for as long as 30 days. This will involve having EKG leads on you continually and attached to a portable recorder (like a Sony Walkperson) and then returning it to your doc. He will then analyze