title: The importance of Purkinje activation in long duration ventricular fibrillation.
abstract: BACKGROUND
  The mechanisms that maintain long duration ventricular fibrillation (LDVF) are unclear. The difference in distribution of the Purkinje system in dogs and pigs was explored to determine if Purkinje activation propagates to stimulate working myocardium (WM) during LDVF and WM pacing.
  
  
  RESULTS
  In-vivo extracellular recordings were made from 1044 intramural plunge and epicardial plaque electrodes in 6 pig and 6 dog hearts. Sinus activation propagated sequentially from the endocardium to the epicardium in dogs but not pigs. During epicardial pacing, activation propagated along the endocardium and traversed the LV wall almost parallel to the epicardium in dogs, but in pigs propagated away from the pacing site approximately perpendicular to the epicardium. After 1 minute of VF, activation rate near the endocardium was significantly faster than near the epicardium in dogs (P<0.01) but not pigs (P>0.05). From 2 to 10 minutes of LDVF, recordings exhibiting Purkinje activations were near the endocardium in dogs (P<0.01) but were scattered transmurally in pigs, and the WM activation rate in recordings in which Purkinje activations were present was significantly faster than the WM activation rate in recordings in which Purkinje activations were absent (P<0.01). In 10 isolated perfused dog hearts, the LV endocardium was exposed and 2 microelectrodes were inserted into Purkinje and adjacent myocardial cells. After 5 minutes of LDVF, mean Purkinje activation rate was significantly faster than mean WM activation rate (P<0.01).
  
  
  CONCLUSIONS
  These extracellular and intracellular findings about activation support the hypothesis that Purkinje activation propagates to stimulate WM during sinus rhythm, pacing, and LDVF.
authors.affiliation: Cardiac Rhythm Management Laboratory, Division of Cardiovascular Disease, Department of Medicine, University of Alabama at Birmingham, AL.
authors.forename: Jian
authors.initials: J
authors.lastname: Huang
authors.forename: Derek J
authors.initials: DJ
authors.lastname: Dosdall
authors.forename: Kang-An
authors.initials: KA
authors.lastname: Cheng
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.forename: Jack M
authors.initials: JM
authors.lastname: Rogers
authors.forename: Raymond E
authors.initials: RE
authors.lastname: Ideker
mesh_terms: D000200:Action Potentials; D000818:Animals; D002304:Cardiac Pacing, Artificial; D004195:Disease Models, Animal; D004285:Dogs; D004699:Endocardium / Q000503:physiopathology; D056149:Epicardial Mapping / Q000295:instrumentation; D008839:Microelectrodes; D010496:Pericardium / Q000503:physiopathology; D011690:Purkinje Fibers / Q000503:physiopathology*; D013552:Swine; D013997:Time Factors; D014693:Ventricular Fibrillation / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology* / Q000628:therapy
keywords: arrhythmia (mechanisms); long duration ventricular fibrillation; ventricular arrhythmia