Predictive value of intraoperative transit-time flow measurement for short-term graft patency in coronary surgery

The aim of this retrospective study was to evaluate the possibility to predict postoperative graft patency in coronary surgery by means of intraoperative transit-time flow measurement.

Of 3567 patients submitted to isolated myocardial revascularization from June 1997 through June 2003, 157 (4.4%) underwent both intraoperative transit-time flow measurement and angiography at follow-up. Thirty-six have been revascularized on a beating heart. Three hundred four grafts, 227 arterial conduits, and 77 saphenous vein grafts were checked.

No patients died, and none of them had an acute myocardial infarction within 12 months after the operation. After a mean of 6.7 +/- 4.8 months from the operation, 266 grafts (group A) were completely functioning, whereas 38 grafts (group B) had failed. The transit-time flow parameters recorded in the latter group had significantly lower mean flow and higher pulsatility index and percentage of backward flow values at both univariate and multivariate analysis. Moreover, mean flow values of 15 mL/min or less, pulsatility index values of 3.0 or greater, and percentage of backward flow values of 3.0% or greater were found to be independent variables for higher incidence of graft failure.

Transit-time flow measurement represents a quick, easy, and reproducible method for intraoperative evaluation of graft function. The combination of the 3 major parameters (mean flow, pulsatility index, and percentage of backward flow) results in the chance to predict a graft failure (either anatomic or functional) within the first postoperative year.