title: Fractal regional myocardial blood flows pattern according to metabolism, not vascular anatomy.
abstract: Regional myocardial blood flows are markedly heterogeneous. Fractal analysis shows strong near-neighbor correlation. In experiments to distinguish control by vascular anatomy vs. local vasomotion, coronary flows were increased in open-chest dogs by stimulating myocardial metabolism (catecholamines + atropine) with and without adenosine. During control states mean left ventricular (LV) myocardial blood flows (microspheres) were 0.5-1 ml·g(-1)·min(-1) and increased to 2-3 ml·g(-1)·min(-1) with catecholamine infusion and to ∼4 ml·g(-1)·min(-1) with adenosine (Ado). Flow heterogeneity was similar in all states: relative dispersion (RD = SD/mean) was ∼25%, using LV pieces 0.1-0.2% of total. During catecholamine infusion local flows increased in proportion to the mean flows in 45% of the LV, "tracking" closely (increased proportionately to mean flow), while ∼40% trended toward the mean. Near-neighbor regional flows remained strongly spatially correlated, with fractal dimension D near 1.2 (Hurst coefficient 0.8). The spatial patterns remain similar at varied levels of metabolic stimulation inferring metabolic dominance. In contrast, adenosine vasodilation increased flows eightfold times control while destroying correlation with the control state. The Ado-induced spatial patterns differed from control but were self-consistent, inferring that with full vasodilation the relaxed arterial anatomy dominates the distribution. We conclude that vascular anatomy governs flow distributions during adenosine vasodilation but that metabolic vasoregulation dominates in normal physiological states.
authors.affiliation: Department of Bioengineering, University of Washington, Seattle, Washington.
authors.forename: Tada
authors.initials: T
authors.lastname: Yipintsoi
authors.affiliation: Department of Bioengineering, University of Washington, Seattle, Washington.
authors.forename: Keith
authors.initials: K
authors.lastname: Kroll
authors.affiliation: Department of Bioengineering, University of Washington, Seattle, Washington jbb2@uw.edu.
authors.forename: James B
authors.initials: JB
authors.lastname: Bassingthwaighte
mesh_terms: D000241:Adenosine / Q000494:pharmacology; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D003326:Coronary Circulation / Q000187:drug effects / Q000502:physiology*; D003331:Coronary Vessels / Q000187:drug effects / Q000502:physiology*; D004285:Dogs; D004837:Epinephrine / Q000494:pharmacology; D017709:Fractals; D006352:Heart Ventricles; D008863:Microspheres; D009206:Myocardium; D009638:Norepinephrine / Q000494:pharmacology; D010276:Parasympatholytics / Q000494:pharmacology; D012039:Regional Blood Flow / Q000187:drug effects / Q000502:physiology; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology*; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology*; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D010276:Parasympatholytics; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D001285:Atropine; D000241:Adenosine; D009638:Norepinephrine; D004837:Epinephrine
keywords: catecholamine-stimulated metabolism; fractal spatial correlation; myocardial blood flow heterogeneity; vasomotor tone