Time flow measurements (TTFM) differ between grafts do transit performed on and off-pump CABG? a comparitive study

Abstract

Background: The aim of this study was to compare intraoperative coronary graft flows performed on and off-pump and to evaluate the effects of hemodilution on coronary graft flows in off-pump CABG patients by using TTFM. Materials and Methods: During a one year period 150 patients undergoing a CABG only procedure were enrolled in a prospective randomized manner. Group 1 consisted of 50 patients undergoing CABG using standard CPB techniques. Group 2 consisted of 50 cases who were planned to undergo revascularization using off-pump techniques. Group 3 consisted of 50 patients undergoing CABG using off-pump techniques under controlled hemodilution. (Htc% levels were kept between a range of 25-28%.) TTFM were performed using the CTS (Cardiothoracic Systems) - USA flometer. Mean Flows (Qmed) Pulsatile _ndex (PI) and flow patterns were evaluated. Twenty-five patients in each group were randomly assigned for control angiography 6 days postoperatively. Reoperations combined cases and emergency operations were not included. Patients requiring high doses of vasoactive drugs were also excluded for the benefit of a controlled vascular resistance. Results: The mean number of anastomoses were higher in Group 1 when compared to Group 2 and 3. (p < 0.05) Mean Arterial Pressure (MAP) heart rate (HR) were similar between groups during measurements. Hematocrit values in Group 2 were higher than Group 1 and Group 3 (p < 0.05). Mean flows (Qmed) for LAD and RCA territories were significantly lower in Group 2 patients (p < 0.05) For the circumflex artery territory despite lower flows again in Group 2 this did not reach significant levels. The pulsatile index were similar in all three groups for all three coronary territories. Postoperative coronary angiography revealed similar graft patencies among three groups (p = ns). All values are shown as mean + SD unless expressed otherwise. The Kruskal-Wallis H test was used for analysing differences between three groups. Dunn's Multiple Comparison test was used for sub-group analysis p < 0.05 was considered significant. Conclusions: Off-pump CABG patients with hemodilution had significantly higher graft flows compared to off-pump CABG patients without hemodilution. It can be hypothesed that hemodilution may help to improve graft patency during the early postoperative period in off-pump CABG patients.