bluuebunny/crossref_metadata_2025_split huggingface dataset:
Atrioventricular Conduction Defects in Patients with Sinus Bradycardia
Authors: NARULA ONKAR S. 
Published: June 2012

A-V conduction was analyzed in 75 patients (mean age, 73 years) with sinus bradycardia (SB) by His bundle (BH) recordings. Forty-five of these patients had normal QRS complexes (≦0.10 sec) and 30 had abnormal QRS complexes (≧0.12 sec). The conduction times through the atrium (P-A), A-V node (A-H), and His-Purkinje system (H-V) were measured during normal sinus rhythm and transient right atrial pacing up to rates of 150/min. The normal range of conduction times through various regions is: P-A = 25 to 45 msec; A-H = 50 to 120 msec, and H-V = 35 to 45 msec. Overall A-V conduction was completely normal only in 25 (33%) patients. Of these 25 patients, 20 had a narrow QRS complex and five had an abnormal QRS complex. The remaining 50 patients showed abnormal A-V conduction in one or more regions (P-A in 10, A-H in five, BH in six, H-V in 10, and mixed in 19). In some patients despite normal ECGs, the H-V time was abnormal and 1:1 A-V conduction was present during atrial pacing up to 150/min. An abnormal H-V time in association with a normal QRS complex is suggestive of delay in the His bundle. Fourteen patients were restudied at intervals of 6 months to 2 years. Three of these 14 patients showed prolongation of conduction times over 1½ to 2 years.
Our data demonstrate that SB is often (67%) associated with A-V conduction abnormalities. A-V conduction was abnormal in 56% of patients with normal and 83% with abnormal QRS complexes. The ECG and atrial pacing are of limited value in assessing A-V conduction. The BH recordings in symptomatic patients with sinus bradycardia may be of clinical significance in the selection of site for pacemaker implantation, that is, atrial or ventricular.
Physiologic Pressure Differences between Main and Branch Pulmonary Arteries in Infants
Authors: DANILOWICZ DELORES A. , RUDOLPH ABRAHAM M. , HOFFMAN JULIEN I. E. , HEYMANN MICHAEL 
Published: June 2012

Systolic pressure differences of 6 to 45 mm Hg were found between the main and branch pulmonary arteries in 37 of 242 infants undergoing diagnostic cardiac catheterization. Eleven of these 37 infants were restudied, and all had lost the pressure difference regardless of the underlying cardiac defect. A similar pressure difference was noted in lambs studied at thoracotomy with direct measurement of main and branch pulmonary arterial pressures. Increasing pulmonary blood flow caused a rise in pressure differences and also evoked a difference in some older lambs when none was originally present.
Cineangiography in infants with a pressure difference showed no discrete narrowing or poststenotic dilatation of the pulmonary arteries. The main pulmonary artery was a large domed structure from which relatively small right and left branches arose at sharp angles from the inferior and posterior surfaces. The size, disparity, and angulation probably caused turbulence with, at times, a loss of pressure. Systolic flow murmurs may be common.
In assessment of pulmonary vascular resistance, it is therefore important to recognize that a portion of the total pressure drop across the lungs after birth reflects maturational changes of the larger pulmonary arteries as well as of the muscular arterioles.
On the Mechanism of the Austin Flint Murmur
Authors: FORTUIN NICHOLAS J. , CRAIGE ERNEST 
Published: June 2012

We studied mitral valve motion in 15 patients with aortic regurgitation and an Austin Flint murmur by recording simultaneously the phonocardiogram, apexcardiogram, and mitral valve echocardiogram. In 14 patients the murmur was presystolic, and in 13 of these a middiastolic component was present as well. The middiastolic component occurred after the period of rapid ventricular filling as the mitral valve was closing. The presystolic component occurred either as the mitral valve was rapidly closing following normal atrial opening movement or during the entire period of atrial systole. In this latter situation the valve did not open completely with atrial systole. All of these patients demonstrated a prominent A wave on the apexcardiogram. In patients with a two-component Flint murmur, isometric handgrip exercise greatly accentuated the murmur, altered the pattern of valve motion so that atrial systole was no longer effective in opening the valve, and reduced the size of the apex A wave.
One patient had only a middiastolic Flint murmur. The mitral valve was open for only a brief period in middiastole and did not reopen with atrial systole. Cardiac catheterization documented elevation of ventricular diastolic pressures above left atrial pressures during most of diastole. Amyl nitrite reduced diastolic ventricular pressure and permitted the mitral valve to open with atrial systole. The apex A wave, which was small at rest, increased in size after amyl nitrite.
Our findings suggest that the Flint murmur is due to antegrade flow across the mitral valve. The rumble occurs during rapid closure of the valve as flow velocity is increasing although actual volume of flow may be decreasing.
Combined Therapy with Vasodilator Drugs and Beta-Adrenergic Blockade in Hypertension
Authors: GOTTLIEB THOMAS B. , KATZ FRED H. , CHIDSEY CHARLES A. 
Published: June 2012

The hypotensive efficacies of two vasodilators, hydralazine and minoxidil, were assessed as these drugs were used individually in combination with beta-adrenergic blockade and diuretics in 11 hypertensive patients in whom elevated blood pressure had not been adequately controlled previously by other antihypertensive therapy.
Control supine blood pressure fell from 191/128 mm Hg on propranolol and hydrochlorothiazide to 169/108 mm Hg on hydralazine, with a significantly greater reduction to 142/92 mm Hg on minoxidil. Although sodium retention and tachycardia were controlled by the use of concomitant diuretics and beta-blockade, an increment in each of these drugs was occasionally required to prevent these complications. Renal function was changed little with the decrease in blood pressure. Plasma renin increased from a standing control of 14.5 mµg/ml/hr to 35.9 and 31.1 mµg/ml/hr, respectively, on hydralazine and minoxidil. These data suggest the role of vasodilators used in combination with beta-blockers and diuretics and indicate the greater therapeutic efficacy of minoxidil.
Present Status of Digitalis Treatment of Acute Myocardial Infarction
Authors: KARLINER JOEL S. , BRAUNWALD EUGENE 
Published: June 2012

The available experimental and clinical data still leave many unanswered questions concerning the role of digitalis therapy after acute myocardial infarction. It seems clear that little is to be gained by glycoside administration to patients with uncomplicated infarctions who do not have cardiomegaly. The precise role of digitalis therapy in the treatment of cardiogenic shock remains undefined on the basis of the available data. However, until evidence to the contrary appears, its use should be continued on the basis of experience with experimental cardiogenic shock and the presumption that this state, when observed clinically, is a form of extreme left ventricular failure.
Digitalis appears to be indicated in the treatment of atrial fibrillation with rapid ventricular rate complicating acute myocardial infarction. Other supraventricular arrhythmias, such as atrial flutter and ectopic atrial tachycardia, frequently require larger doses of the glycoside, and other means of therapy, such as antiarrhythmic agents or electrical conversion, may be preferable in such instances.
Digitalis is commonly utilized early in the treatment of congestive heart failure and cardiomegaly complicating acute myocardial infarction, despite the paucity of experimental and clinical evidence in support of such therapy. Whether the digitalis glycosides should continue to be used routinely in such patients is an important subject for clinical investigation.
Day-to-Day Variation of the Normal Orthogonal Electrocardiogram and Vectorcardiogram
Authors: WILLEMS JOS L. , POBLETE PIO F. , PIPBERGER HUBERT V. 
Published: June 2012

Day-to-day variation of the corrected orthogonal electrocardiogram was investigated in 20 normal subjects. Ten recordings were made in each individual with chest electrode positions left unmarked first, after which 10 subjects underwent another series of 10 consecutive daily recordings with marked electrode locations. Mean and maximal day-to-day variations of durations and amplitudes of different deflections of scalar leads as well as variations of directions and magnitudes of several QRS and T spatial vectors have been studied using computer technics for measurement and analysis.
Repeat variability in the unmarked recordings was relatively large. For example, the maximum (96%) variability in QRS spatial maximum and in R-wave amplitudes in leads X and Z were, respectively, 0.50, 0.61, and 0.35 mv. Marking of the chest did reduce variability of amplitude and angular measurements by approximately 25%, but even then a substantial variation from day-to-day remained. Relative changes in T-wave amplitude and direction were greater than those of the QRS complex.
The results presented can be used as standards to assess ECG changes observed in serial electrocardiography.
Quantitative Angiocardiography in Ischemic Heart Disease
Authors: HAMILTON GLEN W. , MURRAY JOHN A. , KENNEDY J. WARD 
Published: June 2012

Appropriate surgical and medical management of the patient with ischemic heart disease depends upon a thorough assessment of the clinical and pathophysiologic derangements in left ventricular function. This study examined the spectrum of abnormalities in ventricular function found in 66 patients with documented coronary artery lesions.
Catheterization and biplane angiocardiography were used to measure end-diastolic and end-systolic volume (EDV, ESV), systolic ejection fraction (SEF), ventricular mass (LVM), end-diastolic pressure (LVEDP), peak systolic and end-diastolic stress (PSS, EDS), and stroke work (SW). The pattern of ventricular contraction was assessed for hypokinesis, akinesis, and dyskinesis and graded according to severity.
The SEF, SW, and contractile pattern were sensitive and interrelated indicators of left ventricular contractile dysfunction or fiber shortening. Measurements of ventricular filling or fiber lengthening (EDV, LVEDP, EDS) were related but less sensitive parameters of dysfunction. However, when contractile function was reduced to about one half of normal, there was an associated marked increase in EDV, EDS, and LVEDP.
A wide spectrum of derangements was found ranging from virtually normal function in 18 patients with angina alone to severe dysfunction in 18 patients with myocardial infarction, mitral regurgitation, or heart failure.
Abnormalities in ventricular function were uniformly associated with myocardial infarction. Angina alone was associated with minimal or no ventricular dysfunction. Most patients with mitral regurgitation and all patients with heart failure had severe ventricular dysfunction manifested by an increase in EDV, LVM, and PSS, a marked decrease in SEF and SW, and a severe abnormality in contractile pattern.
D-Bulboventricular Loop with L-Transposition in Situs Inversus
Authors: ANDERSON R. H. , ARNOLD R. , JONES R. S. 
Published: June 2012

In the case described anatomically corrected transposition of the great vessels is associated with situs inversus. Anatomically corrected transposition is extremely rare, and has not been previously reported with situs inversus. This type of transposition should not be confused with classical corrected transposition. Thus the case examined exhibited a D-bulboventricular loop with L-transposition and atrial inversion, so that blood flow was physiologically incorrect as in classical complete transposition. In the case examined, it was also found that bulbar musculature was present between the aorta and the mitral valve.
Additional study of the conducting tissue revealed inversion of the sinoatrial node with the atria, and also of the atrial portion of the atrioventricular node. The atrioventricular bundle and its branches were in expected positions in relation to a large ventricular septal defect. These results are discussed with regard to previous reports and to the embryology of the conducting tissue.
Contribution of Quantitative Assay Technics to the Understanding of the Clinical Pharmacology of Digitalis
Authors: SMITH THOMAS W. 
Published: June 2012

Despite recent advances in understanding of the pharmacokinetics and electrophysiologic effects of cardiac glycosides, digitalis toxicity remains distressingly common in clinical practice. Another substantial group of patients is markedly underdigitalized, failing to gain the full therapeutic benefits of optimal use of these drugs. Since cardiac digitalis toxicity is a dose-related phenomenon, and serum or plasma digoxin and digitoxin concentrations rise with increasing doses, at least a statistical correlation between circulating levels and clinical state might be expected. Increasing availability of serum or plasma digitalis concentration measurements thus offers the clinician a potential means of improving the patient's chances of benefiting from treatment with cardiac glycosides. Assay methods in current use include a double-isotope dilution derivative method (digitoxin), red cell
86
Rb-uptake inhibition (digitoxin and digoxin), Na
+
-K
+
ATPase inhibition (digitoxin), ATPase enzymatic displacement (digitoxin and digoxin), gas chromatography (digoxin), and radioimmunoassay (digitoxin, digoxin, and ouabain).

The rapidly expanding literature reporting clinical experience with these technics reflects general agreement that mean serum or plasma digoxini and digitoxin levels are significantly higher in patients with clinical evidence of toxicity compared with nontoxic patients. Nevertheless, multiple factors influence individual responses, and blood level data must be interpreted in the overall clinical context. Hypokalemia, hypercalcemia, hypomagnesemia, acid-base disturbances, hypoxemia, and hypothyroidism all tend to decrease tolerance to any given digitalis dose or blood level. Autonomic nervous system tone and other drugs concurrently received must also be considered. Advanced heart disease in general, and coronary artery disease in particular, appear to predispose patients to apparent digitalis toxicity at relatively lower serum or plasma levels.
Cardiac glycoside assay technics have also proven useful in various studies of the clinical pharmacology of digoxin, digitoxin, and ouabain. Handling of digoxin by patients on cardiopulmonary bypass has been assessed, and gastrointestinal absorption has been evaluated in normal subjects; poor and erratic absorption of the drug has been documented in patients with malabsorption syndromes. Potentially important drug-drug interactions of agents such as phenobarbital and phenylbutazone with digitoxin have been studied, as well as the effects of steroid-binding resins on digoxin and digitoxin metabolism. Studies of ouabain pharmacokineties by radioimmunoassay have demonstrated a plasma half-life of 21 hours, indicating that, as in the case of digoxin and digitoxin, half-life of serum or plasma concentration after establishment of blood-tissue equilibrium bears a close relationship to duration of clinical effect.
Chronic Hemolysis following Fascia Lata and Starr-Edwards Aortic Valve Replacement
Authors: DAVE KAMAL S. , MADAN CHAND K. , PAKRASHI BROJESH C. , ROBERTS BRYON E. , IONESCU MARIAN I. 
Published: June 2012

Sixty-two patients were investigated for chronic intravascular hemolysis from 3 months to 6½ years following aortic valve replacement; 27 patients had Starr-Edwards prostheses and 35 fascia lata grafts.
The findings are suggestive of a significantly higher incidence and degree of hemolysis in patients with Starr-Edwards prostheses compared to those with fascia lata grafts. In both groups regurgitation was an important factor in producing hemolysis. In the absence of regurgitation fascia lata grafts do not produce significant hemolysis, while Starr-Edwards valves traumatize the red cells even in the absence of regurgitation. Starr-Edwards valves of small size are associated with hemolysis more often than larger ones are. Turbulent flow due to the obstructing ball is the probable mechanism of hemolysis in these patients. In most of the patients the degree of hemolysis appears to remain at the same level of activity. In rare instances, however, the hemolysis may regress. The mechanism for this is not clear. In a small number of patients, also, progressive hemolysis may necessitate removal and replacement of the valve.
Evaluation of the Pulse-Contour Method of Determining Stroke Volume in Man
Authors: ALDERMAN EDWIN L. , BRANZI ANGELO , SANDERS WILLIAM , BROWN BYRON W. , HARRISON DONALD C. 
Published: June 2012

The pulse-contour method for determining stroke volume has been employed as a continuous rapid method of monitoring the cardiovascular status of patients. Twenty-one patients with ischemic heart disease and 21 patients with mitral valve disease were subjected to a variety of hemodynamic interventions. These included exercise, isoproterenol infusion, and practolol, morphine or pentazocine administration. The pulse-contour estimations, using three different formulae derived by Warner, Kouchoukos, and Herd, were compared with indicator-dilution outputs. The pressure-pulse-contour computations were performed by a small on-line cardiac catheterization laboratory computer. A comparison of the results of the two methods for determining stroke volume yielded correlation coefficients ranging from 0.59 to 0.84. The better performing Warner formula yielded a coefficient of variation of about 20%. The type of hemodynamic interventions employed did not significantly affect the results using the pulse-contour method. This method yielded nearly as reliable results with the catheter positioned in the axillary artery as in the central aorta. Good results were obtained using the pulse-contour method in patients with atrial fibrillation as compared to those with sinus rhythm.
Although the correlation of the pulse-contour and indicator-dilution stroke volumes is high, the coefficient of variation is such that small changes in stroke volume cannot be accurately assessed by the pulse-contour method. However, the simplicity and rapidity of this method compared to determination of cardiac output by Fick or indicator-dilution methods makes it a potentially useful adjunct for monitoring critically ill patients.
Echocardiographic Diagnosis of Mitral Regurgitation due to Ruptured Chordae Tendineae
Authors: SWEATMAN THOMAS , SELZER ARTHUR , KAMAGAKI MASANOBU , COHN KEITH , Basford Judith 
Published: June 2012

The echocardiographic findings from six patients with ruptured chordae tendineae from the posterial mitral valve leaflet and three with ruptured chordae from the anterior leaflet are reported; in all cases the diagnosis was later proven by open-heart surgery. The constellation of echocardiographic findings suggesting ruptured chordae tendineae to the posterior leaflet are: (1) The appearance of echoes within the left atrial chamber, representing prolapse of the posterior leaflet and flail chordae tendineae. This finding, although not consistently observed, is the most pathog-nomonic echocardiographic sign. (2) Increased amplitude of systolic excursion of the left atrial wall, in most cases associated with normal or only mildly increased left atrial diameter. (3) Recognition of thin, low-intensity (noncalcified) mitral valve leaflets. (4) The anterior leaflet may also manifest increased amplitude of motion, and may not coapt normally with the posterior leaflet in systole. (5) Increased amplitude of motion of the interventricular septum with an increased estimated stroke volume and normal-to-increased ejection fraction.
The findings suggestive of ruptured chordae tendineae to the anterior leaflet are: (1) A markedly increased amplitude of motion of the anterior mitral valve leaflet is evident. This leaflet appears to approach or touch the left ventricular septum in systole and the left atrial wall in diastole. (2) All of the findings of ruptured chordae to the posterior leaflet are also seen here, except for the observation of the posterior leaflet within the left atrial chamber.
This constellation of findings has not been seen in normal indiviuals, nor is it present in patients with mitral insufficiency proven to be due to other factors, such as papillary muscle dysfunction or rheumatic heart disease. Hence, this noninvasive technic enables one to diagnose accurately the presence of mitral regurgitation due to ruptured chordae tendineae.
Nonatheromatous Ischemic Heart Disease following Withdrawal from Chronic Industrial Nitroglycerin Exposure
Authors: LANGE RAMON L. , REID MICHAEL S. , TRESCH DONALD D. , KEELAN MICHAEL H. , BERNHARD VICTOR M. , COOLIDGE GEORGE 
Published: June 2012

This report describes the clinical, angiographic, and hemodynamic findings in nine patients who manifested nonatheromatous ischemic heart disease induced by chronic industrial exposure to nitroglycerin and subsequent withdrawal. They represent nearly 5% incidence in the group of 200 workers with similar exposure. One patient died suddenly, and the disease was commonly without premonitory symptoms. Of the eight survivors, five were studied and none showed evidence of significant organic obstructive disease. However, in one studied during the withdrawal state, coronary and digital arteriospasm was demonstrated, and was readily reversed by nitroglycerin. Survivors exhibited exercise symptomatology and hemodynamic impairment similar to other patients with myocardial dysfunction from ischemic heart disease. Complete left bundle-branch block with late sudden death occurred in one, and chronic recurrent atrial fibrillation is present in a second.
An attractive hypothesis suggests that chronic vasodilatation evokes homeostatic vasoconstriction, the latter persisting during the withdrawal period with cardiac ischemia. A more detailed study of the vasodilator action of organic nitrate and the homeostatic reaction is warranted. In addition, the effect of chronic administration of potent, longacting organic nitrate-based drugs should be examined in the light of this industrial experience.
Left Ventricular Ejection Time in Atrial Fibrillation
Authors: TAVEL MORTON E. , BAUGH DAVID O. , FEIGENBAUM HARVEY , NASSER WILLIAM K. , Stewart Janie 
Published: June 2012

Left ventricular ejection time (LVET; indirect carotid pulse) was studied in 48 patients with atrial fibrillation. In comparison with normal individuals in normal sinus rhythm, ejection times for similar cycle lengths were usually short in patients with atrial fibrillation. Patients without mitral valve disease usually show increasing ejection times following increasing cycle lengths until a certain cycle length is reached (usually around 0.85 sec). Further prolongation of cycle length will not further lengthen the LVET. By contrast, patients with significant mitral stenosis show a continuously sloping curve, i.e. continue to show prolongation of ejection times with progressive lengthening of cycles, eventually reaching ejection times (if cycles are sufficiently long) which exceed those of patients without mitral stenosis. Conversion to normal sinus rhythm (six patients) produced variable results, usually lengthening of ejection time for similar cycle length. Postconversion lengthening of LVET was most pronounced in those cases which lacked progressive increase in LVET with longer cycles during atrial fibrillation. This effect was evident in those patients manifesting relatively slow sinus rates after conversion.
Our results indicate that in order to derive information from ejection times in atrial fibrillation one must plot these values against cycle lengths. Moreover, he cannot use data obtained from patients in normal sinus rhythm to interpret ejection times in those manifesting atrial fibrillation.