Aortic stenosis is a common valvular disease. In clinical practice, cardiac catheterization is often used to assess the severity of aortic valve stenosis. However, in conducting catheterization, the precise position of the catheter tip is often not known or controlled. From the standpoint of hydrodynamics, the position of the catheter tip may affect pressure measurement due to the complicated flow fields distal to the valve. This fact is particularly true when the diagnosed valve is stenotic. The objective of this study, using an in vitro model, was to investigate the flow fields in the vicinity of varying degrees of aortic valve stenosis. Additionally, the effect of the catheter-tip position in cardiac catherization on assessing the severity of aortic valve stenosis was analyzed. In the study, laser flow visualization was used to investigate the flow fields, and a pressure transducer with a side-hole catheter was employed to measure pressures. In the flow visualization study, jet-type flows were observed distal to the stenotic valves. A higher degree of valvular stenosis corresponded to a higher velocity jet. As the flow traveled downstream, the jet-type flow expanded and its velocity decreased. Furthermore, the flow turbulence distal to the valve grew with increasing degree of valvular stenosis. In the catheterization study, some degree of pressure recovery was observed along the axial direction for all the cases studied. The magnitude of pressure recovery increased as the valve became more stenotic. However, there was no significant variation in transvalvular pressure drop measured along the radial direction for all the cases studied (p<0.05). The results of this study show that the pressure recovery along the axial direction distal to a stenotic valve may cause significant underestimation of pressure drop measured by catheterization. However, the position of the catheter-tip along the radial direction in catheterization does not seem to affect pressure drop measurement.
關聯:
JOURNAL OF THE CHINESE INSTITUTE OF CHEMICAL ENGINEERS
