New nurse almost off orientation on telemetry. Pt. was direct admit from MD, walked onto the floor and into my room with no information to moi. When put on monitor hr a fib 160's- 180's, apical the same (if I could really count three irregular beats a second). BP during this time 160/100, pt. reports self to be asymptomatic. I did not really worry about a pulse defecit to see how many beats were perfusing peripherally as I was more worried about rate control at the time. Question: Why is BP so high when heart should not be having time to fill and pump? Thanks for attempts at answering with little information.