[How much blood flow is required by the myocardium?].
OBJECTIVE
The myocardium of the left ventricle exhibits spatial heterogeneity of blood flow under physiological conditions. This study was designed to investigate, whether oxygen supply is jeopardized in low flow areas (blood flow < 50% of mean) under physiological conditions and whether areas of high flow (> 150% of mean) exhibit perfusion in excess of demand ("luxury perfusion").


METHODS
The study was performed in anesthetized and ventilated beagle dogs. Local blood flow was reduced by mechanically narrowing of the r. circumflexus of the left coronary artery; myocardial blood flow was measured by the tracer-microsphere technique, free concentrations cellular adenosine by the SAH-technique, regional metabolism of substrates by the desoxyglucose-technique.


RESULTS
Low flow areas exhibited normal oxygenation of the myocardium, while in high flow areas no luxury perfusion could be demonstrated.


CONCLUSIONS
Myocardial blood flow and metabolism demonstrate significant spatial heterogeneity. There appears to be no absolute threshold of blood flow, where regional myocardial ischemia develops. Probably biochemical evidence of myocardial ischemia is determined by a local ratio of oxygen supply and demand.
Deussen
A
A
Institut für Physiologie, Medizinische Fakultät Carl Gustav Carus, TU Dresden.
Flesche
C W
CW
Loncar
R
R
D000241:Adenosine / Q000378:metabolism; D000758:Anesthesia; D000818:Animals; D000963:Antimetabolites; D003326:Coronary Circulation / Q000502:physiology*; D003847:Deoxyglucose; D004285:Dogs; D006321:Heart / Q000502:physiology*; D008863:Microspheres; D010477:Perfusion; D012121:Respiration, Artificial
D000963:Antimetabolites; D003847:Deoxyglucose; D000241:Adenosine