SYN: divisional block.
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hemi·block 'hem-i-.bläk n inhibition or failure of conduction of the muscular excitatory impulse in either of the two divisions of the left branch of the bundle of His
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hemi·block (hemґe-blok) failure in conduction of the cardiac impulse in either of the two main divisions of the left ventricular conducting system (bundle of His); it is called left anterior hemiblock when the anterior-superior division is interrupted and left posterior hemiblock when the posterior division is interrupted.
Left anterior hemiblock showing marked left axis deviation without significant widening of the QRS duration.
Medical dictionary. 2011.