Long-duration ventricular fibrillation exhibits 2 distinct organized states.
BACKGROUND
Previous studies showed that endocardial activation during long-duration ventricular fibrillation (VF) exhibits organized activity. We identified and quantified the different types of organized activity.


RESULTS
Two 64-electrode basket catheters were inserted, respectively, into the left ventricle and right ventricle of dogs to record endocardial activation from the endocardium during 7 minutes of VF (controls, n=6). The study was repeated with the K(ATP) channel opener pinacidil (n=6) and the calcium channel blocker flunarizine (n=6). After 2 minutes of VF without drugs, 2 highly organized left ventricular endocardial activation patterns were observed: (1) ventricular electric synchrony pattern, in which endocardial activation arose focally and either had a propagation sequence similar to sinus rhythm or arose near papillary muscles, and (2) stable pattern, in which activation was regular and repeatable, sometimes forming a stable re-entrant circuit around the left ventricular apex. Between 3 and 7 minutes of VF, the percent of time ventricular electric synchrony was present was control=25%, flunarizine=24% (P=0.44), and pinacidil=0.1% (P<0.001) and the percent of time stable pattern was present was control=71%, flunarizine=48% (P<0.001), and pinacidil=56% (P<0.001). The remainder of the time, nonstable re-entrant activation with little repeatability was present.


CONCLUSIONS
After 3 minutes, VF exhibits 2 highly organized endocardial activation patterns 96% of the time, one potentially arising focally in the Purkinje system that was prevented with a K(ATP) channel opener but not a calcium channel blocker and the other potentially arising from a stable re-entrant circuit near the apical left ventricular endocardium.
Departments of Medicine, Biomedical Engineering, and Physiology, University of Alabama at Birmingham; and Department of Internal Medicine, CARMA Center, University of Utah, Salt Lake City.
Li
L
Li
Xiangsheng
X
Zheng
Derek J
DJ
Dosdall
Jian
J
Huang
Steven M
SM
Pogwizd
Raymond E
RE
Ideker
D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D016757:Death, Sudden, Cardiac; D004285:Dogs; D022062:Electrophysiologic Techniques, Cardiac; D004699:Endocardium / Q000503:physiopathology; D005260:Female; D005444:Flunarizine / Q000494:pharmacology; D006329:Heart Conduction System / Q000187:drug effects / Q000503:physiopathology*; D054086:KATP Channels / Q000187:drug effects; D008297:Male; D020110:Pinacidil / Q000494:pharmacology; D011690:Purkinje Fibers / Q000502:physiology*; D014693:Ventricular Fibrillation / Q000473:pathology / Q000503:physiopathology*
D002121:Calcium Channel Blockers; D054086:KATP Channels; D020110:Pinacidil; D005444:Flunarizine
arrhythmias, cardiac; ventricular fibrillation