coronary angiography

Coronary angiography is the long-standing reference method for seeing the heart's own arteries. A thin catheter is threaded through an artery in the wrist or groin up to the heart, its tip is engaged in the opening of a coronary artery, and a contrast dye opaque to X-rays is injected while a rapid X-ray movie (fluoroscopy) is filmed. The dye fills the artery and, against the X-ray, paints a moving map of the channel through which blood flows.

On the resulting cine, the cardiologist follows each coronary branch and sees exactly where the lumen narrows, by roughly how much, over what length, and where it is blocked altogether. This direct, high-resolution picture of the arterial anatomy guides the most consequential decisions in coronary disease: whether to treat with medicines alone, to open a narrowing with a balloon and stent, or to refer for bypass surgery. The same procedure can flow straight into treatment in one sitting.

Because it requires entering the arteries, angiography is invasive, with small risks of bleeding, vessel injury, stroke, contrast reaction, and kidney strain, and it uses radiation. It also shows the silhouette of the lumen but not the artery wall itself, and the eye can misjudge whether a moderate narrowing truly limits flow. For that functional question, a pressure wire (fractional flow reserve) or intravascular ultrasound is added.