title: Determinants of coronary blood flow in humans: quantification by intracoronary Doppler and ultrasound.
abstract: The direct determinants of coronary flow are lumen area and blood flow velocity; however, the precise mechanisms that control these factors are not fully understood. The aim of the present study was to assess by which mechanisms lumen area and coronary flow velocity interact with hemodynamic and morphometric factors, thereby influencing coronary flow. Intracoronary Doppler and ultrasound measurements were performed in 28 patients without coronary lumen irregularities. Flow velocity and lumen cross-sectional area were measured in the proximal segments of all three coronary arteries. Global lumen cross-sectional area and global flow were obtained by adding up the values of all three coronary arteries. Left ventricular mass was assessed by echocardiography. Stress-mass-heart rate and pressure-rate products reflecting myocardial oxygen demand were calculated. Global coronary flow increased during adenosine-induced hyperemia from 197 +/- 72 to 637 +/- 204 ml/min (P < 0.001). Global coronary flow closely correlated with the stress-mass-heart rate product (r = 0.62; P < 0.001). Looking at the two constituents of flow separately, global coronary cross-sectional area was closely related to left ventricular muscle mass (r = 0.61; P < 0.001), whereas mean coronary flow velocity at rest showed a strong linear relation with the pressure-rate product (r = 0.64; P < 0.001). There was no interaction between cross-sectional area and blood flow velocity in any of the coronary vessels. Coronary lumen size and flow velocity, the two determinants of coronary flow, are principally determined by different physiological factors. Long-term flow adaptation is achieved by an increase in coronary lumen size, whereas short-term myocardial oxygen requirements are met by changes in resting flow velocity.
authors.affiliation: Department of Cardiology, University Essen, Hufelandstr. 55, D-45122 Essen, Germany. heinrich.wieneke@uni-essen.de
authors.forename: Heinrich
authors.initials: H
authors.lastname: Wieneke
authors.forename: Clemens
authors.initials: C
authors.lastname: von Birgelen
authors.forename: Michael
authors.initials: M
authors.lastname: Haude
authors.forename: Holger
authors.initials: H
authors.lastname: Eggebrecht
authors.forename: Stefan
authors.initials: S
authors.lastname: Möhlenkamp
authors.forename: Axel
authors.initials: A
authors.lastname: Schmermund
authors.forename: Dirk
authors.initials: D
authors.lastname: Böse
authors.forename: Christoph
authors.initials: C
authors.lastname: Altmann
authors.forename: Thomas
authors.initials: T
authors.lastname: Bartel
authors.forename: Raimund
authors.initials: R
authors.lastname: Erbel
mesh_terms: D001783:Blood Flow Velocity / Q000502:physiology*; D003326:Coronary Circulation / Q000502:physiology*; D003331:Coronary Vessels / Q000000981:diagnostic imaging* / Q000502:physiology*; D015150:Echocardiography, Doppler / Q000379:methods*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D018084:Ultrasonography, Interventional / Q000379:methods*; D016277:Ventricular Function, Left / Q000502:physiology