Blood Flow Assessment in Coronary Surgery and Potential Impact on Revascularization Strategies

Study Objective:Transit time flow measurement (TTFM) is, according to ESC - guidelines, applied for graft evaluation. Off pump coronary bypass graft (CABG) allows an estimation of native coronary flow, indicating severity of stenosis. Competitive flow influence TTFM and graft patency at midterm follow up (FU). Cardiac Magnetic Resonance Imaging (MRI) enables FU evaluation.
Methods:26 off pump CABG patients were prospectively included. Native coronary flow was classified: No ante-grade (0), strongly reduced (1), slightly reduced (2) and normal (3) flow. Mean blood flow (MGF in ml/min), pulsation index (PI) and diastolic perfusion (DP) were correlated to native coronary flow and to FU “Stress cardiac MRI” results.
Results:
Impact on TTFM: Increased native flow led to lower MGF and higher PI in arterial grafts to left coronaries. Competitive flow had little impact on veins. Smaller targets were associated to a reduced MGF, with an increased resistance in veins.
Impact on MRI: Good correlation was found for higher MGF rates. Borderline TTFM were reproducible and described as low flow bypass, but not precisely quantifiable.
Conclusions: Arterial MGF + resistance were affected by competitive flow. MGF was reduced in grafts to smaller targets, but resistance was increased in veins. A good correlation was found for higher MGF and MRI flow calculation.