Use of External Counting Technics In Studies of the Circulation

Abstract

A variety of external counting technics has been used to study the circulation. Brief consideration has been given to some of those concerned with measurement of cardiac output, myocardial and other regional blood flows, and cardiopulmonary volumes, and to those related to the evaluation of vascular shunts. These technics have much in common. They are simple to carry out, require little time to accomplish, and entail little risk for the subject. At the same time, they are to varying extents imprecise, and are not as accurate as methods currently available or methods of undetermined validity or both. They do not offer the means to measurement of intravascular pressures and so cannot replace cardiac catheterization. As yet, little new information about the circulation has been gained by application of these methods. The ultimate place of external counting technics in the study of the circulation is still undetermined. The best prediction is that these methods will probably supplement but not replace diagnostic methods now in use. They should serve a valuable function as tests for screening of subjects being considered for more definitive and laborious procedures and as supplementary tools in the performance of these more definitive astudies.

The effect of hypercapnia on myocardial blood flow and metabolism

“…The bulk of measurements of flow in the present study were made by the semi-logarithmic re-plot method. Full details of the theory of inert gas clearance techniques for the measurement of tissue blood flow are given in the papers by Conn (1962), Herd et al (1962), Ross et al (1964) and Zierler (1965).…”

Subendocardial Distribution of Coronary Blood Flow and the Effect of Antianginal Drugs

“…These methods can be criticized because cellular transport mechanisms rather than flow may be the factor limiting uptake, particularly in studies in which 80 Rb is used (28). However, a comparative study of the 8(i Rb method with metered coronary blood flow showed that the method gives an accurate estimate of directional change in coronary flow, although it tends to underestimate metered flow at high flow rates because of decreased extraction (29).…”

Radiocardiography and Pulmonary Radiocirculography Using I¹³¹ Albumin in Cardiopathies

“…If the emptying of the ventricle is retarded as a manifestation of its failure, the isotope activity in the ventricle persists and this manifests itself by a gradual decline of the descendent part (23). The dilution stage is thus retarded (the ratio according to Donato et al [4] is low).…”