Fractal regional myocardial blood flows pattern according to metabolism, not vascular anatomy

• Published in: American journal of physiology. Heart and circulatory physiology Vol. 310; no. 3; pp. H351 - H364
• Main Authors: Yipintsoi, Tada, Kroll, Keith, Bassingthwaighte, James B
• Format: Journal Article
• Language: English
• Published: United States American Physiological Society 01.02.2016
• Series: Quantitative Analyses of Coronary Vascular and Cardiac Mechanics in Health and Disease
• Subjects: Adenosine - pharmacology; Animals; Atropine - pharmacology; Blood; Blood vessels; Call for Papers; Cardiovascular system; Coronary Circulation - drug effects; Coronary Circulation - physiology; Coronary Vessels - drug effects; Coronary Vessels - physiology; Dogs; Epinephrine - pharmacology; Experiments; Fractals; Heart Ventricles; Metabolism; Microspheres; Myocardium; Norepinephrine - pharmacology; Parasympatholytics - pharmacology; Regional Blood Flow - drug effects; Regional Blood Flow - physiology; Vasoconstriction - drug effects; Vasoconstriction - physiology; Vasoconstrictor Agents - pharmacology; Vasodilation - drug effects; Vasodilation - physiology; Vasodilator Agents - pharmacology; fractal spatial correlation; vasomotor tone; catecholamine-stimulated metabolism; myocardial blood flow heterogeneity
• ISSN: 0363-6135; 1522-1539
• DOI: 10.1152/ajpheart.00632.2015

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.