For almost thirty years angiocardiography has been a diagnostic aid in the study of cardiovascular diseases. While valuable, the procedure attains visualization of anatomical structures that by any standard must be regarded as gross. In the authors' department (University of Washington, Seattle, Wash.) recent efforts have been devoted to alterations in technic that might provide better detail. In recent years carbon dioxide has been shown to be practical for intracardiac visualization (1). The possibility of the use of a contrast material with the carbon dioxide to obtain double-contrast detail in vivo has been explored in dogs by several investigators (2, 3). The results, however, were not the most desirable, even though circulatory arrest was employed. This in vitro study was undertaken to explore the potential value of a more perfect double-contrast technic and to facilitate interpretation of conventional angiocardiograms. Dog hearts, contributed by other investigators whose studies resulted in or required sacrifice of the animal, were first employed. The procedures to which the dogs were subjected in no way altered the gross internal cardiac anatomy. All the hearts were fresh except 2, which were twenty and thirty-six hours old, respectively. Subsequently, the technic was used on human necropsy specimens. Technic To reproduce as near an anatomic position as possible, the heart is marked before removal from the thorax. The simplest successful method is by a device utilizing a wire crossbar mounted on a square of malleable lead, constructed with a metal handle for convenience. When the pericardium has been removed, the apparatus is placed in a central position on the surface of the left ventricle. The malleable lead easily conforms to the contour of the surface. The wire crossbar is suspended in clay, allowing horizontal and vertical axes to be demonstrated. A third wire is then placed in the clay at right angles to the crossbar to align the third plane of the heart. When the apparatus is in position, the four corners are marked by fine silk sutures placed shallowly in the epicardium. The apparatus is then carefully removed and placed in a container to prevent any disturbance of the parts. When fixation is complete, the apparatus may be simply reapplied and held in place while positioning for filming takes place. The clay is malleable, yet firm enough to maintain the position required. It must be emphasized, however, that because of in vivo and in vitro differences, this method merely gives an indication of the horizontal, vertical, and transverse axes. Final positioning resulting in near in vivo anatomical positioning depends on the comparison of films with known in vivo silhouettes. Positioning adjustments are made accordingly (Fig. 1). The heart is dissected free of the lungs with sufficient lengths of pulmonary veins and arteries, as well as other vessels, to allow corking and adequate occlusion of the vessels.
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Wright et al. (1964) studied this question.