Clinical History
A 62-year-old man with multiple coronary bypass grafts underwent a coronary CT angiography examination. Grafts were right internal mammary artery to the left anterior descendent artery (RIMA>LAD), left internal mammary artery to the first and second obtuse marginal arteries (LIMA>OM1, OM2), and gastroepiploic artery to the posterior descending artery (GEA>PDA).
Imaging Findings
CT angiography showed patency of all bypass grafts (Fig. 1-2). A calcified plaque was in the distal half of the common trunk, resulting in lumen stenosis less than 50%. The left anterior descending artery was occluded at the middle third, and the first diagonal branches were lined with multiple calcified plaques. The circumflex artery was occluded in its proximal segment and the right coronary artery was occluded from the origin to its middle segment (Fig. 3).
Discussion
The coronary artery bypass graft (CABG) procedure is indicated for the relief of symptoms of cardiac ischaemia (primarily angina) unresponsive to medical treatment or percutaneous transluminal coronary angioplasty (PTCA). Recommended indications include significant left main coronary artery stenosis, stenosis ≥70% in the proximal left anterior descendent (LAD) artery and proximal left circumflex artery, and three-vessel coronary artery disease.
CABG improves prognosis in the early postsurgical years, although this advantage is not thought to be significant after 10–12 years [1].
All-arterial coronary bypass should start with multiple internal mammary artery (IMA) grafts, which are the well-validated long-term conduits for coronary revascularisation [2].
The gastroepiploic artery (GEA) is a branch of the blood supply to the stomach that has been used as a bypass graft usually to the right coronary artery because of the limitation of graft length. If a long GEA was available, the target was extended to the circumflex system. Harvest of the GEA requires laparotomy, which can be performed by extension of the midsternal incision, making the surgical procedure more technically difficult compared with other bypass grafts. The reported abdominal complications include gastric perforation, bleeding from a gastric ulcer, incisional hernia, and pancreatitis. Intraabdominal adhesion can result in a prolonged time for GEA harvest and can cause accidental graft injury. A contraindication to GEA harvesting is the presence of an upper abdominal malignancy, because lymphatic metastasis can occur by way of the GEA and so the artery may be sacrificed for lymph node dissection. For these reasons, GEA bypass grafts surgery is rare today.
In the case of a high-flow coronary artery with mild stenosis, the saphenous vein was used instead of the GEA. Saphenous veins are fairly simple to access and harvest from the lower extremities, and are more versatile and widely available than arterial grafts. The use of saphenous vein is limited by distortion from varicose and sclerotic disease, as well as higher occurrence of intimal hyperplasia and atherosclerotic changes after exposure to systemic blood pressure, resulting in lower patency rates. Graft occlusion can also occur due to vascular damage during harvesting of the saphenous vein [3-4].
Coronary angiography is the current gold standard for the evaluation of bypass graft patency and stenosis. With CT coronary angiography, noninvasive evaluation of bypass graft patency is possible together with plaque characterisation and accurate quantification of graft narrowing. In addition, extracoronary findings and postoperative complications can be investigated with a one-stop-shop imaging examination [5].
Differential Diagnosis List
Gastroepiploic artery graft
Occlusion of artery graft
Saphenous vein graft
Final Diagnosis
Gastroepiploic artery graft
