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Should we ligate coronary conduits when flow measurements indicate competitive flow? a case report
Konstantinos Papakonstantinou1, Panagiotis Lerios2, Mihalis Argiriou2
1Department of Cardiothoracic and Vascular Surgery, Evangelismos General Hospital of Athens, Athens, Greece. kostispap@windowslive.com.
Insights
Competitive flow (CF) in coronary artery bypass grafting (CABG) can cause functional graft occlusion. High backward flow (BF) during transit-time flow measurements (TTFM) indicates CF, warranting revascularization plan changes for better outcomes.
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.
Background:
Competitive flow (CF) in coronary artery bypass grafting (CABG) occurs when graft flow is impaired due to higher competing flow from either the native circulation or another graft and may result in functional graft occlusion. We report a case of functional graft occlusion of a left internal mammary artery (LIMA) due to flow competition with a saphenous vein graft (SVG) and discuss the rationale of ligating the graft responsible for the CF.
Case Presentation:
The case refers to a 56-year-old man with an isolated subtotal ostial left anterior descending (LAD) lesion who underwent conventional double on-pump CABG with an in situ (LIMA) to the LAD and a centrally anastomosed SVG to the Diagonal branch (D1). Concerning the initial Transit-time flow measurements (TTFM), the SVG had a mean graft flow (MGF) of 49 ml/min, a Pulsatility index (PI) of 1 and a Diastolic flow (DF) of 66%. The LIMA graft had an MGF of 31 ml/minute, a PI of 3.8, a DF of 80%, but a Backward flow (BF) of 8%. As the LIMA BF was quite high, we suspected competitive flow of the graft and thus decided to transiently apply a bulldog clamp to the SVG, to check if the LIMA TTFM would change. Indeed, MGF was 44 ml/minute, the PI was 2.3, DF was 60%, and BF was 0.9%. Despite these results, the operating surgeon did not alter the revascularization plan and the operation was finished. The patient was discharged uneventfully. However, in a 6-month follow-up, the patient was symptomatic and with poor ejection fraction, and the diagnostic work-up revealed the functional occlusion of the LIMA graft with a string sign, and a patent SVG. After Heart Team consultation and patient update, he underwent left main stent implantation.
Conclusions:
There should be a great degree of suspicion for CF with high BF values, even when the rest of the parameters measured during TTFM are normal or marginal. Also, the location of the LAD stenosis proximal to the D1 is a risk factor for CF when both arteries are grafted. Changing the revascularization plan based on TTFM is warranted for optimal outcomes.
