ISSN:0009-7322    

出版商:OVID    

年代:1966

数据来源: OVID

摘要:

The volume of blood in the heart and lungs can be measured, by the Stewart-Hamilton principle, as the product of cardiac output and the mean transit time from right atrium to the aortic root. Although previous investigators have estimated a variety of central blood volumes, measurements of the true cardiopulmonary blood volume in man have not previously been reported.Eighty-one measurements of the total cardiopulmonary blood volume were obtained in 15 normal human subjects. At rest, total cardiopulmonary blood volume ranged from 301 to 546 ml/m2, with a mean of 422 ml/m2, and it represented 15% of estimated total blood volume. Cardiopulmonary blood volume was significantly larger in the male subjects than in the female. Reproducibility of measurements was good: the mean discrepancy between successive replications was 25 ml/m2and the mean coefficient of variation 3.7%. There was no correlation between cardiac output and cardiopulmonary blood volume but a significant correlation (r=0.79,P<0.0001) was evident between cardiopulmonary blood volume and stroke volume.With elevation of the legs to the pedals of a bicycle ergometer, a small but statisticallysignificant increase occurred in cardiopulmonary blood volume, but no significant changes occurred in cardiac output, heart rate, or stroke volume. With exercise, no further significant change in cardiopulmonary blood volume occurred, despite significant increases in output, rate, and stroke volume.Analysis of cardiac output measurements, both at rest and during exercise, indicates that aortic root sampling is characterized by an appreciably higher reproducibility than that reported for peripheral arterial sampling.

ISSN:0009-7322    

出版商:OVID    

年代:1966

数据来源: OVID

摘要:

Splanchnic, pulmonary, and systemic hemodynamics were studied in 18 patients afterthe sublingual administration of nitroglycerin. The drug, contrary to expectations, produced an over-all vasoconstrictive effect on the splanchnic circulation rather than vasodilatation. There was no evidence of venous pooling in this bed, and indeed the data may indicate a splanchnic supportive role in augmenting venous return to the heart with disengorgement of its own volume. In contrast, there was vasodilatation and pooling of blood in the pulmonary vascular bed. The systemic circulation probably sustains several effects by nitroglycerin, including arterial vasodilatation. A direct change in large artery distensibility probably explains the modest fall in systolic blood pressure seen. Further decline in arterial pressure may depend on venous pooling of a small or large degree. Probably the fall in systemic and specific organ flows is also linked to decreased venous return and the vascular readjustments provoked thereby. Pulsus alternans was produced by nitroglycerin, a previously unreported effect of the drug, but the mechanism by which it arose could not be defined.

ISSN:0009-7322    

出版商:OVID    

年代:1966

数据来源: OVID

摘要:

The circulatory responses to alterations in posture were determined in 10 patients with idiopathic hypertrophic subaortic stenosis. Tilting to a 45° head-up position augmented the subaortic gradient by an average of 35 mm Hg and intensified the obstruction to left ventricular outflow. In addition, the post-extrasystolic decrease of the arterial pulse pressure became more prominent. Tilting to a 20° head-down position reduced the gradient by an average of 11 mm Hg and tended to reduce the severity of the obstruction. Elevation of the lower extremities also resulted in a reduction of the intraventricularsystolic pressure gradient, the reduction averaging 28 mm Hg, and apparently increased the dimensions of the obstructing orifice.It is postulated that these effects on the obstruction to outflow induced by changes in posture result primarily from alterations in left ventricular volume secondary to changes in venous return. As a consequence, in the upright position, the size of the left ventricular outflow tract is reduced and the intraventricular pressure gradient is augmented while the cardiac output is reduced, resulting in an intensification of the obstruction. The opposite changes occur during the head-down tilt or during elevation of the legs.These hemodynamic findings provide an explanation for the intensification of symptoms commonly experienced by patients with idiopathic hypertrophic subaortic stenosis in the erect position, and for the discrepancies between the symptoms and the severity of obstruction determined by cardiac catheterization carried out in the supine position. Assumption of the head-down, legs-up position is suggested as an emergency therapeutic maneuver for patients with hypertrophic subaortic stenosis.

ISSN:0009-7322    

出版商:OVID    

年代:1966

数据来源: OVID

摘要:

The effects of amyl nitrite inhalation were observed in 12 patients with aortic valve stenosis and five patients with muscular subaortic stenosis during left heart catheterization. In aortic valve stenosis the left ventricular systolic pressure always fell, although less than the brachial arterial pressure, and the transaortic systolic pressure gradient rose by an average of 25% due to the increase in left ventricular ejection rate. In muscular subaortic stenosis, the left ventricular pressure always remained the same or rose despite a marked fall in brachial arterial pressure, and the average increase in transaortic systolic pressure gradient was more than fourfold. This effect was associated with a significant increase in the degree of outflow tract obstruction. The increase in outflow tract obstruction is thought to be due to a decrease in left ventricular volume, causing the hypertrophied walls of the left ventricle to become more closely apposed.We believe that inhalation of amyl nitrite is superior to infusion of isoproterenol as a provocative test for muscular subaortic stenosis during cardiac catheterization and is probably the most potent stimulus available for this purpose.

ISSN:0009-7322    

出版商:OVID    

年代:1966

数据来源: OVID

摘要:

Seven patients with prosthetic aortic valves and anemia are described. In six, the Teflon valves had become incompetent as a result of perforations or tears in the prosthetic cusps, and in the seventh the valve was severely stenotic as well as regurgitant. The anemia in each patient was secondary to intravascular hemolysis resulting from damage to the erythrocytes traversing the malfunctioning valve. Severe renal hemosiderosis, the anatomic indicatorof severe intravascular hemolysis, was present in each patient. Although deposits of iron in the kidney in these circumstances may be extreme, no significant renal damage nor impairment of renal function appears to occur as a result of this deposition.

ISSN:0009-7322    

出版商:OVID    

年代:1966

数据来源: OVID

摘要:

Cardiac catheterization and phonocardiography data were obtained from patients with mitral stenosis at rest and during exercise. There was a linear relationship between the percentage decrease of the interval from closure of the aortic valve to the mitral valve opening snap (A2-OS) and the percentage increase[see figure in the PDF file]of the left atrial mean pressure from rest to exercise. The duration of the A2-OS interval was an effective indicator of the level of the left atrial mean pressure during exercise. The duration of the A2-OS interval during exercise allowed separation of patients with mild stenosis from those with moderate or severe stenosis but could not be used to distinguish moderate stenosis from severe stenosis.

ISSN:0009-7322    

出版商:OVID    

年代:1966

数据来源: OVID

摘要:

There has been considerable dispute concerning the role of atrial contraction in the closure of the atrioventricular valves. Selective angiocardiograms with left ventricular[see figure in the PDF file]opacification in 43 patients having a variety of arrhythmias that resulted in the absence of atrial systole, or in an abnormal temporal relationship between atrial and ventricular contractions, revealed no evidence of mitral regurgitation. From this observation it is concluded that a properly timed atrial contraction is not always essential for effective closure of the mitral valve in man.

ISSN:0009-7322    

出版商:OVID    

年代:1966

数据来源: OVID

摘要:

A total of 532 groups of indicator-dilution determinations of cardiac index were performed in four groups of patients, many with mitral regurgitation. The indicator, indocyanine green, was injected into the right atrium and sampled from both the pulmonary and systemic arterial trees. The potential problem imposed by early recirculation of indicator particles was present in the latter but not the former dilution curves. The absence of physiologically significant differences between the two sampling sites demonstrates that even severe mitral regurgitation does not vitiate indicator-dilution determination of cardiac output after right heart injection and systemic arterial sampling if the downstroke of the primary dilution curve permits a straight line semilogarithmic extrapolation.

ISSN:0009-7322    

出版商:OVID    

年代:1966

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:1966

数据来源: OVID