• 作者： Sung, Hsing-Wen; Yu, Pei-Shin
• 中文摘要： 主動脈瓣狹窄是一種常見的心臟瓣膜疾病,臨床上診斷主動脈瓣狹窄的程度通常是以導管量測的壓力差為依據。然而在測量的過程中,醫生們不易知道導管探頭的實際位置,而以流體力學的觀點來看,導管探頭所在的徑向與軸向位置可能會影響到壓力量測的準確性。為了幫助醫生們瞭解診斷主動脈瓣狹窄程度的壓力量測準確性,我們以體外模型實驗的方式觀察不同狹窄程度瓣膜所產生的流場,以及量測導管在不同軸向和徑向位置的壓力差。在視流觀察方面,我們發現瓣膜狹窄程度愈嚴重其所產生的流場也愈複雜; 在壓力差量測方面,我們發現軸向位置對壓力量測的影響隨著瓣膜狹窄程度的不同而有極大的變化,而徑向位置則影響甚微。
• 英文摘要： 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.
• 中文關鍵字： 主動脈瓣狹窄; 白努利原理; 導管; 壓力回復; 軸向壓力降
• 英文關鍵字： Aortic Valve Stenosis; Bernoulli Theorem; Catheterization; Pressure Recovery; Transvalvular Pressure Drop