ISSN:0009-7322    

出版商:OVID    

年代:1967

数据来源: OVID

摘要:

It is no longer necessary to guess at why embryonic malformations occur. Techniques are now available to test almost any hypothesis concerning developmental phenomena. These include the entire armamentarium of modern cell biology: organ and tissue culture, microsurgery, time-lapse cinematography, autoradiography, and many other related methodologies. The developmental events which lead to the formation of a functional heart in the early embryo can be analyzed with these techniques. Of the pertinent questions concerning developmental processes related to congenital heart disease, those of dextrocardia and differential growth, ventricular septal defects, and cell migration and adhesion in cardiogenesis are discussed. Several experimental systems useful for attacking these questions are described. Relative growth of specific segments of the primitive tubular heart contributed by the right and left wings of the cardiogenic crescent has been examined to elucidate the mechanism of dextral looping of the tube. Migration of precardiac cells to form the heart has been traced with cinematography in the intact embryo, and by following movements of cells labeled in situ with tritium using autoradiographic techniques. To analyze the mechanisms of guidance of such cells, endoderm plus adherent precardiac mesoderm can be explanted and manipulated in tissue culture.

ISSN:0009-7322    

出版商:OVID    

年代:1967

数据来源: OVID

摘要:

An integrated approach, utilizing cine coronary angiography, the standard 12-lead and post-exercise electrocardiograms, and regional myocardial lactate metabolism, is presented for detection of regional myocardial ischemia in patients with coronary heart disease. The normal electrocardiogram was of no predictive value and was present with extensive coronary disease and myocardial production of lactate. The abnormal electrocardiogram gave an accurate indication of a portion, but not all zones of ischemia. Multiple electrocardiographic abnormalities were invariably associated with severe coronary artery disease, although in most patients many more coronary lesions were present than electrocardiographic abnormalities. The regional lactate pattern was very helpful in localizing myocardial ischemia and significant coronary artery lesions. Regional lactate abnormalities may have a great practical value in the selection of patients for myocardial revascularization surgery and in their postoperative evaluation.

ISSN:0009-7322    

出版商:OVID    

年代:1967

数据来源: OVID

摘要:

Beta-adrenergic receptor blockade has been demonstrated to reduce obstruction of the left ventricular outflow tract in patients with idiopathic hypertrophic subaortic stenosis (IHSS) and has also proved helpful in reducing angina pectoris due to ischemic heart disease. Accordingly, the effects of oral propranolol on the level and duration of exercise required to produce angina in seven patients with IHSS were compared with a placebo. Improvement in exercise performance was observed in six patients taking propranolol orally in doses ranging from 80 mg to 480 mg daily. Clinical improvement was sustained in the four patients given propranolol since discharge from the hospital for periods up to 15 months, and in three it has been possible to obviate corrective operations. The mechanism by which propranolol is efficacious in this disease is probably related to the diminution of myocardial O2requirements resulting from the reduction of wall tension, velocity of contraction, and heart rate induced by beta-adrenergic receptor blockade.

ISSN:0009-7322    

出版商:OVID    

年代:1967

数据来源: OVID

摘要:

The instantaneous response of the left ventricle to loss or recovery of effective atrial contraction was studied in 12 patients with valvular aortic stenosis by producing A-V dissociation by electrical pacing of the ventricles so that some ventricular contractions were preceded by an effective atrial contraction while others were not. A conventional hydraulic formula relating size of the aortic valve orifice, pressure gradient, and flow was used to estimate beat to beat stroke volume. A properly timed atrial contraction augmented left ventricular performance in all patients, increasing stroke volume index from 14 to 55% (mean, 27%) and stroke work from 17 to 85% (mean, 45%).The contribution of atrial contraction to integrated cardiac performance was studied in six of the same patients by comparing cardiac performance with right atrial pacing and right ventricular pacing. With right atrial pacing, each ventricular contraction was preceded by an atrial contraction, while with right ventricular pacing many ventricular contractions were not preceded by atrial contraction. Right atrial pacing increased cardiac index in four of six patients: The mean increase for the total group was 13% and the mean increase in left ventricular minute work index was 17%.Although atrial contraction was capable of augmenting left ventricular performance in all patients studied, loss or recovery of effective atrial systole did not always alter integrated cardiac performance. Factors influencing atrial contribution remain poorly understood. Atrial contraction does not appear to have an unusual effect on the performance of the hypertrophied left ventricle.

ISSN:0009-7322    

出版商:OVID    

年代:1967

数据来源: OVID

摘要:

The ratio of the mean systolic transaortic valvular gradient to the mean systolic left ventricular pressure times 100 yields a percentage that represents the portion of left ventricular pressure-volume work per stroke lost because of outflow-tract obstruction. The percentage of the left ventricular stroke work loss and the area of the aortic orifice have been estimated in 49 patients with aortic valvular stenosis and two open-chest dogs with varying degrees of supravalvular aortic constriction. Left ventricular stroke work loss of 30% or greater was associated with calculated aortic valve areas of 1.0 cm2(or 0.60 cm2/m2) or less. These values are representative of serious obstruction to left ventricular outflow, that is, approximately 75% or greater reduction of normal orifice size. The calculation of the percentage of left ventricular stroke work loss, besides being simple, is based upon the most reliable measurements obtainable at left heart catheterization, that of the pressure pulses.

ISSN:0009-7322    

出版商:OVID    

年代:1967

数据来源: OVID

摘要:

The records of 62 patients on whom the diagnosis of aortic dissection was proved are reviewed with particular attention to the clinical features and prognosis in each case. This was the consecutive experience of a large general hospital over approximately 17 years. The initial and long-term survival was far better in patients in whom the ascending aorta was spared by the disease process. No patients in whom such involvement was present were known to survive more than 3 weeks. Eight of 19 patients whose disease began distal to the arch of the aorta are known to have survived 6 to 69 months even though six of these eight were not operated on. Striking differences in the clinical findings of the two groups were also found. Aortic regurgitation, impairment of a radial or carotid pulse, neurological signs, and hypotension were rare in the group whose dissection began beyond the left subclavian artery. Marked systemic hypertension was frequently observed in this group, over a third having a diastolic pressure over 140 mm Hg and nearly two thirds over 120 mm Hg. Such hypertension was unusual when the ascending aorta was the origin of the disease. Despite the present study the available data do not allow any definite conclusions about the efficacy of any form of therapy of this disorder.

ISSN:0009-7322    

出版商:OVID    

年代:1967

数据来源: OVID

摘要:

The renal function, including sodium excretion rates, were studied in 27 patients with early essential hypertension, before and during angiotensin infusions. The patients had a preparatory period of salt loading for four days taking a supplement of 7 g of NaCl. Determinations were made during two 30-minute periods before the angiotensin and for two 30-minute periods afterward. Arterial blood pressure was increased in all 27 patients and renal plasma flow decreased in 25. The glomerular filtration rate changes were not statistically significant, showing some increase in 15 and a decrease in 11 patients. When the group was divided into those in which there was adecreasein sodium excretion (11 patients), and those in which there was anincreasein sodium excretion (16 patients), with angiotensin infusion, a correlation with the control blood pressure was evident. The patients in whom an increase occurred had a control mean blood pressure greater than 136 mm Hg, and those exhibiting a decrease of sodium excretion, a blood pressure less than 136 mm Hg. Salt excretion did not correlate with the increment in blood pressure or renal resistance changes. The minor changes in glomerular filtration of sodium of the two groups could not explain the different excretory patterns which are attributed to an alteration of the tubular transport of sodium.

ISSN:0009-7322    

出版商:OVID    

年代:1967

数据来源: OVID

摘要:

Interrelations between total body water, total exchangeable cation (sodium + potassium), and cation (sodium + potassium) concentration of serum water were examined in 20 normonatremic and 11 hyponatremic edematous cardiac patients. The total exchangeable cation and total body water were highly significantly correlated in the normonatremic and hyponatremic groups. However, for the combined groups the correlation coefficient was lower than that found in the individual populations, and in covariance analysis the cation content in relation to total body water was significantly lower in the hyponatremic than in the normonatremic group. When it is assumed that the total exchangeable cation differs little from the total osmotically active cation, and that the cation concentrations of the extracellular and intracellular water are approximately equal, the ratio: total exchangeable cation ÷ cation concentration in serum water, that is, the cation space, should reflect the total body water. The cation space and total body water were highly significantly correlated in the normonatremic and hyponatremic groups, and the correlation coefficient remained at the same high level for the combined groups. The relationship between cation space and body water was very close to unity, and in covariance analysis no significant difference was found in cation space in relation to total body water. These results were confirmed in 10 sequential studies. It is concluded that the cation space in hyponatremic and normonatremic cardiac patients has proved to reflect the total body water very closely, and the implications of this finding are discussed.

ISSN:0009-7322    

出版商:OVID    

年代:1967

数据来源: OVID

摘要:

Bronchial blood flow was measured in nine patients with tetralogy of Fallot and in two of these cases after radical operation also. The study was made of simultaneous recording of dye-dilution curves from the left atrium and the ear following dye injection into the aortic root. A method of calculating the bronchial blood flow was devised by combining the dye-dilution method with the Fick principle. The bronchial blood flow was increased in all cases. The mean value was 0.46±0.31 L/min, with a range from 0.14 to 1.27 L/min; this is equivalent to 15.3% of the pulmonary artery flow on the average. This study showed no definite relationships among pulmonary artery blood flow, pulmonary artery pressure, arterial oxygen saturation, severity of disease, and patient's age. The postoperative measurement revealed no significant change in bronchial blood flow though its ratios to the pulmonary artery or aortic blood flows were considerably decreased.

ISSN:0009-7322    

出版商:OVID    

年代:1967

数据来源: OVID