title: Monophasic action potentials and activation recovery intervals as measures of ventricular action potential duration: experimental evidence to resolve some controversies.
abstract: BACKGROUND
  Activation recovery intervals (ARIs) and monophasic action potential (MAP) duration are used as measures of action potential duration in beating hearts. However, controversies exist concerning the correct way to record MAPs or calculate ARIs. We have addressed these issues experimentally.
  
  
  OBJECTIVE
  To experimentally address the controversies concerning the correct way to record MAPs or calculate ARIs.
  
  
  METHODS
  Left ventricular local electrograms were recorded in isolated pig hearts with an exploring electrode grid, with a KCl reference electrode on the left ventricular myocardium, the aortic root, or the left atrium. Local activation was determined from calculated Laplacian electrograms.
  
  
  RESULTS
  With the KCl electrode on the aortic root, local electrograms represented local activation. However, with the KCl electrode on the myocardium remote from the exploring electrode, a combined electrogram emerged consisting of local activation recorded from the grid and remote activation recorded from the reference electrode. The remote, inverted monophasic component did not show propagation and did not correlate with the Laplacian complex. When the KCl electrode was placed on the atrium during AV block, remote atrial monophasic components were completely dissociated from local, ventricular deflections. At left ventricular sites with a positive T wave, the Laplacian signal showed that the end of the T wave was caused by remote repolarization. During cooling-induced regional action potential prolongation, the T wave became negative, whereby the positive flank of the T wave remained correlated with repolarization (recorded with a MAP at the same site).
  
  
  CONCLUSIONS
  MAPs are recorded from the depolarizing electrode. In both negative and positive T waves, the moment of maximum dV/dt corresponds to local repolarization.
authors.affiliation: Department of Experimental Cardiology, Academic Medical Center Amsterdam, Amsterdam, The Netherlands. r.coronel@amc.uva.nl
authors.forename: Ruben
authors.initials: R
authors.lastname: Coronel
authors.forename: Jacques M T
authors.initials: JM
authors.lastname: de Bakker
authors.forename: Francien J G
authors.initials: FJ
authors.lastname: Wilms-Schopman
authors.forename: Tobias
authors.initials: T
authors.lastname: Opthof
authors.forename: André C
authors.initials: AC
authors.lastname: Linnenbank
authors.forename: Charly N
authors.initials: CN
authors.lastname: Belterman
authors.forename: Michiel J
authors.initials: MJ
authors.lastname: Janse
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D001145:Arrhythmias, Cardiac / Q000503:physiopathology*; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006329:Heart Conduction System / Q000502:physiology*; D008297:Male; D012032:Refractory Period, Electrophysiological / Q000502:physiology; D013552:Swine; D016276:Ventricular Function