Tu C, Peskin C S
Courant Institute of Mathematical Sciences, New York, NY 10012.
Comput Biol Med. 1989;19(2):95-128. doi: 10.1016/0010-4825(89)90003-6.
This paper uses a mathematical model of the circulations to study the hemodynamics of transposition of the great arteries (TGA) with comparison to ventricular septal defect (VSD). Computer experiments are conducted to determine the influence of the defect conductance and the pulmonary vascular conductance on the pulsatile pressures, flows, and oxygen concentrations of the circulation. In particular, the model is used to determine the waveform of the (possibly bidirectional) shunt through the ventricular and atrial septal defects. The results of the computer experiments consist of two parts. The first set of experiments is devoted to the comparison of VSD and TGA with a ventricular septal defect. The results are theoretical in the sense that most parameters have been fixed at the same levels. In each case TGA is represented by changing the connection of the chambers and reversing the compliance of the two ventricles. In the second set of experiments we attempt to simulate conditions clinically observed in a variety of cases of TGA. In each case we use clinical observations to infer parameters as the input to the model. We find that the model (with appropriate choice of parameters) generally exhibits blood pressure, blood flows and oxygen concentrations similar to the clinical observations. As a byproduct of these computer experiments we predict the effects of changing the pulmonary conductance. The comparison between TGA and VSD shows that as the defect conductance increases, the systemic oxygen concentrations decrease in VSD and increase in TGA. Even at large defect conductance, the two conditions remain distinct, however, since the mixing of the right and left ventricular blood pools is incomplete. This phenomenon of incomplete mixing sets quantitative limits on the benefits that can be achieved by surgical enlargement of the defect. A result of this study that may be useful in the management of TGA patients with a ventricular septal defect is the finding that there is a value of the pulmonary conductance that maximizes the effective flow and hence the systemic oxygen concentrations. The optimal pulmonary conductance is approximately equal to the systemic conductance when the defect is large.
本文使用循环系统的数学模型来研究大动脉转位（TGA）的血流动力学，并与室间隔缺损（VSD）进行比较。通过计算机实验来确定缺损传导率和肺血管传导率对循环系统搏动压力、血流和氧浓度的影响。特别地，该模型用于确定通过室间隔和房间隔缺损的（可能双向的）分流波形。计算机实验结果分为两部分。第一组实验致力于比较VSD和合并室间隔缺损的TGA。这些结果是理论性的，因为大多数参数都固定在相同水平。在每种情况下，通过改变腔室连接并反转两个心室的顺应性来表示TGA。在第二组实验中，我们试图模拟各种TGA病例中临床观察到的情况。在每种情况下，我们利用临床观察来推断参数作为模型的输入。我们发现该模型（在适当选择参数的情况下）通常表现出与临床观察相似的血压、血流和氧浓度。作为这些计算机实验的副产品，我们预测了改变肺传导率的影响。TGA和VSD之间的比较表明，随着缺损传导率增加，VSD中的体循环氧浓度降低，而TGA中的体循环氧浓度升高。然而，即使在大缺损传导率情况下，这两种情况仍然不同，因为右心室和左心室血池的混合不完全。这种不完全混合现象对通过手术扩大缺损所能获得的益处设定了定量限制。这项研究的一个可能对合并室间隔缺损的TGA患者管理有用的结果是发现存在一个肺传导率值，该值可使有效血流量最大化，从而使体循环氧浓度最大化。当缺损较大时，最佳肺传导率大约等于体循环传导率。
