Abstract
ObjectivesWe investigated current mechanisms causing low graft flow (LGF) following coronary artery bypass grafting, particularly for the right coronary artery (RCA).MethodsWe retrospectively assessed 230 individual bypass grafts as the sole bypass graft for the RCA using preoperative and postoperative quantitative angiography. Overall, 155 in-situ gastroepiploic arteries (GEAs) and 75 saphenous vein grafts (SVGs) were included. The size and status of the revascularised area were examined to determine whether these factors were associated with LGF (defined as ≤ 20 mL/min with intraoperative flowmetry). A distal lesion was defined as stenosis at segment #4, whereas a proximal lesion was stenosis at #1, #2 and #3.ResultsGraft flow in the SVG and the GEA for distal lesion was significantly less compared with that for proximal lesion (34 ± 26 vs. 60 ± 46, p < 0.0001 and 22 ± 12 vs. 43 ± 28, p = 0.0004, respectively). For proximal lesion, LGF was significantly more frequent when the minimal luminal diameter was over 1.27 compared with when it was less than 1.27 (p = 0.02). Prior myocardial infarction significantly correlated with LGF in the GEA (p = 0.007) and the SVG (p = 0.03). In 55 bypass grafts with LGF, the causes were competitive flow in 20.0%, small revascularised area in 38.1% and prior myocardial infarction in 32.7%.ConclusionsAlong with the current strategy based on the severity of native coronary stenosis, the incidence of competitive flow decreased remarkably. This resulted in flow demand, myocardial status and collateral vessels more influential on graft patency.
Highlights
Intraoperative transit time flowmetry (TTFM) is useful for detecting technical errors and for short and midterm patency [1, 2] following coronary artery bypass grafting (CABG)
We examined the severity of target coronary artery stenosis and clinical history of the revascularised area to determine the underlying mechanisms for low graft flow (LGF) and the impact of flow demand or peripheral vasculature on graft flow and patency; we assessed the causes of LGF in cases of bypass graft to the right coronary artery (RCA) in the present decade
Our standard procedure involving off-pump CABG and saphenous vein grafts (SVGs) or gastroepiploic arteries (GEAs) was used for RCA revascularisation
Summary
Intraoperative transit time flowmetry (TTFM) is useful for detecting technical errors and for short and midterm patency [1, 2] following coronary artery bypass grafting (CABG). We examined the severity of target coronary artery stenosis and clinical history of the revascularised area to determine the underlying mechanisms for low graft flow (LGF) and the impact of flow demand or peripheral vasculature on graft flow and patency; we assessed the causes of LGF in cases of bypass graft to the RCA in the present decade. Other graft materials, such as the radial artery, internal thoracic artery and composite or sequential grafts, were excluded. This retrospective observational study was approved by our institutional review board that waived the requirement for written informed consent of the patients
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