What defines escape rhythms?

Escape rhythms are characterized as slower rhythms that emerge specifically when the primary pacemaker of the heart, typically the sinoatrial (SA) node, fails to generate impulses at a sufficient rate. In situations where the SA node fails or slows, other cardiac pacemakers, such as the atrioventricular (AV) node or the ventricles, take over to maintain a heartbeat. This backup mechanism ensures that the heart continues to beat, albeit at a slower rate compared to the usual pacing set by the SA node.

The key aspect of escape rhythms is that they inherently follow a compensatory purpose—they "rescue" the heart's function when higher-level pacemaking control is lost. This contrasts with other rhythms, like accelerated rhythms that are consistently fast or irregular rhythms caused by ectopic beats, which don't necessarily relate to the failure of the primary pacemaker but rather reflect alternative electrical activity in the heart. In the case of rhythms originating in the ventricles, while they may be slower and arise under certain conditions, they are categorized differently than typical escape rhythms if they occur without SA node failure.