Group 2 Escape (late) 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.
and premature (early) beats.
A) Escape beats.
The usual pacemaker fails, so a slower pacemaker fires at its
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.
No P wave, normal QRS if not aberrant.
Figure 11: Note all beats are junctional 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.
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.