Rapid method for determination of shunt ratio using a thermodilution technique

Area of Science:

• Cardiology
• Medical Devices
• Diagnostic Techniques

Background:

• Left-to-right intracardiac shunts are common congenital heart defects.
• Accurate measurement of shunt ratio is crucial for clinical management.
• Existing methods for shunt ratio determination can be time-consuming or invasive.

Purpose of the Study:

• To introduce and validate a new thermodilution technique for rapid and convenient determination of shunt ratio in patients with left-to-right intracardiac shunts.

Main Methods:

• A flow-directed balloon-tip thermistor catheter was used to measure cardiac output in 20 patients.
• Thermodilution curves were analyzed, extrapolating the first-pass curve before early recirculation.
• Shunt size was calculated using the ratio of areas under the thermodilution curve (A+B):A.

Main Results:

• The new thermodilution technique (Qp:QSTh) showed good correlation with the Fick technique (Qp:QSF), with r = 0.89.
• The method demonstrated a shunt ratio range from 1.3:1 to 3.6:1.
• Early recirculation was observed and accounted for in the thermodilution curve analysis.

Conclusions:

• The described thermodilution technique is a simple, rapid, and accurate method for quantifying left-to-right intracardiac shunts.
• This approach offers a valuable alternative for clinical assessment of shunt magnitude.
• Further validation in larger patient cohorts may be warranted.