The significance of variations in angiocardiographic circulation times.

Abstract

As a means of demonstrating the morphology of the heart and great vessels, angiocardiography has proved to be practical and valuable. When rapid serial filming is used, the recording of sequential opacification and clearing of the several cardiac chambers and vessels presents an opportunity to study circulatory physiology as well. It seemed of interest and value to correlate the pressures and evidences of shunts obtained at cardiac catheterization with chamber filling and emptying times as shown by short-interval angiocardiography. Methods At the University of Michigan Hospital angiocardiography has been performed with automatic serial filming (1) at the rates of 1.3, 2, and rarely 4 films a second. Tests of the electronic timer employed have shown remarkable uniformity of exposures at these filming rates. The time of appearance and disappearance of contrast in the individual heart chambers and vessels has been recorded for a number of normal and congenitally abnormal hearts. A single observer's visual estimate of the earliest and latest definite opacification was recorded. Films were viewed in large groups, facilitating the recognition of slight changes in density, the influence of respiration, Valsalva effort, hepatic reflux, etc. Certain difficulties were encountered. The initial opacification of a chamber is ordinarily sufficiently abrupt to be easily recognized, but the clearing time, particularly in disease, is often indefinite. At times an overall slight opacity of the right heart remains after the bulk of the contrast medium has passed. In such a case the termination of changing density was used. In some instances filming was not continued long enough to record complete left heart clearing. Superimposition of chambers in certain projections prevents separate recording, i.e., the right auricle and ventricle are superimposed in the left oblique view. Consideration was given to the desirability of densitometric rather than visual measurements (2). With the former, a curve of changing density could be constructed. Previous experience, however, indicated that this would be time-consuming and difficult on account of the nonuniform density and position of the chambers. Also the light transmission of the heavily contrast-filled right heart chambers might be so great as to prevent accurate measurement by the available densitometer. The details of angiocardiographic technic are important as sources of deviation from the commonly studied physiologic states. In this hospital premedication consists of morphine or a barbiturate. General anesthesia is not required, nor is any other drug used. Children up to the age of six or seven are examined recumbent, with no attempt to control respiration. Ordinarily they are quiet at the outset but with the injection may give an apprehensive inspiratory gasp and hold the breath or cough or cry during the latter part of the filming.