bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparison of the Double Two-Step Test and the Maximal Exercise Treadmill Test
Authors: BELLET SAMUEL , ROMAN LAURIAN 
Published: June 2012

A comparison of the double two-step test and a more strenuous type of exercise test was made to assess the value of the latter procedure in increasing the sensitivity of the electrocardiographic exercise test.
In young, normal women, 17 to 20 years of age, who represent a group with minimal chances for significant silent coronary heart disease, both the double two-step test and graded maximal exercise tests were always normal. This is consistent with the view that ischemic electrocardiographic changes are not usually elicited in subjects with normal coronary circulation, even after strenuous exercise.
In middle-aged men and women, 40 to 65 years of age, in whom the possible existence of clinically silent coronary heart disease was suggested by age and other parameters (atypical chest pain, hypertension, or diabetes, or all three), the maximal exercise test on the treadmill, as compared to the double two-step test, increased the yield of positive electrocardiographic results by 12%. These findings suggest that, in selected "coronary-prone" subjects on whom the double two-step test is negative, increasing the amount of exercise might be of value in the evaluation of the exercise test.
Temporary Transvenous Catheter-Electrode Pacing of the Heart
Authors: TANCREDI ROBERT G. , McCALLISTER BEN D. , MANKIN HAROLD T. 
Published: June 2012

Experience with 110 separate periods of transvenous cardiac pacing by means of a catheter-electrode in 91 patients has been reviewed. Indications for the use of the catheter-electrode included (1) complete heart block with and without Adams-Stokes syndrome, (2) other arrhythmias with and without cardiogenic syncope, (3) malfunction of previously implanted permanent pacemaker units, and (4) need for pacing during general surgical procedures in patients with a variety of rhythm disturbances. A case illustrating the combined use of drug therapy and catheter-electrode pacing in controlling paroxysmal ventricular tachycardia is presented.
Only six deaths occurred in spite of the serious heart disease in all 91 patients in this series. Two were related to complications of temporary transvenous intracardiac pacing. The major complications associated with the procedure included perforation of the heart, bacteremia, acute myocardial infarction, cephalic vein phlebitis, and ventricular tachyarrhythmia. Minor problems were primarily related to equipment failure or positional difficulties with the catheter-electrode and were usually of no serious consequence.
Effects of Diphenylhydantoin on Atrioventricular Conduction in Man
Authors: HELFANT RICHARD H. , LAU SUN H. , COHEN STAFFORD I. , DAMATO ANTHONY N. 
Published: June 2012

The effects of intravenous diphenylhydantoin (5 mg/kg) on atrioventricular conduction in man at controlled heart rates in the digitalized and undigitalized state were studied. In undigitalized subjects, diphenylhydantoin administration consistently decreased A-V conduction time in each individual subject when identical heart rates were compared. Ouabain infusion produced an increase in A-V conduction time and this prolongation was always reversed by diphenylhydantoin. In two patients with atrial flutter and in two with atrial fibrillation, diphenylhydantoin caused a decrease in ventricular rate without affecting the atrial arrhythmias.
These findings are of clinical importance, especially in the therapy of digitalis toxicity. When digitalis excess is manifested by both ectopic beats and incomplete A-V block, diphenylhydantoin would have special utility since, in contrast with the commonly used antiarrhythmic agents, it decreases A-V conduction time in addition to suppressing ectopic beats. Diphenylhydantoin-induced depression of the ventricular rate in atrial flutter or fibrillation may also be useful clinically. However, since diphenylhydantoin markedly decreases ventricular automaticity, its use in patients with complete heart block is contraindicated.
Congenital Cardiac Disease Associated with Polysplenia
Authors: MOLLER JAMES H. , NAKIB AHMAD , ANDERSON RAY C. , EDWARDS JESSE E. 
Published: June 2012

The well-recognized association of congenital cardiac disease with asplenia has been termed "bilateral right-sidedness" or dextro-isomerism, since the spleen is absent, the liver is symmetrical, and each lung has three lobes and an epiarterial bronchus. In a study of pathological material from 12 patients with congenital cardiac disease associated with multiple spleens (as contrasted to accessory spleen), we found a definite tendency for the symmetrical development of organs but with a tendency for bilateral left-sidedness or levo-isomerism.
The abnormalities assumed one of three forms as follows: (1) absence of a normal right-sided structure, (2) bilateral organs, each with the structure of a left-sided organ, or (3) excessive tissue of a left-sided organ. Thus, in polysplenia we observed a tendency for (1) absence of the hepatic segment of the inferior vena cava and absence of the gallbladder, (2) two lobes in each lung with hyparterial bronchi, and (3) multiple spleens. Other noncardiac abnormalities were partial or complete abdominal heterotaxia and partial malrotation of the bowel. The cardiac malformations included dextrocardia, bilateral superior venae cavae, anomalous pulmonary venous connection with malposition of the atrial septum, and defects in the atrial septum and in the ventricular septum.
Our study suggests that the developmental complex of multiple spleens is closely related to the asplenic syndrome, with the important difference being left-sided symmetry rather than right-sided symmetry.
Pericardial and Myocardial Disease Associated with Serological Evidence of Infection by Agents of the Psittacosis-Lymphogranuloma Venereum Group (Chlamydiaceae)
Authors: SUTTON GEORGE C. , MORRISSEY RICHARD A. , TOBIN JOHN R. , ANDERSON TRUMAN O. ,   Idiopathic Myocardial Disease Study Group of the Cook County Hospital, Chicago, Illinois.
Published: June 2012

Nine patients with acute pericarditis or myocarditis, or both, were found to have serological evidence of concurrent infection by a psittacosis agent. Three patients had conclusive epidemiological and clinical evidence of complicating pulmonary psittacosis and demonstrated that psittacosis agent does produce inflammatory heart disease in this geographic area.
Six patients had imperfect corroborative evidence of psittacosis and their clinical manifestations were atypical. Indeed, half of these patients were initially believed to have some form of idiopathic myocardial disease. Studies of these patients suggest that psittacotic infection m
ay be causal in certain forms of heart disease commonly designated primary myocardial disease.
Clinical Significance of Coronary Artery Calcification Seen Fluoroscopically with the Image Intensifier
Authors: MCGUIRE JOHNSON , SCHNEIDER HAROLD J. , CHOU TE-CHUAN 
Published: June 2012

Five hundred forty-four unselected patients were examined by a radiologist as to the presence or absence of coronary artery calcification. The overall prevalence of coronary calcification was 20% and there was a definite increase in the prevalence of the finding with increasing age. A comparison of 94 patients with coronary calcification with a matched control group without calcification indicated that the prevalence of symptomatic ischemic heart disease in the group with calcification was approximately twice that of the control group. The correlation was even more significant when the degree of calcification was moderate or severe.
It is concluded that cardiac fluoroscopy with image intensification is a useful supplementary tool in the clinical evaluation of patients suspected of having coronary artery disease. It can be performed easily and imposes no risk to the patient.
Hemodynamic Effects of Nitroglycerin in Patients with Angina Pectoris Studied by an Atrial Pacing Method
Authors: FRICK M. H. , BALCON R. , CROSS D. , SOWTON E. 
Published: June 2012

The hemodynamic effects of nitroglycerin on 20 patients with coronary arterial disease were assessed by using atrial pacing to invoke angina pectoris. This new technique also permitted study of the hemodynamics during pain without the interference of the effects of muscular exercise on the heart affected by coronary artery disease.
The pain threshold of each patient was determined by successive pacing runs and the effects of nitroglycerin were evaluated both before and during the pacing up to the level of pain. With regard to the circulatory status at pain an abnormally elevated pulmonary capillary venous "wedge" pressure was an infrequent phenomenon. This difference from the data of studies in which muscular exercise is used is briefly discussed.
Sublingual nitroglycerin decreased aortic, pulmonary arterial, right atrial, and pulmonary capillary venous pressures. Stroke volume and cardiac output were reduced and this reduction was accompanied by a compensatory rise in heart rate. Tension-time index was reduced and during pacing at identical rates never reached the level at which angina pectoris was experienced before nitroglycerin. End-diastolic heart size as estimated from conventional chest roentgenograms was reduced by nitroglycerin at every pacing step in all six patients studied by this method. The conclusions were that at all heart rates studied nitroglycerin (a) decreased atrial pressures, (b) decreased heart size, (c) caused peripheral vasodilatation, and (d) allowed the heart to be driven at a higher rate without production of anginal pain. These hemodynamic changes reflect a decreased oxygen requirement of the heart and are consistent with the pain-relieving properties of nitroglycerin.
Intravenous Use of Diazoxide in the Treatment of Severe Hypertension
Authors: HAMBY WILLIAM M. , JANKOWSKI GERALD J. , POUGET J. MAURICE , DUNEA GEORGE , GANTT CLARENCE L. 
Published: June 2012

Thirty-three patients with severe hypertension were treated with rapidly injected intravenous diazoxide. Renal function was measured in nine patients and four underwent cardiac catheterization during renal function studies. Diazoxide had a rapid, profound hypotensive effect. Average decrease in mean arterial pressure was 26%, with an average duration of 16 hours. Drug resistance was not observed. Renal function was not impaired despite maintenance of arterial pressure at or near normal levels. Decreased mean arterial pressure was associated with a decrease in systemic vascular resistance and left ventricular end-diastolic pressure while an increase in cardiac index and heart rate occurred. Urine volume was unchanged, whereas the glomerular filtration rate and the effective renal plasma flow increased but urinary sodium excretion decreased markedly.
Intravenous diazoxide is a practical effective agent for treatment of all forms of severe hypertension.
Hemodynamic Consequences of Physical Training after Myocardial Infarction
Authors: FRICK M. H. , KATILA M. 
Published: June 2012

The hemodynamic effects of physical training, three periods weekly for 1 to 2 months, after myocardial infarction were assessed in seven patients by cardiac catheterization at rest and during exercise. The training was followed by reduction in exercise heart rate and tension-time index as determined from brachial artery pressures. Stroke volume during exercise was enhanced. No significant change occurred in the heart volume. Left ventricular function was improved, and a significant increase in the rate of rise of right ventricular pressure occurred. These were interpreted as indicating myocardial hypertrophy, which probably through reduced compliance also accounted for increased ventricular filling pressures. Lactate in arterial blood was reduced during exercise without any change in the arteriovenous oxygen difference. Small and not significant changes occurred in vital capacity, forced expiratory volume, fasting blood sugar, and serum lipids.
Concomitant with the hemodynamic changes exercise tolerance was improved. The data support the thesis that in some patients increased physical activity after myocardial infarction is followed by beneficial hemodynamic effects on the heart and possibly by increased coronary blood flow. The need for proper selection of patients and close medical supervision during training is illustrated and emphasized.
Late, Heparin-Induced Bleeding after Retrograde Arterial Catheterization
Authors: BRISTOW J. DAVID , SEAMAN ARTHUR J. , KLOSTER FRANK E. , HERR RODNEY H. , GRISWOLD HERBERT E. 
Published: June 2012

Three patients with ball-valve prostheses were given heparin after percutaneous retrograde aortic catheterization from the femoral artery. The drug was given prophylactically in one case and because of the development of signs of systemic embolism soon after catheterization in the other two. After 3 or more days of heparin therapy, serious bleeding developed at the site of percutaneous catheter entry. The timing and incidence of this complication are in marked contrast to experience with this procedure in individuals who did not receive heparin.
Preliminary experience is presented from right and left heart catheterizations in patients whose prothrombin-proconvertin times were allowed to remain in or near the therapeutic range. No hemorrhagic complications were observed.
Surgical Correction of Mitral Insufficiency Due to Ruptured Chordae Tendineae
Authors: GERBODE FRANK , HILL J. DONALD , KELLY JOHN J. , SELZER ARTHUR , KERTH WILLIAM J. 
Published: June 2012

During the past six years we have operated on 80 patients with predominant mitral insufficiency. Twenty-two patients had ruptured chordae tendineae. Rheumatic heart disease was frequently the cause when there was considerable valve deformity and ruptured chordae to the anterior mitral leaflet. The etiology of these cases was rheumatic heart disease in only 2 of the 15 patients with ruptured chordae to the posterior leaflet. In eight the etiology was unknown. These cases had a syndrome in which there is an aortic as well as an apical systolic murmur. The left atrium was frequently not so large as in rheumatic mitral insufficiency, and most patients were in sinus rhythm.
Because of a relative excess of reserve tissue of the posterior leaflet, localized rupture of chordae to this leaflet can easily be corrected by a simple plication procedure.
Surgery for Massive Myocardial Infarction
Authors: HEIMBECKER RAYMOND O. , LEMIRE GUY , CHEN CHARLES 
Published: June 2012

Emergency myocardial infarctectomy has been studied experimentally and clinically. The clinical experience describes encouraging results in two of four consecutive patients. The criteria of patient selection are described, along with a suggestion that associated perforation of the ventricular septum, as documented in three of the patients, makes the operative procedure more difficult and the results less satisfactory.
Experimental myocardial infarction was studied in two groups of calves with a mortality rate of 100%. In the first group emergency resuscitation by massage and bypass produced an initial resuscitation rate of 14% but a survival rate of only 11%. In the second control group of fatal infarction, resuscitation was attempted by 45 minutes of bypass, with improvement in the resuscitation rate to only 23% and proportionate improvement in the survival rate to 18%.
Emergency infarctectomy dramatically increased the initial salvage rate to 100% and improved the survival rate to 41%.
Atrial Echo Beats in the Human Heart Elicited by Induced Atrial Premature Beats
Authors: SCHUILENBURG R. M. , DURRER D. 
Published: June 2012

In a patient with atrial septal defect and incomplete right bundle-branch block atrial echo beats were observed after atrial premature beats, induced with a gradually decreasing delay during regular driving of the atrium. The time relations of these atrial echo beats could be accurately defined. Considerable prolongation of the atrioventricular (A-V) conduction of the premature atrial response was found to be a necessary condition for the occurrence of atrial reciprocation, which was restricted to small and very circumscript delay ranges.
Three types of atrial echo responses could be discerned. The concept of a dual A-V conduction system was not sufficient to explain the genesis of these three types. The assumption of a third pathway in the upper part of the A-V node was needed. Arguments in favor of a longitudinal dissociation of one of the two pathways postulated in the concept of dual A-V transmission were given.
Hemodynamic Studies on Cholera
Authors: HARVEY RÉJANE M. , ENSON YALE , LEWIS MILENA L. , GREENOUCH WILLIAM B. , ALLY KHAIROON M. , PANNO ROSALIND A. 
Published: June 2012

The hemodynamic effects of hypovolemia and acidosis were studied in 23 patients with cholera. Studies were made before and during fluid replacement and administration of alkali.
The major hemodynamic abnormalities encountered before rehydration can be ascribed to a reduction in circulating blood volume. Hypovolemia was associated with a reduction in cardiac output, blood pressures, and central blood volume. Restoration of blood volume returned these variables toward normal.
The chief effect of acidosis appeared to be a redistribution of blood from the peripheral to the central circulation; consequently, central blood volume, lesser circulation pressures, and cardiac output were relatively well maintained despite hypovolemia. Fluid administration without correction of acidosis favored a disproportionate increase in central blood volume, while reduction in hydrogen ion concentration attending fluid replacement resulted in a more even distribution of the circulating blood volume and reduced the possibility of engorgement of the pulmonary bed.
It is postulated that this redistribution of blood stems from peripheral venoconstriction and a reduction in the capacity of venous reservoirs induced by acidosis.
Quantitative Angiocardiography
Authors: MURRAY JOHN A. , KENNEDY J. WARD , FIGLEY MELVIN M. 
Published: June 2012

Maximum and minimum volumes of the left atrium (LA) were calculated from the biplane angiocardiograms of 18 men and four women without significant heart disease.
The mean LA maximum volume was 63 cc ± 16 cc; the mean LA minimum volume was 31 cc±10 cc, and their difference, LA cyclic volume change, was 33 cc±13 cc. Larger LA volumes were associated with greater cyclic volume changes. LA cyclic volume changes constituted 38% of LV stroke volume.
No significant correlation between LA volumes and age, sex, surface area, heart rate, LV end-diastolic volume, LV stroke volume, or cardiac output was found.
Volume data in normal subjects support the thesis that the LA serves mainly as a reservoir and conduit for blood destined for the left ventricle and that its contractile function is less important. The relation of LA volume change to LV stroke volume appears abnormal in chronic mitral regurgitation and constrictive pericarditis.
Reference to Transposition, Dextrocardia and the Concept of Four Normal Hearts
Authors: STANGER PAUL , BENASSI ROBERT C. , KORNS MICHAEL E. , JUE KENNETH L. , EDWARDS JESSE E. 
Published: June 2012

A system of loose leaf diagrams is presented for the purpose of portraying the various types of cardiac structure. Appropriate assembly of the diagrams may be used to define the anatomic details in a given case of which a permanent machine-copy may be made and the basic diagrams re-used.
The diagrams may be used as teaching devices to illustrate the interrelationships between (1) transposition of the great vessels, (2) inversion of the various cardiac chambers and great vessels, and (3) dextrocardia.
The material lends itself to illustration of the concept of "four normal hearts;" that is, the fact that although structurally different, there are four anatomic patterns of heart which allow a normal route for the flow of blood.
The diagrams also may be used to illustrate certain features about potential cardiac transplantation. These include the point that for the recipient with a certain body type (situs solitus or situs inversus), normal channels for the flow of blood may be obtained from a donor with one of three types of cardiac structure. These are either the normal or that of corrected transposition of the same body type as the recipient or complete transposition in a donor with the opposite body type from that of the recipient.
Reciprocal Beating Induced by Ventricular Pacing
Authors: BAROLD S. SERGE , LINHART JOSEPH W. , SAMET PHILIP 
Published: June 2012

Ventricular pacing is frequently associated with retrograde ventriculo-atrial conduction. In the absence of atrioventricular (A-V) block, the relatively intact antegrade A-V conduction system supplies the necessary pathway for a re-entry mechanism that may become operative in the presence of delayed retrograde conduction.
Two patients with bradycardia and unimpaired antegrade A-V conduction exhibited reciprocal (echo) beating following nodal beats before ventricular pacing was instituted. After the introduction of an artificial ventricular pacemaker, reciprocal beats followed the paced ventricular beats in both patients.
These observations suggest that a similar mechanism is involved in the production of reciprocal beats linked to impulses originating from the A-V node and the ventricles.
When ventricular pacing is indicated for the treatment of bradycardia in the presence of intact antegrade A-V conduction, a situation which may produce echo beats, demand pacing is considered preferable to fixed-rate pacing as the latter may deliver a stimulus into the vulnerable phase following an echo beat.
Monophasic Action Potentials in Man
Authors: SHABETAI RALPH , SURAWICZ BORYS , HAMMILL WILLIAM 
Published: June 2012

Monophasic action potentials with an amplitude of up to 70 mv were recorded with suction electrodes from the endocardial surface of the right atrium and both ventricles during diagnostic cardiac catheterization. The method was simple and safe. The monophasic action potential of human beings had the same shape and the same relation to the electrocardiogram as the transmembrane action potential of animals has. Also changes in heart rate and administration of calcium and digitalis had the same effect on the monophasic action potential of man as on the transmembrane action potential of animals.
When injections of contrast material into the coronary arteries produced T-wave changes, the monophasic action potential from the ventricle perfused by the contrast medium lengthened, but the monophasic action potential from the other ventricle did not change.
Our study suggests that the monophasic action potential may be helpful in estimating the refractory period at the site of recording and in explaining the pathogenesis of abnormal repolarization in the electrocardiogram.