EP & ICU: Concept of PMT & PVARP

10 mo. old s/p Rastelli for DORV, d-TGA, PS. 3rd deg. AV block. Fig 1: Patients monitor. Fig 2 &3: Temp. pacemaker settings. Pacemaker is set at 100 bpm. On the monitor, it is A-sensing & V-pacing at 133 bpm. Is the pacemaker working properly?

When I attempted to increase upper rate from 140 bpm to 145 bpm, this "warning" came up. What does that mean?

If I really wanted to go up in the upper rate, what are my options to get around the "warning"?

Related questions: What is PVARP? What is PMT? How do you determine the optimal PVARP? (What is retrograde VA conduction time?)