wiwarin_mir - a loud heartbeat - abolutely nothing to worry about at all. Trust me. Your heartbeat is simply loud because of whatever position you are in, or something is making it beat stronger (some attention perhaps) I remember several times when the same as happened to me. Its absolutely nothing. The reason you can feel it pumpin is that it is filling mroe than normal. I'm assuming these episodes are short lived. THey mean nothing, and are not indicative of high blood pressue!
Elles - your path is prob not referring to a fit young bloke. It would be very rare, and possibly only cos of PFO (hole in heart) but that probably wouldn't present as benign as this.
NikNak - one of the main arteries in your brain runs through your middle ear. You can often 'hear' your pulse because of this artery when you have been running, or are aobut to go to sleep. When i was a kid, i always imagined the noise was the sound of the giants from BFG coming to get me, and that if i wasn't aslepp by the time they got here, i would get eaten. Scary thought ey?