I just recently had an episode of my heart beating rapidly, its happened before. its hard to catch my breath, lasts about 30 sec. why does this happe?

SVT: One of the possibilities is supra ventricular tachycardia(svt). This can occur when there is an electrical conduction abnormality or short circuit in the top camber of your heart leading to intermittent rapid heart beating. There are many other things that it could be, this is just one of them. Make an appointment with your doc to discuss, check a thyroid blood test, and avoid caffeine.