Hemodynamic effects of controlled degrees of coronary artery stenosis in short-term and long-term studies in dogs
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Reactive hyperemia
Aortic pressure
Coronary circulation
Reactive hyperemia
Circulation (fluid dynamics)
Coronary circulation
Nitroglycerin (drug)
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The mean total coronary flow of dog hearts, perfused via the aorta by a donor dog, was recorded. The amount of work performed by the recipient heart was varied within wide ranges. Its aortic pressure was also varied, thus determining changes in the coronary flow. When the frequency of stimulation of the heart and the aortic pressure are maintained constant, changes of the work performed do not result in changes of the coronary flow. When the working conditions of the heart are maintained constant, changes of the coronary flow do not cause any variations of the amount of work performed. The work performed does not affect the pressure-flow relationships. It is concluded that with adequate circulation there is a wide margin of safety in the oxygen supply to the ventricle. The heart can increase its work importantly without producing or requiring an increase of its coronary flow.
Aortic pressure
Coronary circulation
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Reactive hyperemia
Coronary circulation
Circulation (fluid dynamics)
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Reactive hyperemia
Coronary circulation
Coronary arteries
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Rabbit (cipher)
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Reactive hyperemia
Supine position
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Objectives Coronary endothelial and circulatory dysfunction plays important roles in the pathogenesis of vasospastic angina (VSA). However, a complete understanding of the entire coronary circulation including microvasculature in patients with VSA is lacking. Patients and methods A total of 32 patients without obstructive coronary artery disease in the left descending coronary artery, who underwent an intracoronary acetylcholine (ACh) provocation test for diagnosis of VSA, were enrolled prospectively. A positive diagnosis of the ACh test was defined as total/subtotal coronary artery narrowing accompanied by chest pain and/or ischemic ECG changes. Angina frequency and severity at baseline, and 1 and 3 months were recorded. Coronary circulation was evaluated invasively using a thermodilution method by obtaining the mean transit time (Tmn) at rest and hyperemia, coronary flow reserve, and index of microcirculatory resistance. Systemic endothelial function was assessed by the reactive hyperemia index. Results There were 14 (44%) and 18 (56%) patients with and without a positive ACh provocation test. The baseline characteristics did not differ significantly between the two groups. Patients with VSA had a significantly lower reactive hyperemia index compared with those without VSA (1.70±0.33 vs. 2.12±0.53, P=0.02). Coronary flow reserve, index of microcirculatory resistance, and hyperemic Tmn were not different between the two groups, whereas resting Tmn was significantly longer in patients with VSA (1.20±0.44 vs. 0.71±0.37, P=0.002). Although the frequency and severity of angina improved from baseline to 1 and 3 months in patients with both positive and negative ACh tests, there was no difference between the two groups. Conclusion Patients with VSA had decreased resting coronary flow and impaired endothelial function.
Reactive hyperemia
Coronary flow reserve
Coronary circulation
Fractional Flow Reserve
Endothelial Dysfunction
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Some aspects of the control mechanism in the coronary circulation were investigated by using analog simulation. The simulation is designed to separate passive or mechanical factor from entire influence on the change in coronary flow consisting of passive and active factors, under different hemodynamic conditions. Simulated waveform was very similar to the blood flow pattern of the left circumflex artery actually obtained by an electromagnetic flowmeter. Pressure flow relationship was almost linear. Coronary flow increased with rise of aortic pressure, with the influence of active factors exceeding greatly that of the passive factors. When the heart rate was increased, the decrease in coronary flow due to the passive factors themselves was found. After the occlusion of the coronary artery the slight reactive hyperemia due to only passive factors was observed in the simulated flow.
Coronary circulation
Aortic pressure
Reactive hyperemia
Circumflex
Coronary occlusion
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Reactive hyperemia
Coronary circulation
Circulation (fluid dynamics)
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Reactive hyperemia
Coronary circulation
Circulation (fluid dynamics)
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