An angiogram of the coronary arteries is performed by threading a small catheter from the femoral artery in the groin up into the aorta, and selectively cannulating the coronary ostia. Radio-opaque dye is then injected and X-ray images are obtained via fluoroscopy to evaluate the coronary anatomy. Fluoroscopy allows for real-time acquisition of images, and is a technique which is conceptually similar to the standard X-ray radiographs which you have seen thus far. A major difference is that radio-dense material appears dark rather than bright. This image of the left coronary system is obtained via a right anterior oblique view of the heart.