Figure 13.

Atrial fibrillation. The waves between each QRS complex are random and indistinct; in essence, they're a mess! Furthermore, the R-R intervals are consistently irregular. This pattern emerges when several ectopic pacemakers emerge in the atrial muscle and all fire more rapidly than the sinuatrial node. This generates multiple depolarizations in the atrial muscle, far more numerous than those with atrial flutter. The atrioventricular node is so overwhelmed with impulses that it cannot allow any to pass through on a regular basis. Therefore, we see this striking irregular ventricular response.