ECG RHYTHM LAB

Second-Degree AV Block · Mobitz II

Atrial impulses intermittently fail to conduct without progressive PR lengthening.

Generated six-second Lead II example · 80 bpm target rate · not a patient recording.

Typical rate

Ventricular rate below atrial rate

Regularity

Intermittent pauses

P waves

Regular; some are not conducted

PR interval

Constant in conducted beats

QRS

Often wide

What to look for

Compare conducted PR intervals: they stay the same around a dropped QRS.

Show this rhythm

Sources and limitations