I have a question I suffer from palpitations one time it slowly increase from 120 bpm to 170; bpm and slowly it comes down and after that two months again all of sudden my pulse rate increase to 185-190 and get normal in 5 minutes during this period I have lot of anxiety is it due to this or psvt and if someone detect with psvt after that it necessary to take beta blocker or wait for next until it's get detected and if someone take betablocker for psvt does it cause first degree heart block