For many years the intraventricular conduction system had been considered as only two branches consisting of right and left bundle branches. Right bundle branch block and left bundle branch block have been known as distinct electrocardiographic entities for decades. Various investigators recognized and described other forms of intraventricular conduction block and coined various names for them (12). There were, however, no clearcut anatomic., physiologic., and electrocardiographic descrip tions of these various electrocardiographic entities. They, therefore, existed as curiosities without implying useful information for the clinician. In 1967, Rosenbaum and colleagues published their text Los Hemibloqueos, which clearly documented, described and demonstrated significance for electrocardiographic patterns signifying blocks in subdivision of the left bundle branch system. These included and superseded to a great extent many of the previously described, partial intraventricular conduction blocks. Since their publication the term, blhemiocks has become a unique and popular electrocardiographic term. There still exists a debate over (a) the real anatomic nature of the intraventricular conduction system and (b) over the true clinical implications of the various forms of hemiblocks. In this Chapter, the purpose is to explore what is known about hemiblocks and what implications this knowledge holds for the clinicians.
KeywordsLeft Bundle Branch Block Versus Node Right Bundle Branch Block Versus Block Cardiac Conduction System
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