Korotkoff sound: the cavitation hypothesis.

Blood pressure is universally measured by the auscultatory method, but the origin of the Korotkoff sounds remains controversial. A reproducible, brief and high amplitude signal, simultaneous to the Korotkoff sound, and instantly followed by the systolic wave, was recorded amongst ten healthy subjects by a pulsed Doppler examination during the deflation of the sphygmomanometer. A device simulating the brachial artery was also built in order to reproduce the high amplitude signal. It is explained by the cavitation phenomenon which takes place when the blood changes to vapor due to the release of the cuff pressure. With the incoming flow, the cavitation bubbles collapse and the energy is released as noise.