Diagnostic catheterization, also known as cardiac catheterization or coronary angiography, is a medical procedure used to evaluate the heart and its blood vessels. It involves inserting a thin, flexible catheter into an artery, usually in the wrist or groin, and guiding it to the heart. Contrast dye is then injected through the catheter to visualize the heart's structures and blood vessels on X-ray imaging. This procedure helps identify blockages or narrowing in the coronary arteries, assess heart function, and guide treatment decisions. It is typically performed on an outpatient basis and takes about 30 to 60 minutes. While generally safe, potential risks include bleeding, infection, and rare complications such as damage to blood vessels.