method of following the passage of blood through the heart and great vessels by means of the intravenous injection of a radiopaque fluid, whose passage is followed by serialized X-ray pictures. A thin plastic tube (catheter) is positioned into a heart chamber by inserting it into an artery, usually in the arm, threading it through the vessel around the shoulder, across the chest, and into the aorta (see cardiac catheterization). The radiopaque dye is then injected through the catheter. With the use of X ray (X-ray), the dye can be seen to flow easily through the healthy sections but narrows to a trickle or becomes completely pinched off where lesions, such as fatty deposits, line and obstruct the lumen of blood vessels (characteristic of atherosclerosis). The most frequently used angiocardiographic methods are biplane angiocardiography and cineangiocardiography. In the first method, large X-ray films are exposed at the rate of 10 to 12 per second in two planes at right angles to each other, thus permitting the simultaneous recording of two different views.

In cineangiocardiography, the X-ray images are brightened several thousandfold with photoamplifiers and photographed on motion-picture films at speeds of up to 64 frames per second. When projected at 16 to 20 frames per second, the passage of the opacified blood may be viewed in slow motion. Angiocardiography is used to evaluate patients for cardiovascular surgery. Although it is a valuable tool in assessing some of the more complicated aspects of heart function, it is also one of the most hazardous of all diagnostic procedures; serious reactions to the iodine-containing compounds used, including radiopaque media, are not infrequent, despite continued efforts to develop less harmful materials. See also contrast medium.