[Left internal mammary artery graft stenosis. Atherosclerosis, spasm or kinking?]

The internal mammary artery is the most frequently used bypass conduit for the left anterior descending coronary artery in patients treated with bypass surgery, with excellent long-term patency rates. However, the mammary artery may also be affected by functionally significant stenoses. Most stenoses of the mammary artery are secondary to the surgical procedure at the anastomosis site, but atherosclerotic lesions may also develop. The mammary artery is often tortuous and extreme kinking of the vessel may cause flow obstruction. The treatment of such kind of stenoses is not codified. The clinical course and interventional procedure of 2 patients with previous mammary artery bypass graft and severe angina due to kinking stenosis of the graft are described. The 2 cases are characterized by the short time frame during which the stenosis became apparent, suggesting a vasoactive component in the first case that was resolved with medical treatment and an aggressive atherosclerotic progression in the second that required a percutaneous intervention. Therefore, etiology of the stenosis of the body of the mammary artery graft may differ from that of the native circulation. The role of marked bends in bypass grafts could deserve selective studies to determine whether they are associated with the development of functional stenosis. This information may be useful when performing mammary artery bypass graft surgery for avoiding extremely twisted vessel courses.