Simplification of continuous intracoronary thermodilution

Area of Science:

• Cardiovascular physiology
• Medical imaging and diagnostics
• Interventional cardiology

Background:

• Continuous intracoronary thermodilution accurately measures coronary blood flow (Q) and microvascular resistance (Rμ).
• Current methods require manual operator adjustment of the saline infusate entry temperature (Ti), introducing potential variability.
• Operator dependence can complicate the precise measurement of coronary blood flow.

Purpose of the Study:

• To develop and validate a method for predicting Ti without operator intervention.
• To simplify continuous intracoronary thermodilution for operator-independent coronary blood flow assessment.
• To maintain the accuracy of volumetric blood flow (Q) calculations.

Main Methods:

• A multivariate linear regression model was derived in 371 patients to predict Ti based on known parameters.
• The predictive equation was validated in 120 patients by comparing standard Q (measured Ti) with simplified Q (predicted Ti).
• Accuracy was further assessed by comparing simplified Q with [15O]H2O positron emission tomography (PET)-derived Q in 23 patients.

Main Results:

• Simplified Q showed strong agreement with standard Q (r=0.94, ICC=0.94) and excellent agreement with PET-derived Q (r=0.86, ICC=0.84).
• No significant differences were found in correlation coefficients or standard deviations of absolute differences compared to standard Q.
• The derived equation for predicting Ti demonstrated high accuracy and reliability.

Conclusions:

• Predicting Ti offers an accurate and reliable method for assessing coronary blood flow.
• This approach significantly simplifies continuous intracoronary thermodilution.
• The method renders absolute coronary flow measurements completely operator independent, improving consistency and ease of use.