Minimum / Maximum Heart Rate

8 minutes at 229bpm?
I don't think so - seriously. You'd feel that "blip" i can tell you.

How did you fell throughout those 8 minutes (apart from slightly perplexed - after noticing those readings?)?

I could feel it racing, and I was a bit out of breath. It didn't get so bad that I felt the need to stop, and there was no terrible crushing pain or tingling down my left arm!