Shunt quantification by mathematical analysis of indicator dilution curves

Area of Science:

• Cardiovascular physiology
• Biomedical engineering
• Medical modeling

Background:

• Intracardiac and great vessel shunts are common in congenital heart defects.
• Accurate quantification of shunts is crucial for patient management.
• Traditional methods may have limitations in precision or applicability.

Purpose of the Study:

• To develop and validate mathematical models for analyzing indicator dilution curves in patients with shunts.
• To simulate various shunt configurations (left-to-right, right-to-left, bidirectional).
• To compare shunt fractions derived from thermodilution curves with oximetric measurements.

Main Methods:

• Utilized linear system block models to represent circulatory segments.
• Developed a shunt analysis algorithm based on discrete analogs of these models.
• Implemented the algorithm in a computer program for analyzing thermodilution curves.

Main Results:

• Left-to-right shunt fractions showed excellent agreement with oximetric data (mean difference 0.7% of pulmonary flow, SD 7.6%).
• Reasonable shunt fractions were computed for bidirectional shunts in preliminary cases.
• Good agreement with oximetric data was observed in two cases with complete bidirectional shunt data.

Conclusions:

• The developed mathematical models provide a reliable method for analyzing indicator dilution curves to quantify intracardiac shunts.
• The approach demonstrates high accuracy for left-to-right shunts.
• Further data are needed for robust statistical validation of the bidirectional shunt analysis, but initial results are promising.