Effect of Exercise and Coronary Artery Narrowing on Coronary Collateral Circulation

Eckstein, Richard W.

doi:10.1161/01.res.5.3.230

Cited by 242 publications

(44 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…This technique allowed completed occlusion or complete release of coronary blood flow within less than 0.1 s. After all recording instruments were connected, a 60-s coronary artery occlusion was produced while lead II of the electrocardiogram was monitored. Only dogs which exhibited significant ST segment elevation, as well as increased heart rate, indicating absence of an effective coronary collateral circulation which might impair the ischemic stimulus produced by coronary occlusion during subsequent studies were used for this study (11). Three of the dogs tested failed to manifest these indications of myocardial ischemia during a 60-s occlusion and were consequently not used for this study.…”

Section: Methodsmentioning

confidence: 99%

Effects of nitroglycerin on transmural myocardial blood flow in the unanesthetized dog.

et al. 1975

View full text Add to dashboard Cite

AB STRA CT This study was designed to determine the effect of nitroglycerin upon transmural distribution of myocardial blood flow in the awake dog during normal conditions and in the presence of ischemia-induced coronary vasodilation. Studies were performed in chronically prepared dogs with electromagnetic flowmeters and hydraulic occluders on the left circumflex coronary artery. Regional myocardial blood flow was estimated by using radionuclide-labeled microspheres, 7-10 im in diameter, injected into the left atrium. During control conditions endocardial flow (0.86±SEMI 0.05 ml/min per g) slightly exceeded epicardial flow (0.72±0.03 ml/min per g, P < 0.05), and this distribution of flow was not significantly altered by nitroglycerin. After a 5-s coronary artery occlusion, reactive hyperemia occurred with excess inflow of arterial blood effecting 360+15 15% repayment of the blood flow debt incurred during occlusion. When arterial inflow was limited to the preocclusion rate during coronary vasodilation after a 5-s total coronary artery occlusion, flow to the subepicardial myocardium was increased at the expense of underperfusion of the subendocardial myocardium, and the delayed reactive hyperemia was markedly augmented (mean blood flow debt repayment = 775±105%, P < 0.01). These data suggested that subendocardial underperfusion during the interval of coronary vasodilation in the presence of a flow-limiting

show abstract

Section: Methodsmentioning

confidence: 99%

Effects of nitroglycerin on transmural myocardial blood flow in the unanesthetized dog.

et al. 1975

View full text Add to dashboard Cite

show abstract

“…There is evidence that exercise conditioning in rats increases their coronary vascularity (6), maximum coronary blood flow, and myocardial 02 consumption (7), and that exercise in dogs with coronary stenosis promotes coronary collateral development (8). Furthermore, it has been reported that after conditioning, patients with coronary heart disease can reach higher values of heart rate and systolic blood pressure before angina develops during exercise (4,9).…”

Section: Introductionmentioning

confidence: 99%

Investigation of the Physiological Basis for Increased Exercise Threshold for Angina Pectoris after Physical Conditioning

Sim¹,

Neill²

1974

J. Clin. Invest.

View full text Add to dashboard Cite

A B S T R A C T Eight patients with coronary heart disease and exertional angina pectoris successfully completed an 11-15 wk program of endurance exercise conditioning. Angina threshold was determined by upright bicycle ergometer exercise and by atrial pacing. The product of heart rate and arterial systolic blood pressure at the exercise angina threshold was higher after conditioning, suggesting that conditioning increased the maximum myocardial 02 supply during exercise. However, when angina was induced by atrial pacing, heart rate, arterial blood pressure, coronary blood flow, and myocardial 02 consumption at the angina threshold were the same before and after conditioning. Myocardial lactate extraction during atrial pacing was abnormal in the same five patients before and after conditioning. Conditioning caused no detectable changes in coronary collaterals as judged by coronary arteriograms.The increase in exercise angina threshold appeared to be due to a functional adaptation in either myocardial 02 supply or the relationship between hemodynamic work and myocardial 02 consumption. The adaptation was limited to exercise, and did not occur during a different stress to myocardial 02 supply, atrial pacing.

show abstract

“…The hypothesis that physical training promotes coronary collaterals was stimulated by the report of Eckstein,27 in which the circumflex coronary artery of dogs was narrowed. Half of the dogs were exercised and the others remained sedentary.…”

Section: Collateral Development With Chronicmentioning

confidence: 99%

Effects of physical training on myocardial vascularity and perfusion.

Scheuer¹

1982

Circulation

View full text Add to dashboard Cite

SUMMARY Physical training is thought to be a stimulus for coronary vascular growth and coronary collateral development. This report is a summary of knowledge in the area. Studies in experimental animals with normal hearts indicate that physical training promotes increased myocardial capillary density and also causes enlargement of the surface coronary vessels. The physiologic effect of these changes on coronary vascular reserve and protection of segments of the heart against myocardial ischemia has not been established. Physically trained dogs and pigs do not appear to be protected against the effects of coronary occlusion, in that the ischemic area appears to be as large in trained animals as in untrained animals for any given coronary lesion. One study in physically trained rats appears to show protection against myocardial infarction, but whether this is related to coronary vascular changes has not been established. Experiments in dogs subjected to chronic narrowing or gradual occlusion demonstrate that physical training in these models does promote collateral blood flow as measured by retrograde flow in open-chest experiments. Studies using the microsphere technique in closed-chest animals confirms increased collateral flow to ischemic areas in some animals, but the magnitude of the increases appears to be small and varies greatly from animal to animal.Studies in athletes suggest that myocardial blood flow is lower at any submaximal level of training in athletes than in sedentary persons. Studies in patients with coronary artery disease have generally failed to show an increase in coronary blood flow or in perfusion of ischemic areas after physical training programs, but the techniques used might not have been sensitive enough to detect changes.The evidence in the experimental animals is sufficiently promising to indicate that the search should be continued to define physical training programs that will most stimulate myocardial vascularity and coronary collaterals in humans.THE HYPOTHESIS that physical training programs are beneficial to the heart is based on evidence that chronic repeated exercise increases myocardial vascularity and protects the myocardium against ischemic insults. It has been suggested that training promotes coronary collateral vessel development so that when coronary artery disease is already established, collateral vessels would permit more abundant blood flow to a potentially ischemic area of myocardium and protect that area against ischemic injury and infarction.The purpose of this paper is to review our knowledge of how myocardial vascularity and coronary collaterals respond to physical training.Evidence crease in capillary density was observed in the absence of cardiac hypertrophy.Bloor and Leon6 explored the relationship of age to capillary fiber ratio in rats trained by swimming. They found that daily or twice-weekly swimming caused an increase in the capillary-myocardial fiber ratio in very young, young adult and old rats, but in the younger rats this change was due to an absolu...

show abstract

Effect of Exercise and Coronary Artery Narrowing on Coronary Collateral Circulation

Cited by 242 publications

References 3 publications

Effects of nitroglycerin on transmural myocardial blood flow in the unanesthetized dog.

Effects of nitroglycerin on transmural myocardial blood flow in the unanesthetized dog.

Investigation of the Physiological Basis for Increased Exercise Threshold for Angina Pectoris after Physical Conditioning

Effects of physical training on myocardial vascularity and perfusion.

Contact Info

Product

Resources

About