[Lesions of the right branch of the bundle of His. Clinical, electrocardiographic and histologic study of 33 cases].

The topography and severity of lesions of the right branch of the bundle of His have been studied as a function of the electrocardiographie changes and the associated heart disorder in 33 cases with more than 50% of the fibres destroyed. It appears that lesions of the right branch of the bundle of His, while severe and diffuse in cases of chronic complete right branch block, were severe but localised in 5 of the 6 cases with a stable incomplete right block. Total, subtotal or partial destruction of the right branch of the bundle of His was associated with lesions of the A-V node and/or the main truck of the bundle of His in the five cases with a complete atrio-ventricular block. The lesions of the right bundle branch involved the superior, middle and inferior portions in the case of aortic valve lesions, the middle portion in mitral valve disease, and the inferior portion in those with myocardial infarction. Ventricular hypertrophy seems to play an important in deciding whether the axis of the QRS, complex is left or right.