Intermittent Bundle-Branch Block

Abstract

INTERMITTENT bundle-branch block, a not uncommon electrocardiographic finding, is encountered mainly in elderly people or patients with organic heart disease.1 Rarely it is found in a person with an otherwise normal heart,2 though its mere presence is taken by some 3 to 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 White 3 wherein 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-workers 4 reached 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 minor influences on conduction are attended by a change in the form of the ventricular complex. When such a delicate balance exists, anoxemia, tachycardia, or metabolic abnormalities may supply the additional burden to the compromised conduction system and cause bundle branch-block to appear ; anything which then affects conduction in a salutary manner may result in the return of normal intraventricular conduction.The present report deals with that form of bundle-branch block which is char¬ acterized by the appearance of both normal and bundle-branch block complexes in a single electrocardiogram, with fluctuations back and forth between the normal and the abnormal conduction patterns. This form of conduction disturbance has been

Normal QRS Interval in Left Bundle‐branch Block. Review of the Literature and Presentation of a Case*

“…Spontaneous disappearance of left bundle‐branch block of four years' duration in a 56‐year‐old soldier was reported by Kalett (6). Shearn and Rytand (7) made a study of 8 cases of intermittent left bundle‐branch block and stated that this type of block probably represents a transitional stage before the development of permanent block. Gardberg and Rosen (8) restored normal conduction upon stimulation of the carotid sinus in a patient with an initial attack of left bundle‐branch block but no evidence of heart disease.…”