The transmission of sound waves in liquid-filled catheter tubes used for intravascular blood-pressure recording

The blood pressure wave-form recorded by a transducer of finite compliance at the end of a liquid-filled tube, is often distorted by acoustic resonance. In most recent publications, e.g.Leraand (1962),Yanov (1963), the theoretical treatment of this problem is based on the dubious asumption that the catheter compliance and the compressibility of the liquid are negligible, and that the system behaves as a simple resonant circuit with one degree of freedom, in which the mass of the fluid, or more correctly its inertance, resonates with the compliance (springiness) of the transducer.