bluuebunny/crossref_metadata_2025_split huggingface dataset:
Alternate Patterns of Premature Ventricular Excitation During Induced Atrial Bigeminy
Authors: COHEN STAFFORD I. , LAU SUN H. , SCHERLAG BENJAMIN J. , DAMATO ANTHONY N. 
Published: June 2012

Alternate patterns of premature ventricular excitation have been observed during induced atrial bigeminy in 18 subjects, including five normal volunteers. Each study was performed in the cardiac catheterization suite where a transvenous catheter electrode was positioned in the right atrium. Coupled or paired stimuli were delivered to the atrium by an isolated battery-powered source at an adjusted interval which resulted in alternate patterns of ventricular excitation from alternate premature beats ("alternating premature ventricular excitation").
In most instances "alternating premature ventricular excitation" occurred when parameters of preceding cycle length, premature coupling interval, and atrioventricular conduction time were constant.
In man also some observations were made of His bundle excitation during premature atrial stimulation, and in the intact dog heart some observations were made of alternating premature ventricular excitation during His bundle stimulation.
A tenable explanation for alternating premature ventricular excitation is advanced which rests on three postulates: (1) A long cycle length is followed by a long refractory period. (2) The refractory period of each branch of the specialized conduction system is dependent on its preceding cycle length or recovery period; and (3) the diastolic recovery period of a blocked segment of the specialized conduction system is shorter than the recovery period when blockade does not occur.
Tricuspid Atresia with Increased Pulmonary Blood Flow
Authors: MARCANO BERTRAND A. , RIEMENSCHNEIDER THOMAS A. , RUTTENBERG HERBERT D. , GOLDBERG STANLEY J. , GYEPES MICHAEL 
Published: June 2012

The pathologic and clinical findings in 13 cases of tricuspid atresia and increased pulmonary blood flow encountered in UCLA Medical Center were reviewed. In seven, the great vessels were normally related (group I), and in six, the great vessels were transposed (group II). In all group II cases, aortic arch anomalies were encountered, a finding not duly emphasized in previous reports. Comparison of the two groups revealed significant clinical and laboratory differences. Group II patients typically presented with severe congestive heart failure and expired within the first 2 months of life. Group I patients usually presented with mild congestive heart failure which responded to therapy. Five of the latter demonstrated progressive change from increased to decreased pulmonary blood flow during their clinical course and eventually required palliative shunt procedures, four prior to the age of 2 years and one at 5 years of age.
While the electrocardiogram demonstrated right atrial enlargement and left ventricular hypertrophy in both groups, the mean frontal plane axis was between –15° and –100° in group I and –75° and +75° in group II. QRS vector loops tended to be superiorly oriented in group I and inferiorly oriented in group II.
Because the natural history and prognosis in these two groups differ significantly, diagnostic efforts should include determination of the relationship of the great vessels. When transposition of the great vessels is demonstrated, aortography should be performed because of the high incidence of aortic arch anomalies.
Studies in Human Atrial Flutter with the Use of Proximity Electrodes
Authors: KISHON YEHEZKIEL , SMITH RALPH E. 
Published: June 2012

Ten patients with the electrocardiographic diagnosis of atrial flutter were investigated by exploration with electrodes within the esophagus and the right atrium. The records obtained were studied in regard to the timing of the intrinsic deflection and the contour of the atrial waves, as recorded at various sites.
In four patients, atrial activation progressed in sequence cephalad in the left atrial wall and caudad in the right atrium. This process continued through two thirds of the total atrial cycle, favoring "circus movement" as the underlying mechanism. In six other patients, activation was believed to originate low in the left atrium, with simultaneous spread of excitation of both atrial walls in a general cephalad direction and terminating within the first half (usually the first third) of the atrial cycle. This pattern is compatible with, but not conclusive of, an ectopic focal mechanism. Serial records in one patient are presented in which transformation of one type into a second type of atrial flutter is suggested. It is likely that at least two mechanisms are present in human atrial flutter.
Effects of Drugs and of Counterpulsation on Myocardial Oxygen Consumption
Authors: BRAUNWALD EUGENE , COVELL JAMES W. , MAROKO PETER R. , ROSS JOHN 
Published: June 2012

A series of investigations on the determinants of myocardial oxygen consumption were reviewed and their relevance to the survival and function of ischemic tissue in the presence of coronary occlusion pointed out. Tension development, contractile state of the myocardium, and heart rate are the most important factors influencing cardiac oxygen consumption, and drugs commonly used in the treatment of patients with acute myocardial infarction appear to influence oxygen consumption by acting upon these three determinants. Thus, digitalis glycosides and sympathomimetic agents tend to increase myocardial oxygen requirements, since they improve the heart's inotropic state. However, this influence may be offset in the enlarged heart in which end-diastolic volume and tension are reduced. Agents which depress the heart exert the opposite effect. Electrocardiographic changes reflecting myocardial ischemia are intensified when isoproterenol is administered following coronary ligation.
Synchronized arterial counterpulsation reduces myocardial tension development and therefore oxygen consumption. An augmentation of myocardial oxygen needs in the presence of coronary occlusion may be expected to increase the size of the necrotic zone and to impair the function of the ischemic zone, while a reduction of oxygen consumption may be expected to exert the opposite effect.
Cerebral Symptoms in Pulmonary Arteriovenous Fistula
Authors: SISEL RONALD J. , PARKER BRENT M. , BAHL OM P. 
Published: June 2012

Two cases of pulmonary arteriovenous fistulas with hemiparesis and other neurologic findings, possibly from paradoxical embolization, are described. Many theories have been put forward to explain the pathophysiology of the frequently present neurologic manifestations. We regard paradoxical embolization through the fistula as the most important factor in the pathogenesis of the neurologic deficit.
Due to the potential hazard of paradoxical cerebral embolization and possible subsequent brain abscess formation, surgical resection of all pulmonary arteriovenous fistulas wherever feasible is recommended.
Predisposing Factors in Sudden Cardiac Death in Tecumseh, Michigan
Authors: CHIANG BENJAMIN N. , PERLMAN LAWRENCE V. , FULTON MARY , OSTRANDER LEON D. , EPSTEIN FREDERICK H. 
Published: June 2012

In an epidemiologic study of the total population of Tecumseh, Michigan, 98 deaths from coronary heart disease were observed between 1959 and 1965. Forty-five of the fatalities occurred within 1 hour of the onset of symptoms and were classified as sudden. The proportion of sudden deaths among men was nearly twice that among women, and the incidence increased progressively with age in both sexes.
Hypertensive heart disease, coronary heart disease, or diabetes mellitus had been detected on prior examination in 62% of those who died suddenly. Physiologic abnormalities associated with a high risk of coronary heart disease were also found more frequently than in the total Tecumseh population.
All but seven of the persons who died suddenly had abnormalities including arrhythmias and conduction defects which were detected in the standard 12-lead electrocardiogram.
Although sudden deaths often seem to occur without warning, the victims are predisposed by conditions which are detectable long before the catastrophic event. The identification of conditions which are precursors of sudden death from coronary heart disease permits a rational consideration of possible preventive measures.
Comparison of Oxygen Saturation of Blood in Azygos Vein and Superior Vena Cava
Authors: JAIN KEWAL K. , WAGNER HENRY R. , LAMBERT EDWARD C. 
Published: June 2012

Blood samples from the superior vena cava (SVC) are usually considered an acceptable representation of mixed systemic venous return in identifying and quantifying left-to-right atrial shunts. However, if during sampling from the SVC unrecognized entrance of the catheter into the azygos vein takes place, diagnostic errors may result. Blood samples from the azygos vein were collected from 60 children with congenital heart disease and the oxygen saturations ranged from 20% to 92%. These saturations were compared to those of samples taken from the superior vena cava above the entrance of the azygos vein. No substantial difference (saturation within ±4%) was found in 24 patients, while 28 patients had a significantly higher saturation in the azygos vein (from +5% to +21%) and eight patients had a lower saturation (from –5% to –16%). A significant left-to-right shunt may be overlooked or erroneously thought to be present when sampling of blood takes place unknowingly from the azygos vein. Examples are presented.
Approaching from the groin it was possible to catheterize the azygos vein in two thirds of the cases when a deliberate attempt was made to do so.
Clinical Application of Serum Digitoxin Levels
Authors: BENTLEY J. D. , BURNETT G. H. , CONKLIN R. L. , WASSERBURGER R. H. 
Published: June 2012

A simple, rapid, and reliable determination of plasma digitoxin levels is now available for clinical use. It can be determined in any clinical laboratory capable of determining a serum phosphorus if ATPase enzyme is available. Maintenance plasma levels range between 10 and 40 mµg/ml with a mean value of 25 mµg/ml. There is overlapping of maintenance and toxic serum levels in the higher ranges. Values over 45 mµg/ml warrant careful evaluation for digitalis intoxication.
Maintenance plasma levels can be achieved with or without the usual digitalizing dosage if time is not a factor. The daily regression rate is variable in cases of digitalis intoxication following drug withdrawal.
ECG changes (the degree of ST-segment depression, PR-interval prolongation, and multifocal premature contractions) were not good criteria for digitalis intoxication, although PR intervals above 0.24 sec consistently correlated with high plasma digitoxin levels. Variable second and third degree A-V block associated with mental confusion was a frequent presenting feature of digitalis toxicity.
Systolic Hypertension in the Elderly
Authors: COLANDREA MICHAEL A. , FRIEDMAN GARY D. , NICHAMAN MILTON Z. , LYND CELIA N. 
Published: June 2012

Isolated systolic hypertension (systolic blood pressure of 160 mm Hg or greater, diastolic blood pressure less than 90) was investigated in the Leisure World population at Seal Beach, California. The prevalence of this condition was 13.9% if the blood pressure at the initial examination was used but dropped to 2.7% if the subsequent two determinations of blood pressure were also reviewed.
Seventy-two of the subjects with persistent systolic hypertension were compared with 72 matched normotensive control subjects. Cardiovascular morbidity and mortality were generally more frequent among subjects with systolic hypertension. That this association is causal has yet to be proven.
In this elderly population isolated systolic hypertension was a labile, relatively infrequent condition associated with an increased risk of developing cardiovascular complications.
Cardiac Transplantation in Man
Authors: BIEBER CHARLES P. , STINSON EDWARD B. , SHUMWAY NORMAN E. , PAYNE ROSE , KOSEK JON 
Published: June 2012

To date, 12 of 18 patients receiving cardiac allografts at the Stanford Medical Center have died. Five of these died with some degree of graft failure resulting from rejection injury. The remaining seven demonstrated some morphologic evidence of rejection, but death was due to other causes including pulmonary hypertension in two, hemorrhage and sepsis in one, infection in two, cerebral embolism in one, and hepatic failure in one. Acute rejection injury was defined in 10 allografts, accelerated acute rejection in one, and chronic rejection in nine.
The clinical signs of allograft rejection and their morphologic correlates were essentially as predicted from the study of orthotopic canine cardiac allografts. The clinical features and most of the anatomic lesions of acute rejection were usually reversible by current methods of immunosuppressive therapy. Chronic rejection, manifested primarily by obliterative intimal proliferation in coronary arteries, was present in most allografts obtained from patients surviving at least 1 month. Its severity was apparently not related to the quality of the host-donor leukocyte antigen match, and it was not routinely detectable clinically. This intimal thickening may limit long survival of patients undergoing cardiac transplantation.
Eradication of Rheumatic Fever
Authors: MARKOWITZ MILTON 
Published: June 2012

Rheumatic heart disease is considered one of the few forms of chronic heart disease which can be effectively prevented today. Yet the incidence of rheumatic fever is still appreciable and the complacency of many physicians and public health officials in regard to the rheumatic fever problem is unwarranted. It is timely, therefore, to reexamine the question of whether this disease can indeed be eradicated by presently available methods.
One of the major factors limiting the prevention of initial attacks with antibiotics is that about two thirds of the patients who develop rheumaic fever do so following either asymptomatic or mild streptococcal infections. Furthermore, the low socioeconomic group, in whom the risk of rheumatic fever is the greatest, is the least likely to receive adequate care even for overt respiratory infections. Although the number of recurrent attacks has been reduced, approximately 10% of rheumatic patients still develop recurrences either because they are not on prophylaxis at all or they take their medication irregularly.
It is clear, therefore, that the availability of effective preventive agents is not synonymous with effective prevention. While the conditions which account for this fact can be modified so that the incidence of rheumatic fever can be reduced, the disease will not be eradicated until a more biologic means to prevent streptococcal infections becomes available.
Wenckebach and Mobitz Type II A-V Block Due to Block Within the His Bundle and Bundle Branches
Authors: NARULA ONKAR S. , SAMET PHILIP 
Published: June 2012

Fourteen patients with conduction defects were analyzed by using bundle of His (BH) recordings. The BH electrograms were validated by BH and right atrial pacing (AP). In 12 patients with Mobitz type II A-V block, failure in impulse transmission for the dropped beats was localized distal to the recording site of the BH. Three of these 12 patients showed normal QRS complexes. In two of these three, the QRS complexes remained unchanged during intermittent periods of complete heart block (CHB), and thus represent His bundle rhythm with subsidiary pacemaker arising above the bifurcation of the BH. The A-H time in this group of 12 patients ranged from 60 to 160 msec and the H-V time ranged from 40 to 90 msec. At any atrial rate (NSR or AP) conduction time through the A-V node (A-H), and His-Purkinje system (H-V) remained constant. With increasing atrial (A) rates during AP, the number of impulses blocked distal to the BH increased. At high AP rates Wenckebach phenomenon between A and BH occurred concomitantly with block distal to the BH.
Of the two additional patients studied, the one with Wenckebach type 2° A-V block during NSR and a narrow QRS complex had the delay localized between two recorded and validated BH potentials ("split" BH). The other patient, with 1:1 A-V conduction during NSR and left bundle-branch block, developed Wenckebach cycles during AP at 110 beats/min. The progressive delay in the P-R interval was localized in the His-Purkinje system (HPS) probably in the right bundle.
Our data support the clinical observations that Mobitz II A-V blocks are associated with bilateral bundle-branch block as well as with BH lesions. The ECG is of limited value in the localization of the delays occurring at two sites simultaneously: namely, in the A-V node and the HPS. Furthermore, demonstration of the Wenckebach cycles within the HPS (BH or either bundle branch), which cannot be determined from the surface ECG, has important clinical implications.
Effects of Age on the Carotid Pulse in Two Greek Populations
Authors: DONTAS A. S. , KEYS A. , ANTHOPOULOS L. , SCHULZ N. 
Published: June 2012

Right carotid pulses were recorded from 795 men in Crete in 1960 and 593 men in Corfu in 1961, representing 95% and 86% of the males, aged 25 to 74 years, in selected areas of the two islands, both areas having remarkably low prevalence of atherosclerotic disease. Five years later carotid pulses were recorded from 677 (from Crete) and 410 (from Corfu) of the same subjects.
Peak times became longer with age, reaching stable values in Corfu men in their thirties and in Crete men in their forties. Beyond this age, medians of peak times were 0.22 sec, and medians of relative peak times 24% in both areas. The relative height of the anacrotic break decreased linearly from a median value of 80 to 85% to 50 to 55% between the ages of 25 and 60 years in both areas. In general, the observed median 5-year (1960-1961 vs. 1965-1966) changes in pulse contours were similar to the differentiated groups at an earlier age than did the anacrotic break but the latter continued to be of differential value to a later age.
Elevated blood pressure had an effect on the carotid pulse similar to that of aging but less intense. However, the rate of change with aging was slower in Crete, an area with relatively higher prevalence of hypertensive disease, than in Corfu, an area with a higher incidence of coronary heart disease.
Cardiac Conduction in Patients with Symptomatic Sinus Node Disease
Authors: ROSEN KENNETH M. , LOEB HENRY S. , SINNO M. ZIAD , RAHIMTOOLA SHAHBUDIN H. , GUNNAR ROLF M. 
Published: June 2012

Cardiac conduction was investigated at the time of pacemaker insertion in 15 patients with symptomatic sinus node disease. Techniques included recording of His bundle potentials, atrial pacing at various heart rates, and atropine administration. Atrioventricular (AV) conduction was impaired in eight patients who manifested one or more of the following: P-R prolongation, P-H prolongation, and development of second degree AV block with atrial pacing at heart rates below 130 beats/min. Five patients had intraventricular conduction defects diagnosed electrocardiographically; none of these had H-Q prolongation. One of these five, with left bundle-branch block, subsequently developed complete heart block and had a calcific lesion involving the His bundle. Depression of cardiac automaticity was noted in four patients, with asystolic periods greater than 2 sec after sudden cessation of atrial pacing at rates of 100-160 beats/min. Responses to 1 mg of intravenous atropine were varied, but no patient developed sinus rates greater than 90 beats/min, suggesting the presence of primary sinus node dysfunction.
In conclusion, abnormalities of conduction and automaticity in specialized tissue in addition to the sinus node are common in patients with symptomatic sinus node disease. These abnormalities should be recognized when present, so that the ideal site for permanent pacing may be chosen.
Measurement of Coronary Sinus Blood Flow by Continuous Thermodilution in Man
Authors: GANZ WILLIAM , TAMURA KOHJI , MARCUS HAROLD S. , DONOSO ROBERTO , YOSHIDA SHINJI , SWAN HAROLD J. C. 
Published: June 2012

A technique was developed for measurement of blood flow in the coronary sinus in man by continuous thermodilution. For single determinations, 5% dextrose at room temperature is injected at a constant rate of 35 ml/min for a period of about 20 sec. In 14 subjects with normal coronary arteries the mean coronary sinus blood flow was 122 ± 25 ml/min (range, 83 to 159 ml/min). The blood flow computed per 100 g of left ventricle was 82 ± 16 ml/min, which is in the range of values obtained by nitrous oxide and coincidence counting methods. In 35 patients with arteriographically confirmed coronary artery disease the mean flow was similar (128 ± 20 ml/min; range, 92 to 167 ml/min).
A special catheter was used for simultaneous measurement of blood flow in the coronary sinus and great cardiac vein. In eight normal subjects the mean great cardiac vein flow was 68 ± 11 ml/min (range, 51 to 78 ml/min) or 65 ± 10% of the coronary sinus blood flow. The method allowed continuous measurement of flow over a period of several minutes and, for the first time, measurement of rapid changes in myocardial perfusion.
Pulmonary Intravascular and Extravascular Fluid Volumes in Exercising Cardiac Patients
Authors: LUEPKER RUSSELL , LIANDER BO , KORSGREN MAGNUS , VARNAUSKAS EDWARD 
Published: June 2012

Pulmonary extravascular (PEW) and intravascular (PBV) fluid volumes were measured during cardiac catheterization by a multiple indicator-dilution technique in 21 cardiac patients at rest and during exercise.
Increased PEW at rest was clearly related to increased left atrial and pulmonary artery pressures but not to blood flow or pulmonary vascular resistance.
Submaximal supine exercise produced increased intracardiac pressures and flow, with PEW and PBV significantly increased in most cases and stable in a few. Transudation at higher pulmonary capillary pressures and increased capillary recruitment were proposed to explain the increases in PEW during this short-term stress.
wo patients developed overt pulmonary edema with rales during exercise. These individuals are discussed separately.
Coronary Hemodynamics during Successive Elevation of Heart Rate by Pacing in Subjects with Angina Pectoris
Authors: YOSHIDA SHINJI , GANZ WILLIAM , DONOSO ROBERTO , MARCUS HAROLD S. , SWAN H. J. C. 
Published: June 2012

Coronary sinus blood flow was studied by the continuous thermodilution method in 13 subjects with normal coronary arteries and 14 patients with coronary artery disease during progressive elevation of the heart rate by atrial pacing. In 11 patients of the coronary group angina pectoris developed during pacing. In subjects with normal coronary arteries the coronary sinus blood flow rose proportionately (1.71 ± 0.19 ml/beat) and the coronary resistance decreased proportionately (0.06 ± 0.01 [See Equation in PDF File] beats) to the rise in heart rate. Similar changes in coronary sinus blood flow and coronary resistance were found in the pain-free pacing periods in patients with coronary artery disease (1.79 ± 0.21 ml/beat and 0.07 ± 0.01 [see Equation in pdf file]/10 beats, respectively). However, in the periods in which anginal pain was induced the changes in both flow and resistance were significantly lower than in either the noncoronary group or in the pain-free periods in the coronary group (0.66 ± 0.16 ml/beat and 0.00 ± 0.01[See Equation in PDF File]/10 beats, respectively).
The study shows that the coronary blood flow in patients with coronary artery disease not only can be normal at rest, but the coronary bed as a whole can respond to increased metabolic demand by normal increases in flow and normal decreases in resistance up to the point at which coronary insufficiency develops.