EKG width

P wave width = 0.12 sec (3ss) (>0.12 or >3ss <=> atrial enlargement)
PR interval (from the beginning of P wave to 1st deflection of QRS) = or <  0.20 sec (5ss = 1ls)  (if >0.20 or 5ss <=> 1st degree AV block)

 

QRS width = 0.12 sec (3ss) (>0.12 or 3ss <=> bundle branch block (BBB)  (partial or full) OR the complex did not take the conduction pathway at all and had a ventricular origin as is seen in a premature ventricular complex or PVC)

QTc width < 450sec => If >450msec, it may be a tip-off that electrolyte abnormalities exist or some toxin is present.  While this concept is more complex than depicted here, it is not so important and can be discussed later when looking at specific EKG’s