A means for the indirect definition of the calibrated, timed contour of the leading edge of the pattern of the Korotkoff sounds was used to examine the timing of the pressure wave in 30 patients with cardiac disease. Following the onset of the QRS complex (Q) of the electrocardiogram in normal subjects, the Korotkoff sounds (K) in the brachial artery at diastolic pressure (QKd) appeared at 195 ± 18 msec. The QKd was earlier than normal in patients with arteriosclerosis or subaortic muscular stenosis; QKd was delayed in subjects with myocardiopathies. The appearance of left bundle-branch block (LBBB) in these patients was associated with a delay in the QKd of approximately 60 msec. The QKd was delayed by 40 to 90 msec during episodes of intermittent LBBB in four subjects, with return to earlier values when conduction returned to normal patterns.
Libanoff AJ, Rodbard S. The Delay in the Korotkoff Sounds in Left Bundle-Branch Block. JAMA. 1967;201(9):666–670. doi:10.1001/jama.1967.03130090030007