Coronary sinus reflux. A source of error in the measurement of thermodilution coronary sinus flow

Area of Science:

• Cardiovascular Physiology
• Diagnostic Techniques

Background:

• Thermodilution coronary sinus flow (TD-CSF) is used to measure myocardial blood flow.
• Ventricular pacing can influence TD-CSF measurements, but the underlying mechanisms are not fully understood.

Purpose of the Study:

• To investigate the accuracy of TD-CSF during ventricular pacing.
• To determine if right atrial admixture affects TD-CSF measurements.

Main Methods:

• Compared TD-CSF with electromagnetic coronary arterial blood flow (CBF) in dogs.
• Induced interventions that increased right atrial pressure, including ventricular pacing and pulmonary artery constriction.
• Visualized right atrial reflux into the coronary sinus using contrast material.

Main Results:

• TD-CSF was significantly higher than electromagnetic CBF during ventricular pacing and other interventions that increased right atrial pressure.
• Evidence of marked reflux from the right atrium to the coronary sinus was observed.
• The discrepancy between TD-CSF and CBF increased with elevated right atrial pressure.

Conclusions:

• TD-CSF measurements may be unreliable when right atrial pressure is elevated.
• Right atrial admixture into the coronary sinus can falsely inflate TD-CSF values.
• Caution is advised when interpreting TD-CSF in clinical scenarios with altered right atrial pressure.