Regularity: R-R intervals are regular, overall rhythm is regular.
Rate: The rate is less than 60 beats/min, but usually more than 40 beats/min.
P WAVE: There is one p wave in front of every QRS. The P waves appear uniform.
PRI: Measures between 0.12 and 0.20 seconds in duration. PRI is consistent.
QRS: Measures less than 0.12 seconds.