Ventricular fibrillation during no-flow global ischemia in isolated rabbit hearts.
BACKGROUND
The dominant frequency (DF) during ventricular fibrillation (VF) in Langendorff-perfused guinea pig hearts is higher in left ventricle (LV) than in right ventricle (RV). However, the onset of VF invariably leads to global ischemia. Whether or not a high DF source exists in LV during global ischemia is unknown.


RESULTS
By using a two-camera optical mapping system, epicardial activation patterns of VF were studied in 12 isolated rabbit hearts during baseline, no-flow global ischemia, and reperfusion. Simultaneous endocardial electrode recording was performed in 4 of the 12 hearts. Optical mapping showed type 1 VF at baseline, with multiple wandering and short-lived wavelets. After the onset of global ischemia, VF showed progressively increased spatiotemporal periodicity. The majority (65%) of VF recorded after 7 minutes of global ischemia showed type 2 VF, containing a single epicardial site with stable (> or = 3.85 seconds in duration) repetitive activities. Among the 33 sites with these activities, 24 were located near the interventricular septum, and 27 showed an epicardial breakthrough pattern with centrifugal propagation and wavebreaks distant from the focal site. After 10 minutes of global ischemia, the DF was lower on LV epicardium (5.0 +/- 1.4 Hz) than on RV epicardium (8.6 +/- 2.5 Hz, P < 0.001). However, there was no DF gradient between RV and LV endocardium (9.7 +/- 1.0 vs 9.6 +/- 0.9 Hz).


CONCLUSIONS
VF during prolonged global ischemia is consistent with type 2 VF with a single subepicardial source of rapid activation, mostly near the interventricular septum. The DF in LV is not higher than in RV.
Wu
Tsu-Juey
TJ
Cardiovascular Center, Taichung Veterans General Hospital, Taipei, Taiwan. tjwu@vghtc.vghtc.gov.tw
Lin
Shien-Fong
SF
Hsieh
Yu-Cheng
YC
Ting
Chih-Tai
CT
Chen
Peng-Sheng
PS
D000200:Action Potentials; D000818:Animals; D001683:Biological Clocks; D001783:Blood Flow Velocity; D018780:Body Surface Potential Mapping; D006329:Heart Conduction System / Q000503:physiopathology*; D066298:In Vitro Techniques; D017202:Myocardial Ischemia / Q000150:complications* / Q000503:physiopathology*; D011817:Rabbits; D014693:Ventricular Fibrillation / Q000150:complications* / Q000503:physiopathology*