Repetitive endocardial focal discharges during ventricular fibrillation with prolonged global ischemia in isolated rabbit hearts.
BACKGROUND
Ventricular fibrillation (VF) during prolonged (>5 min) global ischemia (GI) could be due to repetitive endocardial focal discharges (REFDs). This hypothesis was tested in isolated rabbit hearts.


RESULTS
With optical mapping, simultaneous endocardial (left ventricle, LV) and epicardial (both ventricles) activations during VF with prolonged GI were studied (protocol I, 8 hearts). Lugol solution was applied to the LV endocardium in additional 5 hearts after 5-min GI (protocol II). During prolonged GI, sustained VF (>30 s) was successfully induced in 7 protocol I hearts. The dominant frequency of summed optical signals at the LV endocardium was higher than at the epicardium (P<0.05). Mapping data showed that after 5-min GI, REFDs were present in >90% for recording time. There were 18 windows of optical recording showing spontaneous VF termination. In 10, once REFDs ceased, the VF episode terminated immediately. Electrical defibrillation was also performed on 3 hearts. Eight shocks showed early VF recurrence after successful defibrillation. REFDs were consistently involved in the initiation period of recurrence. In protocol II, Lugol subendocardial ablation diminished REFD genesis during re-induced VF. These VF episodes were all non-sustained.


CONCLUSIONS
REFDs at the LV endocardium were important for both VF maintenance and post-shock recurrence during prolonged GI in this model.
Wu
Tsu-Juey
TJ
Cardiovascular Center, Taichung Veterans General Hospital, Taichung, Taiwan. tjwu@vghtc.vghtc.gov.tw
Lin
Shien-Fong
SF
Hsieh
Yu-Cheng
YC
Chiu
Yung-Tsung
YT
Ting
Chih-Tai
CT
D000200:Action Potentials; D000818:Animals; D002304:Cardiac Pacing, Artificial; D004554:Electric Countershock; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D004699:Endocardium / Q000187:drug effects / Q000503:physiopathology*; D005583:Fourier Analysis; D066298:In Vitro Techniques; D007454:Iodides / Q000494:pharmacology; D017202:Myocardial Ischemia / Q000150:complications* / Q000503:physiopathology; D010477:Perfusion; D010496:Pericardium / Q000503:physiopathology; D011690:Purkinje Fibers / Q000187:drug effects / Q000503:physiopathology*; D011817:Rabbits; D012008:Recurrence; D012815:Signal Processing, Computer-Assisted; D013997:Time Factors; D014693:Ventricular Fibrillation / Q000209:etiology* / Q000503:physiopathology / Q000628:therapy
D007454:Iodides; C010389:Lugol's solution