bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Effects of Propranolol on Cardiac Conduction
Authors: BERKOWITZ WALTER D. , WIT ANDREW L. , LAU SUN H. , STEINER CHARLES , DAMATO ANTHONY N. 
Published: June 2012

The effects of propranolol, 0.1 mg/kg given intravenously, on atrioventricular (A-V) conduction and intraventricular (IV) conduction were studied in eight patients. Atrial pacing was used to control the heart rate. His bundle electrograms were recorded, and the interval from the pacing impulse to the His bundle electrogram (P-H interval) was used as a measure of A-V conduction and the interval from the His bundle electrogram to the S wave (H-S interval) was used as a measure of intraventricular conduction. Propranolol significantly prolonged the P-H interval in every patient at all paced heart rates, and it had no effect on the H-S interval. In two patients propranolol prolonged the effective refractory period of the atrioventricular conducting tissue.
In four dogs during His bundle pacing, propranolol (4 mg/kg iv) had no effect on intraventricular conduction as measured from the His bundle pacing spike to S wave (H-S interval). In two dogs with prolonged H-S intervals secondary to toxic doses of digitalis and procainamide, propranolol had no effect on IV conduction. It is concluded that propranolol prolongs A-V conduction and has no effect on IV conduction when administered to patients in clinically effective dosages. Propranolol's effects on cardiac conduction can be explained on the basis of its capacity to produce beta-adrenergic blockade.
Left Ventricular Diastolic Pressure Elevation Consequent to Pulmonary Stenosis
Authors: HERBERT WALTER H. , YELLIN EDWARD 
Published: June 2012

Patients with mild pulmonary stenosis, predominant mitral stenosis, or aortic valvular disease were studied by standard catheterization technics to determine the effect of their lesions upon both the ipsilateral and contralateral ventricles.
The study suggested (1) that left heart lesions which produce an elevation of left ventricular end-diastolic pressure (LVEDP) do not necessarily cause an abnormal rise in diastolic pressure in the contralateral ventricle, (2) that eccentric right ventricular hypertrophy by definition without septal involvement may produce elevated right ventricular end-diastolic pressure without affecting LVEDP, and (3) that concentric right ventricular hypertrophy appears to effect an elevation in end-diastolic pressure in both the ipsilateral and contralateral ventricles.
Possible mechanisms related to the biventricular architecture are discussed.
Localization of the Site of Myocardial Scarring in Man by High-Frequency Components
Authors: FLOWERS NANCY C. , HORAN LEO G. , TOLLESON W. J. , THOMAS J. R. 
Published: June 2012

The increased incidence of high-frequency components (notching) in electrocardiographic (ECG) recordings previously has been related to coronary artery disease, primary myocardial disease, and biventricular enlargement.
This study included 130 subjects on whom autopsy permission was obtained, who had one or more sets of high-frequency, orthogonal ECG (XYZ) leads and direct-writing standard ECG leads recorded ante mortem. In each instance careful dissection of the heart was performed by two or more of the authors according to fixed protocol.
Correlations were made between the site of infarction and the occurrence of notching in specific high-frequency ECG leads. Postero-inferior infarctions tended to express themselves with a predominance of increased notching in the Y lead, while anterior infarction manifested dominantly in the X lead. This was true in intramural as well as transmural lesions.
The greatest value of notch recognition in diagnosing and localizing infarction appeared to be in subjects with normal sized hearts, with none of the classic ECG criteria for infarction, but who ultimately proved to have intramural scarring. In these subjects the increased incidence of notching clearly could not be attributed to biventricular enlargement, nor could the ECG diagnosis of infarction be arrived at by conventional criteria.
Double-Outlet Left Ventricle with an Intact Ventricular Septum
Authors: PAUL MILTON H. , MUSTER ALEXANDER J. , SINHA SACHCHIDA N. , COLE ROGER B. , VAN PRAAGH RICHARD 
Published: June 2012

Clinical, laboratory, and anatomic findings were presented concerning the first clinically diagnosed and autopsy proved case of origin of both great arteries from the morphologically left ventricle.
The salient pathologic findings were: normally interrelated chambers (noninverted) in situs solitus; no ventricular septal defect; infundibular atresia; infundibulum related only to the right ventricle; absence of infundibular musculature beneath the great arteries, with aortic-mitral and pulmonary-mitral fibrous continuity; semilunar valves side by side, aortic to the right and pulmonary to the left, and at approximately the same height; thick-walled and small-chambered right ventricle with endocardial fibroelastosis of the apical half of the ventricle; hypertrophy and enlargement of both atria and of the left ventricle; absence of the left coronary ostium; and a fistula between the right ventricular apex and the anterior descending coronary artery.
The main developmental implications of this rare case appear to be as follows: (1) strong support is given for the differential conal growth hypothesis concerning the morphogenesis of great arterial interrelationships; (2) truncus arteriosus communis would appear to have atresia, not absence, of the subpulmonary infundibulum; (3) the truncal septum does extend a short distance below the semilunar valves; and (4) the conus arteriosus appears to be a separate cardiac segment, not part of the right ventricle and not part of the great artelies.
Role of Renin in Acute Postural Homeostasis
Authors: OPARIL SUZANNE , VASSAUX CARLOS , SANDERS CHARLES A. , HABER EDGAR 
Published: June 2012

Plasma renin activity has been measured by radioimmunoassay at frequent intervals after passive upright tilting and correlated with pulse and blood pressure in normotensive man. In the normal response to upright posture, renin activity in both peripheral and renal veins increases consistently within a few minutes. The renin rise lags behind the increase in pulse rate and diastolic blood pressure. Renin activity falls to base-line level soon after return to the horizontal position. In the 25% of normal subjects who develop vasovagal syncope after upright tilting, the increase in renin activity is smaller in magnitude and duration than in the normal response. Renin levels fall just before syncope appears and rise sharply after return to the horizontal position. Anephric patients are able to effect adequate postural adjustments even in the absence of renin activity.
This study indicates that the renin angiotensin system participates in the acute response to postural change in normal man and that it functions abnormally in vasovagal syncope.
The Influence of Hypertonic Saline Infusions Upon the Fractional Reabsorption of Urate and Other Ions in Normal and Hypertensive Man
Authors: CANNON PAUL J. , SVAHN DAVID S. , DEMARTINI FELIX E. 
Published: June 2012

Renal hemodynamics and the excretion rates of six ions were studied in a group of 24 normotensive and hypertensive subjects during expansion of extracellular fluid volume (ECF) with intravenous infusions of hypertonic saline. In response to the 2.5% saline infusions arterial blood pressure did not change from control values, but glomerular filtration rate increased, and renal vascular resistance decreased.
Accompanying these hemodynamic alterations the urinary excretion rates of sodium, calcium, magnesium, potassium, chloride, and urate increased significantly. Net fractional reabsorption of the six ions fell significantly below control values. The induced changes in net Ca, Mg, K, Cl, and urate reabsorption in all the subjects were directly and significantly related to the simultaneous depression of Na reabsorption.
The data indicate that increased excretion and net tubular rejection of urate accompany depression of tubular sodium reabsorption during hypertonic saline infusions in normal and hypertensive man. The nonspecificity of depressed fractional ion reabsorption during the infusions is compatible with the hypothesis that physical forces which alter fluid uptake by peritubular capillaries determine to a significant extent the natriuretic response of the human nephron to hypertonic saline infusions. Alternatively, if a natriuretic hormone elicited by ECF volume expansion in man accounts for the depressed fractional Na reabsorption, the data imply that directly or indirectly this substance inhibits net fractional reabsorption of a variety of other ions.
Relationship Between Quantitated Precordial Movement and Left Ventricular Function
Authors: SUTTON GEORGE C. , PREWITT TAYLOR A. , CRAIGE ERNEST 
Published: June 2012

The relationship between external records of precordial movement and ventricular function has been studied in 61 patients with various cardiac disorders by comparing the records of the apical impulse to the left ventricular volume. A significant correlation between external recordings and the volume data was found in patients with normal or increased ventricular volumes: Patients with a normal record in systole usually had normal end-diastolic and left ventricular stroke volumes; those with a hyperdynamic record in systole usually had an appropriate increase in stroke volume for increased end-diastolic volume; and those with sustained records usually had an increased end-diastolic volume without an appropriate increase in stroke volume, indicating poor myocardial function. Patients with a pressure-loaded left ventricle usually had a sustained record, but this appeared to be related to factors other than volume.
These studies demonstrate that records of the apical impulse may provide useful information about left ventricular function.
Skeletal Muscle Capillaries in Nondiabetics
Authors: VRACKO RUDOLF 
Published: June 2012

To evaluate the variations of capillary calibers and those of basal lamina (BL), pericytes, endothelium, and lumen within a sample of skeletal muscle and among samples from different anatomic sites, areas occupied by total capillary cross sections, by the lumen, endothelium, pericytes, and BL were measured on electron micrographs. Twenty capillary cross sections from each of the 41 specimens of skeletal muscle from 23 nondiabetic males were used.
For all parameters, a marked variation was noted within each specimen, between specimens from identical sites of different individuals, and between different anatomic sites of the same individuals. In general, the capillaries are largest in the lower leg and foot muscles; the lumen is smallest at the levels of mid-thigh and lower leg; the capillaries of the lower extremity have a greater investment of BL, endothelium, and pericytes than the capillaries of the trunk and hand muscles. The areas occupied by endothelial cytoplasm, pericyte cytoplasm, and by BL are larger in bigger capillaries apparently owing to greater circumference. In addition, the capillaries of the leg, particularly those of the lower leg, have an absolutely greater investment of BL than capillaries from proximal sites. Reasons for these regional differences in the overall size of capillaries and in the investment of BL are not known.
Congenital Absence of the Left Pericardium
Authors: NASSER WILLIAM K. , HELMEN CHARLES , TAVEL MORTON E. , FEIGENBAUM HARVEY , FISCH CHARLES 
Published: June 2012

Until the past decade, the diagnosis of congenital absence of the pericardium, partial or complete, had rarely been made prior to postmortem examination or thoracotomy.
Since 1963, the condition has been recognized during life in six patients at this institution. Of these six patients, two had partial absence of the left pericardium and four had complete absence of the left pericardium. Characteristic roentgenologic findings were present in all six patients. Associated heart lesions were not present in either patient with a partial pericardial defect. Two of the remaining four had associated heart lesions. One patient had surgical repair of an atrial septal defect. Surgical repair of the pericardial defect was not attempted in any of the six patients. Hemodynamic determinations at rest were normal in all six patients. The two patients with partial pericardial defects, however, had elevation of the pulmonary artery and left ventricular end-diastolic pressures during mild exercise in the recumbent position which suggests that this type of defect is not totally innocuous. In view of the unusual and extreme cardiac mobility in this condition, it is conceivable that a portion of the heart could herniate and transiently incarcerate through the partial defect during exercise. It is suggested that partial pericardial defects may warrant surgical repair. Small defects or complete absence of the left pericardium, however, are apparently without lethal potential and do not require surgical intervention.
Dynamics of Interatrial Shunting in Children with Obstruction of the Tricuspid and Pulmonic Valves
Authors: LEVIN AARON R. , SPACH MADISON S. , CANENT RAMON V. , BOINEAU JOHN P. 
Published: June 2012

The interatrial pressure-flow dynamics in patients with right-to-left shunting at the atrial level in the presence of right heart obstruction were studied. In tricuspid atresia most of the right-to-left gradient occurred during right atrial systole. This gradient, as well as the cineangiocardiograms, indicated that almost all systemic venous return was transferred from the right to the left atrium through the interatrial communication during right atrial contraction. Cine studies also suggesed that right atrial systole (1) contributed significantly to left ventricular filling and (2) produced regurgitant venous flow, especially into the hepatic veins.
In two patients with secundum atrial defect and associated marked pulmonic valve stenosis, bidirectional shunting at the atrial level was defined by pressure gradient and cine and dye-dilution curve technics. The right-to-left gradient and shunt occurred during ventricular diastole with accentuation of this gradient by atrial contraction; the left-to-right interatrial flow and gradient occurred during ventricular systole when both A-V valves were closed. These studies indicate that, in the presence of an interatrial communication, increasing degrees of right heart obstruction not only produce right-to-left shunting but (1) do so primarily by right-to-left flow across the interatrial communication during ventricular diastole and (2) with complete right atrial obstruction, right atrial contraction plays a dominant role in the transfer of systemic venous return to the left atrium.
Peripheral Vascular Volumes and Whole Body Hematocrit During Human Heart Lung Bypass
Authors: GIANNELLI STANLEY , AYRES STEPHEN M. , FLEMING PETER , CONRAD WILLIAM , SCHWARTZ MELVIN S. , GOULD HOWARD 
Published: June 2012

Indicator-dilution curves were obtained across the peripheral vascular bed in 15 patients soon after the beginning of heart lung bypass, and in eight of these persons they were repeated just prior to the conclusion of bypass. A bolus containing labelled red cells and albumin was injected into the arterial inflow line just proximal to the aorta. Serial blood samples were obtained at intervals of 1 second from the venous return line, just distal to the right atrium, and the radioactivity was measured. The interposed volume of blood in the pump oxygenator delayed recirculation, allowing extrapolation of the exponential downslope and calculation of flow rates and indicator distribution volumes by the Hamilton-Stewart equations.
The distribution volume of albumin (average, 56.3 ml/kg) was always greater than that of red cells (average, 44.8 ml/kg). The average ratio of whole body hematocrit to perfusate hematocrit was 0.873. The absence of significant differences between data obtained at the beginning and just prior to the end of bypass suggests that there were no alterations in venous tone or the volume relationships of large vessels to the microcirculation.
The First Derivative Thoracic Impedance Cardiogram
Authors: LABABIDI ZUHDI , EHMKE D. A. , DURNIN ROBERT E. , LEAVERTON PAUL E. , LAUER RONALD M. 
Published: June 2012

When an alternating current of high frequency is applied to the thorax, the first derivative of the impedance to this current is affected by the cardiac cycle resulting in a characteristic wave form.
Phonocardiograms, electrocardiograms, and first derivative thoracic impedance cardiograms were recorded simultaneously in 91 subjects. The first derivative thoracic impedance cardiograms were found to have sharply demarcated points which occur synchronously with the first heart sound, aortic second sound, pulmonic second sound, mitral opening snap, third heart sound, and fourth heart sound. The first derivative thoracic impedance cardiogram may thus be used not only as a reference tracing to help identify heart sounds on the phonocardiogram, but also for directly timing the intervals within the cardiac cycle.
Variations in Maximal Oxygen Intake with Physical Activity in Middle-Aged Men
Authors: MCDONOUGH JOHN R. , KUSUMI FUSAKO , BRUCE ROBERT A. 
Published: June 2012

Data on maximal exercise performance are presented for normal middle-aged men free of cardiovascular disease. Maximal oxygen intake, oxygen pulse, heart rate, and lactate levels all decrease with increasing age.
Physical activity defined by habitual running of any amount had a highly significant effect on maximal oxygen consumption. The enhanced effect of physical activity was found equivalent to nearly 10 years of age effect on maximal aerobic capacity.
Multivariate analysis revealed significant association between maximal oxygen intake and several coronary risk factors; specifically, physical activity, vital capacity, cigarette smoking, and body weight. Notably lacking in significance were other known risk factors, serum cholesterol, and blood pressure.
Data for maximal oxygen intake on healthy men aged 40 to 70 years are presented by age group and physical activity class; and regression equations are provided for estimation of maximal oxygen intake from age, physical activity status, and duration of the multistage treadmill test. These data should prove useful as normal standards for assessment of aerobic capacity in middle-aged men until such time as larger numbers of data on maximal exercise testing become available.
Open Heart Surgery in Infective Endocarditis
Authors: MANHAS DEV R. , HESSEL EUGENE A. , WINTERSCHEID LOREN C. , DILLARD DAVID H. , MERENDINO K. ALVIN 
Published: June 2012

Fourteen patients with bacterial endocarditis had open heart surgery. Thirteen were operated upon because of congestive heart failure, and in one the indication for surgery was persistent infection. The aortic valve alone was involved in six patients; two patients had both aortic and mitral valve endocarditis. Five patients had infection of the mitral valve, and one patient had tricuspid valve involvement. All the patients received preoperative antibiotics for a variable period.
Ten patients left the hospital and four died in the hospital. Of the 10 patients discharged, one died 9 months later of congestive heart failure. Seven patients developed valvular leaks either through the suture line or the homograft, and two deaths resulted. Nine patients are alive and in good functional status. Antibiotics were given for 5 to 10 days postoperatively; one patient, however, received antibiotics for 49 days.
Early open heart surgery is recommended in bacterial endocarditis if heart failure is progressive. Shorter postoperative antibiotic therapy is proposed once the source of residual infection is removed.
Intermittent Claudication
Authors: KANNEL WILLIAM B. , SKINNER JOHN J. , SCHWARTZ MELVIN J. , SHURTLEFF DEWEY 
Published: June 2012

A general population sample of adult men and women was followed biennially over 14 years during which time 79 men and 46 women developed initial symptoms of intermittent claudication. A detailed examination of the incidence of this manifestation of atherothrombosis in comparison to that of coronary heart disease and atherothrombotic brain infarction was undertaken.
As for coronary heart disease (CHD), the incidence of intermittent claudication increased with age. Women lagged behind men by 10 years in incidence. Atherothrombotic brain infarction in contrast exhibited no male predominance and after the early sixties the women actually surged ahead.
Uncomplicated angina, surprisingly, resembled brain infarction more than intermittent claudication in the age-sex trend.
A pronounced increase in risk of intermittent claudication was noted for persons with CHD in general and angina in particular, suggesting a common underlying basis for claudication and coronary disease. The principal hazard for subjects with claudication appeared to derive from an increased propensity to cardiovascular morbidity and mortality rather than from the consequences of impaired circulation to the limb. Risk of death was twofold for those with claudication as compared to those without.
Banding of the Pulmonary Artery for Transposition of the Great Arteries and Ventricular Septal Defect
Authors: STARK JAROSLAV , TYNAN MICHAEL , TATOOLES CONSTANTINE J. , ABERDEEN EOIN , WATERSTON DAVID J. 
Published: June 2012

The palliative procedures for TGA with VSD and pulmonary hypertension include pulmonary artery banding, atrial septostomy, and, when necessary, ligation of a patent ductus arteriosus. This paper presents the surgical results and physiological consequences of the palliative approach. The overall mortality was 12% (4 of 33 patients).
It was possible to lower the Pp to below 45 mm Hg in all 15 infants with pulmonary artery banding. Ten infants recatheterized after the operation had no evidence of progressive pulmonary vascular disease. In 6 of 18 children older than one year, the Pp remained higher than 45 mm Hg distal to the band. In six children recatheterized, the pulmonary flow had decreased from preoperative levels, and the calculated Rp/Rs ratio had not changed significantly. The arterial oxygen saturation was decreased after banding of the pulmonary artery in 16 of 20 patients in whom it was measured.
These data suggest that pulmonary artery banding can prevent the development of pulmonary vascular disease in infants. In children older than one year, pulmonary vascular disease can be arrested at the stage that it had reached at the time of banding the pulmonary artery.
Surgical Treatment of the Subelavian Steal Syndrome
Authors: RESNICOFF SETH A. , DEWEESE JAMES A. , ROB CHARLES G. 
Published: June 2012

From an experience with 16 patients exhibiting a symptomatic subclavian steal syndrome, the following conclusions were reached:
1. Prompt and lasting relief from transient ischemic episodes can be provided by operative intervention.
2. When the right subclavian artery is involved, endarterectomy through a cervical approach is the procedure of choice.
3. Involvement of the left subclavian artery is best handled by employing a carotid-subclavian bypass or ligating the left vertebral artery.
4. Vertebral ligation on either side is particularly effective in the poor-risk patient in whom it can be performed under local anesthesia.
5. Concurrent significant stenosis of an internal carotid artery should be repaired at the time of correction of the subclavian steal, with the latter procedure performed after the carotid endarterectomy.