Pulse Measurement of Heart Arrhythmia

Python [on Windows], 262 bytes

from time import*
import os,random
t,i=time(),0
while time()-t<15:print([""",d88b.d88b,
88888888888
`Y8888888Y'
  `Y888Y'
    `Y'""",""" d8b d8b
888888888
`Y88888P'
 `Y888P'
  `Y8P'
   `Y'"""][i%2]);i+=1;sleep(random.randint(3,14)/10);os.system('cls')
print(i*4)

For linux and macOS use os.system('clear') for 2 more bytes.