Model-based analysis of effects of systolic blood pressure on frequency characteristics of the second heart sound.

Previous studies have shown that it is possible to estimate pulmonary and systemic blood pressure using the spectral information of the second heart sound. A mathematical model for the vibration of the closed aortic valve is proposed in the paper with the introduction of the nonlinear elasticity of the aortic wall tissue. Based on the parametric analysis, the effect of the aortic blood pressure at the moment of valve closure on vibration of aortic valve and produced sound is examined. The simulation results show that the increasing aortic pressure results in an increase in frequency and amplitude of produced sound. The results of this study also suggest that it is the increasing resonant frequency of the blood column induced by elevated distending pressure that plays significant role in the process. The application of the modeling study could be extended to interpret the relations of the second heart sound to pulmonary blood pressure.