Velocity detection of Korotkoff sounds

High-speed oscillograms were made showing the time relationships between the ECG and arterial pressure waves detected by three microphones successively placed beneath a standard blood pressure cuff along the brachial artery. As the cuff was deflated through the systolic/diastolic range, the indicated propagation velocity of the Korotkoff waves changed from approximately 1 m/sec near systolic pressure to about 2.5 m/sec near diastolic pressure. Non-Korotkoff waves (noise artifacts), on the other hand, were observed to propagate at much higher velocities, on the order of 5-10 m/sec. This phenomenon can be utilized to identify Korotkoff waves in the presence of other disturbances, particularly in exercise situations, and to determine diastolic pressure in the presence of arterially conducted valve and turbulence noise.