Kurasu 1 Kofuseimyakuyaku Niyoru Shinshitsunai Dendo Yokusei to Shinkin Seni Soko (Effects of Class 1 Antiarrhythmic Drugs on the Intraventricular Conduction: Influence of Fiber Orientation)
(Englisch)
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Class 1 drugs, such as Na channel blockers, were used for ventricular arrhythmia to lower the conductivity and excitability of the ventricle. Recently, it was revealed that the inhibition of conductivity caused reentry in the ventricle. The conduction and fiber orientation of ventricular epicardium surface when lidocaine or flecainide was added, in order to clarify the mechanism of arrhythmia caused by class 1 antiarrhythmic agents was examined. The ventricle was extracted from rabbit hearts, and the extracellular potential was recorded and mapped to draw isochronic lines of conduction on the surface. These lines became stable after 2 hours of perfusion, and drew ellipses extended to the longitudinal direction of the fibers (L-direction). Lidocaine inhibited the L-direction conduction at the stimulating frequency of 2.0 Hz or more, and flecainide showed the similar inhibition within the range of 0.2 to 3.0 Hz. These inhibitions augmented with increase of stimulating frequency. This rate-dependency may result from use-dependent block of Na channel. However, both lidocaine and flecainanide did not inhibit the conduction to the transversal direction of the fibers.
Kurasu 1 Kofuseimyakuyaku Niyoru Shinshitsunai Dendo Yokusei to Shinkin Seni Soko (Effects of Class 1 Antiarrhythmic Drugs on the Intraventricular Conduction: Influence of Fiber Orientation)