OBJECTIVETo compare the blood flow of left internal mammary artery (LIMA) anastomosed to left anterior descending artery (LAD) with variable degree of stenosis in off pump coronary artery bypass grafting (OPCAB).

METHODSFrom 2000.9 to 2002.12, 167 cases (from a total of 209 OPCAB) were involved in this study. According to the degree of stenosis of LAD, all the cases were divided into group A (< 75%), group B (75% approximately 95%) and group C (> 95%). Blood flow of LIMA, routinely anatomized to LAD was immediately measured after anastomosis with transit-time flowmeter (TTFM) and several parameters were recorded.

RESULTSThe mean blood pressure at measurement was not significantly different (P = 0.08). Mean blood flow of group A (11.1 +/- 1.2) ml/min, B (16.3 +/- 1.6) ml/min and C (28.3 +/- 3.2) ml/min and diastolic flow of group A (26.3 +/- 2.8) ml/min, group B (34.8 +/- 3.2) ml/min and group C (55.1 +/- 5.3) ml/min, were significantly different between every two groups (P < 0.01) and the latter was bigger than the former. Systolic blood flow among group A (5.3 +/- 0.7) ml/min, group B (4.3 +/- 1.4) ml/min and group C (4.6 +/- 1.3) ml/min were not different (P = 0.91). Pulsatility index (PI) of group C (2.75 +/- 0.14) was significantly smaller than that of group A (4.36 +/- 0.47) and group B (3.72 +/- 0.31) (P < 0.01), but PI between groups A and B was of no significant difference (P = 0.12).

CONCLUSIONMean and diastolic blood flow of LIMA were closely related to the degree of stenosis of LAD. The higher the degree, the bigger the blood flow, and the smaller the value of PI. However, systolic blood flow was not influenced by the degree of lesion.