Beat-to-beat variability of cardiac action potential duration: underlying mechanism and clinical implications

• Published in: Canadian journal of physiology and pharmacology Vol. 95; no. 10; p. 1230
• Main Authors: Nánási, Péter P, Magyar, János, Varró, András, Ördög, Balázs
• Format: Journal Article
• Language: English
• Published: Canada 01-10-2017
• Subjects: Action Potentials - drug effects; Animals; Anti-Arrhythmia Agents - therapeutic use; Arrhythmias, Cardiac - drug therapy; Arrhythmias, Cardiac - metabolism; Arrhythmias, Cardiac - physiopathology; Heart Conduction System - drug effects; Heart Conduction System - metabolism; Heart Conduction System - physiopathology; Heart Rate - drug effects; Humans; Ion Channels - metabolism; Models, Cardiovascular; Time Factors; durée du potentiel d’action; action potential duration; arrhythmia; arythmie; beat-to-beat variability; canaux ioniques; ion channels; variabilité battement par battement
• ISSN: 1205-7541
• DOI: 10.1139/cjpp-2016-0597

Beat-to-beat variability of cardiac action potential duration (short-term variability, SV) is a common feature of various cardiac preparations, including the human heart. Although it is believed to be one of the best arrhythmia predictors, the underlying mechanisms are not fully understood at present. The magnitude of SV is basically determined by the intensity of cell-to-cell coupling in multicellular preparations and by the duration of the action potential (APD). To compensate for the APD-dependent nature of SV, the concept of relative SV (RSV) has been introduced by normalizing the changes of SV to the concomitant changes in APD. RSV is reduced by I
, I
, and I
while increased by I
, suggesting that ion currents involved in the negative feedback regulation of APD tend to keep RSV at a low level. RSV is also influenced by intracellular calcium concentration and tissue redox potential. The clinical implications of APD variability is discussed in detail.