Intraoperative graft flow: Luxury or necessity?

Objective: Outcome of CABG depends critically on the quality of anastomoses. Traditionally, the vein graft outflow is assessed, which is simple and cheap, but only semi-quantitative. In this study, this graft outflow was compared with the more expensive, quantitative Transit Time (TT) measurement after cessation of ECC. These data were correlated with early postoperative markers of ischemia and the clinical outcome.

Patients and methods: From 2/05 to 9/05, 32 patients (Pts; m: 27; age: 67±10ys; LVEF>50%; blood cardioplegia/Calafiore). After completion of the distal vein graft anastomoses, flow through these grafts was assessed using a rollerpump. After cessation of ECC, graft flow was measured by non-invasive TT. Early postoperative markers of ischemia (CK, CK-MB) were measured, and 8 days and 6 months postoperatively, LV function was assessed using echocardiography.

Results: Graft outflow did not correlate with TT measures. Neither graft outflow nor TT nor pulsatility-index correlated with postoperative markers of ischemia or outcome. In two cases, suspicion of graft closure was confirmed by TT, and the graft could successfully be revised. Early mortality was zero. Late postoperatively, all Pts were alive and in good clinical condition (NYHA I). LVEF (echocardiography) was 58±5%. All Pts were in sinus rhythm.

Conclusion: Measurement of graft outflow permits only information on whether or not, the distal graft anastomosis is open. Routine quantitative TT measurement did not allow prediction of postoperative ischemia-related complications. After completion of revascularization, the grafts should be scrutinized by TT in case of doubt.