Microvascular sites and mechanisms responsible for reactive hyperemia in the coronary circulation of the beating canine heart.

Kanatsuka, Hiroshi; Sekiguchi, Nobuyo; Sato, Kouichi; Akai, Kenjiro; Wang, Yan; Komaru, Tatsuya; Ashikawa, Kouichi; Takishima, Tamotsu

doi:10.1161/01.res.71.4.912

Cited by 76 publications

(46 citation statements)

References 41 publications

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“…19 This triggers a number of mechanisms, some of which involve endothelium-derived nitric oxide, adenosine, K + ATP channels, and certain cyclooxygenase-derived metabolites to maintain the elevated flow velocity during the period of reactive hyperaemia. [20][21][22][23][24] Peak hyperaemic blood flow is only partially regulated by the release of endotheliumderived nitric oxide. 25 On the other hand, among the various vasodilators, such as prostaglandins and endotheliumderived hyperpolarizing factor, released from the endothelium, nitric oxide is the primary mediator of FMD.…”

Section: Discussionmentioning

confidence: 99%

The optimal measure of microvascular function with velocity time integral for cardiovascular risk prediction

et al. 2012

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Methods Study population and study designThis study included 399 male subjects, a subset of the Firefighters and Their Endothelium (FATE) study cohort. The FATE study protocol has been described previously. 12 Briefly, all subjects were assessed for cardiovascular risk factors through physical examination and blood work. TheThe optimal measure of microvascular function with velocity time integral for cardiovascular risk prediction Vincent Lee, Billie-Jean Martin, Marinda Fung and Todd J Anderson Abstract Recent evidence suggests that microvascular function may be important in cardiovascular risk prediction. One measure of microvascular function is hyperaemic velocity time integral (VTI). We assessed whether the VTI of more than one beat of reactive hyperaemia would provide a stronger correlate to traditional cardiovascular risk factors using a subset of subjects from the Firefighters and Their Endothelium (FATE) study. Vascular function was assessed by measurement of hyperaemic blood velocity with high-resolution ultrasound of the brachial artery. We evaluated three measures in the current analysis: the VTI of the first beat, average VTI of 10 beats, and maximum VTI of 10 beats post-cuff release. A total of 399 male subjects (45.5 ± 10 years) were included in this analysis. Univariate correlations between the three end points and cardiovascular risk factors were calculated, and multivariable regression models constructed. Intra-observer variability was approximately equal for all VTI end points (coefficient of variation: first = 1.6%, average = 1.4%, maximum = 1.4%). Univariate correlations between VTI and cardiovascular risk factors were similar across all three end points. In multivariable analyses, there were no differences in the relationships between cardiovascular risk factors and the various VTI end points (R 2 from 0.090 to 0.102). Age, systolic blood pressure, and BMI were predictors of the three VTI end points (p < 0.05). In conclusion, the first beat of reactive hyperaemia remains the suitable measure of microvascular function.

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Section: Discussionmentioning

confidence: 99%

The optimal measure of microvascular function with velocity time integral for cardiovascular risk prediction

et al. 2012

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“…The precise mechanisms involved and their interactions and roles at different times in the response are, however, still not clearly understood. Vasodilation of downstream vessels during occlusion has been attributed to the myogenic response (20), extracellular (22,23) and potentially intracellular (25) changes in metabolite concentration, release of vasodilators from endothelial cells (24), and viscoelastic wall properties (16).…”

Section: Discussionmentioning

confidence: 99%

Albumin Excretion Rate and Cardiovascular Risk

et al. 2005

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Elevated albumin excretion rate (AER) independently predicts total and cardiovascular mortality in a variety of conditions, although the exact mechanisms are unknown. Laser Doppler fluximetry was used to study associations with risk factors and renal damage (AER calculated from a timed overnight urine collection) in 188 people without diabetes and 117 individuals with diabetes. Skin flow (flux) in response to arterial occlusion (ischemia) was measured. Three distinct patterns of postischemic peak flow were observed: 1) gradual rise to peak (normal), 2) nondominant early peak, and 3) dominant early peak. Those with a dominant early peak were more likely to have diabetes (P ‫؍‬ 0.01), hypertension (P ‫؍‬ 0.001), and obesity (P < 0.001) and had a higher AER (12.6 g/min [95% CI 7.8 -20.2] vs. 7.2 [5.5-9.5] nondominant early peak group and 3.7 [3.2-4.1] normal group; P < 0.001 for trend). This could not be accounted for by conventional cardiovascular risk factors (P < 0.001 after adjustment). A rapid peak flow response after ischemia is associated with an elevated AER and increased cardiovascular risk. This may represent shared mechanistic pathways and causative or consequential changes in the microvasculature and supports the hypothesis that microvascular dysfunction may contribute to large vessel pathophysiology.

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“…Therefore, in the present study, flow distributions during maximal vasodilation were approximated by those measured during the peak plateau of the reactive hyperemia. Although region-to-region or microvascular site-to-site asynchronous vasodilation during reactive hyperemia (13,24) prohibits the complete removal of coronary tone effects on regional flows, coronary tone could not be involved in causing the differences of flow distributions under Tyrode and blood perfusion. Future experiments should, however, be designed to elucidate more clearly the role of corpuscular mechanistic factors in the determination of regional flows.…”

Section: Discussionmentioning

confidence: 99%

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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Microvascular sites and mechanisms responsible for reactive hyperemia in the coronary circulation of the beating canine heart.

Cited by 76 publications

References 41 publications

The optimal measure of microvascular function with velocity time integral for cardiovascular risk prediction

The optimal measure of microvascular function with velocity time integral for cardiovascular risk prediction

Albumin Excretion Rate and Cardiovascular Risk

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

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