Hydraulic and hemodynamic studies on the blood flow through the cardiovascular system

To investigate the hemodynamic aspects across a stenosis in the cardiovascular system, in vitro, in vivo, and clinical studies were performed. The results are summarized as follows: 1) Remarkable changes in the pressure profile were recognized downstream. The relationship between pressure gradient and flow across the stenotic orifice revealed an inverse linear relationship in in vitro studies, but showed a slight convex curve in in vivo studies. 2) The critical stenosis in vitro and in vivo studies 10% and 25%, respectively. 3) In the group of mitral valve area larger than 0.5 cm2, flow coefficient C was smaller than 1.0 and blood flow could be "vena contracta". 4) Gorlin's formula is considered to be appropriate in the cases with valve area larger than 0.5 cm2. But Gorlin's formula may over-estimate in the group with valve area smaller than 0.5 cm2.