Antegrade filling of mammary graft by inappropriately revascularized artery

Area of Science:

• Cardiovascular Surgery
• Interventional Cardiology
• Medical Imaging

Background:

• Coronary artery bypass grafting (CABG) is a common surgical procedure for treating coronary artery disease.
• Internal mammary artery (IMA) grafts are frequently used due to their long-term patency rates.
• Sequential grafting involves using a single graft to revascularize multiple coronary arteries.

Observation:

• A 57-year-old male patient presented with recurrent chest discomfort 21 months post-CABG.
• Repeat angiography revealed a nonfunctional proximal left internal mammary artery (LIMA) graft.
• The distal portion of the sequential LIMA graft supplied the left anterior descending (LAD) artery via the diagonal branch, a phenomenon known as "string sign".

Findings:

• The proximal segment of the LIMA graft demonstrated occlusion or severe stenosis, rendering it nonfunctional.
• Antegrade flow was observed in the distal part of the sequential graft and the LAD artery, originating from the diagonal branch.
• This angiographic pattern indicates successful collateralization and flow diversion, despite proximal graft failure.

Implications:

• The findings underscore the potential for competitive flow to maintain myocardial perfusion even with proximal graft occlusion.
• This uncommon angiographic presentation emphasizes the importance of assessing graft function and flow dynamics in patients with graft failure symptoms.
• Understanding competitive flow mechanisms is crucial for optimizing surgical strategies and interpreting postoperative angiograms in CABG patients.