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

Abstract

Yipintsoi T, Kroll K, Bassingthwaighte JB. Fractal regional myocardial blood flows pattern according to metabolism, not vascular anatomy. Am J Physiol Heart Circ Physiol 310: H351-H364, 2016. First published November 20, 2015 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 ϩ atropine) with and without adenosine. During control states mean left ventricular (LV) myocardial blood flows (microspheres) were 0.5-1 ml·g Ϫ1 ·min Ϫ1 and increased to 2-3 ml·g Ϫ1 ·min Ϫ1 with catecholamine infusion and to ϳ4 ml·g Ϫ1 ·min Ϫ1with adenosine (Ado). Flow heterogeneity was similar in all states: relative dispersion (RD ϭ SD/mean) was ϳ25%, 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 ϳ40% 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. THERE IS MARKED HETEROGENEITY of regional blood flows in the heart. The SDs of the distributions of the flows divided by the mean flow, the relative dispersion (RD) are 20 -30% of the mean. (RD is the coefficient of variation.) Myocardial perfusion heterogeneity was recognized in early studies of myocardial regional blood flows by investigators using microspheres in anesthetized dogs (20, 56), in isolated blood-perfused dog hearts (6, 64), and in awake, resting, or exercising animals (22,23,35). In awake baboons, King et al. (35), using 15-m carbonized microspheres in pieces weighing ϳ0.6% of the total mass of the heart, found that the RDs for the left ventricular (LV) flow distributions were 26 Ϯ 7%. This variation is real, since only a small component of it is due to methodology: estimates using the deposited tracer "molecular microsphere" iodinated desmethyl imipramine showed method variation of 2-3% while the microsphere method variation is 5-8% (10), affirming the earlier estimates of method error appropriate to the numbers of spheres per piece and the counting statistics (1,6,20,25,35,48,42). It is a truism that the finer the spatial resolution of the observations, the more heterogen...

Morphometric Reconstruction of Coronary Vasculature Incorporating Uniformity of Flow Dispersion

“…These figures are comparable to the experimental value of 0.4 using a similar sample mass (0.2 mg) (Matsumoto and Kajiya, 2001), and close to some experimental estimates using higher sample masses (Mori et al, 1995; Yipintsoi et al, 2016). …”

“…This validation has three related but different aspects (Bassingthwaighte and Beyer, 1991; Yipintsoi et al, 2016). The flow dispersion level (CV), the flow fractal nature (self-similarity), and the flow spatial auto-correlation.…”

The fractal heart — embracing mathematics in the cardiology clinic

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Application of fractal dimension analysis and photodynamic diagnosis in the case of differentiation between lichen planus and leukoplakia: A preliminary study

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