Can pvcs ever be fatal in a structurally normal heart ? even in couplets or runs ? also are they suppose to be painful and feel like a punch?

Not as such: Pvcs or short runs in a structurally normal heart are very unlikely to persist into a life threatening rhythm. Can be painful. A potential problem would be in the very rare case if there was a high burden of pvcs as a percentage of normal beats, that a cardiomyopathy occurs. A holter monitor is a 24 hr device that assesses each beat and gives a pvc%. Number of beats in 24 hours is approx 100000.