Why Selective Angiography?

Abstract

The role of the radiologist in the preoperative evaluation of patients with congenital or acquired heart disease is an increasingly important one. With the widespread application of direct-vision surgical technic, he may no longer be satisfied with the mere classification of a lesion but is frequently called upon to specify its anatomic site and to draw conclusions as to its physiologic sequelae. Such precise knowledge is essential to intelligent surgical planning. Catheterization of the right and left sides of the heart furnishes much valuable information (1), but the results of such studies may often be indirect or inferential. The sites of origin and termination and the approximate magnitude of circulatory shunts can be determined in most instances by this means, but the specific type of anatomic defect responsible for the shunt must ordinarily be deduced from clinical findings viewed in the light of past experience. For example, a coronary arteriovenous fistula and an aneurysm of the sinus of Valsalva ruptured into the right atrium both result in left-to-right shunts originating in the proximal aorta and terminating in the right atrium, but the indications for operation and the surgical technics to be employed are quite different. Only with direct visualization by contrast radiography can the two conditions be conclusively differentiated before operation. Although radiographic visualization of the cardiac chambers and great vessels is usually possible following the intravenous injection of a contrast medium, the disadvantages of this method are becoming increasingly apparent. The medium is frequently diluted in its passage through the circulation to such an extent that insufficient contrast is obtained for precise diagnosis. This is particularly true when the heart is large, when venous stasis exists, or a left-to-right shunt is present. The left atrium, left ventricle, and aorta frequently are poorly visualized following intravenous injection. Furthermore, the medium reaches the heart in a stream rather than as a discrete bolus, and several chambers are often opacified more or less simultaneously. Although all these and other disadvantages of intravenous angiocardiography are well documented in the European literature (2–4), the procedure is still widely employed in America. The term “selective angiography,” as used in this paper, refers to introduction of a contrast substance directly into the central circulation by means of a cardiac catheter. In the present study, selective injections were made into the heart, pulmonary artery, or ascending aorta. The opaque medium was thus delivered in high concentration at the site deemed most likely to reveal the lesion. When certain precautions were observed, the procedure was found to be safe and to furnish diagnostic information not obtainable by any other means. More than 200 radiographic examinations with selective injection have been carried out at the National Institutes of Health.