By recording the arterial sounds of sphygmomanometry simultaneously with a reference electrocardiographic tracing, an objective index of the vascular disturbance resulting from subclavian artery stenosis is obtained. This technique (sphygmorecording) records the time of appearance of the Korotkoff sounds in each beat, and the intensity and duration of these sounds. The slope and contour of the arterial pressure upstroke is displayed as the leading edge of the sequence of sounds. In normal subjects, the arterial sounds of the two brachial arteries at each pressure level appear within 10 msec of each other, and the derived arterial pressure contours are identical. Subclavian artery stenosis in four patients was studied by catheterization, angiography, and sphygmorecording. The severity of the obstruction may be estimated from the difference in the timing and intensity of the brachial arterial sounds.
Rahman A, Rodbard S. Timing of the Arterial Sounds in the Subclavian Steal Syndrome. Arch Intern Med. 1970;125(6):1027-1029. doi:10.1001/archinte.1970.00310060105012