A comparative study on grafts' blood flow after on-pump and off-pump coronary artery bypass surgeries

OBJECTIVE: To compare the grafts' blood flow after on-pump and off-pump coronary artery bypass graftings. METHODS: Five hundred and forty-seven cases were studied, including four hundred and three cases undergoing off-pump coronary artery bypass (OPCAB, off-pump group) and one hundred and forty-four cases undergoing on-pump coronary artery bypass (CCABG, on-pump group). In all cases left internal mammary artery (LIMA) was routinely anastomosed to left anterior descending artery (LAD), and saphenous vein (SV) to the other target vessels in sequential mode when there were more than two anastomoses. After all anastomoses were completed and hemodynamic status was stable, transit time flow-meter was utilized to measure and record the grafts' flow wave, pulsatility index (PI), value of mean flow, diastolic and systolic peak flow, vascular resistance, insufficiency ratio and mean blood pressure. RESULTS: PI, insufficiency ratio and diastolic peak flow of LIMA in off-pump group were 2.7 +/- 1.8, (2.2 +/- 4.3)%, (46.8 +/- 2.7) ml/min respectively; those in on-pump group were 2.8 +/- 2.0, (3.4 +/- 3.1)% and (52.8 +/- 3.7) ml/min respectively. And those of SV in off-pump group were 2.8 +/- 0.1, (1.8 +/- 0.3)% and (85.8 +/- 3.2) ml/min respectively and those in on-pump group were 2.6 +/- 0.2, (1.3 +/- 0.2)% and (93.9 +/- 5.6) ml/min respectively. For both LIMA and SV grafts' blood flow there was no significant difference in PI, insufficiency ratio, diastolic peak flow and mean blood pressure in both groups (P > 0.05). The mean flow and systolic peak flow in off-pump group were significantly less than those in on-pump, while the vascular resistance in off-pump group was significantly greater than that in on-pump group (P < 0.01). CONCLUSION: There is no significant difference in grafts' patency between OPCAB and CCABG.