bluuebunny/crossref_metadata_2025 huggingface dataset:
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.
Regression of Body Compositional Abnormalities of Heart Failure after Intracardiac Operations
Authors: PACIFICO ALBERT D. , DIGERNESS STAN , KIRKLIN JOHN W.
Published: June 2012

Alterations in body composition are present in patients with heart disease and congestive heart failure, and additional changes occur acutely after corrective surgery. The reversibility and time course of reversion to normal body composition have not been demonstrated. Nine patients were studied preoperatively and 2 to 4 weeks and 6 to 12 mo postoperatively. Measurements were made, using the isotope-dilution technic, of the volumes of total body water, extracellular water, plasma, and red cells, and of the amounts of total exchangeable sodium and potassium. Values were derived for body fat, indices of body cell mass, and the intracellular and extracellular distribution of water and potassium. Significant changes (
P
< 0.05) occurring 2 to 4 weeks after operation were increased in total body water (8.2%), intracellular water (15.0%), exchangeable sodium (7.1%), and intracellular potassium content (7.7%), and decrease in body weight (4.6%) and body fat (21.6%); 6 to 12 mo postoperatively there was increase in exchangeable potassium (6.8%), body weight (7.8%), and decrease in exchangeable sodium (16.1%), extracellular fluid (7.8%), plasma (8.0%), and the ratio of exchangeable sodium to exchangeable potassium (23.6%). Late postoperative values were similar to predicted normal values and indicate that postoperative recovery from valvular replacement in these patients is accompanied by resolution of most of the body compositional abnormalities of heart failure.
Site of Reentry in Paroxysmal Supraventricular Tachycardia in Man
Authors: GOLDREYER BRUCE N. , BIGGER J. THOMAS
Published: June 2012

His bundle recordings during spontaneous and induced episodes of paroxysmal supraventricular tachycardia (SVT) demonstrated that the site of reentry responsible for this arrhythmia was in the A-V node. In five patients studied, A-V conduction time and refractory periods were normal, but atrial premature depolarizations (APD) within a portion of the relative refractory period of the A-V node consistently produced atrial reentry—echoes or sustained SVT. In two patients, APDs falling within the A-V effective refractory period failed to excite the His bundle but still reentered within the A-V node and began SVT. It was noted that the various relationships between atrial and ventricular depolarizations on the surface ECG did not reflect different mechanisms for SVT, but only variations in A-V nodal conduction time.
Resting and Postexercise Phonocardiogram and Electrocardiogram in Patients with Angina Pectoris and in Normal Subjects
Authors: ARONOW WILBERT S. , UYEYAMA RONALD R. , CASSIDY JOHN , NEBOLON JOSEPH
Published: June 2012

One hundred patients with angina and 100 normal subjects, mean age 51 years, had simultaneous phonocardiograms and electrocardiograms at rest and after a double Master's test. A fourth heart sound was present at rest in 43% of the patients and 14% of the normal subjects, and after exercise in 94% of the patients and 29% of the normal subjects. All patients and the normal subject who had a third heart sound at rest had a fourth heart sound at rest, and all who had a third heart sound after exercise had a fourth heart sound after exercise. Fifty-nine per cent of the patients and 4% of the normal subjects had an ST-segment shift ≥1.0 mm, and 67% of the patients and 6% of the normal subjects had an ST-segment shift ≥0.5 mm. After exercise, 97% of the patients and 30% of the normal subjects had a fourth heart sound or an ST-segment shift ≥0.5 mm.
Relationship Between Cardiac Output and Peripheral Resistance in Borderline Hypertension
Authors: JULIUS STEVO , PASCUAL ARTURO V. , SANNERSTEDT RUNE , MITCHELL CHARLES
Published: June 2012

Eighty-eight observations on 77 patients with borderline hypertension and 82 single observations in healthy control subjects are reported. Hemodynamic effects of assumption of the sitting position, mild exercise, infusion of dextran, blockade with propranolol and with a combination of propranolol and atropine are evaluated. In the recumbent position, patients with borderline hypertension have increased cardiac output and "normal" peripheral resistance. Under all other experimental conditions, the peripheral resistance in patients with borderline hypertension was elevated. Increased resistance was accompanied by a decrease of the cardiac output. After administration of the atropine and propranolol combination, cardiac output in patients with borderline hypertension was significantly below the normal. Nevertheless, whether cardiac output was high or low and resistance normal or elevated, patients with borderline hypertension maintained mild elevations of the blood pressure. Consequently, borderline hypertension is not caused solely by elevations of cardiac output.
Postexercise Electrocardiogram in Patients With Abnormal Resting Electrocardiograms
Authors: COHN PETER F. , VOKONAS PANTEL S. , HERMAN MICHAEL V. , GORLIN RICHARD
Published: June 2012

One hundred and ten patients with chest pain syndromes and resting electrocardiograms demonstrating ST-T abnormalities and/or prior transmural myocardial infarctions were studied by means of the Master's two-step exercise test and selective coronary cine arteriography. Criteria for negativity were modified so that subjects with postexercise heart rates less than 110 beats/min, who did not develop significant ST-segment changes, were excluded from evaluation. Eighty-six per cent of the coronary artery disease group and 27% of the normal coronary artery group had positive postexercise electrocardiograms. Conversely, of the patients with positive results, 88% had anatomic coronary artery disease. With this degree of stress, positive responses ≧2 mm were invariably associated with multi-vessel disease. The type of pre-existing ECG abnormality did not influence either the frequency or severity of positive responses. False-negative subjects had no distinctive features relating to type of abnormal electrocardiogram, or location of vessel involvement, although most of these patients had significant disease of only one major coronary artery.
Hemodynamic Effects of Volume Loading in Dogs Following Cardiac Homotransplantation
Authors: NELSON RONALD J. , CASTAGNA JOHN T. , NEDELMAN ARNOLD L. , FELDMAN IRA M. , CLEVELAND RICHARD J.
Published: June 2012

The response to an acute volume load of 25 cc/kg of homologous whole blood was evaluated in ten control dogs and five dogs with orthotopic cardiac transplants at the time of combined hemodynamic-cineangiographic study 7 to 12 days after thoracotomy or transplantation. Both groups elevated their mean left ventricular end-diastolic pressures to similar levels. Cardiac output, mean systemic aortic pressure, systemic vascular resistance, and stroke work did not differentiate the two groups.

The following abnormalities in diastolic filling of the transplants were noted: (1) the maximum rate of change of left ventricular area during early rapid diastolic filling was lower (
P
= 0.01); (2) the baseline left ventricular end-diastolic area was smaller (
P
= 0.15), although the left ventricular end-diastolic pressure was elevated and the heart rate lower; and (3) the increase in left ventricular end-diastolic area was less with volume loading. Decreased distensibility of the left ventricle and a lower baseline heart rate with absence of effective atrial contractions are possible explanations for this difference. Multiple factors may account for the decrease in distensibility.
The Bainbridge Reflex in Canine Cardiac Autotransplants
Authors: REITZ BRUCE A. , DONG EUGENE , STINSON EDWARD B.
Published: June 2012

The effects of volume infusion were examined in cardiac autotransplants to determine the role of cardiac innervation in the Bainbridge reflex. In autotransplantation the atria are transected ventral to the vena cavae and pulmonary veins. The remaining atria ("host") are innervated. The autotransplanted atria and ventricles ("donor") are extrinsically denervated. Host and donor heart rate, arterial pressure, aortic flow, and, in several experiments, venous pressure were monitored. Sixteen volume infusions (saline or 6% dextran) of 300 to 800 cc were given to five unanesthetized animals. In three additional experiments infusions were given after atropine, 2 mg, and propranolol, 1 mg/kg.

In all of these animals, volume infusion was accompanied by a small change in donor rate and a consistent increase in the host rate. The venous pressure, when measured, increased 7 cm H
2
O, the aortic pressure mean change was +3 mm Hg, and the cardiac output increased 0.2 L/min. Atropine and propranolol both attenuated the host rate response to infusion.

A venous pressure rise distributed equally to innervated and denervated portions of the same heart resulted in an increase only in the innervated portion. It is concluded that local stretch does not appear to be responsible for the tachycardia in the intact animal.
Circulatory Support by a Left Ventricular Balloon Pump
Authors: DONALD DAVID E. , MCGOON DWIGHT C.
Published: June 2012

The ability of a left ventricular balloon pump to provide support of the circulation when myocardial function had been severely impaired was examined in six dogs. When the unassisted damaged left ventricle could not maintain systemic blood flows adequate for survival, left ventricular balloon pumping resulted in peripheral blood flows which ranged from 37 to 77 ml/min/kg. These balloon-generated blood flows have been maintained for periods up to three hours. Assist of the circulation by balloon pumping was accompanied by an increase in systemic arterial blood pressure and a decrease in left atrial end-diastolic pressure. The effectiveness of left ventricular balloon pumping was reduced in hypovolemia and in the presence of ventricular extrasystolic beats. Left ventricular balloon pumping was not effective in generating a sustained peripheral flow of blood when the heart was fibrillating.
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.
Radiologic Notes in Cardiology
Authors: BARON MURRAY G.
Published: June 2012

The diagnosis of a dissecting aneurysm can be suggested by the clinical findings or plain films of the chest but a definitive diagnosis cannot be made without angiography. Selective aortography is the procedure of choice as it provides the maximum amount of information at a relatively low risk. Important diagnostic findings include a double lumen within the aorta, separation of the opacified channels by a linear lucency, absence of filling of one or more major branches of the abdominal aorta, or a thickening of the aortic wall when there is no flow in the false channel. Because of the seriousness of the lesion, once the diagnosis of a dissecting aneurysm is suggested, aortography should be performed with a minimum of delay.
New Functional Concept of Valvular Mechanics in Normal and Diseased Aortic Valves
Authors: STEIN PAUL D. , MUNTER WILLIAM A.
Published: June 2012

The orifice area of the functioning aortic valve was measured roentgenographically and related to flow across the valve in 27 patients (12 with normal valves). The orifice area of normal valves was linearly related to stroke index and to left ventricular ejection rate. Less than half of the cross-sectional area of the valve was utilized in most patients during the resting state. A larger percentage of the anatomical cross-sectional area was utilized during states of higher flow. Cinematographic studies of porcine valves in vitro showed a comparable flow-dependent orifice size. These results suggest the concept of a functional or physiologic cross-sectional area of the aortic valvular orifice. The anatomic cross-sectional area may be restricted without impingement upon the functional cross-sectional area in states in which flow across the valve is low.
Hemodynamic Evaluation of Glucagon in Symptomatic Heart Disease
Authors: ARMSTRONG PAUL W. , GOLD HERMAN K. , DAGGETT WILLARD M. , AUSTEN W. GERALD , SANDERS CHARLES A.
Published: June 2012

Glucagon was administered as a 5 mg intravenous bolus in 26 patients. Studies were performed in the Cardiac Catheterization Laboratory and soon after cardiac surgery. When the response to glucagon was compared on the basis of functional classification, patients with class I and II heart disease had a significantly greater increase in cardiac output (+700 ml) than patients with class III and IV heart disease (+100 ml). Isoproterenol augmented cardiac output by a significantly greater amount (+2500 ml) than glucagon in eight of these patients. It is concluded that glucagon is a less effective inotropic agent than isoproterenol and that glucagon's usefulness is limited in patients with advanced symptomatic heart disease.
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.
Intermittent Ventricular Parasystole Due to Entrance Block Failure
Authors: STEFFENS THOMAS G.
Published: June 2012

An interaction between three pacemakers (one artificial) has made possible a number of observations on the nature of intermittent parasystole. Evidence shows that the intermittency is due to temporary failure of entrance block. The fixed coupling of the first beat of an intermittent series is observed to be a consequence of temporary entrance block failure rather than a manifestation of a more complex mechanism. The records also demonstrate that the reason for failure of the entrance block may be due to preferential penetration of the parasystolic focus early in its diastole.
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.
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.
Abnormalities of the Mitral Valve in Endocardial Cushion Defects
Authors: BARON MURRAY G.
Published: June 2012

Absence of the atrioventricular septum and a cleft in the anterior leaflet of the mitral valve is characteristic of almost all anomalies resulting from maldevelopment of the endocardial cushions. These changes produce a specific angiocardiographic picture, characterized in systole by a scalloped right border of the left ventricular outflow tract, with a small lucent notch within it, and in diastole by a gooseneck appearance of the subaortic portion of the ventricle. This appearance is independent of the associated hemodynamic changes or the presence of other lesions. Because the angiocardiogram provides a direct demonstration of the underlying anatomic abnormalities, it is the most sensitive diagnostic method for the recognition of an endocardial cushion defect.
Ventricular Tachycardia with Narrow QRS Complexes (Left Posterior Fascicular Tachycardia)
Authors: COHEN HOWARD C. , GOZO EDILBERTO G. , PICK ALFRED
Published: June 2012

Ectopic atrial, A-V junctional, and ventricular tachycardias in man have been associated with digitalis medication. Recently it has become possible to distinguish various locations of pacemakers within the specialized conduction system of the ventricles on the basis of the form of the QRS complexes in the standard electrocardiogram. Tachycardias originating in the left bundle branch and documented by right, left, and His bundle recordings have been produced in animals given excessive digitalis. We have noted a similar tachycardia in a patient with ischemic heart disease receiving digitalis during hypokalemia. The QRS complexes were 0.10 sec in duration and by contour suggested an ectopic focus located in the posterior fascicle of the left bundle; His bundle recordings were consistent with this diagnosis. As the ectopic rhythm became synchronized with a slightly irregular sinus rhythm, bidirectional depolarization of the His bundle with fusion His potentials could be demonstrated.
Effects of Intraaortic Balloon Counterpulsation on the Severity of Myocardial Ischemic Injury following Acute Coronary Occlusion
Authors: MAROKO PETER R. , BERNSTEIN EUGENE F. , LIBBY PETER , DELARIA GIACOMO A. , COVELL JAMES W. , ROSS JOHN , BRAUNWALD EUGENE
Published: June 2012

The effects of intraaortic balloon counterpulsation (IABC) on the magnitude and severity of myocardial ischemic injury were studied in 19 dogs following acute coronary occlusion and in two patients with cardiogenic shock. In the experimental group, epicardial electrocardiograms were taken from 10-14 sites on the anterior surface of the left ventricle following occlusion of the left anterior descending coronary artery or its apical branch. The average S-T-segment elevation ([see Equation in PDF File]) was used as an index of the magnitude of myocardial ischemic injury. In six dogs, two successive 20-min occlusions were performed, and IABC was started prior to the second occlusion. [see Equation in PDF File] 15 min following occlusion decreased from 3.3 ± 0.9 mv after the control occlusion to 1.4 ± 0.4 mv (
P
< 0.01) after the occlusion with IABC. In three dogs in which the occlusion was maintained and IABC initiated 30 min later, [see Equation in PDF File] decreased from 1.2 to 0.6 mv. In six dogs in which IABC was started 3 hours after occlusion, it induced a reduction of [see Equation in PDF File] from 4.2 ± 1.1 to 2.8 ± 1.0 mv (
P
< 0.01). In four dogs, ischemic injury was augmented by isoproterenol infusion (0.25 µg/kg/min), and while continuing the infusion IABC was initiated. It reduced [see Equation in PDF File] from 8.0 ± 1.9 to 5.7 ± 1.8 mv (
P
< 0.05). Thus, IABC reduced the magnitude and extent of myocardial ischemic injury after experimental coronary occlusion, both when IABC was employed prior to, and 3 hours following, coronary occlusion. IABC was also effective in reducing myocardial ischemic injury which had been increased by isoproterenol infusion. Employing a noninvasive technic, which utilizes 35 electrodes on the thorax, the effects of IABC were examined in two patients with cardiogenic shock associated with acute myocardial infarction. Preliminary observations in these patients confirmed the experimental results indicating that IABC reduced myocardial ischemic injury.
Mechanisms of Action of Cholestyramine in the Treatment of Hypercholesterolemia
Authors: NAZIR D. J. , HORLICK L. , KUDCHODKAR B. J. , SODHI H. S.
Published: June 2012

Cholestyramine (12 g/day) was administered to four subjects with familial hyperchloesterolemia (type II) for 12 to 15 days. Plasma cholesterol values fell by 24 to 28% in all subjects. Total endogenous fecal steroids increased from 2.0 to 2.5 times over the control values. This increment was mainly in the acidic fraction which increased from 1.4 to 6.5 times during treatment. The neutral steroid fraction showed a slight increase (nonsignificant) in two subjects and a significant increase (
P
< 0.05) in one subject. The total fecal steroid increment was considerably in excess of the decrement in plasma cholesterol, thus indicating either (a) a substantial increase in cholesterol synthesis, (b) a transfer of cholesterol from depots, or (c) both. Plasma cholesterol specific activity time curves showed a sharp increase in the slope immediately after the commencement of treatment, reflecting an increase in the rate of entry of unlabeled cholesterol into the readily miscible pool. Since cholestyramine did not change the absorption of the dietary cholesterol, the increase in the contribution of unlabeled cholesterol could only be from an increase in endogenous synthesis. In accordance with previous findings from this laboratory, no evidence of degradation of the steroid nucleus was detected during its passage through the gastrointestinal tract.
The Mitral Apparatus
Authors: PERLOFF JOSEPH K. , ROBERTS WILLIAM C.
Published: June 2012

This review deals with the functional anatomy of the six components of the mitral apparatus, namely, the left atrial wall, annulus, leaflets, chordae tendineae, papillary muscles, and left ventricular wall. Each component is considered individually, in the context of the apparatus as a whole, in relation to the mode of closure of the normal mitral valve, and in the light of many acquired and congenital disorders that disturb the harmony of the finely coordinated mitral mechanism and render it incompetent.

The left atrium is related to mitral valve competence in terms of contraction and relaxation and in terms of dilatation of its posterior wall. The annulus not only serves as a fulcrum for the leaflets but exhibits sphincteric contraction in systole that decreases the size of the orifice. The two leaflets differ in shape but are nearly identical in area, and together are about two and one half times the area of the orifice that they are required to close. Leaflet abnormalities causing acquired or congenital mitral regurgitation result from deficient leaflet tissue, excessive leaflet tissue, or restricted leaflet mobility. Chordae tendineae are considered according to their leaflet attachments, ventricular attachments, thicknesses, lengths, and arborization patterns. Mitral regurgitation due to chordal abnormalities results from chordae that are abnormally long, abnormally short, ectopically inserted, or ruptured. In this context, systolic clicks and late systolic murmurs are discussed, and severe
acute
mitral regurgitation is contrasted with severe
chronic
mitral regurgitation. The papillary muscles and the left ventricular wall represent the two muscular components of the mitral apparatus. An appraisal of papillary muscle dysfunction includes dysfunction with loss in continuity (rupture) and dysfunction without loss in continuity (fibrosis, ischemia, replacement). Finally, the role of altered left ventricular shape is discussed in the context of mitral regurgitation, and the effect of dilatation is ascribed chiefly to alterations in the position of papillary muscles and their directional axes of tension.
Current Results of Operation for Mitral Stenosis
Authors: MULLIN EDWARD M. , GLANCY D. LUKE , HIGGS LAWRENCE M. , EPSTEIN STEPHEN E. , MORROW ANDREW G.
Published: June 2012

Among 124 consecutive patients undergoing operation for pure or predominant mitral stenosis between 1964 and 1969, closed commissurotomy was carried out in 53 (43%). There were no early or late deaths, and the hemodynamic and symptomatic results of operation were excellent. In 51 (41%) of the patients, valvular anatomy was such that valve replacement proved necessary. As a group, these patients were more severely symptomatic preoperatively and had worse hemodynamics than patients in the closed-commissurotomy group. With replacement, operative (24%) and late (12%) mortality were high, but surviving patients enjoyed hemodynamic and symptomatic benefits comparable to those of the patients undergoing closed commissurotomy. In 20 patients whose preoperative clinical and hemodynamic characteristics were intermediate between those of the closed-commissurotomy and valve-replacement groups, open commissurotomy was performed. Early (10%) and late (5%) mortality were less than with mitral replacement, but in general hemodynamic and symptomatic benefits were modest.
Altered Distribution of Tritiated Digoxin in the Infarcted Canine Left Ventricle
Authors: BELLER GEORGE A. , SMITH THOMAS W. , HOOD WILLIAM B.
Published: June 2012

In order to determine the distribution pattern of digoxin in infarcted and ischemic tissue, the early uptake of tritiated digoxin (
3
H-digoxin) in the acutely and chronically infarcted canine left ventricle (LV) was studied. Seven open-chest anesthetized dogs were given
3
H-digoxin intravenously 1 hour following acute anterior-wall infarction produced by serial coronary arterial branch ligations. Central and peripheral zones of infarction, ischemic border zones, and nonischemic myocardium were demarcated by epicardial electrode mapping. Two hours after
3
H-digoxin administration, animals were sacrificed and epicardial and endocardial samples from each zone were analyzed for
3
H-digoxin uptake. Significantly lower digoxin concentrations (ng/g wet weight ± (
sem
) were found in both endocardial (endo) and epicardial (epi) regions of the center (endo 27 ± 11; epi 58 ± 10) and periphery (endo 51 ± 13; epi 112 ± 13) of the infarct as compared to the border (endo 217 ± 21; epi 242 ± 15) and nonischemic (endo 256 ± 22; epi 220 ± 20) zones. Significant transmural gradients of the glycoside observed in infarct zones (endo/epi ratio 0.46) were the reverse of those found in nonischemic portions of the myocardium (endo/epi ratio 1.16). Four dogs with chronic infarcts showed
3
H-digoxin uptake patterns similar to acutely infarcted animals. In four sham-operated dogs,
3
H-digoxin uptake was homogeneous in all areas of the LV. This marked alteration of early
3
H-digoxin uptake by the infarcted LV may predispose to electrical instability and the genesis of ectopic rhythm disturbances. The pattern of LV digoxin uptake appears to reflect, at least in part, regional blood flow to infarcted, ischemic, and nonischemic tissue.
Longevity and Cardiovascular Mortality among Former College Athletes
Authors: POLEDNAK ANTHONY P.
Published: June 2012

Among 681 former Harvard College athletes (lettermen), longevity and cardiovascular mortality differed not by type of sport but by extent of participation. Relative to one-letter and two-letter athletes, men with three or more letters died slightly earlier from natural causes, and significantly more often and slightly earlier from cardiovascular diseases and (specifically) coronary heart disease. The three-or-more-letter athletes differed in physique, being significantly more mesomorphic (muscular, bony) than the other two groups. Further analysis suggested that physique did not account for these differences; other possible explanations were discussed.
Atrial Standstill Secondary to Atrial Inexcitability (Atrial Quiescence)
Authors: WALDO ALABERT L. , VITIKAINEN KARI J. , KAISER GERARD A. , BOWMAN FREDERICK O. , MALM JAMES R.
Published: June 2012

Atrial standstill secondary to atrial inexcitability or atrial quiescence was diagnosed in 11 patients and atrial standstill, in which atrial excitability was still present though depressed, was diagnosed in two patients during the immediate period following open-heart surgery. Atrial quiescence was successfully treated in six patients and atrial standstill with depressed excitability in both patients by the infusion of small doses of isoproterenol. Atrial quiescence was not treated in the other five patients and reverted spontaneously within 24 hours after surgery. It is suggested that atrial quiescence results from relative depolarization of the atrial membrane and that the success of therapy with isoproterenol results from hyperpolarization of the atrial membrane by this drug.
Increase in Severity of Proximal Coronary Disease after Successful Distal Aortocoronary Grafts
Authors: BOUSVAROS GEORGE , PIRACHA ABDUL R. , CHAUDHRY MUHAMMAD A. , GRANT COLIN , OLDER THOMAS M. , PIFARRE ROQUE
Published: June 2012

Aortocoronary vein grafts were placed in seven patients to bypass severe proximal stenosis in nine coronary arteries. Routine postoperative angiography showed patent grafts in all patients and substantial increase of proximal occlusive disease, diffusely or at the points of narrowing, in six of nine arteries (four patients), with complete obstruction of four of the six vessels. Two of the four patients experienced improvement in angina which was sustained despite the advanced proximal disease. The third patient suffered a late postoperative myocardial infarction and the fourth had recurrence of angina, both probably as a result of the increased proximal disease. The possibility is considered that a successful vein graft, by diverting flow from the poststenotic segment, may accelerate its occlusion and that consequences of advancing occlusive disease may not be prevented by vein-grafting surgery.
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.
Right Ventricular Volume Determinations in Children
Authors: GRAHAM THOMAS P. , JARMAKANI JAY M. , ATWOOD GERALD F. , CANENT RAMON V.
Published: June 2012

Right ventricular (RV) volumes were calculated from biplane cineangiocardiograms in 46 patients undergoing diagnostic cardiac catheterization. Validation of methodology was performed by comparison of known and calculated volumes of postmortem RV casts as well as by comparison of cineangiocardiographic RV and left ventricular (LV) stroke volumes of patients without shunts or valvular insufficiency. Seven infants, <1 year of age, with normal right hearts as compared with older children showed smaller RV end-diastolic volumes (39 ± 8 vs 70 ± 13 ml/m
2
,
P
< 0.001) as well as decreased RV systolic indices (SI) (3.71 ± 0.68 vs 4.66 ± 1.10 liters/min/m
2
,
P
< 0.05). There were no differences between normal infants and older children for RV ejection fraction (EF), RVEDV/LVEDV = 1.01, RVSI/LVSI = 0.99, and RVEF/LVEF = 1.04 vs 0.99. In 13 patients with isolated pulmonary stenosis, RVEDV, RVEF, RVSI, RVEDV/LVEDV, and RVSI/LVSI were not different from normal, but RVEF/LVEF averaged 1.13 vs 0.99 in normal infants,
P
< 0.05. In contrast, 11 patients studied with atrial septal defect or total anomalous pulmonary venous connection had significant increases in RVEDV (128 ml/m
2
), RVSI (9.34 liters/min/m
2
), RVEDV/LVEDV (2.36), RVSI/LVSI (2.81), and RVEF/LVEF (1.17), but normal values for RVEF. There was a significant linear relationship between Q
p
/Q
s
from oxygen data and RVSI/LVSI. In three patients studied an average of 1 year following atrial septal defect (ASD) repair, RVEDV remained elevated. In volume overload, alterations in RV volume characteristics are apparent and can be useful in shunt estimation; adaptation to an RV pressure overload, however, is not associated with detectable volume alterations.
Effect of Breathing Oxygen in Patients with Severe Pulmonary Vascular Obstructive Disease
Authors: KRONGRAD EHUD , HELMHOLZ H. FREDERIC , RITTER DONALD G.
Published: June 2012

During cardiac catheterization in nine patients with ventricular septal defect and seven patients with truncus arteriosus, all with severe pulmonary vascular obstructive disease, hemodynamics were compared while they were breathing first room air and then 100% oxygen. Patients with higher pulmonary vascular resistance had higher systemic vascular resistances. With 100% oxygen, pulmonary vascular resistance decreased and systemic vascular resistance increased in both groups. The effect of oxygen was found to be more pronounced on the systemic than on the pulmonary vascular bed in the patients studied. Indicator-dilution dye curves changed and exhibited characteristics of left-to-right shunts in patients with severe pulmonary vascular obstructive disease, as a result solely of an increase in systemic resistance; that is, without a decrease in pulmonary resistance. It is suggested that in patients with severe pulmonary vascular obstructive disease maintenance of an increased systemic resistance is essential to well being and is a factor in longevity. It is also suggested that any transient decrease in systemic resistance in these patients might initiate a vicious cycle leading to sudden death.
Electrical Stability of Acutely Ischemic Myocardium
Authors: KENT KENNETH M. , SMITH ELDON R. , REDWOOD DAVID R. , EPSTEIN STEPHEN E.
Published: June 2012

Previous investigations have shown that a slower heart rate (HR) and myocardial ischemia independently diminish the electrical stability of the heart. It therefore was suggested that increasing heart rate during myocardial infarction might diminish the incidence of serious ventricular arrhythmias. However, since increased HR during experimental acute myocardial ischemia augments the degree of ischemia, an evaluation of the presumed "protective" effects of increased HR on the electrical stability of acutely ischemic myocardium was undertaken. The differences in refractory periods (RP) of eight contiguous areas of the left ventricle were determined as a function of HR. In nonischemic myocardium, the disparity of RP was less at an HR of 180 than 60. However, in ischemic myocardium the disparity increased in three of six animals as the HR was increased from 60 to 90, in seven of 10 animals as HR was increased from 60 to 120, and in all animals when the HR was increased from 60 to 180. The increased disparity of RP is believed to favor development of reentrant arrhythmia. The vulnerability of the heart to develop ventricular fibrillation was assessed by determining ventricular fibrillation threshold (VFT). During ischemia, VFT was not only an inverse function of HR but also was found to be independently influenced by electrical stimulation of the cervical vagus nerves. In the absence of vagal stimulation VFT was lowered in only one of four dogs as HR was increased from 50 to 90, but decreased 30% (
P
< 0.01) as HR reached 120 and 74% at 180 beats/min. When vagal stimulation was used to control HR VFT was lowered 37% as HR was increased from 50 to 60 to 90 (
P
< 0.05). We conclude that increasing HR within a physiologic range by diminishing vagal tone during myocardial ischemia decreases electrical stability of the ventricle by (1) increasing ischemia consequent to the rate-induced increase in myocardial oxygen requirements, and (2) a direct electrophysiologic action of the vagus on the ventricular myocardium.