An ultrasonic method for noninvasive estimation of vascular impedance to an absolute level: in vitro validation of the relationship between impedance and phase velocity

Vascular impedance is a quantity that characterizes the properties of the vascular bed. Assuming Newtonian fluid, laminar flow and linear system, impedance is related to phase velocity. The agreement between theoretical relationship and measured data is evaluated in an in vitro study. The setup consist of a computer-controlled flow generator, a variable fluid impedance and a measuring section. Phase velocity is calculated from multiple recorded vessel pulsations detected by ultrasonic pulse-echo technique. The reference impedance is calculated from simultaneously measured high-fidelity pressure and flow data. The impedance is analyzed in the range of 1-40 Hz with 1-Hz resolution. The evaluation of the noninvasive ultrasonic technique is focused on the resonance frequencies and the characteristic impedance. No significant difference (p>0.05) is found in the resonance frequencies nor in the characteristic impedance. However, the impedance below 5 Hz is underestimated and the extension of the measuring section causes spatial averaging effects with reduced frequency resolution.

[1]  G. G. Stokes.  "J." , 1890, The New Yale Book of Quotations.

[2]  J. Tarbell,et al.  Measurement of oscillatory flow pressure gradient in an elastic artery model. , 1995, Biorheology.

[3]  N. Westerhof,et al.  Forward and backward waves in the arterial system. , 1972, Cardiovascular research.

[4]  B. L. Langille,et al.  Pressure wave propagation and input impedance in thoracic aorta of conscious newborn sheep. , 1995, The American journal of physiology.

[5]  W E Walker,et al.  Input Impedance of the Systemic Circulation in Man , 1977, Circulation research.

[6]  W. Mccomb,et al.  The physics of fluid turbulence. , 1990 .

[7]  D Bergqvist,et al.  Non-invasive measurement of pulsatile vessel diameter change and elastic properties in human arteries: a methodological study. , 1993, Clinical physiology.

[8]  D. Farrar,et al.  Large Vessel Impedance in Peripheral Atherosclerosis , 1977, Circulation.

[9]  M F O'Rourke,et al.  Vascular impedance in studies of arterial and cardiac function. , 1982, Physiological reviews.

[10]  W. Laskey,et al.  Characteristics of vascular hydraulic load in patients with heart failure. , 1985, Circulation.

[11]  R S Reneman,et al.  A noninvasive method to estimate arterial impedance by means of assessment of local diameter change and the local center-line blood flow velocity using ultrasound. , 1996, Ultrasound in medicine & biology.

[12]  J. Tarbell,et al.  Nonlinear analysis of oscillatory flow, with a nonzero mean, in an elastic tube (artery). , 1995, Journal of biomechanical engineering.

[13]  M. O'Rourke.  Impact pressure, lateral pressure, and impedance in the proximal aorta and pulmonary artery. , 1968, Journal of applied physiology.

[14]  E A Geiser,et al.  Vascular load defined by the aortic input impedance spectrum. , 1980, Federation proceedings.

[15]  J P Shillingford,et al.  Pressure-flow relationships and vascular impedance in man. , 1970, Cardiovascular research.

[16]  Aaas News,et al.  Book Reviews , 1893, Buffalo Medical and Surgical Journal.

[17]  J. Womersley.  Method for the calculation of velocity, rate of flow and viscous drag in arteries when the pressure gradient is known , 1955, The Journal of physiology.

[18]  M. G. Taylor,et al.  Use of Random Excitation and Spectral Analysis in the Study of Frequency‐Dependent Parameters of the Cardiovascular System , 1966, Circulation research.

[19]  R. D. Latham,et al.  Regional wave travel and reflections along the human aorta: a study with six simultaneous micromanometric pressures. , 1985, Circulation.

[20]  D. Cox,et al.  An Analysis of Transformations , 1964 .

[21]  D. A. Mcdonald,et al.  Use of Fourier series for the analysis of biological systems. , 1966, Biophysical journal.

[22]  M. O'Rourke.  Arterial Hemodynamics in Hypertension , 1970, Circulation research.

[23]  D. A. Mcdonald,et al.  The relation of pulsatile pressure to flow in arteries , 1955, The Journal of physiology.

[24]  Evaluation of a three point pressure method for the determination of arterial transmission characteristics. , 1980, Journal of biomechanics.

[25]  W. Milnor,et al.  Arterial impedance as ventricular afterload. , 1975, Circulation research.

[26]  B. Sonesson,et al.  Sex difference in the mechanical properties of the abdominal aorta in human beings. , 1994, Journal of vascular surgery.

[27]  Non-invasive estimation of vascular impedance , 1996, 1996 IEEE Ultrasonics Symposium. Proceedings.

[28]  A. Fenster,et al.  A geometrically accurate vascular phantom for comparative studies of x-ray, ultrasound, and magnetic resonance vascular imaging: construction and geometrical verification. , 1993, Medical physics.

[29]  D E Dick,et al.  Measurement of Nonlinearity in the Arterial System of the Dog by a New Method , 1968, Circulation research.

[30]  W. Nichols,et al.  Aortic Input Impedance in Heart Failure , 1978, Circulation.

[31]  N Westerhof,et al.  Effects of Exercise on Aortic Input Impedance and Pressure Wave Forms in Normal Humans , 1981, Circulation research.

[32]  H. Schröder,et al.  Input impedance of the lower abdominal aorta in chronically instrumented fetal sheep. , 1994, Circulation research.

[33]  R. Stephenson.  A and V , 1962, The British journal of ophthalmology.