Blood pressure app

There are Bluetooth enabled Blood Pressure measuring devices that pair with an app on your iPhone. They all have a pressure cuff that you wrap around either your upper arm (most accurate), or some will wrap around your wrist. The wrist cuffs tend to be at least 2-3 inches wide, the upper arm cuffs tend to be about 4-5 inches wide.

No there isn't one yet,that would need some serious hardware upgrade from apple,maybe apple watch 10.