Definition: A coronary arterial grafting surgery (CAGS) is preformed on patients who require improvement to the blood flow to their heart. Most often, this surgery is for those with severe coronary heart disease. CAGS is the most common open heart surgery operation in the US. The procedure involves taking veins from other parts of the body, commonly the legs, and stitching them to the aorta and coronary artery. This helps open up the blocked or narrowed coronary artery.