Key result
Review details mechanisms of ectopic pacemakers, escape rhythms, and AV dissociation during sinus node failure.
This text provides an overview of the mechanisms of ectopic pacemakers, escape rhythms, and atrioventricular dissociation.
Subsidiary pacemaker physiology guides arrhythmia recognition; leaves open prospective studies on escape rhythm management in contemporary practice.
The sinus node is the dominant pacemaker in the normal human heart. Rhythms arising from any part of the heart other than the sinus node are considered ectopic.1Most tissues in the conduction system can manifest pacemaker activity. When the dominant pacemaker slows or fails (default, see below) or when conduction is interrupted (block, see below), these pacemakers have the potential to escape and become the dominant pacemaker of the heart. The more distally located a subsidiary pacemaker, the slower its escape rate (Lewis' "law of the heart"). Under pathologic conditions, these ectopic pacemakers can accelerate and become the dominant pacemaker of the heart (usurpation, see below). Under usual circumstances, the atria and ventricles are driven by a single pacemaker. When the atria and ventricles are driven by different pacemakers, atrioventricular (AV) dissociation is said to be present. Pick and Langendorf2have described four basic mechanisms for AV
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Eric Duncan (1987) conducted a review in Atrioventricular dissociation. The abstract describes the physiological mechanisms of ectopic pacemakers, escape rhythms, and atrioventricular dissociation when the dominant sinus node slows or fails.
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