Talk to General Physician on Heartbeat Increases

my sister is facing a problem from a got worse heart beat increases suddenly, breatg gets shorten and then she fells body gets paralyzed for some feels anxiety and depression when this condition attacks.... we had her echo and ECG test yesterday... everything is normal according to is using andreal medicine for hearbeat and a muscle she had this attack this morning again. we are unable to figure out the reason... please if anyone can me know