血循環結構與血液壓力波分佈相關性的探討

Abstract

我們透過理論計算和水管實驗模擬探討動脈系統。以徑向振動血液壓力波動方程式計算末端封閉的TY 型、TO 型和T 型主動脈系統的天然頻率和血液壓力波分佈，並探討血液壓力脈波響應各諧頻分佈和左心室輸血時間佔整個心跳週期的比例的關係。我們以不同材質的乳膠管模擬主動脈血管，並透過電腦設定控制訊號驅動步進馬達輸出脈衝水量或週期水量模擬心臟的血液輸出。我們發現兩種不同材質的水管相接成T 型或TY 型時，當兩種水管的長度比例和兩者的波速比例相同時，水管系統的各個天然震盪頻率會是整數倍(諧頻)。TO 型和TY 型主動脈系統的天然頻率和血液壓力波分佈是一致的。在主動脈系統中，血液壓力脈波響應各諧頻分佈會和左心室輸血時間佔整個心跳週期的比例有關，且當血液壓力波以不同頻率的供水輸入，發現在一些特定頻率時壓力脈波響應有峰值。The blood pressure wave of different structures of ventricular-arterial system was studied theoreticallyand by tube simulations. The natural frequencies and the pressure distributions of the T、TY、TO arterial systems were predicted by solving the blood pressure wave equation. The effect of heart on the blood pressure response in the arterial system was analyzed. We used latex tubes to simulate the arterial system, and a pump driven by PC controlled stepping motor to simulate the heart. A T shape system (or a symmetric TY shape system) is constructed by connecting two different kind of elastic latex tubes. When the ratio of the length for the two latex tubes is proportional to the ratio of their pressure wave velocity, the natural frequencies of the system are in harmonics. The natural frequencies and the pressure distributions of the TY system and the TO system are similar. The harmonic components of the blood pressure response in the arterial system are correlated with the ejection time of the left ventricle. And the pressure response of the tube attains extreme values for some particular pumping frequencies.