Related Experiment Video
Updated: Sep 25, 2026
Evaluation of Coronary Flow Reserve After Myocardial Ischemia Reperfusion in Rats
Published on: June 28, 2019
[Discrepancy between the blood flow in hyperperfused epicardial coronary vessels and myocardial microcirculation
Jin-hua Feng1, Wen-chao Ou, Jian Liu
1Department of Cardiology, Nanfang Hospital, First Military Medical University, Guangzhou 510515, China.
Insights
Reactive hyperemia (RH) following short-term ischemia shows a mismatch between epicardial coronary blood flow (ECBF) and myocardial microcirculation (MMC). ECBF increases significantly more than MMC during reperfusion.
Area of Science:
- Cardiovascular Physiology
- Hemodynamics
- Myocardial Ischemia Research
Context:
- Investigating hemodynamic responses post-myocardial ischemia is crucial for understanding cardiac recovery.
- Reactive hyperemia (RH) is a known phenomenon after ischemia, but its differential effects on epicardial and microcirculatory flow require further elucidation.
- Canine models provide a valuable platform for studying coronary circulation dynamics.
Purpose:
- To examine the hemodynamic alterations in epicardial coronary blood flow (ECBF) and myocardial microcirculation (MMC) during RH after 2-minute ischemia.
- To compare the dynamic changes in ECBF and MMC during reperfusion.
- To identify potential discrepancies between epicardial and microcirculatory responses.
Summary:
- This study utilized Doppler flowmetry and myocardial contrast echocardiography in canines subjected to 2-minute left anterior descending coronary artery occlusion.
- Measurements of ECBF and MMC were taken before, during, and after reperfusion to assess hemodynamic changes.
- Results revealed that while both ECBF and MMC exhibited hyperemic responses, ECBF showed a significantly greater peak flow increase, indicating a mismatch.
Impact:
- The findings highlight a discrepancy between epicardial and microcirculatory flow during RH after short-term ischemia.
- This mismatch suggests mechanisms involving capillary recruitment and shunt opening, potentially altering myocardial perfusion reserve.
- Understanding these differential responses is vital for developing targeted therapeutic strategies for ischemic heart disease.
Objective:
To investigate the hemodynamic changes in the epicardial coronary blood flow (ECBF) and myocardial microcirculation (MMC) during reactive hyperemia (RH) in response to reperfusion following 2-min ischemia in the left anterior descending coronary artery of canines.
Methods:
Twelve adult mongrel dogs were used, whose left anterior descending coronary artery was separated and ligated for 2 min twice below the first branch. The heart rate, systolic blood pressure, diastolic blood pressure, mean blood pressure, ECBF and MMC were measured respectively before and after the ligation and at 5, 10, 15, 30, 45, 60, 90 and 120 s after reperfusion. ECBF was determined with Doppler coronary flowmeter and MMC derived from the ultrasonic intensity measured by myocardial contrast echocardiography.
Results:
During the course of RH, ECBF and MMC both evinced responses to hyperperfusion but in manners different in view of their hemodynamic changes, demonstrating the mismatch between them in this condition. ECBF exhibited a much higher peak flow increase than MMC.
Conclusions:
RH occurs in response to reperfusion after short-term (2 min) myocardial ischemia, when the discrepancy arises between ECBF and MMC. The primary mechanism might involve the recruitment of the capillaries and the opening of the shunt through the capillaries, and as a consequence, the myocardial perfusion is increased at the cost of decreased reserve of the coronary microcirculation.
