bluuebunny/crossref_metadata_2025_split huggingface dataset:
Use of Exercise Testing for Diagnostic and Functional Evaluation of Patients with Arteriosclerotic Heart Disease
Authors: BLOMQVIST C. GUNNAR 
Published: June 2012

Myocardial oxygen demand generally increases with increasing levels of energy expenditure, but several factors which modify this relation must be considered, both in the design of the test methods and in interpretation of results of exercise tests in patients with arteriosclerotic heart disease (ASHD).
A wide variety of exercise test methods are currently used. Master's test is simple to perform and requires no elaborate equipment. It has been more widely employed than any other test and much clinicopathologic and correlative data are available. However, Master's test provides little information on the patient's physical work capacity. Multistage tests, carried to a symptom-limited or maximal/near-maximal workload level, provide quantitative data on physical performance capacity and also result in fewer false-negative ECG responses among patients with ASHD.
Follow-up studies of asymptomatic subjects have demonstrated that a horizontal S-T depression during or after exercise is associated with a high risk of developing clinical ASHD. The prognostic significance of the exercise test appears to be independent of other known risk factors.
Studies correlating the ECG response to exercise with findings at coronary angiography have demonstrated an abnormal ECG response in 0-30% of patients with no demonstrable arterial disease. The number of patients with significant coronary artery disease and negative ECG response tends to be higher.
Evaluation of physical performance capacity is the primary indication for exercise testing in patients with known ASHD. The results of the test form a basis for recommendations on occupational and recreational physical activity. Serial tests may be used to evaluate objectively the effect of medical and surgical therapy.
Effect of Sustained Isometric Handgrip Exercise on Left Ventricular Performance
Authors: HELFANT RICHARD H. , DEVILLA MARIA A. , MEISTER STEVEN G. 
Published: June 2012

Sustained isometric handgrip exercise was studied in 28 patients, 19 with and nine without catheterization evidence of heart disease. Significant increases occurred in left ventricular systolic and left ventricular end-diastolic pressures (LVEDP), heart rate, cardiac output, and cardiac index, with decreases in stroke volume and stroke index. When control and abnormal groups were compared, no differences could be demonstrated in systolic pressure or heart rate increases. However, the LVEDP increase in the abnormal subjects (9.7 ± 1.7) was significantly (
P
< 0.01) higher than in the controls (2.1 ± 0.7). In addition, cardiac index rose significantly (
P
< 0.025) in the controls (0.8 ± 0.2), but not (
P
< 0.1) in the abnormal subjects (0.2 ± 0.1). Conversely, there was a significant fall in stroke index in the abnormal (
P
< 0.005) but not in the control (
P
< 0.4) group.

When work or stroke-work index-LVEDP relations were compared, the controls uniformly exhibited steep curves, whereas abnormal patients demonstrated curves that were either less steep or flat. ΔWork/ΔLVEDP ratio was [See Equation in PDF File]1.0 in the controls, with one exception, and [See Equation in PDF File]0.77 in the abnormal subjects, with one exception.
The test was performed in less than 4 min and no adverse effects were observed. By virtue of its ease, simplicity, safety, and ability to distinguish normal and abnormal ventricular performance, sustained handgrip is a valuable new stress test.
Prehospital Care of Acute Myocardial Infarction
Authors: YU PAUL N. 
Published: June 2012

It has been estimated recently that half of deaths among the patients with acute myocardial infarction occur before they ever reach the hospital for definitive medical care. One of the major reasons for the high incidence of death was attributed to delays in reaching medical care, involving patients themselves, physicians, transportation, and receiving areas of the hospital. In order to reduce this high mortality substantially we should focus our attention on the prehospital care of this disease, which may include several major approaches.
A. To shorten the delay in securing medical care:
1. Public education, with emphasis on the early warning symptoms and signs of acute myocardial infarction, and the need and importance of seeking early medical care, with special attention directed toward the high-risk coronary patients.
2. Professional education.
3. Mechanisms to direct and/or bring patients with suspected or proven acute myocardial infarction promptly to the system of medical care with special emphasis on the utilization of a telephone information center and provision of rapid transportation.
B. Establishment of emergency life-support stations for screening, monitoring, and early stabilization of cardiac arrhythmias:
1. Fixed.
a. Emergency department of hospitals, preferably with an attached precoronary care area.
b. Areas where many employees are working on weekdays.
c. Areas where many people move in and out from day to day.
d. Areas where there is periodic concentration of mass population.
2. Mobile.
a. Mobile coronary care unit.
b. Mobile intensive care unit.
C. Prevention of sudden death:
1. Study of mechanism and clinical environment of sudden death.
2. Development of techniques for early diagnosis and management of acute myocardial infarction prior to inception of symptoms.
3. Identification of individuals prone to sudden death.
4. Preventive measures directed toward the individuals prone to sudden death.
a. Effective control of risk factors.
b. Intermittent or periodic electrocardiographic monitoring in these individuals.
c. Long-term antiarrhythmic therapy for these individuals.
d. Possibility of implanting an automatic defibrillator in patients with previous myocardial infarction or in those recovered from ventricular fibrillation.
5. Early administration of antiarrhythmic drugs in patients with suspected or proven acute myocardial infarction.
Complete Heart Block Complicating Bacterial Endocarditis
Authors: WANG KYUHYUN , GOBEL FREDARICK , GLEASON DONALD F. , EDWARDS JESSE E. 
Published: June 2012

Among 142 cases of bacterial endocarditis (BE), complete heart block (CHB) was found in six cases (4%) and first-degree (1°) or second-degree (2°) A-V block in 14 cases (10%).
The aortic valve was involved in 18 of 20 cases with atrioventricular (A-V) conduction disturbance, including all six cases of CHB.
Anatomic observations (four autopsy, one operative) were made in five of the six cases of CHB. In these cases, a common finding, in addition to involvement of the aortic valve, was extension of the infection to adjacent structures resulting in cardioaortic fistulae. CHB likely resulted from extension of infection to the major conduction tissues.
Five of the six patients with CHB died suddenly while in the hospital. One patient was treated with electric pacing while the infection was being controlled and, 38 days later, underwent successful replacement of the aortic valve. Conduction abnormalities are important possible complications of aortic valvular BE. Prompt pacing may be a lifesaving procedure, allowing eradication of infection as a prelude to surgical therapy.
Aneurysmlike Formations in Relation to Membranous Ventricular Septum
Authors: TANDON RAJENDRA , EDWARDS JESSE E. 
Published: June 2012

A left ventriculogram may show an aneurysmal protrusion toward the right ventricle in the subaortic area with or without an associated interventricular communication. The pathologic basis for such a finding is variable.
It may well represent an aneurysm of the membranous ventricular septum which may be congenital or acquired. Either variety has the potential of rupturing into the right ventricle. The acquired aneurysms are usually mycotic.
An aneurysm resulting from adhesion of the septal leaflet of the tricuspid valve to the rim of a membranous ventricular septal defect and causing complete or incomplete closure may also yield an aneurysmal formation.
Pouches of the tricuspid valve resulting from excessive tissue, in association with a ventricular septal defect, can also be misinterpreted as an aneurysm of the membranous septum or as incomplete closure of a ventricular septal defect with aneurysm formation.
In some cases, even at pathologic examination, the exact nature is difficult to identify. Separation of a true aneurysm of the membranous septum with adherent tricuspid valve from a spontaneously closed ventricular septal defect with aneurysmlike protrusion in the septal leaflet may not be possible.
Artificial Pacemakers
Authors: WRIGHT KINSMAN E. , MCINTOSH HENRY D. 
Published: June 2012

The development of artificial pacemakers for the electrical control of the cardiac rhythm has greatly enhanced the physician's ability to treat cardiac dysrhythmias. Pacemakers have been useful in treating Stokes-Adams syndrome and symptomatic bradyeardias; they have helped control the occurrence of tachyarrhythmias and have played an important role in the management of arrhythmias accompanying myocardial infarctions. With their more frequent use, pacemakers have contributed to our knowledge of underlying conduction and natural pacemaker disorders. As new indications for artificial pacemaking have been elucidated, more complex pulse generators have been developed, and newer technics found for their insertion. In spite of recent development the pulse generators in general use have a limited useful lifetime.
This paper reviews the indications for pacemaker insertion that are commonly employed. In addition, an approach to the problem of pulse generator replacement is presented.
Postoperative Hemodynamic Evaluation of a New Fabric-Covered Ball-Valve Prosthesis
Authors: O'ROURKE ROBERT A. , PETERSON KIRK L. , BRAUNWALD NINA S. 
Published: June 2012

Previous in vitro and in vivo experimental studies have indicated that insertion of the Braun-wald-Cutter fabric-covered ball-valve prosthesis results in negligible thromboembolic complications and hemodynamic performance comparable to that of noncovered mitral and aortic ball-valve prostheses. To assess the clinical efficacy of this fabric-covered valve prosthesis, 35 patients have been followed for 4 to 26 months (540 patient-months) after mitral and/or aortic valve replacement, and 13 have had extensive hemodynamic re-evaluation.

In eight patients with the mitral valve prosthesis, the mean diastolic gradient averaged 4.8 mm Hg (range 0 to 8) and the end-diastolic gradient 0.8 mm Hg (range 0 to 2) at a time when the mean heart rate was 75 beats/min (range 50 to 100) and the cardiac output averaged 5.1 L/min (range 3.4 to 8.0). The calculated effective mitral valve orifice size averaged 2.68 cm
2
(range 1.92 to 3.46). In six patients with the aortic valve prosthesis, the average peak systolic gradient was 13 mm Hg (range 0 to 22), and the mean systolic gradient averaged 14.5 mm Hg (range 0 to 24) when the mean heart rate was 82 beats/min (range 64 to 120) and the cardiac output averaged 6.2 L/min (range 3.2 to 9.3). The average effective aortic valve size in the five patients with a mean systolic transvalvular gradient was 1.41 cm
2
(range 1.26 to 1.62).

Only one postoperative thromboembolic complication has been observed, and this occurred in a patient with atrial fibrillation and a large left atrium three weeks after discontinuing anticoagulant therapy because of gingival bleeding.
These data indicate that use of the fabric-covered Braunwald-Cutter ball prosthesis produces few thromboembolic complications and a satisfactory hemodynamic result.
Diagnostic Electrocardiographic Sequences in Acute Pericarditis
Authors: SPODICK DAVID H. 
Published: June 2012

Diagnostic electrocardiographic patterns were analyzed in 50 consecutive patients who had unequivocal clinical evidence of acute pericarditis. Distributions of P and QRS, and of P-R segment, ST-segment and T wave changes were plotted by lead and by mean frontal vector (Â). Transient gross deviations of P-R segments, mainly in Stages 1 and/or 2, occurred in 41 patients (82%) and could produce an optical illusion of ST elevations when the J-points were actually on the baseline. Â P-R was close to 180° opposite to Â P and was not related to P wave or heart rate changes. In Stage 1, Â ST tended to be concordant with Â QRS and Â T. T wave inversions in Stage 3 produced an Â T which was distributed over an arc of 210° with no range of predilection.
Transient increase in magnitude of a normally oriented PR vector was consistent with the subepicardial atrial injury of acute pericarditis. It is the analogue of the classic Stage 1 ST-segment abnormalities of subepicardial ventricular injury and was equally as widespread in the electorcardiogram and almost as prevalent. P-R segment deviations were always depressions for leads of "epicardial" patterns. ST-segment deviations departed from the classic elevation pattern in 10 patients: 7 patients in whom ST was depressed in Lead III, 5 of whom had a horizontal QRS axis; and 3 patients in whom ST was depressed in aVL, two of whom had a vertical QRS axis. In Stage 3, the much wider range for Â T as compared with the relatively concentrated early injury vectors, Â P-R and Â ST, is ascribed to greater inhomogeneity of post-injury ventricular repolarization.
Regional Myocardial Blood Flow in Patients with Residual Anterior and Inferior Transmural Infarction
Authors: DWYER EDWARD M. , DELL RALPH B. , CANNON PAUL J. 
Published: June 2012

Regional myocardial perfusion rates were estimated in ten patients with a residual transmural anterior wall infarction and ten patients with a residual transmural inferior infarction. The results in these two groups of patients were compared to the regional myocardial perfusion patterns obtained in 25 patients with normal coronary arteriograms who failed to demonstrate any electrocardiographic evidence of a myocardial infarction. Clearance rates of xenon-133 from multiple areas of the heart were monitored externally with a multiple-crystal scintillation camera following selective injection of the isotope into either coronary artery. Local myocardial blood flow rates were calculated by the Kety formula.
In patients with normal coronary arteriograms, mean myocardial perfusion rates in the left ventricle (62 ml/l00g/min) exceeded flow rates in the right ventricle and atrium. There was slight inhomogeneity of local perfusion rates but no significant differences among major subregions (anterior descending, diagonal, or circumflex) within the left ventricle.

In the group with an anterior transmural infarction, myocardial blood flow rates were significantly depressed (44 ml/l00g/min) and asynergy was present in the region of the left ventricle supplied by the anterior descending artery, which was >80% narrowed. Diminished capillary blood flow was found in the right ventricular region in the patients with an inferior transmural infarction and right coronary artery narrowing of >80%. There was no evidence of nutrient flow to the inferior surface of the left ventricle after right coronary
133
Xe injection.

The data indicate that myocardial perfusion was reduced in regions of the heart which correspond to the electrocardiographic and angiographic location of residual transmural infarction. The perfusion rates observed in areas showing electrocardiographic evidence of transmural infarction and regional ventricular asynergy, although subnormal, were surprisingly high and suggested the presence of residual viable myocardial cells.
Reproduction of Maximal Exercise Performance in Patients with Angina Pectoris Despite Ouabain Treatment
Authors: NIEDERBERGER MANFRED , BRUCE ROBERT A. , FREDERICK RICHARD , KUSUMI FUSAKO , MARRIOTT ARTHUR 
Published: June 2012

Eight patients with a diagnosis of atherosclerotic heart disease and a history of typical angina pectoris, uncomplicated by cardiac dilatation or heart failure, were studied by means of standardized, symptom-limited treadmill exercise test. Repeatability of such testing was determined during two control tests 1-1.5 hours apart. From two to six days later, the same patients performed two treadmill tests after pulmonary and brachial arterial catheterization. The study design allowed evaluation of the effects of 0.005 mg/kg of ouabain at rest-both supine and standing-and during submaximal and maximal exercise.
Measurements were made of oxygen uptake, arterial-mixed venous oxygen difference, heart rate, systemic arterial pressures and pulmonary arterial mean pressure. The ratio of mean systemic to mean pulmonary arterial pressure relative to cardiac output indicated that acute left ventricular dysfunction limited aerobic work. Treatment with ouabain did not significantly change performance or capacity and angina was not alleviated.
Graded Exercise Stress Tests in Angiographically Documented Coronary Artery Disease
Authors: BARTEL ALAN G. , BEHAR VICTOR S. , PETER ROBERT H. , ORGAIN EDWARD S. , KONG YIHONG 
Published: June 2012

Graded exercise stress tests performed on 650 consecutive patients with proven or suspected coronary disease undergoing evaluation by cardiac catheterization were correlated with clinical, hemodynamic, and angiographic findings. Among 451 patients with significant coronary stenosis, 332 (74%) had interpretable stress tests and 65% of these were positive (sensitivity). The rate of "false positives" was 8%.
The clinical syndrome of typical angina identified significant coronary disease in 89% of the patients, and 58% of that group had a positive exercise test defined by objective electrocardiographic criteria.
Patients were not eliminated from this study because of recent digitalis ingestion. Although a higher frequency of uninterpretable exercise tests was found in this group (40%), the test results reflected more severe coronary disease. None of the patients with "false positive" tests were taking digitalis. It is concluded that recent digitalis ingestion should not be considered a contraindication for exercise stress testing.
Among the patients with interpretable exercise tests, the angiographic severity of coronary artery disease correlates strongly with the frequency of positive tests (40%, 66%, and 76%, with 70% or greater occlusion of one, two or three vessels respectively). Left main coronary stenosis of 70% or greater was associated with more severe ST segment changes, inability to achieve target heart rate during stress, and a lower maximum heart rate during exercise. The angiographic occurrence of collateral vessels was related to the extent of coronary disease and was associated with a higher percentage of positive exercise tests; no protective effect of collateral circulation could be demonstrated. Patients with abnormal resting hemodynamics or left ventricular asynergy had no significant difference in the frequency of positive tests after adjustment for the angiographic severity of disease.
Alterations of Systolic Time Intervals During Pregnancy
Authors: BURG JOHN R. , DODEK ARTHUR , KLOSTER FRANK E. , METCALFE JAMES 
Published: June 2012

Systolic time interval measurements were made sequentially throughout pregnancy and during the postpartum period. Recordings were made in the supine and lateral positions. Although the greatest deviations from predicted values were present in the third trimester, changes were evident as early as the first trimester. During the first two trimesters the pre-ejection period (PEP) was significantly shortened. The left ventricular ejection time (LVET) remained normal while the PEP/LVET decreased.
The third trimester was characterized by a markedly shortened LVET, a prolonged PEP, and an increased PEP/LVET, all more apparent in the supine than in the lateral position. These findings are consistent with impaired left ventricular performance and are probably due to decreased left ventricular preload resulting from diminished venous return secondary to inferior vena caval obstruction by the gravid uterus.
In the postpartum period, the PEP/LVET remained elevated in both positions; the PEP was prolonged and the LVET shortened in the lateral posture. It is concluded that alterations in systolic time interval measurements occur normally during the course of uncomplicated pregnancy and persist into the postpartum period. Possible mechanisms are discussed.
Pathophysiologic Observations in Prehospital Ventricular Fibrillation and Sudden Cardiac Death
Authors: LIBERTHSON RICHARD R. , NAGEL EUGENE L. , HIRSCHMAN JIM C. , NUSSENFELD SIDNEY R. , BLACKBOURNE BRIAN D. , DAVIS JOSEPH H. 
Published: June 2012

In order to better understand the problem of prehospital sudden cardiac death (SCD) two groups of individuals were studied. One group was monitored by rescue squads during attempted rescue. These subjects were defibrillated from prehospital ventricular fibrillation (VF) and hospitalized if they survived or autopsied if they could not be resuscitated. The second group were SCDs which were witnessed and described by observers. Detailed past histories of both groups were collected, and either clinical or autopsy diagnoses were obtained.
On the day of death or VF, one quarter reported new symptoms (primarily chest pain and dyspnea) preceding collapse by more than 30 minutes, one quarter reported symptoms lasting from 1 to 30 minutes, and one half collapsed instantaneously or within 1 minute of acute symptoms. A history of old myocardial infarction (MI) was present in 41% and of angina pectoris in 54%, and 27% reported new or changing symptoms within four weeks.
In defibrillated survivors, "would-be SCDs," electrocardiographic (ECG) changes of acute myocardial infarction (AMI) or ischemia were nearly three times more frequent than changes detected histologically in SCDs, and in the former involved predominantly the anterior wall in contrast to the inferior wall in most autopsied deaths. This disparity implicates acute myocardial lesions, particularly of the anterior wall, in the majority of SCDs.
Acute coronary lesions were found in 58% of SCDs autopsied. Most of these were ruptured plaques although almost one fifth of all autopsied SCDs had thromboses without intimal rupture. Severe chronic multivessel stenosis was present in most subjects, although 15% had only disease of a single vessel and in these, the left anterior descending (LAD) or left main coronary artery were involved in three quarters.
The SCD population may be subgrouped into those with recent MI, those with only myocardial ischemia, and those with no detectable myocardial change. When rescuers were able to monitor prehospital SCDs, VF was found in the majority; however, 28% did have other terminal rhythms.