Showing papers in "Circulation Research in 1954"
TL;DR: By stimulating different parts of the hypothalamus in the cat, it has been possible to show that adrenal medullary secretion often contains preferentially adrenaline or noradrenaline.
Abstract: By stimulating different parts of the hypothalamus in the cat, it has been possible to show that adrenal medullary secretion often contains preferentially adrenaline or noradrenaline. The results indicate that the two horomones are secreted from different cells with separate innervation.
195 citations
TL;DR: The ability of the right ventricle to compensate as the pulmonary artery is constricted appears to be determined by four major factors: there occurs the well-known increased force of contraction as the right heart becomes distended, and the greater the blood volume, the greater is the limit of compensation before right ventricular failure occurs.
Abstract: The ability of the right ventricle to compensate as the pulmonary artery is constricted appears to be determined by four major factors: (1) there occurs the well-known increased force of contraction as the right heart becomes distended; (2) the adequacy of the coronary circulation determines to a great extent the Degrees of pulmonary arterial constriction which can occur before failure occurs; (3) the circulatory reflexes apparently aid the compensation to a moderate extent; and (4) the greater the blood volume, the greater is the limit of compensation before right ventricular failure occurs.
156 citations
TL;DR: It was found that anoxia, adenylic acid, compression of the aorta or pulmonary artery reduces coronary vascular resistance while epinephrine increases it, and a revival of the “massaging theory” in modified form is suggested.
Abstract: By integrating phasic coronary sinus flow curves in such a way that volume flow during systole plus isometric contraction and that during the remainder of diastole can be compared, the relative contribution of ventricular compression and coronary resistance to mean coronary flow can be assessed. It was found that anoxia, adenylic acid, compression of the aorta or pulmonary artery reduces coronary vascular resistance while epinephrine increases it. The augmentation in coronary mean flow following epinephrine is due solely to the greater force of ventricular contractions. On the basis of such evidence a revival of the "massaging theory" in modified form is suggested. Evidence was incidentally obtained which supports a former conclusion that the coronary sinus drains territories supplied by the right as well as the left coronary artery.
134 citations
TL;DR: It is concluded that the pulmonary artery wedge pressure pulse is a reasonably accurate reflection both in magnitude and in contour of the left atrial pressure pulse in man during normal respiration and also during assisted respiration at operation.
Abstract: In 17 patients with atrial septal defect, in 12 patients with mitral stenosis and in four patients with unilateral lung tumor but without evidence of mitral valve disease, a similarity in pressure pulse contours in the left atrium and pulmonary artery wedge position was obtained at cardiac catheterization. It is concluded that the pulmonary artery wedge pressure pulse is a reasonably accurate reflection both in magnitude and in contour of the left atrial pressure pulse in man during normal respiration and also during assisted respiration at operation.
128 citations
TL;DR: Interarterial anastomoses in young pigs have been compared with those in mongrel dogs by direct flow measurements during life and by injections after death and indicate that pigs have minimal functional collaterals in comparison with dogs.
Abstract: Interarterial anastomoses in young pigs have been compared with those in mongrel dogs by direct flow measurements during life and by injections after death. Results indicate that pigs have minimal functional collaterals in comparison with dogs and that injection studies roughly predict the Degrees of collateral function. The data indicate that the extent of collateral development in dogs is independent of dog or heart weight and hence offers more protection against the effects of coronary occlusion in small hearts than in large hearts. Other studies indicate that coronary flow, myocardial oxygen consumption and coronary vasomotor responses in pigs are similar to those in dogs.
111 citations
TL;DR: A mathematical and physical basis for heart vector projection concepts is presented and its significance for current practices in frontal-plane and spatial electrocardiography is discussed in this paper, where assumptions underlying the theory are stated and utilized to derive a general relationship between the heart dipole and the potentials it produces in the body.
Abstract: A mathematical and physical basis for heart-vector projection concepts is presented and its significance for current practices in frontal-plane and spatial electrocardiography is discussed. Assumptions underlying the theory are stated and utilized to derive a general relationship between the heart dipole and the potentials it produces in the body. Specific equations are given for unipolar and bipolar leads and the Wilson central-terminal voltage. Coefficients determined experimentally for human torso models differ markedly from those that stem from Einthoven's hypothesis. Einthoven's equilateral triangle represents a special case of the general theory. Geometric interpretations are applied to a quantitative frontal-plane example, to the Wilson central-terminal voltage and extended to the concept of an image surface corresponding to the human body surface.
107 citations
TL;DR: From determinations of radioactivity and potassium content at intervals after the injection of Rb86, it was inferred that most organs of the dog contained exchangeable rubidium in a concentration paralleling but exceeding that of potassium, as compared with their relative concentrations in the plasma.
Abstract: From determinations of radioactivity and potassium content at intervals after the injection of Rb86, it was inferred that most organs of the dog contained exchangeable rubidium in a concentration paralleling but exceeding that of potassium, as compared with their relative concentrations in the plasma. A "lag phenomenon" resulting in higher rubidium specific activity in the myocardium than plasma was present. Analysis indicated that this was dependent on the relationship of myocardial rubidium exchange rate and the rate of decline of plasma rubidium specific activity. In experiments requiring prolonged observation, Rb86 (half life, 19.5 days) is a useful tracer of potassium.
103 citations
TL;DR: Ventricular fibrillation can be initiated in the isolated, perfused heart by injections of calcium chloride into the perfusion stream and can also be initiated by perfusion with a K-free perfusion medium.
Abstract: Ventricular fibrillation can be initiated in the isolated, perfused heart by injections of calcium chloride into the perfusion stream. It can also be initiated by perfusion with a K+-free perfusion medium. These are related phenomena since the latter type of fibrillation will not occur if Ca++ is also removed from the perfusion medium. The mechanism by which Ca++ initiates fibrillation is unknown. The facility with which Ca++ causes fibrillation is increased when the K+ concentration of the tissue fluid is lowered. When it is very low the normal Ca++ content of Krebs solution is sufficient to initiate fibrillation.
97 citations
TL;DR: In dogs anesthetized with chloralose, innervated loops of intestine were isolated so as to permit periodic interruptions of blood flow to record pressure-volume diagrams from the venous bed, interpreting direct evidence of venoconstriction accompanying pressor responses of the cardiovascular system.
Abstract: In dogs anesthetized with chloralose, innervated loops of intestine were isolated so as to permit periodic interruptions of blood flow to record pressure-volume diagrams from the venous bed. Pressor reflexes were found to produce alterations in the venous distensibility diagrams which, on the basis of comparison with distensibility changes produced by constrictor drugs, are interpreted as direct evidence of venoconstriction accompanying pressor responses of the cardiovascular system.
95 citations
TL;DR: During restriction of left coronary flow, the left ventricular function curve (modified Starling curve), which does not normally show a descending limb even at high filling pressures, developed a pronounced descending limb.
Abstract: Left main coronary artery blood flow, cardiac output and pressures in the pulmonary artery, the aorta and both atria were continuously recorded in the dog. Restriction of left coronary flow increased left atrial pressure substantially, but right atrial pressure only slightly; left ventricular work, cardiac output and arterial pressure fell markedly. During restriction of left coronary flow, the left ventricular function curve (modified Starling curve), which does not normally show a descending limb even at high filling pressures, developed a pronounced descending limb. Unilateral ventricular failure was demonstrated.
93 citations
TL;DR: Experimental data indicate that the retractile force in isolated aortic strips of the dog is entropic, and studies of aorti strips extracted with alkali suggest that the latter force arises from the elastic tissue itself.
Abstract: A detailed thermodynamic study of isolated strips of dog aorta is basic to the interpretation of the nonlinear and apparently rubber-like elastic behavior of such specimens. Experimental data indicate that the retractile force in isolated aortic strips of the dog is entropic. Volume changes with elongation in such strips are negligible. However, a large negative internal energy contribution to the total force is present at small elongations. Studies of aortic strips extracted with alkali suggest that the latter force arises from the elastic tissue itself.
TL;DR: Evidence is presented that the area of the cardiac silhouette and the area and diameter of the left ventricle all diminish in response to thoracotomy and during recovery return toward the pre-operative dimensions.
Abstract: Changes in heart size have been studied by means of intraventricular gages, serial roentgenography and cinefluorographic angiocardiography. Evidence is presented that the area of the cardiac silhouette and the area and diameter of the left ventricle all diminish in response to thoracotomy and during recovery return toward the pre-operative dimensions. Since fundamental concepts of cardiac function and control are based largely on investigation of exposed hearts, these concepts must be re-examined in intact, unanesthetized animals and man.
TL;DR: Changes in left ventricular diameter occur very rapidly, often being manifest within the duration of a single cardiac cycle, and mechanisms by which changes in ventricular size can be directly affected by neural and hormonal influences are briefly considered.
Abstract: Left ventricular dimensions have been directly measured for extended periods of time in intact unanesthetized dogs under various conditions. The diameter of the left ventricle during diastole is very large in relation to the change in diameter during each cycle. Thus, considerable quantities of blood remain within the chamber at the end of systolic ejection. The stroke output can be increased by either more complete systolic ejection during exercise or by greater diastolic filling during a startle reaction. Accelerated heart rate occurs in both cases. Changes in left ventricular diameter occur very rapidly, often being manifest within the duration of a single cardiac cycle. Mechanisms by which changes in ventricular size can be directly affected by neural and hormonal influences are briefly considered.
TL;DR: The theory of dynamic fluid motion involving the forces manifested by mass, acceleration, viscous friction and vessel wall tension have been considered and studied when arterial blood flow and pressure are pulsatile and it is concluded that arterials blood pressure is dependent upon all of these parameters.
Abstract: The theory of dynamic fluid motion involving the forces manifested by mass, acceleration, viscous friction and vessel wall tension have been considered and studied when arterial blood flow and pressure are pulsatile. These studies and considerations have resulted in the conclusion that arterial blood pressure is dependent upon all of these parameters and that the relationship of pressure and flow is more complex and nonlinear than heretofore generally believed.
TL;DR: Coronary blood flow and myocardial oxygen and carbohydrate metabolism were studied in normal intact dogs subjected to different Degreess of hypoxia, which resulted in negative arteriovenous differences for lactate and markedly decreased or negative values for pyruvate.
Abstract: Coronary blood flow and myocardial oxygen and carbohydrate metabolism were studied in normal intact dogs subjected to different Degreess of hypoxia Total left ventricular oxygen consumption was maintained during administration of 10 per cent and 5 per cent oxygen owing to increase in coronary flow and myocardial oxygen extraction Ten per cent oxygen administration had little effect on carbohydrate uptake by the heart Five per cent oxygen resulted in decreased coefficients of extraction for glucose, lactate and pyruvate, but total utilization was maintained Complete anoxia resulted in negative arteriovenous differences for lactate and markedly decreased or negative values for pyruvate
TL;DR: Studies of the splanchnic venous system of intestinal loops gave evidence of the same type of distensibility phenomena as seen in the aorta, although at low pressures the venous distensible tends to be actually decreased by vasoconstriction.
Abstract: The distensibility of the aorta was measured in anesthetized dogs by injecting blood at controlled rates into an isolated segment. Constrictor drugs produce a moderate increase in distensibility of the aorta at low pressure ranges and a more marked increase in distensibility at normal pressures. Studies of the splanchnic venous system of intestinal loops by the same method, and also by a method which does not require interruption in blood flow, gave evidence of the same type of distensibility phenomena as seen in the aorta, although at low pressures the venous distensibility tends to be actually decreased by vasoconstriction. The splanchnic venous system also differs from the aorta in that it is very dependent upon the rate of pressure-volume change. These results are analyzed in terms of the basic mechanisms involved and their physiologic implications.
TL;DR: The functional status of the myocardium in hypothermia was investigated by means of pulse contours and no evidence for myocardial failure was uncovered on the basis of established criteria.
Abstract: The functional status of the myocardium in hypothermia was investigated by means of pulse contours. No evidence for myocardial failure was uncovered on the basis of established criteria. Artificial cardiac acceleration proved to be a dangerous procedure in the hypothermic heart.
TL;DR: Hypercholesterolemia was induced in pure-bred dogs by cholesterol feeding and propylthiouracil or radioiodine and increased the severity of aortic atherosclerosis even in normotensive dogs.
Abstract: Hypercholesterolemia was induced in pure-bred dogs by cholesterol feeding and propylthiouracil or radioiodine. Hypertension induced by the injection of silica into the renal artery increased the severity of aortic atherosclerosis. Marked hypercholesterolemia increased the severity of aortic atherosclerosis even in normotensive dogs.
TL;DR: Congenital cardiovascular anomalies were observed in the offspring when rats were placed on a dietary regimen deficient in pteroylglutamic (“folic”) acid during gestation, at a time when the heart and aortic arches were in the initial stages of development.
Abstract: Congenital cardiovascular anomalies were observed in the offspring when rats were placed on a dietary regimen deficient in pteroylglutamic ("folic") acid during gestation. These cardiovascular malformations occurred only when the mothers were given this diet for specific periods, as short as two or three days, in early pregnancy, at a time when the heart and aortic arches were in the initial stages of development.
TL;DR: These experiments suggest that the state of contraction and resistance to stretch of the barosensitive arterial walls is controlled by sympathetic innervation through local release of norepinephrine and/or epinephrine and, thus, in the pathogenesis of hypertension.
Abstract: The state of contraction and resistance to stretch of the arterial wall of the carotid sinus modulates sensitivity of pressoreceptors to intra-arterial pressure. Experiments show that electric stimulation of efferent sympathetic pathways to the carotid sinus leads to blood pressure fall and decrease of the carotid sinus hypertensive reflex. This effect can be prevented by local application of Regitine to the carotid sinus. These experiments suggest that the state of contraction and resistance to stretch of the barosensitive arterial walls is controlled by sympathetic innervation through local release of norepinephrine and/or epinephrine. Disturbances of this innervation could have a role in development of abnormal relaxation and decreased pulsatile expansion of the barosensitive arterial walls, and, thus, in the pathogenesis of hypertension.
TL;DR: It is concluded that in dogs the Beck operation is protective against the major effects of coronary ligation because of retrograde capillary flow early and intercoronary anastomoses later.
Abstract: Studies were made on dogs at various times up to one year following the coronary sinus anastomosis of Beck to determine the chronic effects of the operation. The results indicate that the graft perfuses the capillary bed of the occluded circumflex artery for about five weeks after the operation and then loses its functional contact with the capillary bed probably because of obliterative venous changes. However, as a result of an anoxia, there is definite development of intercoronary collateral vessels during the first few weeks, which persist throughout the year even though there is no arterial occlusion. It is concluded that in dogs the Beck operation is protective against the major effects of coronary ligation because of retrograde capillary flow early and intercoronary anastomoses later.
TL;DR: In severe hypothermia resistance in the coronary vascular bed is reduced and flow continues despite very low aortic pressure, which is due to the longer periods of extravascular compression in each cardiac cycle.
Abstract: In severe hypothermia resistance in the coronary vascular bed is reduced and flow continues despite very low aortic pressure. Moderate artificial acceleration of the hypothermic heart at constant coronary perfusion pressures produces a decrease in coronary blood flow. This decrease in flow is roughly proportional to the increase in heart rate and is due to the longer periods of extravascular compression in each cardiac cycle. Epinephrine produces transient improvement in blood pressure and coronary blood flow but is followed in a matter of minutes by ventricular fibrillation.
TL;DR: Certain segements of the ventricular myocardium appear to be supplied by fixed portions of the conducting system, without cross connections operating physiologically, in dogs exhibiting various Degreess of right and left bundle-branch block.
Abstract: Controlled studies of ventricular excitation were performed in dogs exhibiting various Degreess of right and left bundle-branch block. Increases in the intraventricular conduction time during complete bundle-branch block are attributed to free wall as well as septal factors. Incomplete bundle-branch block may be either segmental or diffuse. In the segmental type, delayed excitation is present in only a portion of the involved ventricle. In the diffuse type, delayed excitation of the entire homolateral ventricle occurs, but some portions of the ventricle tend to be delayed to a greater extent than others. Certain segements of the ventricular myocardium appear to be supplied by fixed portions of the conducting system, without cross connections operating physiologically. The clinical implications of these observations are briefly discussed.
TL;DR: Cardiac output was determined in dogs over a wide range of pressures before and after preclusion of compensatory reflex mechanisms, and total peripheral resistance remains relatively constant although appreciable deviations may be observed in individual cases.
Abstract: Cardiac output was determined in dogs over a wide range of pressures before and after preclusion of compensatory reflex mechanisms. When the moderator reflexes are functional, total peripheral resistance increases markedly with moderate reductions in arterial pressure. When reflex alterations of vasomotor tone are obviated, pressure and flow usually vary proportionately as arterial pressure is altered. In the average experiment, total peripheral resistance remains relatively constant although appreciable deviations may be observed in individual cases.
TL;DR: Direct puncture of the left atrium with a needle allows pressure measurements in atrium, left ventricle and aorta, considered to be more helpful than right heart catheterization in evaluation of patients with mitral and aortsic valvular lesions.
Abstract: Direct puncture of the left atrium with a needle, through which a catheter can be passed, allows pressure measurements in atrium, left ventricle and aorta. This procedure is considered to be more helpful than right heart catheterization in evaluation of patients with mitral and aortic valvular lesions.
TL;DR: Excised arterial tissue is shown to differ from other excised tissues by its property of retaining fractions of serum lipids that are transfiltered under pressure in the form of zonal deposits at the elastic tissue membranes.
Abstract: Excised arterial tissue is shown to differ from other excised tissues by its property of retaining fractions of serum lipids that are transfiltered under pressure in the form of zonal deposits at the elastic tissue membranes. The mode of deposition of artificially produced lipid accumulations and spontaneously formed ones is probably very similar. Various factors that influence the deposition of lipid in excised arteries are examined in detail. The most important of these prove to be the structural peculiarities of arterial tissue and the concentration of lipid in the serum.
TL;DR: Hexamethonium bromide in normotensive and renal hypertensive dogs resulted in significant reductions in arterial blood pressure, cardiac output and cardiac work and the calculated cardiac efficiency was decreased.
Abstract: Hexamethonium bromide in normotensive and renal hypertensive dogs resulted in significant reductions in arterial blood pressure, cardiac output and cardiac work. The decrease in cardiac output relative to that in blood pressure suggests that the blood pressure reduction was largely due to the decrease in cardiac output. There was a decrease in coronary flow accompanied by an increase in myocardial oxygen extraction of such Degrees that cardiac oxygen consumption remained unchanged. Since myocardial oxygen consumption remained unchanged despite the decrease in cardiac work the calculated cardiac efficiency was decreased.
TL;DR: The effect of Cedilanid on the mechanical and electrical activity of extracted and nonextracted heart muscle strips of dogs was studied and the problem of whether digitalis is bound to the membrane or the cell protein was investigated by temporary destruction of the cell membrane by water.
Abstract: The purpose of this investigation was to study the effect of Cedilanid on the mechanical and electrical activity of extracted and nonextracted heart muscle strips of dogs. The glycoside did not influence the work, the speed of contraction, or the length-resting tension relationship of extracted heart muscle. It produced changes in membrane action potentials, but none in membrane resting potentials. The problem of whether digitalis is bound to the membrane or the cell protein was investigated by temporary destruction of the cell membrane by water. The effects of cardiac glycosides on contractile proteins and on membrane activity are probably inseparable; they act through changes in ionic gradient between muscle cells and the surrounding medium.
TL;DR: A pump of 50 cc.
Abstract: A pump of 50 cc. reservoir capacity, only 10 cm. in diameter, was placed in the systemic circuit between the left auricular appendage and the left common carotid artery in each of 10 dogs so that the systemic circulation was maintained by the pump during complete cardiac arrest resulting from experimentally produced ventricular fibrillation. All dogs recovered completely.