Intermittent complete left bundle-branch block: phonocardiographic and mechanocardiographic study of one case.

Since the work of Wolferth and Margolies (1935), the modifications of both the heart sounds and the sequence of ventricular events induced by left bundle-branch block have been well known.Yet there has been some disagreement on details, mainly because left bundle-branch block is seldom aft isolated abnormality.The opportunity was offered to record the heart sounds, the indirect carotid pulse, and the apex cardiogram in the same patient, in conditions of both normal and abnormal left intraventricular conduction, making it possible to describe the changes due to the complete bundle- branch block alone. METHODThe electrocardiogram, phonocardiogram, indirect carotid pulse curve, and the apex cardiogram were recorded with a photographic 4-channel Hellige Multicardiotest.The phonocardiogram, dissociated into three frequency bands, low, medium, and high, ranging respectively from 5 to 50, 25 to 150, and 50 to 250 cycles per second, was taken successively from three areas, apical, pulmonary, and aortic, simultaneously with the electrocardiographic lead I. Next, these same phono- cardiograms (low and high frequencies only) and electro- cardiographic lead I were recorded either with an in- direct carotid pulse curve (capacitance transducer Infraton-E system) or with an apex cardiogram (piezo- electric crystal transducer).Paper speed was 50 mm.per second with 0-02 sec.intervals between the vertical lines.The following time intervals were measured after Tafur, Cohen, and Levine, 1964 (Fig. 1).(1) Electromechanical interval (EMI) from the onset