[Discrepancy between the blood flow in hyperperfused epicardial coronary vessels and myocardial microcirculation following reperfusion: a study in canines].
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.
Feng
Jin-hua
JH
Department of Cardiology, Nanfang Hospital, First Military Medical University, Guangzhou 510515, China.
Ou
Wen-chao
WC
Liu
Jian
J
Bin
Jian-ping
JP
Zha
Dao-gang
DG
Liu
Yi-li
YL
D000818:Animals; D001794:Blood Pressure; D003326:Coronary Circulation; D004285:Dogs; D005260:Female; D006339:Heart Rate; D008297:Male; D008833:Microcirculation; D015425:Myocardial Reperfusion