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Coexistence of Two Types of Ventricular Fibrillation During Acute Regional Ischemia in Rabbit Ventricle
Author(s) -
LIU YENBIN,
PAK HUINAM,
LAMP SCOTT T.,
OKUYAMA YUJI,
HAYASHI HIDEKI,
WU TSUJUEY,
WEISS JAMES N.,
CHEN PENGSHENG,
LIN SHIENFONG
Publication year - 2004
Publication title -
journal of cardiovascular electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.193
H-Index - 138
eISSN - 1540-8167
pISSN - 1045-3873
DOI - 10.1046/j.1540-8167.2004.04337.x
Subject(s) - medicine , cardiology , ventricle , ischemia , ventricular fibrillation , border zone , repolarization , optical mapping , nerve conduction velocity , electrophysiology , anesthesia , myocardial infarction
We previously reported that a normal ventricle can demonstrate two types of ventricular fibrillation (VF), depending on the underlying electrophysiologic characteristics at the time of VF induction. We hypothesize that the two types of VF can coexist in acutely ischemic ventricles. Methods and Results: Optical mapping studies were performed with di‐4ANEPPS in 15 Langendorff‐perfused rabbit hearts. Coronary artery branches were ligated to create regional ischemia in 10 hearts. Action potential duration measured to 50% repolarization (APD 50 ) during ischemia showed an area with uniformly shortened APD 50 (zone 1), an area with normal or lengthened APD 50 (zone 3), and an area in between with an APD 50 gradient (zone 2). Ischemia flattened APD restitution (APDR) slope and reduced conduction velocity in zone 1, creating a condition for type II VF. APDR steepened and the conduction velocity changed little in the nonischemic zone (zone 3), creating a condition for type I VF. During induced VF, the dominant frequency in zones 2 and 3 progressively increased after ischemia onset. The dominant frequency in zone 1 (ischemic zone) first decreased and then slightly increased but typically remained less than the dominant frequency in zone 3. The number of wavebreaks increased with time in all three zones (baseline: 4.3 ± 1.5; 30 min: 11.7 ± 5.6; 60 min: 15.6 ± 11 per frame; P < 0.01). Conclusion: Two types of VF can coexist during acute regional ischemia. Both ischemic and nonischemic regions develop proarrhythmic changes during regional ischemia, thus contributing to increased ventricular vulnerability to VF and sudden death during acute coronary occlusion.