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FACTORS REGULATING CORONARY BLOOD FLOW IN THE NORMAL AND DISEASED HEART
Author(s) -
White Saxon W.,
Reid John V. O.
Publication year - 1973
Publication title -
medical journal of australia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.904
H-Index - 131
eISSN - 1326-5377
pISSN - 0025-729X
DOI - 10.5694/j.1326-5377.1973.tb129949.x
Subject(s) - cardiology , medicine , autoregulation , blood flow , blood pressure , hemodynamics , frank–starling law of the heart , pressure gradient , ischemia , heart rate , stroke volume , physics , mechanics
Phasic changes in intramyocardial tension during the cardiac cycle interrupt coronary blood flow (CBF) so that most of the nutrient flow to the ventricular myocardium occurs in ventricular diastole. Rapid changes in mean arterial pressure cause transient changes in CBF before autoregulatory factors return flow toward previous levels. Myocardial oxygen consumption (MVo 2 ) appears to the major determinant of CBF and the factors determining MVo, (mainly developed tension and contractile state) are, therefore, major determinants of CBF. The direct effects of autonomic excitation on CBF appear relatively minor, however; the vagus, sympathetic nerves and adrenal medullary hormones profoundly alter CBF indirectly through changes in MVo r In the ischaemic heart with atheromatous occlusion of large vessels there Is a reduced capacity for autoregulation, and nutrient flow is more dependent on pressure gradient. Hypertension and valvular disorders are often associated with raised MVo 2 but associated abnormalities in pressure gradient and resistance to flow often hinder the supply of CBF needed to meet high demands.