jremington:
Your ISR stops because it tries to print. NEVER print from within an interrupt, because printing depends on interrupts and those are turned off in an ISR.
The code isnt written by me it written by [developer](https://pulsesensor.com/pages/pulse-sensor-amped-arduino-v1dot1) of sensor so how to print data processed out of ISR . should i do this after calling ISR in void loop()`?
The ISR should collect and store the absolute minimum data necessary, set a global flag (declared "volatile") that the data need to be processed, and exit.
Can you clear your point more ?