Group 2 Escape (late) beats
and premature (early) beats.

The bottom line for Group 2 arrhythmias is that the rhythm is fairly regular - then you will notice an early or late beat; try to figure out whether that beat is a premature atrial contraction, premature ventricular contraction, etc.

A) Escape beats.

The usual pacemaker fails, so a slower pacemaker fires at its inherent rate.

Atrial escape

Different appearing and late P wave.

Figure 10: Atrial Escape Rhythm. Note differing appearance of the P waves for Sinus Rhythm vs. Atrial Escape Rhythm.

Junctional escape

No P wave, normal QRS if not aberrant.

Figure 11: Note all beats are junctional escape.

Ventricular escape

No P, wide, bizarre QRS.

Figure 12: Ventricular escape.

B) Premature Beats.

An ectopic pacemaker fires early before the next scheduled beat.

Premature atrial contraction

"PAC", early and differently shaped P wave, narrow QRS.

Figure 13: Premature Atrial Contraction noted by arrow.

Premature junctional

No P, normal QRS if not aberrant.

Figure 14: Note the two early, narrow beats at the arrow. These are probably PJCs.

Premature ventricular contraction

No P, wide bizarre QRS. PVCs that occur three (3) or more in a row (ventricular tachycardia), multifocal PVCs (different shapes), or PVCs that land on a previous T wave (R on T phenomenon) can be dangerous ion a patient with underlying heart disease.

Figure 15: Note: Every fourth beat is a PVC (beginning with the second beat).

Continue to Group 3.