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Characteristics of Ischemic and Peri‐Ischemic Regions During Ventricular Fibrillation in the Canine Heart
Author(s) -
RANKOVIC VLADIMIR,
PATEL NIKHIL,
JAIN SANDEEP,
ROBINSON NIKKI,
GOLDBERGER JEFEREY,
HORVATH GEORGE,
KADISH ALAN
Publication year - 1999
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 - 10.1111/j.1540-8167.1999.tb00282.x
Subject(s) - medicine , ischemia , cardiology , ventricular fibrillation , ligation , qrs complex , fibrillation , anesthesia , atrial fibrillation
Ischemic Ventricular Fibrillation. Introduction : Although premature heats originating in areas of ischemia have been shown to he important in initiating ventricular fibrillation (VF), the participation of the ischemic zone in maintenance of VF has not been investigated. Methods and Results : Ten normal dogs underwent induction of two separate episodes of VF, before and 10 minutes after left anterior descending coronary artery ligation. Ischemic VF was allowed to occur spontaneously or was induced by burst pacing after 10 minutes of ischemia. Unipolar epicardial electrograms were recorded using an 8 × 14 plaque electrode array (interelectrode distance 2.5 mm) placed over the anterior wall. Activation during VF was characterized by VF cycle length (CL) and wavefront organization based on linking analysis of epicardial activation directions at adjacent sites. Individual plaque sites were separated into regions based on electrogram morphology during ischemia: R1 = no ischemia; R2 = mild‐to‐moderate ischemia (minor ST elevation and QRS widening); and R3 = severe ischemia (marked ST elevation and QRS widening). Percent conduction block was calculated based on the percent of cycles during which sites were not activated during VF. There were no significant differences noted in mean CL or mean percent conduction block in the peri‐ischemic region R1 compared to the same region under nonischemic (control) conditions. During ischemia, the mean CL was noted to increase in R2 from 111 ± 14 msec (control) to 128 ± 29 msec (ischemia) and in R3 from 113 ± 14 msec (control) to 150 ± 42 msec (ischemia) (P < 0.05). The percentage conduction block in R2 increased from 6%± 11% (control) to 14%± 16% (ischemia) and in R3 from 4%± 6% (control) to 44%± 21% (ischemia) (P < 0.05). Linking analysis revealed no significant changes in VF organization at distances of 2.5 mm in regions R1 and R2 under both control and ischemic conditions. Premature heats initiating fibrillation originated at the border between the normal and mildly ischemic zones. Conclusions : (1) Some VF characteristics are altered in ischemic regions including a longer VFCL and greater percentage of functional block. (2) VF characteristics are unchanged in immediately adjacent nonischemic myocardium. (3) Although the ischemic zone may he involved in the initiation of VF and has unique activation characteristics during VF, it does not affect VF characteristics in the adjacent nonischemic zone, suggesting that it may not play a major role in VF maintenance.