Determination of aortic valve efficiency through vortex physical parameters in normal, regurgitate, and stenotic valve by using Doppler-mode echocardiography
Background and objective: Doppler ultrasound technique has been proposed as a noninvasive means of quantifying diastolic and systolic cardiac function by measuring flow propagation into the left ventricle and ejection blood to the body. The relationship between Doppler-derived parameters and underlying fluid dynamics is still unclear.
Methods: The purpose of this study is to deduce effective physical parameters used in measuring the change in the geometrical shapes of the aortic valve leaflets during the vortex formation. These parameters are defined as the “Blockage factor, Strouhal number and Formation number”. One hundred fifty subjects were selected; The B-factor was correlated with Strouhal number and Formation number for 100 normal aortic valve subjects, and 50 abnormal subjects divided equally into regurgitate (25), and stenotic aortic valve (25), other physical parameters are also calculated. Doppler Echocardiography technique as a noninvasive technique that provides unique hemodynamic information which can not be achieved by any other means.
Results: The accuracy of the results depends, however, on meticulous technique and an understanding of Doppler principles and flow dynamics. This technique recommended through scientific literature. It has been found that the mean values and standard deviation of (ST-No) and (F-No) for normal aortic valve are (l.55 ± 0.55) and (10.12 ± 3.16), regurgitate (2.823± 0.992) and (5.722± 1.68), and for stenotic aortic valve subjects are (0.939± 0.14) and (l5.82± 2.20) respectively.
Conclusion: The results show that (St-No) of normal aortic valve is larger than that for stenotic, which may indicate that the inertial effects of normal valve are larger than those of stenotic valve. This because pressure energy is expanded to overcome inertia rather than converted solely to kinetic energy. The results obtained showed significant elevation of (ST-No) with aortic valve dimensions, and the improvement in efficiency decreases with increasing Strouhal number. A significant elevated (F-No) has been also noted to be increased with aortic valve area. The study of the Formation number and Strouhal number' is important to determine the severity of the stenotic and regurgitate aortic valve and gives a good parameters that can be used in medical diagnosis.
Robin Shandas. “Literature Review for numerical simulation of vortex ring field”. Dept. of mechanical engineering, University of Colorado at Boulder. l998; p:1-12.
Gharib, M., Rambod, E. & Shariff, K. “A universal time scale for vortex ring formation”. J. Fluid Mech. 360. 1998; p: 121-140.
Marsha, J. Berger. "Coherent locomotion as an attracting state for a free flapping body" J. Fluid Mech. 2004; pp 180-186
Crow S. C. and Champagne, F. H. "Orderly structures in jet turbulence" J. Fluid Mech. 1971; P: 547-548.
Yule A. J. “Large-scale structures in the mixing layer of a round jet” J. Fluid Mech. 1978; Pp 389-413
Lasheras J. C, Cho J. S. and Maxworthy T. “On the origin and evolution of stream- wise vertical tructures” . J. Fluid Mech. 1986; P: 230-271.
Martin J. E. and Meiburg E. “Numerical investigation of three-dimensionally evolving jet subject to ax symmetric and azimuth perturbations plane free shear-layer”. J. Fluid Mech. 1991; P: 172-231.
Becker H. A. and Masaro T. A. “Vortex evolution in a round jet”. J. Fluid Mech. (1968). Pp 31-35
Agui J. C. and Hesselink, L. “Flow visualization and numerical analysis of a coflowing jet: a three-dimensional Approach”. J. Fluid Mech. 1988; P: 191-195.
Mahboba M. H., Younis A-R. S., and Al-Dabbag MR. “A correlation Between the Amplitude, Duration of Aortic Valve Separation, and Left Ventricular Stroke, Volume”. Ph. D. thesis submitted to College of Medicine – Al-Mustansyria University. 1998.
Gumark, E. and Ho, C. M., “Preferred modes and the spreading rates of jets”. J. Physics Fluids 1983; 26: 29-32.
Kelman G. R. “Applied Cardiovascular physiology”. 2nd ed. Butter-worth London-Boston. 1977
Taylor G., Nudds, R., and Thomas, A. L. R. “Flying and swimming animals cruise at a Strouhal number turned for high power efficiency”. J. Nature. 2003; P: 425-707.
John D. Enderle, Susan M., Blanchard Joseph D., Bronzing. “Introduction to Biomedical Engineering”. Academic press. 2003; P: 524-527.
Gharib, M., Rambod, E., Dabiri, D., Hammache, M., Shiota, T., and Sahn, D., “Pulsatile Heart Flow: A Universal Time Scale". 1997.
Harvey Feigenbaum, M.D "Echocardiography" 2nd ed. Lea and Febig Philadelphia. 1976; P:142-143.
Johannes M.A. Stijnen. “Interaction between the mitral and aortic heart valve: an experimental and computational study”. – Eindhoven : Technische Universiteit Eindhoven. Proefschrift. – ISBN 90-386-2566-9 NUR 954. Universiteitsdrukkerij TU Eindhoven, Eindhoven, the Netherlands. 2004; P: 1-114.
The copyright on any article published in Zanco J Med Sci is retained by the author(s) in agreement with the Creative Commons Attribution Non-Commercial ShareAlike License (CC BY-NC-SA 4.0).