Billings R G, Clark J S, Veasy L G, Cutler C A
Cathet Cardiovasc Diagn. 1978;4(2):143-62.
Mathematical models are presented for describing and analyzing indicator dilution curves recorded in patients with intracardiac and great vessel shunts. The models treat individual segments of the circulation as linear system blocks, each having, at its output, a characteristic time response to a rapid injection of indicator at its input. These blocks are combined in feedback and feed-forward configurations to simulate left-to-right, right-to-left, and bidirectional shunts. A shunt analysis algorithm, using discrete analogs of the linear system models, was implemented in a computer program and used to analyze thermodilution curves recorded in patients with congenital heart defects. Results are presented comparing shunt fractions obtained from thermodilution curve analyses with oximetrically determined values in 20 patients. Comparing left-to-right shunts measured by the two methods, the mean systematic difference was 0.7% of pulmonary flow and the standard deviation was 7.6% of pulmonary flow. Statistical validation of the bidirectional shunt method will require acquisition and analysis of more data; however, reasonable shunt fractions were computed in five cases studied and good agreement with oximetric determinations was obtained in two cases where complete oximetric data were available.
提出了数学模型，用于描述和分析心内及大血管分流患者记录的指示剂稀释曲线。这些模型将循环的各个部分视为线性系统模块，每个模块在其输出端对输入端快速注入的指示剂具有特征性的时间响应。这些模块以反馈和前馈配置组合，以模拟左向右、右向左和双向分流。一种使用线性系统模型离散模拟的分流分析算法在计算机程序中实现，并用于分析先天性心脏病患者记录的热稀释曲线。给出了20例患者热稀释曲线分析得到的分流分数与血氧测定值比较的结果。比较两种方法测量的左向右分流，平均系统差异为肺血流量的0.7%，标准差为肺血流量的7.6%。双向分流方法的统计验证需要获取和分析更多数据；然而，在所研究的5例病例中计算出了合理的分流分数，在有完整血氧测定数据的2例病例中，与血氧测定结果取得了良好的一致性。
