bluuebunny/crossref_metadata_2025 huggingface dataset:
Treatment of Supraventricular Tachycardias by Rapid Atrial Stimulation
Authors: LISTER JOHN W. , COHEN LAWRENCE S. , BERNSTEIN WILLIAM H. , SAMET PHILIP
Published: June 2012

In 10 patients, 24 episodes of supraventricular tachycardia were treated by rapid electrical stimulation of the right atrium. One episode of sinus tachycardia, eight episodes of atrial tachycardia, two episodes of atrial flutter, and 13 episodes of A-V junctional tachycardia occurred. In each case the diagnosis of the arrhythmia was documented by obtaining unipolar and bipolar intra-atrial electrograms.

In three cases of supraventricular tachycardia the ventricular rate was slowed as a result of an increased atrial rate. The increased atrial rate caused an increase of the functional refractory period of the A-V junction, and thus, fewer atrial impulses were transmitted to the ventricles.

In seven cases, 21 episodes of supraventricular tachycardia were terminated by rapid atrial stimulation. In six of these cases the tachycardia was converted to normal sinus rhythm either during or shortly after atrial stimulation. In one case, 12 episodes of A-V junctional tachycardia were converted to rhythms varying between normal sinus rhythm and a slow A-V junctional rhythm. In this case, after termination of the last episode of A-V junctional tachycardia, the rhythm was stabilized by atrial pacing.
Alterations in Cardiac Function Immediately Following Electrical Conversion of Atrial Fibrillation to Normal Sinus Rhythm
Authors: SHAPIRO WILLIAM , KLEIN GARNER
Published: June 2012

An assessment was made of cardiac function by means of right heart catheterization before and immediately after conversion of atrial fibrillation to sinus rhythm in 11 studies on 10 human subjects. Comparable data during exercise were available in five studies. Medical management of patients in this study was identical to that employed routinely for this procedure. After conversion to normal sinus rhythm cardiac output response was significantly increased only during exercise. The relationship of mean right atrial and mean pulmonary wedge pressures to right and left ventricular stroke work was uniformly improved both because of decreases in these pressures and increases in work. Indirect evidence of mitral valvular regurgitation was diminished to absent after conversion. "A" waves and the pulse pressure of atrial contraction were very small in the right atrial tracings after conversion and these contours were usually inapparent on pulmonary wedge tracings. It is concluded that over-all cardiac performance was improved with re-establishment of sinus rhythm and that diminutions in atrial-venous pressure behind each ventricle may be important in explaining symptomatic improvement following electroconversion. Measures of both pressure and flow were required for complete description of the alterations induced by this intervention.
Dynamic Reactions Produced by Deflating a Blood Pressure Cuff
Authors: FREIS EDWARD D. , SAPPINGTON R. FRANCIS
Published: June 2012

Intra-arterial pressure was recorded at various points in the compressed segment of brachial artery during deflation of a standard blood pressure cuff in human subjects with arms of normal girth. Cuff pressure and the Korotkoff sounds also were recorded simultaneously. The data were analyzed in terms of the various dynamic reactions produced by cuff deflation, which may influence the auscultatory indications of systolic and diastolic blood pressure. Cuff pressure was incompletely transmitted to the compressed arterial segment. As a result, muffling, the auscultatory indication of diastolic pressure, occurred at a cuff pressure higher than the directly recorded intra-arterial diastolic blood pressure. The first Korotkoff sound, on the other hand, provided a close approximation of intra-arterial systolic pressure. This may be due to a delay in penetration of the diminutive pulse waves into the distal part of the compressed arterial segment at systolic levels of cuff pressure. This effect appears to compensate for other influences tending to raise the indirect reading of systolic blood pressure. The extent of the delay in penetration should be dependent on the length of the collapsed segment, which in turn is a function of cuff width.
Permanent Pacing in the Absence of Heart Block
Authors: HORNBAKER JOHN H. , HUMPHRIES J. O'NEAL , ROSS RICHARD S.
Published: June 2012

Permanent pacemakers are useful in the management of certain patients with arrhythmias in the absence of heart block. Five patients are presented, four of whom obtained a satisfactory response to pacing. Continuous electrocardiographic monitoring by means of a magnetic tape system is useful in diagnosis as well as in the evaluation of the effects of therapy.
Nonrheumatic Mitral Insufficiency
Authors: KLUGHAUPT MARTIN , FLAMM M. D. , HANCOCK E. WILLIAM , M.D. DONALD C. HARRISONN
Published: June 2012

Twenty patients with mitral insufficiency (MI) due to ruptured chordae tendineae, papillary muscle infarction, or left ventricular enlargement with no organic disease of the mitral valve have been studied during the past 3 years. Nineteen had valve replacement, and one had plastic repair of ruptured chordae tendineae; all have been followed from 6 months to 3 years. Preoperative data were different in those who were improved by surgery (13 patients) and those who were not (seven patients). The group in which good results were obtained had a short history of heart failure, little or no evidence of left atrial (LA) enlargement in the electrocardiograms and x-rays, and striking LA ν waves at catheterization. In the group demonstrating poor results, heart failure was of longer duration, gross four-chamber cardiomegaly was present, and LA ν waves were only moderate. Thus, patients with nonrheumatic mitral insufficiency with high-pressure LA regurgitant waves and only moderate LA enlargement are likely to benefit from mitral valve surgery, even when the primary cardiovascular disease is hypertension, arteriosclerosis, or a cardiomyopathy. These patients generally have ruptured chordae tendineae.
The Relationship of Increased Left Atrial Volume and Pressure to Abnormal P Waves on the Electrocardiogram
Authors: KASSER IRWIN , KENNEDY J. WARD
Published: June 2012

Left atrial volume and pressure measurements in 23 normal subjects and 117 cardiac patients were compared with several electrocardiographic criteria for left atrial disease. Both P duration in lead II and V
1
terminal force (the area inscribed by the terminal portion of the P in lead V
1
) showed a highly significant correlation with changes in left atrial volume but related less well to increases in left atrial pressure. Diagnostically, both criteria accurately predicted normal or increased left atrial size in two thirds of all patients. The V
1
terminal force was more accurate in predicting left atrial pressure abnormalities in all subjects and particularly reliable in detecting increased pressure and volume in mitral stenosis. The P/PR segment ratio was less helpful in the detection of left atrial disease.
Exercise and Intermittent Claudication
Authors: ALPERT JOSEPH S. , LARSEN O. ANDRÉE , LASSEN NIELS A.
Published: June 2012

Nineteen patients with obliterative arteriosclerotic disease of the legs and suffering from intermittent claudication were studied before and during a 6 months' training program. The maximal walking distance and the calf muscle blood flow during walking (xenon-133 clearance technique) was recorded at monthly intervals. A significant correlation was established between improvement in maximal walking distance and a change on exercise toward more normal (that is, more adequate) blood flow in the calf. In particular, it was found that calf muscle blood flow during walking was increased by physical training. The data suggest that functional factors (for example, better coordination of the working muscles or a decrease of in-between-step intra-muscular pressure) as well as anatomic factors (increase in number or diameter of collateral vessels, or both) are involved in increasing collateral efficiency.
The Effect of Intracardial Pacemaker Therapy on Cerebral Blood Flow and Electroencephalogram in Patients with Complete Atrioventricular Block
Authors: SULG I. A. , CRONQVIST S. , SCHÜLLER H. , INGVAR D. H.
Published: June 2012

In seven patients with complete A-V block of long duration (five suffering from Adams-Stokes attacks), the cerebral blood flow was found to be significantly decreased and there was also moderate slowing of the electroencephalogram. Artificial pacing increased the heart rate from 39 to 72/min. Postoperative studies showed that in six of the seven cases the cerebral blood flow had increased and that the mean spectral frequency of the EEG had increased. In two patients follow-up studies suggest that the normalization of the EEG and cerebral blood flow may take some time to develop fully. The changes in EEG and cerebral blood flow paralleled the clinical improvement which accompanied the pacemaker therapy in all the patients.
Autopsy Findings with Permanent Pervenous Pacemakers
Authors: ROBBOY STANLEY J. , HARTHORNE J. WARREN , LEINBACH ROBERT C. , SANDERS CHARLES A. , AUSTEN W. GERALD
Published: June 2012

Of 130 patients who received permanent pervenous pacemakers in the last 2 years at the Massachusetts General Hospital, 21 have died; complete postmortem data are available on seven who died 5 days to 18 months after insertion of the pacemaker. No deaths were related to pacemaker malfunction. No patient received routine anticoagulant therapy. The intracardiac portions of all pacemaker electrodes were 30 to 80% endothelialized. In three cases tiny, organized mural thrombi formed on these sheaths, but none appeared to give rise to pulmonary emboli. All pacemaker electrode tips were wedged firmly beneath the trabecular system of the right ventricular apex and elicited varying degrees of local fibrous tissue reaction. Further focal fibrotic attachments occurred in the right atrium and superior vena cava. Although in four cases the electrodes adhered to the chordae tendineae, the long-term presence of an electrode did not appear to compromise tricuspid valve function. Late removal of an electrode may be hazardous because of its firm attachments to the endocardium and tricuspid valve.
Possible X-Linked Congenital Heart Disease
Authors: MONTELEONE PATRICIA L. , FAGAN LEONARD F.
Published: June 2012

Four male members of a family are known to have congenital mitral and aortic insufficiency, a fifth male has congenital mitral insufficiency only, and a sixth male had congenital heart disease by history. The involved males comprised all males in three generations of this family. Chromosomal and dermatoglyphic studies of the two living affected males are normal.

The involvement of males in this family is best explained on the basis of X-linked recessive inheritance. To our knowledge, this is the first report of possible X-linked inheritance of isolated congenital heart disease.
Bacteremia and Thrombus on Prosthetic Heart Valves in Dogs
Authors: JONES RICHARD D. , AKAO MOTOICHI , CROSS FREDERICK S.
Published: June 2012

Gram-negative bacteria are a frequent contaminant during cardiopulmonary bypass in dogs. The source of bacteria may be the donor blood or the experimental animal, presumably as a consequence of release from the gastrointestinal tract. The bacteremia is easily controlled with prophylactic cephaloridine therapy. Over 90% of dogs living more than one day after prosthetic valve replacement have survived for longer than one month. Control of this bacteremia allows meaningful evaluation of heart valve prostheses in the dog.
Quantitative Methods for the Recognition of Atrioventricular Junctional Rhythms in Atrial Fibrillation
Authors: URBACH JOHN R. , GRAUMAN JACOB J. , STRAUS SANDOR H.
Published: June 2012

This paper describes a method of analyzing electrocardiograms that detects and identifies nonfibrillatory atrial, A-V junctional, and ventricular pacemakers in atrial fibrillation, measures the ventricular beat intervals produced by the detected pacemaker, and estimates the block between pacemaker and ventricle. The identification and measurements are made with a known degree of assurance which may be increased or diminished since it depends entirely upon the number of heart beats analyzed. By applying the method to 61 recordings of 31 patients, we detected 18 instances of A-V junctional tachycardia and escape rhythm of which only three had been identified by ordinary electrocardiographic interpretation. The procedure consists of recording the electrocardiogram on magnetic tape, reducing the contained information to certain displays, and testing statistically the hypotheses suggested by them.

The displays employed are: (1) A plot of the duration or the reciprocal of the duration of successive electrocardiographic R-R intervals against elapsed time (tachogram); (2) a plot of the number of R-R intervals in the recording within each duration class against the duration of the class (interval histogram); (3) a plot of the number of beat-to-beat interval sequences formed by intervals with equal durations, successively diminishing durations, and durations representing multiples of a common time segment against the duration of the identifying interval of each sequence (sequence histogram); and (4) a graphic presentation of the averaged electrocardiographic presystolic potential.

The paper also presents evidence that A-V junctional escape rhythm in atrial fibrillation is due to pathological A-V block and should be considered to be the result of digitalis excess when this drug is exhibited.
Abscesses of the Valve Rings of the Heart, a Frequent but Not Well Recognized Complication of Acute Bacterial Endocarditis
Authors: SHELDON WALTER H. , GOLDEN ABNER
Published: June 2012

Abscesses of the valve rings of the heart were encountered at autopsy in 86 per cent of patients with acute bacterial endocarditis who had received antibiotic therapy. The abscesses, which appeared to arise from mycotic aneurysms in the valve rings, represented in most instances the only persistent focus of acute inflammation. They may account in part for the unsatisfactory results in the treatment of acute bacterial endocarditis, and their frequent occurrence suggests a relationship to antibiotic therapy.
The Fixation of Radioactive Digitoxin by Isolated Hearts
Authors: SJOERDSMA A. , FISCHER C. S.
Published: June 2012

The nature of digitoxin fixation in isolated hearts was studied with C
14
labelled digitoxin. Fixation was greatest in the early stages of perfusion. The amount of drug fixed was measured directly. A considerable percentage of the digitoxin in cardiac muscle was changed to other substances. These substances are more firmly bound to the heart than digitoxin.
The Mechanics of Ventricular Contraction
Authors: RUSHMER ROBERT F. , THAL NATHAN
Published: June 2012

Linear and planimetric measurements have been made on tracings of the right and left ventricular chambers from successive motion picture frames, obtained by cinefluorographic angiocardiography in anesthetized dogs. At the end of systole, varying amounts of residual blood, some 35 per cent of the diastolic volume, remain in the chamber. Filling occurs more rapidly than ventricular ejection and is virtually completed in early diastole. The left ventricular chamber is reduced in size during systole primarily by a reduction in width rather than a shortening of the longitudinal axis. Increased stroke output was accomplished by three mechanisms: (1) increased emptying of the ventricle by progressive shortening of the ventricular chamber; (2) increased filling in early diastole; (3) increased filling in the presystolic period, persumably because the atrial contraction more effectively distended the ventricle. The mechanisms responsible for the systolic residual blood and the retardation of filling which occurs early in diastole are discussed in terms of the anatomy, geometry and functional characteristics of the ventricular myocardium. A comparison is made of the right and left ventricles with reference to their luminal pressure and fiber tension relationships.
Cheyne-Stokes Respiration in Patients with Cardiac Enlargement and Prolonged Circulation Time
Authors: PRYOR WILLIAM W.
Published: June 2012

A study has been made of arterial blood changes during the respiratory cycle in patients with cardiac enlargement, prolonged circulation time, and Cheyne-Stokes breathing. In these patients, Cheyne-Stokes breathing appeared to depend upon the delay in passage of blood from the lungs to the arterial chemoreceptors and respiratory center. This delayallowed cyclic over- and underventilation. There was little or no central nervous system depression. In contrast, one case of Biot's breathing is presented as an example of another mechanism responsible for periodic breathing. Here irregular breathing seems to depend on fluctuations in activity of a severely damaged central nervous system.
Cardiodynamic Effects of Mitral Commissurotomy
Authors: MUNNELL EDWARD R. , LAM CONRAD R.
Published: June 2012

During commissurotomy for stenosis of the mitral valve, it has been possible to record the moment to moment changes in left auricular and pulmonary arterial pressures, using an electronic manometer system. The left auricular pulse patterns have varied depending on the degree of stenosis and the presence or absence of auricular fibrillation or unsuspected regurgitation. The degree of success attending operative intervention on the mitral valve has been predictable by a study of the postcommissurotomy tracings.
Anticoagulant Therapy in Peripheral Vascular Disease
Authors: BARKER NELSON W.
Published: June 2012

The anticoagulant drugs, heparin and dicumarol, have been of great value in the prevrention and treatment of peripheral thromboembolic disease. The use of both drugs requires individualization of dosage based on the results of the appropriate tests of their effect on coagulation. The risk of bleeding is very small if heparin and dicumarol are properly used. New anticoagulant drugs are being studied and evaluated clinically in an effort to increase even further the effectiveness and safety of anticoagulant therapy.
Regional Vasomotor Tone in Normotensive and Hypertensive Dogs
Authors: WILLIAMS ARNOLD H. , SCHROEDER HENRY A.
Published: June 2012

A new method for estimating vasomotor tone in a local circulation by means of the asystolic arterial pressure gradient was applied to the renal, femoral, brachial, and mesenteric vascular beds of normal dogs and of dogs made hypertensive by various technics. The splanchnic circulation apparently contributes the greatest proportion of the increase of resistance in anesthetized hypertensive animals. The correlation of vasomotor tone with diastolic pressure was good only in the mesenteric area. Some differences in these four areas were found between renal and neurogenic hypertension.
Principles of a Low Fat Diet
Authors: HILDRETH E. A. , HILDRETH D. M. , MELLINKOFF S. M.
Published: June 2012

From personal experience on low fat diets and through experience gained treating patients with low fat diets, the authors suggest that when such a diet is prescribed carefully it may be quite palatable and also reduce serum cholesterol concentration. The principles of a low fat diet and methods for making the diet appetizing are presented. Sample diet instruction sheets which can be individualized for different patients are also illustrated.
Temporal Relationships of Myocardial Lactate Metabolism, Left Ventricular Function, and S-T Segment Depression During Angina Precipitated by Exercise
Authors: PARKER JOHN O. , WEST ROXROY O. , CASE ROBERT B. , CHIONG MIGUEL A.
Published: June 2012

Continuous monitoring of myocardial lactate metabolism and the electrocardiogram in association with an assessment of left ventricular function were carried out in a group of 14 patients before, during, and after a period of supine leg exercise. Of the 12 patients who were shown to have coronary artery disease, seven experienced exertional angina whereas five remained free of pain. Marked increases in arterial and coronary sinus lactate concentrations were observed in all subjects early in exercise although arterial lactate levels were higher in the angina group. In the normal subjects and in the non-angina group, myocardial lactate extraction increased to 36.7 and 28.5%, respectively, during exercise. In the angina group, however, lactate extraction remained abnormal during exercise, increasing to only 8.8%, but in this group only two patients showed myocardial lactate production. Left ventricular end-diastolic pressure was consistently elevated during exertional angina and showed a close temporal relationship to ischemic S-T segments. Left ventricular stroke work was unchanged at these elevated filling pressures indicating impaired left ventricular contractility. While correlation of exertional angina, S-T segment depression, and hemodynamic abnormalities was close, it was not possible to relate these changes to metabolic evidence of ischemia since this was obscured by the elevated arterial lactate concentrations.
A New Simple Model for the Synthesis of the Electrocardiogram
Authors: UHLEY HERMAN N.
Published: June 2012

This paper reports the development of a simple, inexpensive apparatus that can be constructed and programmed to simulate normal as well as abnormal depolarization and repolarization of the heart and to reproduce an electrocardiogram. The device utilizes a modulated light beam, a series of differential photocells, a patch cord programmer, and a synthesizer consisting of an array of dipoles in a saline conductor. Changes occurring on a cellular level are simulated and programmed and in proper temporal sequence to the multiple dipoles, thereby forming a resultant spatial generator of QRS and T complexes.
Sudden Death in Idiopathic (Congenital) Right Atrial Enlargement
Authors: TENCKHOFF LORE , STAMM STANLEY J. , BECKWITH J. BRUCE
Published: June 2012

A case of idiopathic enlargement of the right atrium is presented and 13 other cases are reviewed. The patient whose case is reported died suddenly at home 6 months after onset of atrial flutter. This represents the first case in which postmortem findings are available. The patient demonstrates that the anomaly cannot be considered entirely benign as has been suggested in previous reports. Other complications that may occur particularly in cases of massive atrial enlargement are atrial arrhythmias, syncope, and right ventricular compression. The importance of recognizing this condition as a clinical entity is stressed because surgical excision of a portion of the enlarged atrium appears to be both easy and curative and because these cases may be mistakenly diagnosed as mediastinal tumor or pericardial effusion. The possible relationship of this apparently congenital abnormality to Uhl's anomaly is discussed.
Stress Electrocardiography in the Evaluation of Surgical Revascularization of the Heart
Authors: KASSEBAUM DONALD G. , JUDKINS MELVIN P. , GRISWOLD HERBERT E.
Published: June 2012

Electrocardiography was carried out during hypoxemia and graded exercise tests before and at intervals between 2 and 20 months after attempts to revascularize the heart by internal mammary artery implantation in 44 patients with angiographically documented coronary disease and angina pectoris. Eleven patients had single vessel disease; the right coronary was involved in seven of these patients. Thirteen patients had single vessel implants, employing the left internal mammary artery in 11 patients and a saphenous vein graft from the aorta in two. Thirty-one patients had double internal mammary artery implantation accompanied by gastroepiploic arterial implantation in four.

Fifty per cent of the patients were symptomatically improved after surgery, the best results occurring in two patients with isolated anterior descending coronary disease. Of the 34 patients having postoperative coronary and mammary arteriography, 15% showed improvement which could be ascribed to mammary revascularization; 24% had limited myocardial revascularization and no symptomatic improvement; 29% had patent implants without development of collateral vessels, and the implanted vessels were occluded in 32%. Eleven of the 34 (32%) had fair or good symptomatic improvement in the absence of revascularization.

The results of postoperative stress electrocardiography correlated closely with the findings on postoperative coronary and mammary angiography. The stress tests were persistently positive after operation in 83% of the patients having angiographically confirmed implant occlusion or nonrevascularization. The stress ECG response was reversed, becoming negative postoperatively, in five cases of angiographically proved significant revascularization. Thus, stress electrocardiography provided objective evidence of improvement in a small number of patients with limited coronary disease who developed good collateral circulation and correlated with the lack of revascularization in the majority even in those subjectively improved.
Effect of Site of Shunt on Left Heart-Volume Characteristics in Children with Ventricular Septal Defect and Patent Ductus Arteriosus
Authors: JARMAKANI M. M. , GRAHAM THOMAS P. , CANENT RAMON V. , SPACH MADISON S. , CAPP M. PAUL
Published: June 2012

Quantitative cineangiocardiographic technics have been utilized to determine left ventricular (LV) and left atrial (LA) volumes and LV muscle mass in 58 patients with isolated ventricular septal defect, 14 of whom were infants less than 2 years old, and in 25 patients with isolated patent ductus arteriosus, 13 of whom were infants. Patients were divided according to the degree of left-to-right shunt into small (<35%), moderate (35 to 50%), and large (>50%) shunt groups. Data obtained in both the VSD and the PDA groups were compared with normal values. Left ventricular end-diastolic volume and mass and LA maximal volumes in the patients of both groups who had shunts of 35% or more were greater than normal and showed a linear increase with increasing left-to-right shunt. The LV ejection fraction was decreased from normal in infants with either VSD or PDA and a shunt of more than 50%. This variable was normal in older children with either VSD or PDA.

Patients with an aortic or a ventricular defect and equivalent shunts did not differ significantly in terms of LV end-diastolic volume, LV mass, LV ejected fraction, or LA maximal volume, normalized for body surface area. Patients with a patent ductus demonstrated the following differences when compared with patients with ventricular septal defect: (1) elevated LV end-diastolic pressure, (2) elevated LV end-diastolic stress, and (3) elevated value for LV mass (/m
2
BSA) per degree of shunt in children over 2 years of age with a patent ductus (
P
<0.05). These results indicate that left ventricular distensibility is decreased in patients with aortic left-to-right shunts compared to that in patients with ventricular left-to-right shunts of equivalent magnitude.
Hemodynamic Performance of a Transplanted Human Heart
Authors: CARLETON RICHARD A. , HELLER STANLEY J. , NAJAFI HASSAN , CLARK JAMES G.
Published: June 2012

Cardiac catheterization studies, performed 3 weeks after cardiac homotransplantation, revealed nearly normal cardiac performance. Alteration in heart rate by right atrial pacing, passive elevation of the legs, and exercise modified cardiac performance predominantly by variation in ventricular filling. Isoproterenol infusion increased stroke volume above the level predicted from the ventricular end-diastolic pressure.

The heart was hypersensitive to beta-adrenergic stimulation with isoproterenol as judged by a greater responsiveness of the donor sinus node than the recipient sinus node, by prolongation of ventricular filling time, and by shortening the P-R interval for any given paced heart rate. These measures permitted tests for endogenous catecholamine effects during passive leg elevation and during exercise. Only after the 3 minutes of exercise was a small beta-adrenergic effect detectable.

These data demonstrate the dependence of the denervated human heart upon variation in ventricular filling as the predominant mode of regulation of cardiac performance.
Recurrent Left Atrial Myxoma
Authors: BAHL OM P. , OLIVER G. CHARLES , FERGUSON THOMAS B. , SCHAD NIKOLAUS , PARKER BRENT M.
Published: June 2012

Recurrence of a left atrial myxoma 6 years after the initial resection is reported. This, to our knowledge, is the second such case, and it emphasizes the need for a complete resection of the underlying atrial septum or atrial wall in cases of myxoma.
Use of the Dipole Moment in the Assessment of Left Ventricular Hypertrophy
Authors: ELLISON R. CURTIS , FISCHMANN EUGENE J. , MIETTINEN OLLI S. , HUGENHOLTZ PAUL G.
Published: June 2012

A multi-electrode grid lead system, suited for the measurement of the total outward electromotive force of the heart expressed as a dipole moment, was tested in 64 subjects without heart disease and in 44 patients with left ventricular overload. The normal group showed the maximum dipole moment to the left (L-MDM) to be proportional to body weight, and by inference to left ventricular weight. For the patients with heart disease, the degree of hypertrophy was assessed in terms of LV weight derived from biplane angiocardiograms; for these patients, L-MDM was found to be proportional to LV weight (r = 0.85). The grid allowed for a more accurate assessment of LV weight than parameters obtained from the Frank lead system in the same patients.

A substantially improved estimation of LV weight was achieved with both systems when body weight was considered in addition to the electrocardiographic measurements.

Among the reasons for the better performance of the grid system are surface potential integration instead of sampling, consideration of individual torso dimensions, and as a result of distributed multiple electrodes, absence of distortion in the local field.
Maintenance of Cell Viability
Authors: BRACHFELD NORMAN
Published: June 2012

An early distinction between the early and reversible changes of cellular ischemia and the irreversible changes of cell necrosis is essential to a rational program for the treatment of coronary artery disease, to a definition of the permissible limits of nonperfusion of the anoxic arrested heart at open-heart surgery, and to a determination of the maximal allowable transport time for cardiac transplantation. The factors in the myocardial cellular environment that support cellular viability and help maintain homeostasis are reviewed. Reversible surgically induced anoxic arrest is contrasted with the irreversible arrest and cell necrosis which often attend the myocardial anoxia of coronary occlusion. The enhancement of glycolysis, other changes in carbohydrate metabolism, and the depressed oxidation and lipid storage associated with alterations in lipid metabolism are outlined and their interrelationships discussed. The effect of the myocardial tissue acidosis which accompanies ischemic metabolism is an important factor in determining the reversibility of the effects of ischemia. The probable role of myocardial acid hydrolases in pathological ischemic autolysis is described. A sequence of cellular events induced by ischemia and leading to ultimate cell death is outlined. Promising areas for future investigation into the pathogenesis of myocardial infarction and into improved methods of treatment are suggested.
Treatment of Power Failure by Means of Mechanical Assistance
Authors: SOROFF HARRY S. , BIRTWELL WILLAIM C. , GIRON FABIO , RUIZ ULISES , NISHIMURA A. , MANY MOSHE , EL-ZAWAHRY M. , DETERLING RALPH A.
Published: June 2012

It appears that shunt types of assist have a place at the present time in the management of patients with cardiogenic shock secondary to a correctable cardiac lesion. A shunt assist helps to maintain an adequate perfusion pressure during the period immediately preceding or subsequent to cardiac surgery. Venoarterial bypass with an oxygenator seems to offer promise for temporary correction of rightheart failure. It does not alter the basic pathology, and most patients have succumbed to their original disease following this type of cardiac assist, except where the lesion was surgically correctable. Left atrial-to-femoral artery bypass is indicated for decompression of the left atrium and augmentation of the arterial perfusion pressure and flow.
Certain Chemorheologic Considerations Regarding the Blood Vascular Interface with Particular Reference to Coronary Artery Disease
Authors: FRY DONALD L.
Published: June 2012

The locations of coronary atheroma in a hyperlipemic dog are shown to occur at points in the arterial tree where one would expect the most intense exposure to physical stress. Studies are presented that were designed to quantify certain aspects of the histological and physicochemical response of the arterial intima to a variety of acutely imposed mechanical stresses. These results indicate that the endothelial-cell population has an acute yield stress to shear of about 400 dynes/cm
2
; that exposure to stress in excess of this is associated with cytological and chemical changes, suggesting that physical processes are occurring, such as "yielding," "melting," "dissolving," "imbibition," and "permeation" of the interfacial tissues; and that even in the absence of cytological changes, the permeability of the interface for albumin is increased by increasing the stress acting on the interface whether in shear, compression, or tension. The relations of these events to tissue rheology, the strain energy density of the interfacial region, and the "critical energy" of molecular separation in the interfacial substance are discussed in terms of the energetics of molecular interactions. Classical rate process theory is used in an effort to express these ideas in more conventional chemical terminology. Arguments are presented in support of the postulate that mechanical energy added to the vascular interface may be used either as the driving force for a chemical process or can be used to increase the rate constant for such processes as interfacial yielding, melting, dissolving, imbibition, or permeation by serum proteins. The added mechanical energy is assumed to increase the rate constant by increasing the number of defects in the array of interfacial molecules or by increasing the average energy level of the molecules, thus decreasing the activation energy for the particular process being considered. As a corollary to this, it follows that the chemical "barrier function" of the vascular interface is enhanced by maintaining its energy density as low as possible and will be degraded in regions of increased energy density. These notions lead to the suggestion that the topography of increased serum protein flux as well as atheromatous plaques is determined among other things by the distribution of mechanically induced increased energy density in the vascular interface.
Aortic Homograft Valve Replacement
Authors: BARRATT-BOYES B. G. , ROCHE A. H. G. , BRANDT P. W. T. , SMITH J. C. , LOWE J. B.
Published: June 2012

An initial series of 101 patients with a homograft aortic valve has been reviewed from 4 to 6 years postoperatively. There were six hospital and 24 late deaths, eight of which were due to homograft valve failure. The 71 surviving patients were all symptomatically improved. Anticoagulants were not used, and emboli were thought not to originate from the valve.

Important incompetence occurred in 27 patients and reoperation was undertaken in 17 of these. The causes were peripheral leaking of the suture line, cusp rupture, bacterial endocarditis, and valve misplacement.

Leaflet calcification produced stenosis, requiring reoperation in two patients, and was significant in eight other valves. Precipitating causes, present in eight of the 10 cases, were imperfections in the original homograft, valve misplacement, or endocarditis.

Both cusp rupture and leaflet calcification were related to the method of valve preparation as neither was encountered in untreated valves. For this reason, chemical sterilization and freeze drying have been replaced by sterilization and storage in an antibiotic Hank's solution.
Use of Superior Vena Cava-Right Pulmonary Artery Anastomosis in Congenital Heart Disease with Decreased Pulmonary Blood Flow
Authors: BORUCHOW IRWIN B. , BARTLEY THOMAS D. , ELLIOTT LARRY P. , WHEAT MYRON W. , KROVETZ L. JEROME , SCHIEBLER GEROLD L.
Published: June 2012

Clinical, hemodynamic, and angiocardiographic findings on eight long-term (more than 3 years) survivors of anastomosis of the superior vena cava (SVC) to the right pulmonary artery (RPA) are described. All patients had severe cyanotic congenital heart disease with decreased pulmonary blood flow. Postoperative cardiac catheterization and angiocardiography defined the physiology of the shunt. SVC pressure was elevated after the creation of the SVC-RPA shunt. This was without obvious clinical effect in six patients. Mild SVC syndrome developed in the immediate postoperative period but was associated with overall clinical improvement in two cases. A late, and more severe SVC syndrome associated with clinical deterioration developed in three patients with severe pulmonic stenosis as part of their cardiac malformation. Clinical improvement and relief of SVC syndrome followed systemic-pulmonary artery shunt or open heart repair of the underlying cardiac malformation, leaving the SVC-RPA anastomosis intact. Clinical improvement following open heart repair of tetralogy of Fallot has persisted in spite of severe postoperative pulmonic valve insufficiency and elevated mean pressure in the left pulmonary artery. This is believed to be a result of the SVC-RPA shunt, which reduced the venous return into the right heart.
Acute Pulmonary Edema in the Absence of Left Ventricular Failure
Authors: RITTENHOUSE EDWARD A. , MERENDINO K. ALVIN
Published: June 2012

Two patients have been observed to develop acute repetitive pulmonary edema in the absence of left ventricular failure as evidenced by a normal or near normal left atrial pressure recorded during these periods. Continuous monitoring of the left atrial pressure was made possible by a catheter inserted during open-heart surgery. Both patients suffered brain damage, presumably secondary to cerebral air embolism, and eventually succumbed.

Although the authors think that a causal relationship between cerebral damage and pulmonary edema best explains the mechanism in these two patients, this must remain conjectural. Neurogenic pulmonary edema, however, has been assumed to be secondary to elevated left atrial and left ventricular end-diastolic pressures. If a specific relation exists in these patients, the findings herein described strongly suggest that this may not be the mechanism.
The Accuracy of Pulmonary Angiography in Assessing Resolution of Experimental Thromboemboli
Authors: WOLF PHILLIP S. , GENTON EDWARD
Published: June 2012

Quantification of pulmonary emboli has become important in assessing the results of thrombolytic therapy and in following the natural history of thromboemboli. This study evaluated angiography as a quantitative procedure by comparing sequential changes in emboli of known size and weight with alterations on angiograms.

Twenty-four aged thrombi formed in vivo were embolized intact into 12 recipient dogs. Serial angiograms showed the location of each thrombus and allowed evaluation of its changes. Urokinase was administered to some animals to produce a spectrum of lysis.

Quantification proved accurate when thrombolysis exceeded 80%. When less, angiograms over or underestimated lysis in 11 of 18 instances (61%). Postmortem dissection suggested four reasons for these discrepancies: (1) downstream movement impacted emboli and increased obstruction; (2) coiling of an embolus compromised more vessel area and increased obstruction; (3) circumferential flow of contrast material obscured some emboli; and (4) second emboli redistributed flow to an area with prior embolus, producing apparent improvement.

These data suggest that quantifying changes in emboli by angiography are frequently misleading when less than 80% lysis occurs. The discrepancy, when present, usually results in overestimation of the amount of embolus remaining.
Evidence for Propagation of Activation Across an Accessory Atrioventricular Connection in Types A and B Pre-excitation
Authors: BOINEAU JOHN P. , MOORE E. NEIL
Published: June 2012

The sequence of atrioventricular activation was studied in two human subjects with type B Wolff-Parkinson-White syndrome (WPW) and in a dog with spontaneous type A WPW. In all three subjects a focal spot of pre-excitation was demonstrated at the A-V margin of the right ventricle (RV). In the two human subjects with type B WPW, the area of pre-excitation was located on the anterior aspect of the RV and in the dog with type A the pre-excited area was located on the posterior aspect of the RV. A probable Kent bundle electrogram was recorded from the A-V margin in one of the human patients. Serial sections (7 µ) of a block taken from the region of pre-excitation in the dog revealed an anomalous A-V communication (Kent bundle). Propagation velocity across this pathway was estimated to be 0.3 mm/msec. Electrophysiologic data recorded from one of the human subjects at the onset and during an episode of supraventricular tachycardia demonstrated an atrioventricular-atrial sequence of excitation. The mechanism of initiation of the tachycardia was a ventriculo-atrial echo following a premature atrial contraction blocked in the anomalous pathway. Surgical separation of right atrium and RV at the site of pre-excitation normalized the activation and ECG and abolished the tachycardia in both patients.

Ventricular fibrillation occurred repeatedly in the dog as a direct result of the rapid ventricular rate permitted by the Kent bundle subsequent to induced atrial fibrillation. Correlation of the activation sequence with the body surface potentials suggests an updated conceptual model for electrocardiographic typing of WPW. In a third patient, who demonstrated an atypical form of WPW, the region of pre-excitation could not be precisely defined and interruption of an accessory pathway was unsuccessful.
His Bundle Electrograms in Two Cases of Wolff-Parkinson-White (Pre-excitation) Syndrome
Authors: CASTELLANOS AGUSTIN , CHAPUNOFF EDUARDO , CASTILLO CESAR , MAYTIN ORLANDO , LEMBERG LOUIS
Published: June 2012

The catheter technic for recording the electrical activity of the specialized conducting system in the human heart showed in two patients studied that ventricular pre-excitation was apparently due to a bypass of the His bundle. Intermediate forms of WPW complexes appeared to be combination beats resulting from the activation of the ventricles through impulses traversing both the His bundle and accessory communications. Preferential iatrogenic activation of an intra-atrial (and perhaps even of an atrioventricular) tract appeared to occur in one of the patients. The patients with the WPW (pre-excitation) syndrome and long histories of paroxysmal arrhythmias were successfully treated with a combination of oral propranolol and implanted (transvenous) demand pacemaker.
Studies on Ventriculo-Atrial Conduction and the Reentry Phenomenon
Authors: DAMATO ANTHONY N. , LAU SUN H. , BOBB GUSTAVUS A.
Published: June 2012

Ventriculo-atrial conduction and the reentry phenomenon was studied during right ventricular and bundle of His pacing in the intact dog heart. Bipolar electrogram recordings were obtained from the sinus node, Bachman's bundle, the right and left atria, the bundle of His, and the ventricle. Retrograde conduction resulted in a specific change in the sequence of atrial activation. The recording of both antegrade and retrograde His deflections provided a more accurate means of comparing A-V and V-A conduction times. In all experiments retrograde conduction time exceeded antegrade conduction time. The A-V nodal region was found to be the zone of retrograde conduction delay and block. Increasing the driving rate of the heart, vagal stimulation, and isoproterenol, affected V-A conduction similar to the way in which these maneuvers affect A-V conduction. Reentry (ventricular echoes) commonly occurred when right ventricular or bundle of His pacing resulted in the reverse Wenckebach phenomenon.
The Prognosis of an Abnormal Electrocardiographic Stress Test
Authors: DOYLE JOSEPH T. , KINCH SANDRA H.
Published: June 2012

Treadmill walking for 10 min at 3 mph against a 5% grade has been used as an electrocardiographic (ECG) stress test as part of a prospective epidemiologic study of 2,437 men. From 1953 through 1966, 22,223 tests have been done without untoward event.

The criteria of an abnormal postexercise ECG were ischemic flattening or coving of the S-T segment, T-wave changes consistent with focal left ventricular epicardial ischemia, and paroxysmal left bundle-branch block.

Of the 2,003 men exercised two or more times, 264 developed some manifestation of ischemic heart disease (IHD) and in 75 (30%) this was an abnormal ECG response to exercise. They had higher blood pressures and were more often heavy smokers than normal responders. Body weight and serum cholesterol were similar in the two groups. Over the next 5 years there was an 85% probability that these abnormal responders would develop angina pectoris or experience a myocardial infarction.

These relatively insensitive but highly specific and reproducible ECG criteria accurately identify men with clinically silent but far-advanced coronary atherosclerosis, attested by the poor prognosis of an abnormal response. An abnormal postexercise ECG is valid evidence of IHD. A submaximal ECG stress test is useful in clinical and epidemiologic studies and might be useful in assessing the effectiveness of efforts to reduce the risk of IHD.
Relationship of Myocardial Potassium Content and Atrial Fibrillation
Authors: EBERT PAUL A.
Published: June 2012

Serum, red blood cell, and atrial potassium concentrations were measured in 148 patients undergoing cardiac surgery. No significant difference was noted between serum and red cell potassium concentration and atrial arrhythmias. Seventy-six patients were in sinus rhythm prior to and following operation and had an average atrial potassium concentration of 38.2 mEq/100 g. Thirty patients in sinus rhythm developed atrial flutter or fibrillation after surgery, and the average atrial potassium concentration was 30.4 mEq/100 g. Forty-two patients were in atrial fibrillation before operation and had an average atrial potassium concentration of 26.6 mEq/100 g. A direct relationship existed between chronic atrial fibrillation and atrial potassium concentration. All developing postoperative atrial fibrillation had a reduced atrial potassium concentration in the preoperative biopsy. However, nine patients had reduced potassium concentration but did not develop atrial fibrillation.
Ultrasonic Evaluation of Prosthetic Valve Motion
Authors: JOHNSON MICHAEL L. , PATON BRUCE C. , HOLMES JOSEPH H.
Published: June 2012

1. Ultrasound echo tracing is a simple, atraumatic method for examining prosthetic valve function.

2. In vitro experiments have elucidated the meaning of traces obtained from various types of caged balls.

3. By the use of this method ball diameter, poppet excursion, and opening and closing velocities can be measured in patients.

4. Both in vitro and in vivo experience has demonstrated that the measurements obtained are accurate and reproducible.