Second-Degree Block (Type II)

Second-Degree Block (Type II)

Regular; P to P is regular, rate is variable

Regular; until QRS is dropped, rate is less than atrial rate

More P waves than QRS complexes

Unchanged unless aberrant conduction due to premature beat or increased rate, but dropped in a cyclic pattern

PR: 0.12 to 0.20 sec where they can be measured 

QRS: variable