ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

The evaluation of left ventricular (LV) compliance by use of the pressure-volume (P-V) relationship encounters several serious difficulties. Since the P-V relationship is curvilinear, it is difficult to quantitate. Furthermore, alterations of resting heart size and geometry also produce marked changes in the P-V curve. The first derivative of the P-V relationship, however, is a precisely linear function expressed by the formula dP/dV = aP+b. The slope of this linear function, a, termed the passive elastic modulus, has been shown to be independent of initial volume and primarily and predominantly determined by changes in the stiffness of the myocardium. Myocardial wall stiffness was evaluated in three groups of subjects during LV catheterization. In 13 normal subjects a = 0.005; in 13 with coronary artery disease a = 0.011; and in 12 with acute infarction a = 0.045. The differences in stiffness among the groups were highly significant (P< 0.005).It was concluded that a measurable change in ventricular compliance occurs with the development of coronary artery disease and that a further increase in wall stiffness occurs with the development of acute infarction. The magnitude of increase in LV wall stiffness correlated directly with immediate prognosis: 87% of those subjects with a &Dgr;P/&Dgr;V greater than 0.5 mm Hg/cc died of power failure during the acute stage of their illness. These alterations in compliance may invalidate certain traditional concepts of LV function and heart failure.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

An assay of serum digoxin and other cardiac glycosides by displacement of3H-ouabain from Na-K ATPase is described. It is rapidly set up by any laboratory with a liquid scintillation counter. It can also assay digitalis leaf, digitoxin, and gitalin (Gitaligin), and has uncovered unsuspected administration of them.The assay takes less than 1 hour. No quench correction of counts is required. One technician can assay 30 samples/day with results that afternoon. No interfering compounds have been found in over 1,800 assays. It is unaffected by lung scans.Incidence of toxicity from digoxin is 10%, 25%, and 50% at serum levels of 1.4, 2.0, and 2.9 ng/ml, respectively. Toxic levels of digitalis and digitoxin are usually over 40 ng/ml.Serum digoxin levels are also highly correlated with computed total-body concentrations of digoxin, obtained from data of dosage, route of administration, and the patient's weight and renal function.Physicians may now select a serum digoxin level and computed total-body concentration of digoxin which are associated with an incidence of arrhythmias which they feel is reasonable for the urgency of each patient's clinical situation. These selected serum levels are associated with specific loading and maintenance dosage regimens, individualized to that patient's body weight, renal function, and route of digoxin administration.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Hypertrophic cardiomyopathy usually involves the left ventricle more severely than the right, and when asymmetrical may produce the syndrome of idiopathic subaortic stenosis. Less commonly, clinical manifestations of inflow-tract obstruction predominate and produce a syndrome that may be mistaken for mitral stenosis, principally because of an apical diastolic rumbling murmur. The probability of this diagnostic error and the risk of a consequent unnecessary operation can be reduced by appreciating the significance of the clues to left ventricular disease revealed by the electrocardiogram and the chest roentgenogram. Furthermore, proper timing of the heart sounds differentiates the protodiastolic filling sound of cardiomyopathy from the opening snap of mitral stenosis. The correct diagnosis is established following ventriculographic and hemodynamic studies.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

The effects of practolol, a new beta-adrenergic blocking agent, and propranolol were studied in volunteers. At rest, practolol caused a very small reduction in cardiac index (CI), 190 ml,P< 0.25, and preejection period (PEP) lengthened 3 msec,P< 0.025. In contrast, propranolol caused a reduction in CI of 770 ml,P< 0.001. Heart rate (HR) slowed 10 beats/min,P< 0.001, stroke volume index (SVI) fell 6 ml,P< 0.005, PEP lengthened 16 msec,P< 0.001, and peripheral vascular resistance (PVR) increased 419 dynes-sec-cm−5,P< 0.001. Practolol reduced the increase in CI caused by an isoproterenol infusion by 65%,P< 0.005, by blocking the increase in HR by 73%,P< 0.05. Practolol also reduced the shortening of PEP and LVET caused by isoproterenol. PVR decreases due to isoproterenol were not blocked by practolol although they were slightly attenuated,P< 0.025. Practolol reduced the increase in CI caused by exercise by 22%,P< 0.05, by blocking the increase in HR by 29%,P< 0.01. Practolol also reduced the increase in tension-time index due to exercise by 25%,P< 0.025.Practolol has little effect on the performance of the normal heart at rest. It does block the cardiac effects of isoproterenol and exercise, largely through chronotropic mechanisms. The reductions in pressure-time relationships with exercise indicate reduced oxygen consumption by the heart, and therefore imply a therapeutic benefit in exercise-induced angina.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

This study was designed to test the efficacy of glucagon in the treatment of hemodynamic abnormalities of acute and healing experimental canine myocardial infarction. Myocardial infarction was produced in intact, conscious dogs by gradual inflation of a balloon cuff device implanted around the left anterior descending coronary artery 1 to 2 weeks prior to the study. Hemodynamic and metabolic effects of 50 &mgr;g/kg of glucagon were assessed serially in the control state, 1 hour after myocardial infarction and again 1 week later. In the control state glucagon improved cardiac performance and increased myocardial oxygen consumption. One hour after acute myocardial infarction glucagon improved cardiac performance and reduced the degree of left ventricular failure, without any increase in myocardial oxygen consumption. Similar effects of glucagon were noted in the healing phase of myocardial infarction. It is postulated that in this animal model in the presence of heart failure due to myocardial infarction there are reciprocal changes in the factors that increase myocardial oxygen consumption (glucagon-induced inotropy) and decrease oxygen consumption (fall in ventricular end-diastolic volume and wall stress), resulting in no net change in oxygen requirement.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Several important indices of myocardial performance depend upon accurate and frequent measurement of ventricular volume. Studies employing such measurements have been limited because of the difficulty of manually measuring and calculating volumes frequently enough to obtain meaningful data. We, therefore, have developed an automated method for determination of ventricular volume in man. Left ventricular cineangiograms taken in the right anterior oblique position at 60 frames/sec are projected with a flickerless projector onto a Plumbicon television camera. A second television camera is used by a skilled operator for masking out noncontributory portions of the film and for shading selected areas to facilitate accurate recognition of the opacified chamber. An electronic video-tracking device then simultaneously determines the area and the maximum length of the opacified chamber in each cine frame. These data are recorded as analog signals on magnetic tape. Volumes are calculated by computer and plotted against time. When volumes determined by this automated method are compared with those obtained by manual planimetry, the correlation coefficient is 0.96. Aluminum prolate spheroids, left ventricular casts, and left ventricular cineangiograms were studied. This automated technic permits rapid and accurate measurement of ventricular volume in patients having diagnostic left ventriculograms.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Nuclear angiocardiography with a gamma camera, a pinhole collimator, and99mTc pertechnetate was performed on 43 children aged 3 years or less, including 10 neonates. Twenty-six children had congenital heart disease, which was confirmed at cardiac catheterization; the rest had no structural cardiac anomaly. Use of the pinhole collimator allowed magnification of cardiac images, with enhancement of resolution. Sensitivity was improved by positioning the pinhole 14 cm rather than 19 cm from the crystal of the gamma camera. Anterior and left lateral angiocardiograms were obtained with both 35-mm images at 0.3-sec intervals and cine-images at 18 frames/sec.Abnormalities in origin, size, and position of the great arteries, in chamber configurations, and in the time and course of activity in right and left heart, lungs, and great vessels were used to assist in identification of anomalies such as transposition of the great arteries, pulmonary atresia with intact ventricular septum, truncus arteriosus, and aortic atresia.99mTc in a dose of 18.5 mCi/M2of body area was used and produced whole-body and gonadal radiation doses less than 1 rad. The low risk and simplicity of the technic make it promising as a screening procedure and as an adjunct to cardiac catheterization for cyanosed infants.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID