Incomplete bilateral bundle branch block a simplified diagram for its recognition

A simple quantitative diagram for analysis of electrocardiographic tracings suspected of bilateral bundle branch block is presented. It is particularly useful in cases of unequal asynchronous block of the two bundle branches. Four cases in which the diagram was of great help are presented. It is believed that the more widespread use of this diagram will facilitate teaching of the subject of bilateral bundle branch block and unearth many new cases. It is suggested that the diagram be used in cases showing changing QRS complexes, changing P–R intervals and some degree of atrioventricular block or a combination of at least two of these features.