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At least 19 recordsLinked to original sources
PubMed1979

Shunting of microspheres across the canine coronary circulation.

Coronary shunting of 9 +/-1 micrometer and 25 +/- 5 micrometer radiolabeled microspheres was examined in anesthetized, open-chest dogs, whose left common coronary arteries were perfused at controlled pressures. Shunting was estimated from the difference in radioactivity between perfusion line and coronary sinus blood samples during selective elevations of coronary perfusion pressure (CPP), left ventricular afterload, and inspired oxygen. A linear relationship was found between coronary shunting of 9-micrometer microspheres and CPP over the range 100-200 mmHg. According to regression analysis, percent shunt flow was 4.0% at control CPP (100 mmHg) and 10.0% at CPP of 200 mmHg. No shunting of 25-micrometer microspheres occurred at any CPP. Raising afterload did not affect shunting at control CPP but attenuated the increase in shunting at elevated CPP. Changing inspired gas from room air to 100% oxygen did not influence shunting at control or elevated CPP. Raising CPP to 150 and 200 mmHg also released 2.5% and 5.9% of pretrapped 9-micrometer microspheres, respectively. This study demonstrates that vessels permitting passage of microspheres across coronary circulation are sensitive to elevated perfusion pressure.

Animals↗
PubMed1990

Fibrinopeptide A is released into the coronary circulation after coronary spasm.

To examine whether acute myocardial ischemia activates the coagulation system and platelet activation in the coronary circulation, we measured plasma levels of fibrinopeptide A and beta-thromboglobulin in the coronary sinus and the aortic root simultaneously in 15 patients with coronary spastic angina before and after the left coronary spasm induced by intracoronary injection of acetylcholine and in 15 patients with stable exertional angina before and after acute myocardial ischemia induced by rapid atrial pacing. Fifteen patients with chest pain but normal coronary arteries and no coronary spasm served as controls. The coronary sinus-arterial difference of fibrinopeptide A increased markedly (p less than 0.001) from 0.1 +/- 0.2 to 4.3 +/- 0.7 ng/ml after the anginal attacks in the coronary spastic angina group. However, fibrinopeptide A levels remained unchanged after the attacks in the stable exertional angina group and after intracoronary injection of acetylcholine in the control group. Plasma beta-thromboglobulin levels remained unchanged after the attacks in both patient groups and after acetylcholine in the control group. Our data indicate that coronary spasm induces thrombin generation and may lead to thrombus formation in the coronary artery involved, but pacing-induced ischemia does not activate the coagulation system.

Angina Pectoris↗
PubMed1990

Effects of anesthetics on the coronary circulation.

The coronary circulation holds a unique position among the different vascular beds because it perfuses the organ that generates the perfusion pressure for the entire circulation. Therefore the maintenance of an adequate perioperative coronary flow is one of the primary goals of good anesthetic management. This is especially important when coronary flow is already diminished such as is the case with arteriosclerotic disease. All anesthetics influence coronary flow to some extent. Some of them however also affect the normal physiologic responses of this system and may compromise coronary circulation and hence myocardial function. Therefore, knowledge of the coronary physiology and the effects of anesthetics on it is essential for every anesthetist dealing with patients with coronary artery disease. This article reviews the anatomy and physiology of the coronary circulatory system and resumes the present state of knowledge of the effects of the common used anesthetics on the coronary circulation.

Anesthetics↗
PubMedDate not supplied

Effect of CO2 on the systemic and coronary circulations and on coronary sinus blood gas tensions.

The responses to hypocapnia and to hypercapnia of both the systemic and the coronary circulations have been studied in the dog during intermittent positive pressure ventilation under halothane anaesthesia. In the absence of significant variations of myocardial contractility, the reduction of cardiac output, because of hypocapnia, was determined by the increase of systemic vascular resistance, while the increase of cardiac output because of hypercapnia was determined by an increase of heart rate without change of stroke volume. The alterations of coronary blood flow (reduction following hypocapnia, augmentation following hypercapnia) were considerably larger than the changes of cardiac output and of myocardial oxygen consumption. Such disparity between oxygen supply and demand, together with the effect of pH and PCO2 on the oxyhaemoglobin dissociation curve led to a marked reduction of coronary sinus PO2 in response to hypocapnia and a marked increase of coronary sinus PO2 in response to hypercapnia. The data suggests that PCO2 (or respiratory alterations of pH) may have a direct effect on the regulation of coronary blood flow. The low coronary sinus PO2 observed at hypocapnia may suggest the risk of myocardial ischaemia.

Animals↗
PubMed1977

[Coronary circulation in abnormal left coronary artery arizing from the pulmonary artery trunk, before and after correction].

Two patients, both of them young girls, aged 14 and 15, had this condition and were studied by haemodynamic methods preoperatively and during the seventh postoperative month. In both cases, the retrograde perfusion of the left coronary vascular tree was shown up well, demonstrating the "coronary steal" and a left-right shunt of 2 volumes. In both cases also, the postoperative coronary arteriogram showed a return of the left coronary circulation to normal, disappearance of the large anastomatic vessels, and above all a return to normal dimensions of the right coronary artery, previously extremely tortuous and dilated. The 30 or so cases of total correction published in the world literature have been reviewed in the light of these two new cases.

Adolescent↗
PubMed1977

[Effect of nonachlazine and oxyfedrine on coronary circulation in dogs].

Coronary circulation was measured in the anesthetized and nonanesthetized dogs by means of ultrasonic Doppler's radiotelemetric apparatus. The ultrasonic pick-up was placed on the upper third of the descending branch of the left coronary artery. Nonachlazine considerably increased the coronary circulation in the anesthetized and nonanesthetized dogs. However, the action of the preparation lasted 2 to 3 minutes only and depended on the changes in the cardiac activity. In difference from nonachlazine, oxphedrine increased the coronary circulation to a lesser degree, but for a much longer time (20min on the average). Taking into consideration a high efficacy of these preparations under clinical conditions a conclusion was drawn that an increase of the coronary circulation was not the principal way of action for reaching the antiangina effect in the patients with ischemic heart disease.

Analgesics↗
PubMed1992

[Specific features of the regulation of coronary circulation during reperfusion after coronary insufficiency of different degrees].

Coronary insufficiency of various degrees was reproduced in experiments with anesthetized dogs by using coronary artery catheterization by progressively limiting the regional blood flow by 30, 50, 70, and 90%, the dog chest being closed. The specific features of regulatory reactions of cardiac vessels were also studied under subsequent reperfusion. It was shown that regulation of coronary circulation became changed in most cases after markedly limited coronary blood flow, as manifested by impaired reperfusion hyperemia and its rapid cessation that prevented the "payment" of blood flow debt and a secondary increase of cardiac vascular resistance above the preocclusive level. There was a significant relationship between the detected disorders and the degree of prior limited coronary perfusion.

Animals↗
PubMed1991

Effects of synthetic human atrial natriuretic peptide on the human coronary circulation in subjects with normal coronary arteries.

Atrial natriuretic peptide (ANP) is recognized as an "endogenous vasodilator". The purpose of this study was to determine the effects of a clinical therapeutic dose of synthetic alpha-human ANP on the coronary circulation in 15 subjects with normal coronary arteries and normal ventricular function. The epicardial coronary arterial diameter was measured by selective coronary arteriography. Coronary blood flow was estimated from the arterial cross-sectional area and the flow velocity determined using an subselective intracoronary Doppler catheter. ANP, 0.03 micrograms/min/kg given intravenously over 15 minutes, caused a dilation of the large epicardial coronary artery (n = 8): the diameter of the proximal left anterior descending artery dilated from 2.6 +/- 0.4 to 3.1 +/- 0.5 mm (p less than 0.01). Mean arterial pressure decreased from 89 +/- 5 to 83 +/- 5 mmHg (p less than 0.01); heart rate did not change during ANP infusion. Estimated coronary blood flow significantly increased (n = 6, p less than 0.01), and thus the coronary vascular resistance decreased after ANP infusion, suggesting an ANP-induced dilation of resistance vessels. The present study demonstrates that in human subjects a clinical dose of ANP by intravenous infusion dilates both the large epicardial and small resistance coronary vessels. These results suggest a potentially beneficial role for ANP in reducing the severity of myocardial ischemia in patients with ischemic heart disease.

Adult↗
PubMed1991

[Characteristics of the regulation of coronary circulation in progressive disorders of coronary perfusion].

Coronary failure was demonstrated to be followed by impaired coronary circulation regulation in the hypoperfused area, as manifested by quantitative (incomplete realization of dilator reserve) or qualitative (greater coronary resistance) alterations of coronary responses to ischemia. The disorders detected were shown to be directly related to the manifestations of limited coronary flow, predominant with its 70% decrease and represent an essential mechanism of further progression of coronary failure.

Animals↗
PubMed1975

Coronary circulation in patients with and without coronary artery disease and the effects of chewable isosorbide dinitrate.

Coronary arteriograms of 38 patients with suspected coronary artery disease (CAD) were first evaluated to decide whether or not the disease was present and, if so, whether easily recognizable collateral channels were demonstrated. In this evaluation, we found CAD in 26 of the 38 patients. Eighteen of 21 patients with severe obstructions or occlusions had functioning collateral vessels. The films were then evaluated a second and third time to determine the effects of chewable isosorbide dinitrate (ISDN) on the coronary circulation. Visual inspection of the arteriograms revealed significant increases in 1) the apparent number and diameter of collateral vessels, 2) the opacification of vessels distal to occlusions, and 3) the diameter of coronary arteries following the administration of 2.5, 5, or 10 mg chewable ISDN. Computer analysis of the arteriograms showed an average 16% increase in the diameters of specific segments of major coronary arteries following ISDN. All patients showed some degree of vasodilatation following ISDN; however, patients without CAD consistently showed more vasodilatation than patients with disease. Mean aortic blood pressure decreased an average of 10% following ISDN. These results demonstrate that the chewable form of ISDN reliably dilates the coronary arteries in patients both with and without CAD and enhances the collateral circulation to the ischemic areas in patients with CAD.

Adult↗