im 18, my heart rate speeds up and leaves me out of breath, should i be worried???

Preoccupied123,

Thanks for your question. 

It sounds like your doctor is doing all the right things.  Unfortunately you are still experiencing symptoms.  It's time to see him/her again for another evaluation.  At this point, I suggest you discuss what further testing is appropriate at this point.  Ask your physician about a Holter Monitor, which is a 24 hour recording of your heart beat.  Should you have your symptom during this time, the monitor will help in identifying the problem.  Another study to discuss with your physician is an echocardiogram which uses sound waves to look at your heart, looking for abnormalities of the chambers and valves.

Should all of these prove to be negative, then a consultation with a cardiologist would be my next suggestion. 

I hope this has been helpful.  Best wishes and feel better.

Martin Cane, M.D.

As a nurse, two things come to mind: 1.) Panic Attacks or 2.) hyperthyroidism causing a thyroid storm at times.  Either of these conditions could cause the symptoms that you have described.