bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Method for Measuring Plasma Levels of Digitalis Glycosides
Authors: LOWENSTEIN JEROLD M. 
Published: June 2012

A method is described for measuring plasma levels of cardiac glycosides, utilizing their inhibitory effect on the rubidium-86 uptake of human red cells. As little as 0.05 mµg. of digoxin/ml. of plasma produces detectable inhibition, but due to the variable effect of other substances in human plasma the practical limit of the method is 1.0 mµg./ml., about 20 times as sensitive as the duck embryo heart or the C
14
-labeled technics.

Patients on digitalis leaf were found to have much higher circulating levels than patients on digoxin (average value 7.5 mµg./ ml. of digoxin equivalent for digitalis leaf, 0.05 mµg./ml. for digoxin). Patients toxic on digoxin averaged 6 mµg./ml.
Of patients not taking digitalis, 7 per cent had significant levels of digitalis-like substances in their plasma; these were mostly individuals with metastatic carcinoma, severe fluid and electrolyte disturbances, or heart failure. No drug (other than cardiac glycosides) gave consistent high levels by this test.
Myocardial Function and Left Ventricular Volumes in Acquired Valvular Insufficiency
Authors: MILLER GRAHAM A. H. , KIRKLIN JOHN W. , SWAN H. J. C. 
Published: June 2012

The effect of valvular insufficiency on left ventricular volumes was studied by an angiographic method in 37 patients. Ejection of the additional volume load imposed by valvular insufficiency was achieved by an increase in end-diastolic volume and not by increasing the proportion of end-diastolic volume ejected. Of the 37 patients, 16 (43 per cent) had a significant reduction in the fraction of end-diastolic volume ejected per beat. These patients performed significantly less stroke work from a given end-diastolic fiber length (end-diastolic volume) than did the others and evidence is presented that they had impaired myocardial function. An index of myocardial contractility is derived which relates stroke work to end-diastolic volume.
The magnitude of left ventricular volumes is determined in part by the severity of the volume load but a further increase in volume without necessarily a further increase in ejection occurs in those patients with impaired myocardial function. Valvular insufficiency is quantitated from the difference between left ventricular ejection volume determined angiographically and forward stroke volume determined from indicator-dilution curves. The results show good agreement with subsequent surgical findings in the 15 patients who underwent operation.
Experimental Demonstration of Concealed AV Conduction in the Human Heart
Authors: LANGENDORF R. , PICK A. , EDELIST A. , KATZ L. N. 
Published: June 2012

Artificial pacing of patients with Stokes-Adams disease provided an opportunity to study experimentally the ways of operation of concealed antegrade or retrograde conduction, or both, in the AV junction.
With a catheter electrode in the right atrium the classical experiment of Lewis and Master was repeated, revealing, during a 2:1 ventricular response to an atrial tachycardia, the delaying effect of seemingly blocked atrial impulses on subsequent AV conduction.
Shifting the position of a single premature atrial impulse within a constant driving cycle of the atria produced graded effects of "blocked" atrial impulses on AV junctional refractoriness, permitting an estimation of the duration of the "phase of concealed AV conduction."
Interpolation of such premature atrial impulses into successive driving cycles resulted in "repetitive concealed conduction."
In an artificially produced atrial parasystole there was observed "concealed discharge" of a subsidiary (escaping) AV junctional pacemaker by an apparently nonconducted atrial impulse.
With a catheter electrode in the right ventricle in a case of advanced AV block, concealed retrograde conduction of pacer stimuli disturbed the rhythmicity of a spontaneous AV junctional pacemaker.
In a case of advanced AV block with preserved retrograde conduction (unidirectional block), evidence of penetration of the upper AV junction by the "blocked" antegrade impulse was found.
With electrodes implanted in the left ventricle in a case of advanced AV block, concealed retrograde conduction of the artificial pacemaker stimuli enhanced antegrade conduction by transiently changing an area of unidirectional block to one of supernormal conduction.
Thus, all known manifestations of concealed atrioventricular and ventriculo-atrial conduction, occurring spontaneously in clinical records or induced in animal experiments, were artificially reproduced in the human heart.
Red Blood Cell Survival in Patients with Aortic Valvular Disease and Ball-Valve Prostheses
Authors: BRODEUR MICHAEL T. , SUTHERLAND DONALD W. , KOLER ROBERT D. , STARR ALBERT , KIMSEY JEAN A. , GRISWOLD HERBERT E. 
Published: June 2012

Red blood cell survival was determined in patients with aortic valvular disease, postoperative patients with aortic valvular ball-valve prostheses and postoperative patients with multiple ball-valve prostheses. The red blood cell survival was reduced in the majority of patients in each group when compared with the red blood cell survival from a normal control group.
A detailed analysis of the survival curves suggested that in many patients there was more than one population of red blood cells. The first population displayed rapid random destruction. This population was not present in normal persons in the control group. The second population showed the usual decline in radioactivity due to random destruction and loss of the red cell label due to elution. The shortened red blood cell survival in some patients was due to a large percentage of the first population of randomly destroyed red blood cells, in other patients to an accelerated rate of destruction of the usual single population of cells while others had a combination of the two mechanisms.
A mechanism of mechanical hemolysis due to increased intracardiac turbulence was suggested as a cause for the shortened survival. When the turbulence was increased by a leak around the aortic or mitral valve prosthesis the red blood cell survival was found to be further decreased. In some cases this reduction in survival was enough to produce hemolytic anemia.
The Coombs antiglobulin test was positive in three patients. The suggestion was made that the development of autoantibodies to red blood cells was secondary to increased destruction of red blood cells.
Exercise Graded by Heart Rate in Electrocardiographic Testing for Angina Pectoris
Authors: SHEFFIELD L. T. , HOLT JOHN H. , REEVES T. JOSEPH 
Published: June 2012

Standardization of an exercise electrocardiographic test for myocardial ischemia is desirable. Standardization of exercise should be based upon a standardized challenge to the coronary circulation, not upon a standardized challenge to the skeletal muscles, for the stresses upon the heart are not identical.
With the use of heart rate during exercise as an index of cardiac stress, the levels of exercise prescribed on the basis of age, sex, and weight in standard "two-step" test tables produce widely varying levels of cardiac stress-sometimes too low to induce significant ST-segment depression in patients with angina pectoris and, occasionally, much greater than necessary to produce such diagnostic electrocardiographic changes.
The graded exercise test, using 85 per cent of the maximal age-predicted heart rate that may be induced by exercise, produces a closer approximation of a standardized cardiac stress, regardless of age, sex, or body build. Its use with angina pectoris patients and normal subjects results in increased sensitivity (fewer false negatives) and increased specificity (fewer false positives).
Use of the graded exercise test as described is considered not to increase the hazard of testing, and perhaps even to decrease it.
Influence of Respiration on Venous Return in Pulmonary Emphysema
Authors: NAKHJAVAN FRED K. , PALMER WILFRED H. , MCGREGOR MAURICE 
Published: June 2012

The influence of respiration on the flow of blood from the abdominal vena cava into the thorax was studied in 15 patients with pulmonary emphysema and in 10 control subjects without thoracic disease or heart failure. In control subjects, during quiet breathing blood flowed into the thorax throughout the respiratory cycle at a rate which was greatest during inspiration. Simultaneously the transmural pressure of the abdominal vena cava fell and transmural right atrial pressure increased. The same pattern of flow was observed in nine of the patients with emphysema. In the other six patients, however, flow was greatly reduced or completely arrested during inspiration, with simultaneous increase in transmural caval pressure and reduction in transmural atrial pressure. This inspiratory obstruction at the thoracic inlet was associated with gross hyperinflation of the lungs and a low diaphragmatic position. It probably was not the result of the high negative and positive intrathoracic pressures that develop during inspiration and expiration, respectively, in such subjects.
It is possible that this phenomenon may account for the peripheral edema that occurs in patients who have emphysema without associated pulmonary hypertension or cardiomegaly.
Relationship of Fibrillatory Waves and P Waves in the Electrocardiogram
Authors: PETER ROBERT H. , MORRIS JAMES J. , MCINTOSH HENRY D. 
Published: June 2012

The amplitude of the fibrillatory waves and the P terminal force were compared in 100 consecutive patients. These electrocardiographic measures of atrial activity were made first in atrial fibrillation and then after electrical conversion to sinus rhythm. When the same patient was studied, the occurrence of a coarse fibrillatory wave and an abnormal P terminal force, or a fine fibrillatory wave and a normal P terminal force, was found to be a highly significant relationship.
This relationship suggests that the factors responsible for the characteristic of the terminal portion of the P wave recorded in sinus rhythm probably determine the magnitude of the fibrillatory wave that occurs when atrial fibrillation is present. The finding of a coarse fibrillatory wave or an abnormal P terminal force should suggest the electrocardiographic diagnosis of left atrial hypertrophy or "strain."
Coronary Angiographic Findings in Correlation with Age, Body Weight, Blood Pressure, Serum Lipids, and Smoking Habits
Authors: CRAMÉR KIM , PAULIN SVEN , WERKÖ LARS 
Published: June 2012

Radiological findings by coronary angiography in 224 patients, 173 males and 51 females, were graded according to the rate of filling of coronary arteries and to the presence or absence of obstruction of vessel lumen. The material was then grouped according to age, diastolic blood pressure, serum total cholesterol, serum glycerides, and smoking habits.
Age and diastolic blood pressure were not found to have any influence on frequency of coronary artery changes, presumably because of selection of patients.
In the males, elevated total serum cholesterol had only a minor influence on the frequency of coronary artery changes, while elevated glycerides were found in high frequency in patients with obstructed coronary arteries, especially in those with severe obstruction. If patients put on lipid-reducing therapy or diet were added to those with serum cholesterol higher than 280 mg/100 ml, a slight overrepresentation of coronary changes was found when compared with patients with total serum cholesterol equal to or lower than 280 mg/100 ml. The influence of elevated total serum cholesterol was in all instances inferior to that of elevated serum glycerides.
Smokers showed the frequency of coronary changes the same as or higher than patients with elevated glycerides. The influence of smoking was evident also within classes of low or elevated serum lipids.
While all conclusions must be interpreted with reference to the material selected as the source of our data, the importance of smoking as a causative agent independent of serum lipids appears conclusive.
Stethoscope Acoustics
Authors: ERTEL PAUL Y. , LAWRENCE MERLE , BROWN RICHARD K. , STERN AARON M. 
Published: June 2012

This paper describes a fully calibrated and standardized acoustical test method for evaluating the transmission patterns and the filtration patterns of intact stethoscopes. An essential component of the test system is the artificial ear which duplicates the acoustical contribution of the average human ear to the stethoscope's acoustics. The transmission patterns of bell-type stethoscopes fall into four distinct groups which correspond to their basic design features. Shallow bells and single tubing design both result in attenuation at higher frequencies. A deep, trumpet-shaped bell with double tubing design may provide amplification at higher frequencies. Diaphragms attenuate the transmission acoustics of stethoscopes. When the low frequencies are selectively attenuated, high frequencies are heard more distinctly. Some diaphragms were found to attenuate at all frequencies.
The acoustical performance of any stethoscope is critical. Any attenuation of clinically significant sounds of low intensity may render them totally inaudible. The majority of stethoscopes tested (bell and diaphragm chestpieces) attenuate high frequency sounds. The adoption of stethoscopic performance criteria is urged. Few modern stethoscopes show any significant acoustical improvement since the time of Laennec.
A Hemodynamic Study of Left Ventricular Aneurysm
Authors: KLEIN MICHAEL D. , HERMAN MICHAEL V. , GORLIN RICHARD , Vayo H. Westcott 
Published: June 2012

Thirteen patients with left ventricular aneurysm due to coronary heart disease were studied by left heart and coronary sinus catheterization, including cineventriculography and measurement of ventricular mechanics and energetics at rest, and in some subjects, during either isoproterenol infusion or supine leg exercise. Eight patients had an aneurysm estimated to comprise greater than 20% of the left ventricular surface area, associated with increased left ventricular end-diastolic volume and pressure and mean systolic force. Average isometric rate of pressure rise and mean fiber shortening velocity and distance were uniformly decreased. Five patients had an aneurysm, estimated to comprise less than 15% of the left ventricular surface, associated with normal or nearly-normal left ventricular end-diastolic volume and pressure and mean systolic force. Average isometric rate of pressure rise was normal, but fiber shortening velocity and distance were moderately depressed. Stroke output and cardiac output were reduced in both groups.
Aneurysms exhibited either paradoxical systolic expansion or apparent lack of motion (akinesis), or both. A theoretical analysis presented indicated that when approximately 20 to 25% of left ventricular area is inactivated by any pathological process, the degree of shortening distance required of the myofiber to maintain stroke volume exceeds physiological limits, and cardiac enlargement (Starling mechanism) must ensue to maintain adequate ejection of blood. The magnitude of the salutary response of isoproterenol coupled with an increase in mechanical efficiency during catecholamine infusion suggested that myocardial catecholamines were depleted with additional aggravation of heart failure in this disease.
Effects of Induced Ventricular Fibrillation on Ventricular Performance and Cardiac Metabolism
Authors: REIS ROBERT L. , COHN LAWRENCE H. , MORROW ANDREW G. 
Published: June 2012

The effects of induced ventricular fibrillation on ventricular performance and cardiac metabolism were studied in dogs. When ventricular fibrillation was induced by a brief 7.5-v a-c stimulus and allowed to persist spontaneously for one hour, no significant effects on subsequent cardiac function were apparent. An increase in myocardial oxygen consumption and a decrease in coronary vascular resistance occurred during the period of fibrillation.
When ventricular fibrillation was maintained by constant a-c stimulation, however, immediate and significantly deleterious effects on cardiac performance resulted. Coronary vascular resistance rose; myocardial oxygen consumption increased, but the increase was significantly less than in animals in which fibrillation persisted without electrical stimulation. Anerobic glycolysis ensued, leading to lactate accumulation in coronary venous blood.
The small a-c current used to maintain ventricular fibrillation impairs oxygen utilization, interferes with oxygen availability, and has a markedly deleterious effect on cardiac performance. A more satisfactory method of dependably maintaining the heart in ventricular fibrillation is needed before induced ventricular fibrillation can be safely employed to arrest cardiac contraction for prolonged periods during open cardiac operations.
Radiological Findings in Endomyocardial Fibrosis
Authors: COCKSHOTT W. PETER , ŠARIĆ SUZANNA , IKEME A. C. 
Published: June 2012

The radiological findings in 102 cases of endomyocardial fibrosis occurring in Equatorial Africa are presented. Postmortem studies confirmed the diagnosis in 39 cases. Angiocardiography was done in 78. The right side of the heart was primarily involved in 48 patients and the cardiac silhouette was characteristically globular suggesting a pericardial effusion, the large heart having a conspicuous background of oligemic pulmonary fields. Angiocardiography usually revealed a dilated right atrium and ventricle, extremely slow transit of the contrast material, and tricuspid incompetence. Occasionally, a filling defect in the right atrium, interpreted as thrombus, was seen.
The left side of the heart was established as being primarily involved in 13 cases and the picture of rheumatic mitral disease was simulated. Angiocardiography revealed a rather small left ventricle and mitral regurgitation. Biventricular disease was present in 42 patients, the main differentiating point in routine films from right endomyocardial fibrosis being the size of the superior pulmonary veins. The complete diagnosis is difficult to detect without angiographic studies.
Vectorcardiographic Changes During Intracoronary Injections
Authors: SMITH RAPHAEL F. , HARTHORNE J. WARREN , SANDERS CHARLES A. 
Published: June 2012

To determine mechanisms of myocardial toxicity of radiopaque media and to correlate specifically induced changes in the composition of coronary artery blood with changes in the surface electrocardiogram, simultaneous recordings were made from Frank leads X, Y, and Z during intracoronary injections of radiopaque media and special test solutions. The study group consisted of 19 patients, 29 to 64 years of age, with either abnormal or normal-appearing coronary vessels on cineangiography. Recordings were analyzed with an electronic integrator, an oscilloscope, and directly from photographic tracings.
With injections of sodium-containing radiopaque media into the right coronary system, the spatial mean T vector increased in magnitude and deviated to the left and superiorly. With injections into the left coronary system, the T vector increased in magnitude and shifted to the right, downward, and anteriorly. Changes in the QRS complex were less constant but, when present, consisted of slight prolongation of the QRS duration and shift of the QRS vector toward the area of myocardium perfused by the coronary system injected.
Similar T-vector changes could be produced by intracoronary injections of saline solutions, but minimal or no changes were observed with injections of hypertonic mannitol, Ringer's solution, hypoxic blood, plasma, and 5% dextrose in water.
It is concluded that the T-wave changes are caused by regional prolongation of the repolarization process, presumably due to extracellular sodium excess or sodium-calcium antagonism. Delay of the repolarization process and the resulting potential difference may be responsible for re-entrant excitation and the ventricular arrhythmias observed during coronary angiography.
The Ultra Low Frequency Force Ballistocardiograph in Acute Cardiomyopathy
Authors: PHIBBS BRENDAN , LOWE CHARLES R. , HOLMES ROY W. 
Published: June 2012

In this study, ultra low frequency force ballistocardiograms were recorded throughout the course of various types of acute cardiomyopathy. Conditions studied included rheumatic carditis, lupus myocarditis, sarcoid carditis, viral myocarditis, acute glomerulonephritis, idiopathic myocarditis, and familial fibrous disease of the myocardium. The instrument used was characterized by an unusually light platform and a very high performance accelerometer. In 14 of the 15 cases studied, tracings were abnormal initially; the recorded force pattern subsequently manifested progressive change which appeared to parallel the clinical course of the disease. Changes included appearance of abnormal forces in early ventricular systole, progressive change in amplitude of acceleration and deceleration forces, appearance of abnormal high frequency components in various portions of the complex, and appearance of abnormal footward forces in late systole.
The alterations thus recorded appear to offer a useful means of diagnosing and following the course of such disease entities. In some cases, this type of recording appears to provide information not available through any other conventional means.
Thromboembolic Complications of Prosthetic Cardiac Valves
Authors: AKBARIAN MOHAMMED , AUSTEN W. GERALD , YURCHAK PETER M. , SCANNELL J. GORDON 
Published: June 2012

Our experience with thromboembolism in 283 patients surviving at least 1 week following insertion of Starr-Edwards valves is reported here. Of these patients, 155 underwent aortic valve replacement, 21 had aortic valve replacement with mitral commissurotomy, 80 had mitral replacement, and 27 had both aortic and mitral valve replacement. Complete follow-up data were obtained on all patients, from 3 to 49 months following surgery (mean, 20 months).
Thromboembolic episodes developed in 68 of the 283 patients (24%). Seventeen of these 68 patients died (25%), three had serious neurological residual (4%), but the majority of survivors recovered completely.
Use of long-term anticoagulant therapy appeared to reduce incidence of embolic episodes only in patients with aortic valve replacement. Control of anticoagulant therapy (good, fair, or poor) bore no relationship to incidence of embolism within this group. Anticoagulant therapy in untreated patients with emboli reduced the incidence of subsequent thromboembolism. Hemorrhagic complications occurred in 23 patients (8%); one died.
Thromboembolism is a serious complication of prosthetic valves. Its incidence in some patients is reduced but not eliminated by anticoagulant therapy.
Prognosis of Men with Coronary Heart Disease as Related to Blood Pressure
Authors: FRANK CHARLES W. , WEINBLATT EVE , SHAPIRO SAM , SAGER ROBERT V. 
Published: June 2012

Hypertension prior to the onset of the initial myocardial infarction in men is associated with an excess early mortality rate: among men with elevated blood pressure the proportion dead within 1 month is more than twice that found among normotensive men with a first infarction. Hypertensives who survive the acute attack show twice the risk of recurrence and more than five times the risk of cardiac death over the next several years in comparison with men with normal blood pressure prior to infarction.
Among men whose first clinical evidence of coronary disease is angina pectoris, those with an elevated blood pressure have two and one half times the likelihood of experiencing a first myocardial infarction and cardiac death within a follow-up period of 30 months.
These findings are from the HIP (Health Insurance Plan of Greater New York) study of the incidence and prognosis of coronary heart disease, an ongoing prospective study of a general population of 110,000 men and women aged 25 to 64 years.