The septal artery and its collaterals in dogs with and without circumflex occlusion

Circulation Journal Official Journal of the Japanese Circulation Society http://www. j-circ.or.jp or a long time, the functional role of the coronary collateral circulation as a blood-conveying channel has been disputed. 1-4 Because a well-developed coronary collateral circulation is usually associated with severe coronary stenosis, some investigators assumed that the existence of collateral circulation is a marker of coronary artery disease (CAD). 1 Over the past 3 decades, accumulating evidence has documented that pre-existing well-developed coronary collateral circulation at the onset of acute myocardial infarction plays an important functional role in preserving left ventricular function, 2,5 reducing infarct size, 6 preventing left ventricular aneurysm formation 7 and survival. 2 Thus, a significant functional role of coronary collateral circulation is now well appreciated. 8 In the past decades, 9-11 we and others have emphasized the importance of arteriogenesis of the collateral vessels for enhanced coronary collateral circulation, compared with angiogenesis of the capillaries in areas perfused by occluded or critically stenosed coronary arteries. On the other hand, there has been considerable controversy concerning the stimulus for coronary collateral growth. It is now clear that long-standing high-grade coronary stenosis is mainly responsible for collateral vessel growth. 12 Severe coronary narrowing results in myocardial ischemia and a pressure gradient between the providing and receiving coronary arteries across the collateral network. New establishment of a pressure gradient leads to recruitment of collateral blood flow and increased shear stress at the site of pre-existing collateral vessels. Thus, severe coronary narrowing is inevitably accompanied by 2 potential stimuli for the development of collateral circulation, namely, myocardial ischemia and shear stress.One of the hot topics of coronary collateral growth is the role of bone-marrow-derived stem or endothelial progenitor cells in arteriogenesis. 13-16 It is still controversial whether these cells contribute to collateral growth by supplying cytokines and proteases related to arteriogenesis or by building up the collateral vessel as a result of the incorporation of these cells into vessel walls. 17 Thus, this review constitutes a summary of the historical background and current knowledge of coronary collateral growth in reference to the therapeutic potential for treating CAD. Stimulus of Coronary Collateral Growth Animal ModelsFor a long time, there was no general idea concerning the principal stimulus for coronary collateral growth. In 1967, Schaper proposed a new concept concerning the importance of mechanical factors on collateral growth. 18 He emphasized the crucial role of increased tangential (radial) shear stress at small pre-existing collateral arterioles, which results from increased intravascular pressure and arteriolar dilatation.In contrast, Scheel et al considered that myocardial ischemia is important for coronary collateral growt...

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“…19 In a model using an excised canine heart, conductance of coronary and collateral circulation can be separately and …”

Section: Animal Modelsmentioning

confidence: 99%

Coronary Collateral Growth and Its Therapeutic Application to Coronary Artery Disease

Fujita

Sasayama

2010

Circ J

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“…The mean maximal difference in flow rates for all the pressure-flow relations derived in the beating heart at a left main pressure of 100 mm Hg was 11 ml/min. Collateral flow rates of this magnitude in the acutely occluded canine circumflex artery have been described: 11.3 ml/min in dogs weighing 16 kg (Scheel et al, 1980), 20.8 ml/min in dogs weighing 16-24 kg (Schaper et al, 1976), and 21.1 (11.8) ml/min per 100 g (Gottwik et al, 1984) in dogs weighing 24-32 kg. In our microsphere experiments, the collateral flow rate was also of this magnitude.…”

Section: Effects Of Interarterial Pressure Gradientsmentioning

confidence: 99%

Effects of pressure gradients between branches of the left coronary artery on the pressure axis intercept and the shape of steady state circumflex pressure-flow relations in dogs.

Messina¹,

Hanley²,

Uhlig³

et al. 1985

Circulation Research

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SUMMARY. When steady state pressure-flow relations are studied in the circumflex coronary artery, pressure gradients develop between it and other branches of the left coronary artery. To assess the effects of these pressure gradients, we compared the pressure axis intercept and shape of steady state circumflex pressure-flow relations in the presence and absence of gradients after autoregulation was abolished, both in the beating heart and during long diastoles in dogs. We used peripheral coronary pressures and radionuclide-labeled microspheres to assess arterial collateral flow. In the beating heart, interarterial pressure gradients reduced the curvature at low circumflex pressures, and overestimated the mean pressure axis intercept by 7.8 mm Hg (P < 0.05). The results were similar for the pressure-flow relations derived during long diastoles. This overesrimation exaggerates the difference between the pressure axis intercept and coronary sinus pressure. The peripheral coronary pressure and microsphere results indicate that these effects are mediated largely by arterial collateral flow. {Circ Res 56: 11-19, 1985) CORONARY arterial pressure-flow relations have been used to investigate the physical forces that regulate coronary blood flow (Cross et al., 1961;Downey and Kirk, 1975;Bellamy, 1978). The pressure axis intercept of these relations has been interpreted as the downstream pressure opposing forward flow in the coronary circulation; however, this pressure has greatly exceeded the coronary sinus pressure, which traditionally has been assumed to be the downstream pressure. The shape of these relations, found to be linear by some (Dole and Bishop, 1982;Eng et al., 1982) but curvilinear by others (L'Abbate et al., 1980;Klocke et al., 1981), is thought to convey information about the conductance of the coronary circulation. Because of this variability of the pressure axis intercept and the shape of coronary arterial pressure-flow relations, the physiological significance of both remains uncertain.One factor that might account for this variability is the specific coronary artery in which the pressureflow relation is obtained. In our laboratory, we have consistently found that the pressure axis intercept of a steady state circumflex pressure-flow relation (Verrier et al., 1980;Vlahakes et al., 1982) is much higher than that in a steady state left main coronary arterial pressure-flow relation (Rouleau et al., 1979;Uhlig et al., 1984). A possible explanation for the higher pressure axis intercept of the circumflex pressure-flow relation may be that when circumflex pressure is selectively lowered below that in the other branches of the left coronary artery, interarterial pressure gradients occur and are accompanied by collateral flow that is not measured by the upstream flow transducer. This error in measurement could underestimate total circumflex flow and thus overestimate the pressure axis intercept. Whether these pressure gradients also affect the shape of a circumflex pressure-flow relation is unknown.To assess...

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“…In 11 animals, a third pair of crystals was placed in the LAD region of the myocardium between the main coronary artery and a diagonal branch. In all animals, crystal placement was confirmed by the presence of decreased wall thickening in the LCx region in response to a brief occlusion (15)(16)(17)(18)(19)(20) Initial data analysis used a data reduction function built into the EGAA system. The data reduction function accepted inputs from the two systolic Wth and the blood pressure measurements and calculated HR, systolic left ventricular blood pressure (SBP), dP/dt, and percent systolic Wth.…”

Section: Surgical Proceduresmentioning

confidence: 99%

Chronic reduction of myocardial ischemia does not attenuate coronary collateral development in miniswine.

1992

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Background. Myocardial ischemia is considered to be a possible stimulus for development of the coronary collateral circulation. We therefore hypothesized that chronic reduction of myocardial oxygen demand to lessen ischemia would attenuate coronary collateral development over an 8-week period using left circumflex coronary artery (LCx) ameroid-induced constriction in pigs.Methods and Results. Collateral development was assessed by myocardial blood flow (radioactive microspheres) and left ventricular regional function (sonomicrometer dimension gauges). 1-Adrenoceptor blockade with propranolol (160 or 320 mg b.i.d. p.o.) was initiated in 15 animals 1 day after surgery.

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The septal artery and its collaterals in dogs with and without circumflex occlusion

Cited by 14 publications

References 15 publications

Coronary Collateral Growth and Its Therapeutic Application to Coronary Artery Disease

Coronary Collateral Growth and Its Therapeutic Application to Coronary Artery Disease

Effects of pressure gradients between branches of the left coronary artery on the pressure axis intercept and the shape of steady state circumflex pressure-flow relations in dogs.

Chronic reduction of myocardial ischemia does not attenuate coronary collateral development in miniswine.

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