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August 28, 1967

The Delay in the Korotkoff Sounds in Left Bundle-Branch Block

Author Affiliations

From the Division of Medicine, Department of Cardiology and Cardiac Research, City of Hope Medcial Center, Duarte, Calif (Drs. Libanoff and Rodbard), and the University of Southern California School of Medicine, Los Angeles (Dr. Rodbard).

JAMA. 1967;201(9):666-670. doi:10.1001/jama.1967.03130090030007

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.