TRANSSEPTAL LEFT HEART DYNAMICS IN THIRTY-TWO NORMAL SUBJECTS

Relations between pressure in pulmonary artery, left atrium, and left ventricle with special reference to events at end diastole

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Determinants of pulmonary blood volume

Pulmonary blood volume was determined by the radiocardiographic technique in 49 patients coming to cardiac catheterization. Since this method has not been directly compared with the more commonly used double injection of dye. 25 comparisons were carried out in 13 patients of the series. Agreement was good over a range of 4.5-21.1 heart cycles since there was no statistically significant difference between transit time values measured by the two methods. The relation of pulmonary blood volume to other hemodynamic factors in these 49 patients, with and without cardiac or pulmonary disease, was evaluated by means of multiple regression analysis. The analysis carried out for mean transit time indicates that this parameter varies predominately with flow. Pulmonary blood volume, in this series of resting recumbent individuals, varies to a significant degree only with total blood volume and with pulmonary venous pressure. No parameters of vascular distensibility, such as pulmonary vascular resistance, were found to affect the volume of blood in the lungs. The fact that variations in pulmonary blood volume among the subjects could be described by a multiple regression equation linear with respect to total blood volume and pulmonary venous pressure indicates that these variations are the result of passive distention of components of the vascular bed.

The 'A' wave of the apex cardiogram in aortic valve disease and cardiomyopathy

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Methodology of true pulmonary blood volume determination

"True" pulmonary blood volume has been determined by three indicator-dilution methods in 96 subjects. In two methods a right or left ventricular mixing chamber is interposed between the injection and sampling sites while in the third such a mixing chamber is absent. The results strongly suggest that a ventricular mixing chamber is essential for valid determination of true pulmonary blood volume.