摘要:

The effect of electrically induced auricular and ventricular tachycardia of various rates was studied in the anesthetized dog. When, the control heart ranging between 140 and 190 per minute, atrial tachycardia of a rate only slightly higher than the control rate was induced, a very temporary initial decrease in arterial blood pressure, cardiac output and coronary blood flow occurred, then all three parameters essentially returned to control level. With atrial tachycardia of a higher rate, blood pressure, cardiac output and coronary flow fell more markedly, then blood pressure and cardiac output rose to or toward control level, remaining below control level with higher rates of tachycardia, whereas the coronary flow rose to or above control level and only exceptionally remained below control level. Ventricular tachycardia had essentially the same effects as atrial tachycardia, but a ventricular tachycardia of a given rate had the same quantitative effect as an atrial tachycardia of a higher rate.

ISSN:0009-7330    

出版商:OVID    

年代:1958

数据来源: OVID

摘要:

Mean and phasic coronary flows were recorded simultaneously by an electromagnetic meter, and peripheral coronary pressure was recorded distally from the temporarily occluded descending branch of the left coronary artery. From the results of these studies we conclude that: 1. The sympathetic cardiac nerves, as does levarterenol, increase myocardial contraction, (indicated by a shorter, more abrupt systole and more rapid isometric relaxation), and cause a slight degree of coronary arteriolar dilation. 2. Parasympathetic fibers exert no significant effect, although acetylcholine diminishes coronary arteriolar tone and may slightly diminish ventricular contraction. 3. That measurements of mean coronary flow and resistance are relatively satisfactory for indicating changes in coronary arteriolar tone, but are of relatively little value in evaluating myocardial contraction.

ISSN:0009-7330    

出版商:OVID    

年代:1958

数据来源: OVID

摘要:

Studies on the intracoronary administration of epinephrine and norepinephrine in the beating, fibrillating or potassium-arrested dog heart indicate that the primary action of these compounds on the coronary vessels is vasoconstriction. The vasodilation observed with epinephrine and norepinephrine is probably secondary to the increased rate of myocardial metabolism induced by these drugs.

ISSN:0009-7330    

出版商:OVID    

年代:1958

数据来源: OVID

摘要:

The current views of the authors regarding the relationship of the cardiac performance and its myocardial oxygen consumption and the relationship of the latter to coronary blood flow are presented. Recent attempts, including our own, to devise an index of total cardiac effort that will relate to the myocardial oxygen consumption are discussed. It is concluded that the cardiac performance requiring oxygen determines coronary flow while the arteriovenous oxygen difference across the bed remains constant. However, the level of the arteriovenous oxygen difference is altered by local conditions of oxygen and carbon dioxide concentrations, and the presence of catecholamines. Hence, the level of coronary flow for a given amount of cardiac oxygen consumption is altered by these circumstances.

ISSN:0009-7330    

出版商:OVID    

年代:1958

数据来源: OVID

ISSN:0009-7330    

出版商:OVID    

年代:1958

数据来源: OVID

ISSN:0009-7330    

出版商:OVID    

年代:1958

数据来源: OVID