title: Periods of highly synchronous, non-reentrant endocardial activation cycles occur during long-duration ventricular fibrillation.
abstract: Periods of Highly Organized Activation During VF.
  
  
  BACKGROUND
  Little is known about long-duration ventricular fibrillation (LDVF), lasting 1-10 minutes when resuscitation is still possible.
  
  
  RESULTS
  To determine global left ventricle (LV) endocardial activation during LDVF, 6 canines (9.5 ± 0.8 kg) received a 64-electrode basket catheter in the LV, a right ventricular (RV) catheter, and a 12-lead electrocardiogram (ECG). Activation sequences of 15 successive cycles after initiation and after 1, 2, 3, 5, 7, and 10 minutes of LDVF were determined. Early during VF, LV endocardial activation was complex and present throughout most (78.0 ± 9.7%) of each cycle consistent with reentry. After 3-7 minutes of LDVF in 5 animals, endocardial activation became highly synchronized and present for only a small percentage of each cycle (18.2 ± 7.7%), indicating that LV endocardial reentry was no longer present. During this synchronization, activations arose focally in Purkinje fibers and spread as large wavefronts to excite the Purkinje system followed by the subendocardial working myocardium. During this synchronization, the ECG continued to appear irregular, consistent with VF, and LV cycle length (183 ± 29 ms) was significantly different than RV cycle length (144 ± 14 ms) and significantly different than the LV cycle length when synchronization was not present (130 ± 11 ms).
  
  
  CONCLUSIONS
  After 3-7 minutes of LDVF, a highly organized, synchronous, focal LV endocardial activation pattern frequently occurs that is not consistent with reentry but is consistent with triggered activity or abnormal automaticity in Purkinje fibers. The ECG continues to appear irregular during this period, partially because of differences in LV and RV cycle lengths.
authors.affiliation: Department of Medicine, Division of Cardiovascular Disease, University of Alabama at Birmingham, Birmingham, USA.
authors.forename: Robert P
authors.initials: RP
authors.lastname: Robichaux
authors.forename: Derek J
authors.initials: DJ
authors.lastname: Dosdall
authors.forename: Jose
authors.initials: J
authors.lastname: Osorio
authors.forename: Nicholas W
authors.initials: NW
authors.lastname: Garner
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.forename: Jian
authors.initials: J
authors.lastname: Huang
authors.forename: Raymond E
authors.initials: RE
authors.lastname: Ideker
mesh_terms: D000818:Animals; D001683:Biological Clocks; D004285:Dogs; D004562:Electrocardiography / Q000379:methods; D004699:Endocardium / Q000503:physiopathology*; D006329:Heart Conduction System / Q000503:physiopathology*; D006339:Heart Rate; D008955:Models, Cardiovascular; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000503:physiopathology; D014693:Ventricular Fibrillation / Q000503:physiopathology*