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.