人体体循环输入阻抗的T-Y型管模型

T-Y Tube Model of Human Ascending Aortic Input Impedance

本文提出了模拟人体体循环输入阻抗的T－Y型管模型，它是O‘Rourke[1]提出的，柳兆荣等[2]发展的非对称T型管模型的改进和推广．我们在非对称T型管基础上加添了代表人体两条腿的倒Y字型分叉管，从而形成了T－Y型模型，同时将模型中所有分支管都处理成具有纵向约束的粘弹性管，上肢终端小动脉床采用弹性腔模型，下肢终端小动脉床则采用传统的纯阻力形式．选取了适当参数值后，计算了正常生理情形下和高血压病理情形下的人体体循环的输入阻抗．结果显示理论模拟值和实测结果无论是生理情形或是病理情形都有良好的符合程度．T－Y型管模型比非对称T型管模型更接近人体体循环的生理结构．同时又比过份复杂的多重分叉管模型简单明了得多，因此在考察各种参数对升主动脉输入阴抗的影响．研究心室和血管的耦合机制中将是一个有实用价值的模型．

This paper proposed a T-Y tube model to simulate the input impedance ofarterial system. It improved and extended the asymmetric T-tube model whichwas firs t proposed by O'Rourke[1] and developed later by Liu et al. [2]. Based onthe asymmetric T-tube model, a T-Y tube model was proposed by adding branching tubes which represent the iliac arteries. All the tubes are considered tobe uniform, viscoelastic, longitudinally tethered cylindrical tubes. The uppertube terminates with a windkessel model, while the terminal arterioles of thelower tube are expressed as a resistance. After proper evaluation of the parameters, the impedance of the arterial system is calculated under normal physiological and hypertensive condition. The model can predict impedance in goodagreement with the experimentally obtained data no matter in normal physiological condition or in pathological condition. In comparison with the asymmetricT-tube model, T-Y tube model is closer to anatomy structure of the humanarterial system and at the same time much simpler than the extremly complexmultiple-branching tube model. Therefore it will be a valuable model in studying the influences of various parameters on aorta impedance and ventricular vascular coupling.