title: Arrhythmogenic consequences of action potential duration gradients in the atria.
abstract: BACKGROUND
  Atrial action potential duration (APD) has been shown to decrease with increasing distance from the sinoatrial node in several species, including humans. This gradient has been postulated to be cardioprotective by reducing repolarization gradients.
  
  
  OBJECTIVE
  This study tests the effect of the APD gradient on reentry initiation and characteristics.
  
  
  METHODS
  This study used a geometrically accurate atrial computer model to examine arrhythmogenic consequences of an APD gradient on reentry initiation by ectopic beats applied at several locations. As well, dominant frequency maps of any ensuing reentries were analyzed to determine how APD gradients affected rotor behaviour.
  
  
  RESULTS
  When the APD gradient was increased, anatomic reentry that used the coronary sinus as a critical pathway was prevented, but initiation of functional reentry was unaffected. If a rotor did form, APD gradients led to more disorganized behaviour. For rotors circulating around the pulmonary veins, discrete interatrial coupling accounted for left atrium-right atrium frequency gradients, irrespective of an APD gradient.
  
  
  CONCLUSIONS
  Gradients are protective against anatomic reentry but also increase the complexity of arrhythmias that arise.
authors.affiliation: Department of Geography and Geology, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Marc-Etienne
authors.initials: ME
authors.lastname: Ridler
authors.forename: Mike
authors.initials: M
authors.lastname: Lee
authors.forename: David
authors.initials: D
authors.lastname: McQueen
authors.forename: Charles
authors.initials: C
authors.lastname: Peskin
authors.forename: Edward
authors.initials: E
authors.lastname: Vigmond
mesh_terms: D000109:Acetylcholine / Q000502:physiology; D000818:Animals; D018880:Atrial Premature Complexes / Q000503:physiopathology; D003198:Computer Simulation; D004285:Dogs; D004558:Electric Stimulation; D004562:Electrocardiography; D006325:Heart Atria / Q000503:physiopathology*; D006339:Heart Rate / Q000502:physiology; D012307:Risk Factors; D012815:Signal Processing, Computer-Assisted; D012849:Sinoatrial Node / Q000503:physiopathology; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000503:physiopathology*; D014630:Vagus Nerve / Q000503:physiopathology
chemical_list: D000109:Acetylcholine