asthma test/ lung test/ ecg?

hi
i was wondering what an ecg determines? it sounds saft but what can it detect?

also i had a lung scan, well i had to lie on this bed and just my head was sticking out and this machine went around me, then when it stopped they injected this stuff into my arm which went to my lungs straight away and they did the whole scan thing again.

before all that i had to have this clip thing over my nose and mouth piece in and blow into it, then hold my breathe etc.

i was just wondering what this test would determine? as in wld it pick up if anything was wrong with my breathing in everyday to day life. it came back clear but my complaimt is ALWAYS feeling short of breathe, always get breathless easy and cant even walk without feeling breathless etc. it panics me.

people say its anxiety? surely it cant be? can i be that sressed? yes i have a hell of a lot going on but surely i cant fdeel like im dying all the time etc?

thanks

I believe an ECG picks up any irregular heart beats, if all tests come back clear then the doctors might suggest having an oxygen monitor on through the night, its just a small device that fits on the finger and records your oxygen levels, if all are clear then Anxiety is the most likely cause, sorry

hi iv had an oxygen levels test when i was in hospital recent. Last week from having a baby. They do it routine i think, and even when i felt i couldnt breathe they oxygen thing said i was fine. strange