group of cells that leak sodium. A slow influx of sodium leads to a less negative resting membrane potential. This leads to inactivation of fast sodium channels, spontaneous depolarizations, and an action potential threshold of -40mV due to ion movement across slow calcium channels. SA impulses go to the AV node. Lower fibers of the AV node form the common bundle of His which pass to the interventricular septum and divide into left and right branches forming the Purkinje fibers which depolarize ventricles (Morgan & Mikhail, 1996). Lidocaine controls the ventricular arrhythmias suppressing automaticity in the His-Purkinje system. It suppresses spontaneous depolarization of the ventricles. It is thought to combine with fast sodium channels while in their inactive state and inhibit recovery following repolarization in a time- and voltage-dependent manner (Medscape, 2001).
Local anesthetics reversibly block the conduction of nerves near the
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