Heterogeneity of myocardial blood flow under normal conditions and its dependence on arterial PO2

Wolpers, H. G.; Hoeft, Andreas; Korb, H.; P, Lichtlen; Hellige, G.

doi:10.1152/ajpheart.1990.258.2.h549

Cited by 15 publications

(7 citation statements)

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“…Regional myocardial flow heterogeneity, i.e., CV, is likely to be related inversely to perfusion rate when myocardial O 2 availability is limited (10,30,40,47). In Tyrode-perfused hearts, perfusion rate is high, but myocardial oxygenation is limited and consistent with those earlier studies, CV was lower than that in blood-perfused hearts (Fig.…”

Section: Discussionsupporting

confidence: 87%

Pattern differences between distributions of microregional myocardial flows in crystalloid- and blood-perfused rat hearts

Matsumoto¹,

Tachibana²,

Asano³

et al. 2004

American Journal of Physiology-Heart and Circulatory Physiology

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hiko Kajiya. Pattern differences between distributions of microregional myocardial flows in crystalloid-and blood-perfused rat hearts. Am J Physiol Heart Circ Physiol 286: H1331-H1338, 2004. First published December 11, 2003 10.1152/ajpheart.00120.2003.-Regional myocardial flow distributions in Langendorff rat hearts under Tyrode and blood perfusion were assessed by tracer digital radiography (100-m resolution). Flow distributions during baseline and maximal hyperemia following a 60-s flow cessation were evaluated by the coefficient of variation of regional flows (CV; related to global flow heterogeneity) and the correlation between adjacent regional flows (CA; inversely related to local flow randomness). These values were obtained for the original images (64 2 pixels) and for coarsegrained images (32 2 , 16 2 , and 8 2 blocks of nearby pixels). At a given point in time during baseline, both CV and CA were higher in blood (n ϭ 7) than in Tyrode perfusion (n ϭ 7) over all pixel aggregates (P Ͻ 0.05, two-way ANOVA). During the maximal hyperemia, CV and CA were still significantly higher in blood (n ϭ 7) than in Tyrode perfusion (n ϭ 7); however, these values decreased substantially in blood perfusion and the CV and CA differences became smaller than those at baseline accordingly. During basal blood perfusion, the 60-s average flow distribution (n ϭ 7) showed a smaller CV and CA than those at a given point in time (P Ͻ 0.05, two-way ANOVA). Coronary flow reserve was significantly higher in blood than in Tyrode perfusion. In conclusion, the flow heterogeneity and the local flow similarity are both higher in blood than in Tyrode perfusion, probably due to the different degree of coronary tone preservation and the presence or absence of blood corpuscles. Under blood perfusion, temporal flow fluctuations over 60-s order are largely involved in shaping microregional flow distributions. regional myocardial perfusion; O2 carrying capacity; blood corpuscles; coronary tone; tracer digital radiography THE ISOLATED HEART MODEL USING crystalloid perfusates has been extensively used for characterizing myocardial contractility and energetics and the distribution of regional myocardial flows as well (5, 18, 49). However, most of the knowledge on regional crystalloid flows could not be extrapolated to explain the mechanisms of local regulation and coordination of regional myocardial flows under blood perfusion. Low O 2 carrying capacity of crystalloid perfusates makes an intracellular O 2 tension inadequate or just above the threshold for impaired myocardial function (6, 38) and reduces coronary tone or reserve (12,28,34). The distribution of regional myocardial flow is greatly under the influence of coronary tone (2, 5), and therefore there will be differences between spatial flow patterns in crystalloid-and blood-perfused myocardium. Furthermore, the presence or absence of blood corpuscles will augment those differences, because rheological, stochastic, and functional behaviors of corpuscles alter regional flows greatly at micr...

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Section: Discussionsupporting

confidence: 87%

Pattern differences between distributions of microregional myocardial flows in crystalloid- and blood-perfused rat hearts

Matsumoto¹,

Tachibana²,

Asano³

et al. 2004

American Journal of Physiology-Heart and Circulatory Physiology

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“…In fact, MBF was inversely correlated with SaO 2 (an extrapolated index of PaO 2 ) but not with PEtCO 2 (Figure 3). This is in agreement with findings in experimental animals showing that diminished oxygen tension in the myocardium may be the main stimulus for coronary dilation 28 and that carbon dioxide only plays a minor role at this altitude. 27 The lack of significance in the MBF increase at 2000 m, with a significant but slight decrease in SaO 2 , does not necessarily imply an increase in the oxygen extraction ratio.…”

supporting

confidence: 92%

Increased myocardial blood flow during acute exposure to simulated altitudes

Kaufmann

Schirlo

Pavlíček

et al. 2001

Journal of Nuclear Cardiology

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“…Figure 11 plots the estimated coefficient of variation (CV, defined as the standard deviation divided by the mean) of flow per terminal segment in the various classes (pooled results from 30 simulations). The straight line indicates the fit of the model predictions to the fractal relation CV(Nt)=CV, * Nt(l-D) (9) where CV(N1) is the coefficient of variation of flow per terminal segment through subtrees that consist of N1 terminal segments, CV1 is the extrapolated value of this quantity in single end segments, and D is the fractal dimension. D=1 would indicate a homogeneous distribution of flow, whereas D= 1.5 indicates the absence of correlation of flow in connected segments.…”

Section: Prediction Of Local Pressure and Flowmentioning

confidence: 99%

“…The ordinate indicates the coefficient of variation (also called the relative dispersion) of the flow per terminal segment along the tree. The straight line in this double-logarithmic plot is a fit of the fractal relations in Equation9.…”

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Branching patterns in the porcine coronary arterial tree. Estimation of flow heterogeneity.

vanBavel

Spaan

1992

Circulation Research

154

135

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The aim of this study is to quantify the porcine coronary arterial branching pattern and to use this quantification for the interpretation of flow heterogeneity. Two casts of the coronary arterial tree were made at diastolic arrest and maximal dilation. The relation between length and diameter of arterial segments was quantified, as well as the area expansion ratio and diameter symmetry of vascular nodes. These relations were used to construct computer models of the coronary arterial tree, covering diameters between 10 and 500 microns. Topology of these simulated trees was analyzed using Strahler ordering: Bifurcation ratio, diameter ratio, and length ratio were constant along orders 2-8 and equal to 3.30, 1.51, and 1.63, respectively. In each order, the number of segments per Strahler vessel was almost geometrically distributed. For the lowest orders, these predictions were confirmed by direct observations. From the network model, local pressure and flow were also predicted: Pressure fell from 90 to 32 mm Hg at the 10-microns level. The coefficient of variation (CV) of flow in individual segments was dependent on the number of perfused terminal segments (Nt) according to the fractal relation CV(Nt) approximately Nt(1-D), where D is the fractal dimension (1.20). CV of flow in 1-g tissue units was predicted to be 18%. This study shows that the structure of the coronary arterial bed is an important determinant of the fractal nature of local flow heterogeneity.

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Heterogeneity of myocardial blood flow under normal conditions and its dependence on arterial PO2

Cited by 15 publications

References 0 publications

Pattern differences between distributions of microregional myocardial flows in crystalloid- and blood-perfused rat hearts

Pattern differences between distributions of microregional myocardial flows in crystalloid- and blood-perfused rat hearts

Increased myocardial blood flow during acute exposure to simulated altitudes

Branching patterns in the porcine coronary arterial tree. Estimation of flow heterogeneity.

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