P waves/slow rate/regular -> supraventricular bradycardias
P waves/fast rate/regular -> supraventricular tachycardias
no P waves/irregular -> a fib
grouped beats with decreasing R-R -> AV block / 2nd deg / type I
dropped beats without decreasing R-R -> AV block / 2nd deg / type II
no relationship between P and QRS -> AV block / 3rd degree