Showing papers by "Eugene Braunwald published in 1969"
TL;DR: The effect of deep respiration on blood velocity in the ascending aorta and pulmonary artery was studied and the highest velocities and stroke volumes were achieved during late expiration while in the pulmonary artery blood velocity and stroke volume were greatest in inspiration.
Abstract: Twenty-three patients were investigated during diagnostic right and left cardiac catheterization with an electromagnetic catheter-tip velocity probe. The catheter contained a pressure lumen for sim...
176 citations
TL;DR: Assessment of cardiac function has centered on techniques that examined the heart's action as a pump through Hemodynamic analysis within the framework of the Franckian framework.
Abstract: In the past, assessment of cardiac function has centered on techniques that examined the heart's action as a pump. Hemodynamic analysis of cardiac function within the framework of the Fran...
172 citations
TL;DR: In congestive heart failure, both the cutaneous and muscle beds of the forearm are abnormally constricted at rest, there is excessive vasoconstriction in both beds during leg exercise, and postexercise cutaneous vasodilation is abolished.
Abstract: The purpose of this study was to determine the relative effects of various levels of exercise on blood flow to skin and muscle of the resting extremity of normal subjects and the manner in which this distribution is modified by congestive heart failure. Blood flow to the skin and muscle of the forearm was determined plethysmographically with the aid of epinephrine iontophoresis at rest and during supine leg exercise in 12 normal subjects and in 9 patients with failure. In normal resting subjects, forearm blood flow averaged 6.30 ml/min/100 ml, 52% partitioned to muscle and 48% to skin. In the patients, forearm blood flow averaged 2.94 ml/min/100 ml, with 48% to muscle and 52% to skin. In normal subjects performing mild exercise, forearm muscle flow was not significantly changed, but during moderate and strenuous activity it was significantly reduced. Cutaneous blood flow, however, declined early at all levels of exertion. In the normal subjects, cutaneous hyperemia occurred late during moderate exercise but with strenuous exercise, was delayed until after exercise had been discontinued. In contrast, in the patients, forearm muscle blood flow decreased strikingly during leg exercise, cutaneous flow fell and remained depressed during the entire period of exercise, and no postexercise hyperemia occurred. Thus, in congestive heart failure, both the cutaneous and muscle beds of the forearm are abnormally constricted at rest, there is excessive vasoconstriction in both beds during leg exercise, and postexercise cutaneous vasodilation is abolished.
161 citations
TL;DR: It is indicated that a cold environment increases peripheral resistance at rest and during exercise, and the consequent rise in arterial pressure, by augmenting myocardial oxygen requirements, would thus more readily provoke an attack of angina.
Abstract: The physiologic basis for the frequent complaint of worsening of symptoms in a cold environment was investigated in six patients with and five without coronary-artery disease, at rest and during identical levels of mild upright exercise at 25 and 15°C, with similar results. Significantly higher at the lower temperature were mean systemic arterial pressure (105 vs 92 mm of mercury at rest and 110 vs 92 during exercise; p less than 0.001), total peripheral resistance (1821 vs 1609 dynes-sec-cm-5 at rest, 1213 vs 993 during exercise; p less than 0.02) and left ventricular minute work (6.5 vs 5.7 kg-m at rest, 10.9 vs 9.0 during exercise; p less than 0.001). Exposure to cold did not change heart rate, cardiac output or stroke volume at rest or during exercise. These results indicate that a cold environment increases peripheral resistance at rest and during exercise. The consequent rise in arterial pressure, by augmenting myocardial oxygen requirements, would thus more readily provoke an attack of angina.
94 citations
88 citations
TL;DR: The effects of carotid sinus nerve (CSN) stimulation were studied at rest and during a mild level of supine bicycle exercise in seven patients in whom CSN stimulators had been implanted for the treatment of angina pectoris.
Abstract: The effects of carotid sinus nerve (CSN) stimulation were studied at rest and during a mild level of supine bicycle exercise in seven patients in whom CSN stimulators had been implanted for the treatment of angina pectoris. At rest, CSN stimulation produced a fall in mean arterial pressure (MAP) averaging 23% and an 8% decrease in cardiac output (CO). Total peripheral resistance (TPR) fell by 14% and forearm vascular resistance (FVR) by 16%. During exercise, MAP fell 16%, but no significant change occurred in CO. Thus, the fall in MAP could be attributed to a reflexly induced decrease in peripheral vascular resistance. Only small decreases occurred in heart rate. No changes in venous tone, central venous pressure, or the maximum transverse end-diastolic diameter of the heart were produced by stimulation either at rest or during exercise. Thus, at rest, CSN stimulation reduces MAP by reflexly decreasing both vascular resistance and CO; during exercise, the diminution in CO no longer occurs. Finally, the ve...
87 citations
TL;DR: Tension development, contractile state of the myocardium, and heart rate are the most important factors influencing cardiac oxygen consumption, and drugs commonly used in the treatment of patients with acute myocardial infarction appear to influence oxygen consumption by acting upon these three determinants.
Abstract: A series of investigations on the determinants of myocardial oxygen consumption were reviewed and their relevance to the survival and function of ischemic tissue in the presence of coronary occlusion pointed out. Tension development, contractile state of the myocardium, and heart rate are the most important factors influencing cardiac oxygen consumption, and drugs commonly used in the treatment of patients with acute myocardial infarction appear to influence oxygen consumption by acting upon these three determinants. Thus, digitalis glycosides and sympathomimetic agents tend to increase myocardial oxygen requirements, since they improve the heart's inotropic state. However, this influence may be offset in the enlarged heart in which end-diastolic volume and tension are reduced. Agents which depress the heart exert the opposite effect. Electrocardiographic changes reflecting myocardial ischemia are intensified when isoproterenol is administered following coronary ligation.
Synchronized arterial counterpulsation reduces myocardial tension development and therefore oxygen consumption. An augmentation of myocardial oxygen needs in the presence of coronary occlusion may be expected to increase the size of the necrotic zone and to impair the function of the ischemic zone, while a reduction of oxygen consumption may be expected to exert the opposite effect.
81 citations
TL;DR: The radioisotope-angiocardiogram provides a new approach for visualization of the cardiovascular system, does not require the use of radiopaque medium, is safer than angiography, and does not disturb circulatory function.
Abstract: The recent development of the instantaneously sensing Anger scintillation camera, capable of recording wide-field radioisotope images from the precordium, and a system for video storage and analysis has provided a means of visualizing the anatomic and hemodynamic features of the heart and great vessels without the hazards involved in introducing a radiopaque agent. Sodium pertechnetate (99mTcO4-) produces no cardiocirculatory effects or untoward actions and delivers only 0.13 rads of total body radiation. Following injection, the rapidly changing distribution of radioactivity within the heart is recorded by the scintillation camera-television system which includes no inherent dead time or overlap of the scanned field from frame to frame. Video tape replay is available immediately and sequential integrated pictures are possible at any rate up to 60 sec. Radioisotope images of longer intervals are easily obtained by the integration of successive stop-action fields reproduced on a high resolution television ...
68 citations
62 citations
44 citations
TL;DR: Patients with supraVentricular tachycardia may be terminated by manual pressure on the carotid sinuses or by the administration of parasympathomimetic or of pressor agents.
Abstract: SUPRAVENTRICULAR tachycardia may be terminated by manual pressure on the carotid sinuses or by the administration of parasympathomimetic or of pressor agents. Recently developed technics for the tr...
TL;DR: It is concluded that in this form of experimentally produced heart failure the utilization of ∼P is reduced but only in relation to the reduction in contractile element work and that the direct conversion of chemical energy to mechanical work is not an inefficient process in this state.
Abstract: This investigation was designed to determine whether a defect in energy utilization exists in heart failure. Accordingly, the direct conversion of chemical energy to mechanical work was studied in right ventricular papillary muscles from normal cats and cats with experimental right ventricular failure secondary to pulmonary artery constriction. Energy production was inhibited by iodoacetic acid and N2. After resting or performing variable amounts of internal contractile element work under isometric conditions, muscles were instantly frozen, and the total amount of chemical energy (~— P = creatine phosphate + ATP) used was correlated with work performed and the number of contractions. The contractile properties of papillary muscles from cats with heart failure were severely depressed. There was a significant depression in initial *-~P stores in muscles from cats with heart failure, but there was no significant change in the resting rate of '—P utilization. Although the muscles from cats with heart failure performed, on the average, 13% as much work and were activated 64% as many times, the average amount of energy used was only 7% of that used by normal muscles. It is concluded that in this form of experimentall y produced heart failure the utilization of *—-P is reduced but only in relation to the reduction in contractile element work and that the direct conversion of chemical energy to mechanical work is not an inefficient process in this state.
TL;DR: The investigations described in this report were undertaken to determine the manner in which the intrinsic contractile state of isolated myocardium is altered by the development of ventricular hypertrophy and failure, by norepinephrine depletion, and by changes in the thyroid state.
Abstract: The investigations described in this report were undertaken to determine the manner in which the intrinsic contractile state of isolated myocardium is altered by the development of ventricular hypertrophy and failure, by norepinephrine depletion, and by changes in the thyroid state. Several recent developments have made it possible to examine these questions. The mechanics of isolated cat papillary muscles from the normal heart have been described in a manner similar to that employed for skeletal muscle.' Further, it has been shown that these mechanical functions can be quantitatively measured and norms established, that the variability of function is small among muscles from groups of similar animals, and that the function of muscles from different groups of animals can therefore be compared in a quantitative and meaningful manner.* In order to study the effects of ventricular hypertrophy and heart failure on myocardial contractility, papillary muscles were obtained from normal cats and cats with right ventricular hypertrophy, with or without overt congestive heart failure produced by chronic constriction of the main pulmonary artery, a procedure described in detail el~ewhere.~, A circular clip with an internal diameter (I.D.) of 3.5 mm or 2.8 mm was placed around the proximal main pulmonary artery under sterile conditions. Between 21 and 90 days later, the cats were anesthetized with pentobarbital, and right-heart catheterization was carried out; the hearts were then excised rapidly, and the papillary muscles were removed and studied in a myograph at 30° C and at a contraction frequency of 12 per minute.2 Heart failure occurred after constriction of the lumen of the pulmonary artery with the 2.8-mm I.D. clip. The presence of heart failure was defined on the basis of the existence of one or more ,of the following findings: (1) pleural effusion, (2) ascites, and (3) an abnormally elevated right ventricular end-diastolic pressure in combination with either an abnormally low cardiac index or a high arterio-mixed venous oxygen difference. In the 11 cats with heart failure, the average right ventricular weight was increased from a normal value of 0.55 g/kg to 1.33 g/kg. Right ventricular hypertrophy without heart failure occurred in cats in which the lumen of the pulmonary artery had been reduced to 20% of normal by the application of the 3.5-mm I.D. clip. Cats were included in this group only if there was no pleural fluid or ascites and if values for right ventricular end-diastolic pressure, cardiac index, and arteriomixed venous oxygen difference were within the range of normal. The right ventricular weight was almost double the normal in this group and averaged 1.05 g/kg. In the muscles removed from both of these groups of animals, the actively developed tension was less than normal (FIGURE 1 ) . Maximum isometric tension in the muscles from animals with right ventricular hypertrophy was slightly,
TL;DR: With the waning of newspaper headlines proclaiming the technical feat of another "successful" human heart transplantation (followed only too often by the announcement on an inside page of the paper...
Abstract: With the waning of newspaper headlines proclaiming the technical feat of another "successful" human heart transplantation (followed only too often by the announcement on an inside page of the paper...