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Effects of Acute Ischemia on Anisotropic Conduction in Canine Ventricular Muscle
Author(s) -
MIZUMAKI KOICHI,
FUJIKI AKIRA,
TANI MASANAO,
MISAKI TAKURO
Publication year - 1993
Publication title -
pacing and clinical electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.686
H-Index - 101
eISSN - 1540-8159
pISSN - 0147-8389
DOI - 10.1111/j.1540-8159.1993.tb01036.x
Subject(s) - medicine , cardiology , ischemia , anatomy , anterior wall , circumflex , ventricular fibrillation , artery , anesthesia
The effects of acute ischemia on conduction velocities in the longitudinal (θ L )and transverse (θ T )fiber axis were determined from epicardiai activafion patterns, recorded with 48 bipolar electrodes (piaque eiectrode, 25 × 35 mm) on the left anterior ventricuiar wail of eight dogs and the posterior wall of seven dogs. During left ventricuJar stimulation (cycle length = 300 msec)in the center of the piaque electrode, θ L , θ T , and the ratio of longitudinai to transverse conduction velocities (θ L/t )were measured before and 2 to 5 minutes after occiusion of the left anterior descending coronary artery or the left circumflex coronary artery. During the control state θ L was greater thon θ T demonstrating anisotropic properties of cardiac muscle, not only in the anterior but also in the posterior wail. During acute ischemia θ L and θ T were decreased from the control value and θ T was decreased by a greater extent than θ L , resuiting in an increase in θ L/T from 1.83 ± 0.31 (mean ± SD)to 2.19 ± 0.36 in the anterior wall and from 1.58 ± 0.17 to 1.92 ± 0.28 in the posterior wall. During ventricuiar fibriiiation some lines of conduction block were parallel to the long axis of epicardial muscie fiber bundle and the others were perpendicular. In conclusion, acute ischemia increased anisotropic conduction (Bl/t) in the epicardial ventricular muscle mainly due to greater reduction in θ T , in the anterior and the posterior wall. This augmented anisotropic ventricuiar conduction may have some relation to the initiation of ventricular fibrillation during acute ischemia.