An experimental approach to quantitative thermal coronary angiography

Area of Science:

• Cardiovascular Surgery
• Medical Imaging
• Biomedical Engineering

Background:

• Coronary artery bypass grafting (CABG) surgery requires intraoperative assessment of graft patency.
• Current noninvasive methods for assessing graft patency are not yet quantitative.
• Accurate intraoperative graft flow assessment is crucial for CABG success.

Purpose of the Study:

• To develop a quantitative method for assessing graft flow during CABG surgery.
• To evaluate the use of thermal coronary angiography to measure myocardial temperature changes induced by graft perfusion.
• To establish a correlation between thermal imaging parameters and actual graft flow rates.

Main Methods:

• Utilized thermal coronary angiography to monitor myocardial temperature changes in response to graft perfusion.
• Perfused saphenous vein grafts (SVGs) to the left anterior descending artery (LAD) with warm saline at varying flow rates (16-105 ml/min).
• Employed a high-resolution thermal scanner and a non-linear fit procedure to calculate the time constant (tau) at each flow rate.

Main Results:

• Demonstrated an increase in myocardial temperature along the LAD corresponding to different graft perfusion flow rates.
• Calculated time constants showed an excellent correlation with actual graft flow rates (r = 0.96, p < 0.0002).
• The time constant derived from thermal imaging provides a reliable estimate of graft flow.

Conclusions:

• Thermal coronary angiography, by measuring perfusion-induced temperature changes, can quantitatively estimate graft flow in CABG surgery.
• The calculated time constant is a strong predictor of actual graft flow.
• Further clinical studies are needed to validate the time constant as a predictive tool for graft flow in patients.