Should we ligate coronary conduits when flow measurements indicate competitive flow? a case report

Area of Science:

• Cardiovascular Surgery
• Vascular Surgery
• Surgical Innovation

Background:

• Competitive flow (CF) in coronary artery bypass grafting (CABG) can impair graft function and lead to occlusion.
• This case highlights functional occlusion of a left internal mammary artery (LIMA) graft due to flow competition with a saphenous vein graft (SVG).

Purpose of the Study:

• To report a case of LIMA graft occlusion caused by competitive flow from an SVG.
• To discuss the implications of transit-time flow measurements (TTFM) in identifying and managing CF.

Main Methods:

• A 56-year-old male patient with left anterior descending (LAD) stenosis underwent CABG with LIMA to LAD and SVG to Diagonal branch (D1).
• Transit-time flow measurements (TTFM) were performed, revealing high backward flow (BF) in the LIMA graft, suggestive of CF.
• The SVG was temporarily clamped, showing improved LIMA graft flow parameters, but the surgical plan remained unchanged.

Main Results:

• Initial TTFM showed a high BF (8%) in the LIMA graft, decreasing to 0.9% upon SVG clamping.
• Despite TTFM findings, the patient developed symptomatic LIMA graft occlusion (string sign) at 6-month follow-up.
• The patient subsequently underwent successful left main stenting.

Conclusions:

• High BF values during TTFM should raise suspicion for CF, even with otherwise normal parameters.
• Stenosis location (LAD proximal to D1) is a risk factor for CF when both vessels are grafted.
• Altering the revascularization strategy based on TTFM is crucial for achieving optimal patient outcomes in CABG.