Clinical Studies on the Korotkoff Sound Part III Production mechanismus of the Korotkoff Sound

Abstract

Many theories have been given concerning the occurence mechanismus of the Korotkoff Sound, but they has been no established theory as yet. In an effort to attain a definite theory I carried out my experiment measuring the time relativity of Korotkoff Sound and other hemodynamics, and also made a further study of frequency analysis of the Korotkoff Sound. From the facts is recorded of part 1 and 2 I may say that in the Korotkoff Sound origin there are two different mechanismus, the ton and the murmur origins. The 2nd phase sounds alone are caught as the murmur, which arises when the stoppage of the blood vessel advances to 78-60%, as Gupta-Wigger's report. And when the pressure decreases from a complete stoppage gradually to the degree of 78% with the accompanying widening of the blood vessel, then it is said to have reached Swan's 2nd points, 60% corresponds to Swan's 3rd points, only in the 2nd phase points, between Swan's 2nd and 3rd points, the murmur are caught and as the constriction degree lowers below 60% with the accompanying widening of the blood vessel, they become the 3rd and 4th phase sounds, and only the tones are caught in each point. Murmurs are caused by the vibration of blood stream, and are called the murmurs arising in blood stream. They arise because of the stenotic flow and naturally they are seen conspicuously at the time of distal hyperemia and congestion. And a conspicuous distribution difference of frequency is seen. Next, the tone segment shows nearly the same frequency distribution at both distal hyperemia and congestion, and murmurs arising from the vibration of blood vessels. They are the murmurs arising in vessel walls. The arterial system constitutes a series of Windkessel, but the vibration alone of Windkessel does not originate sounds of high frequency elements. Due to cuff pressure on the brachial artery the vessel becomes partially narrow and the blood flow through this narrowed part increases its velocity, resulting in a decrease of lateral pressure energy and a lowering of lateral pressure while the blood vessel walls come closer together causing a greater contraction. This series of processes continues until the vessel is completely up, when the velocity becomes O and all the energy is utilized as lateral pressure. The next pulse wave reaching the stoppage point will push out the closed vessel with a strong force and at this moment the walls are pushed out causing the so-called flutter of blood vessel walls. This flutter phenomenon together with Windkessel function, and the acoustic effect of cuff pressure, work together to originate the high frequencied yet transient Korotkoff Sound.