Intermittent Bundle-Branch Block

INTERMITTENT bundle-branch block, a not uncommon electrocardiographic finding, is encountered mainly in elderly people or patients with organic heart disease.1Rarely it is found in a person with an otherwise normal heart,2though its mere presence is taken by some3to be evidence of heart disease. The rarity of this condition in the absence of heart disease was borne out by the study of Comeau, Hamilton, and White3wherein they found only 6 patients of a total of 77 with intermittent bundle-branch block in whom myocardial disease could not be implicated. In reviewing the pertinent medical literature since Comeau's analysis, Sandberg and co-workers4reached a similar conclusion; they found that only 6 patients of a total of 82 with intermittent bundle-branch block had no apparent heart disease. Because of the underlying disease in patients with this condition, the conducting system becomes so modified that a point is reached where even