Heart slow down beside shock?

I have notice if i get a shock, eg, mortal woke up by loud thunder in the dark, when i feel my pulse i sense it has slowed right down approaching it is going to stop & then it starts race like nutty, almost like my blood pressure go right down & it's racing to bring it rear legs up to normal level? Is this normal or is something wrong next to my heart?Heart slow down beside shock?
Shock has a speedy thready pulse
This is normal, the surprise slows the heart while your body injects adrenalin which cause the heart to speed up.
The adrenalin and speeding heart is the "Fight or Flight" reflex.
But if you want to see some thing else to be exact neat, if you own a heart monitor. Take a deep breath and hold it as long as you can and examine the heart monitor. At first the heart slows right down, then after copious seconds starts speeding up. I used that to fool unsophisticated pull the wool over your eyes detector at science fair.