Intraoperative flow profiles of arterial and venous bypass grafts to the left coronary territory

Abstract

OBJECTIVES The different mechanical and vasodilatory properties of arteries and veins may influence their flow profiles when used for coronary artery bypass grafting (CABG). This may be of significance when assessing the cut-off values for adequate flow. However, conduit-related flow differences are less examined. METHODS In a study of 268 patients, transit time flowmetry parameters of 336 arterial and 170 venous conduits all grafted to the left coronary territory were compared. With transit time flowmetry, the mean graft flow (MGF), pulsatility index, percentage of diastolic filling and percentage of backwards flow were measured. Conduit-related differences were further compared according to on- or off-pump CABG (ONCABG versus OPCABG) surgery. RESULTS Overall MGF and pulsatility index were comparable between arterial and venous grafts, but in arterial grafts, MGF was higher during ONCABG than during OPCABG (49.1 ± 35.3 ml/min vs 38.8 ± 26.6 ml/min; P = 0.003). Percentage of diastolic filling was higher in arterial grafts than in venous grafts (overall 71.0 ± 7.9% vs 63.7 ± 11.1%; ONCABG 69.9 ± 7.1% vs 63.9 ± 10.4%; OPCABG 71.9 ± 8.3% vs 63.4 ± 12.2%; all P < 0.001). Furthermore, percentage of backwards flow was higher in arterial grafts than in venous grafts in the overall (2.3 ± 3.2% vs 1.7 ± 3.2%, P = 0.002) and in the ONCABG (2.3 ± 3.2% vs 1.3 ± 2.5%, P < 0.001) cohorts. In venous grafts, percentage of backwards flow was lower during ONCABG versus OPCABG (1.3 ± 2.5% vs 2.6 ± 3.9%, P = 0.016). CONCLUSIONS No statistically significant difference was observed for MGF and pulsatility index between arterial and venous conduits. However, arterial grafts have significantly higher diastolic filling and backwards flow than venous grafts. Furthermore, arterial grafts have a significantly higher MGF in ONCABG versus OPCABG.

Use of the right internal mammary artery and the great saphenous vein for left anterior descending artery revascularization in patients whose left internal mammal artery cannot be used: a study based on transit-time flow measurement

“…Our previous study also found that the intraoperative blood flow of an in situ IMA graft was close to the blood flow in other related research results, but the flow of the LIMA would increase significantly 1 week postoperatively, which was considered to be related to the intraoperative use of vasoactive drugs and selfregulation [11]. Previous studies have demonstrated that studies on TTFM should consider arterial versus venous grafts and different coronary territories [5]. However, owing to the high patency, the use of the LIMA for LAD grafting has been a cornerstone of CABG surgery; thus, few studies have compared the TTFM parameters of different conduits used for LAD.…”

“…Transit-time flow measurement (TTFM) has been increasingly applied to judge the quality of anastomosis and blood flow during CABG, because TTFM is less invasive, more reproducible, and less time consuming [4]. A previous study demonstrated that studies on TTFM should consider conduit materials and different coronary territories, while few studies on the comparison of different conduit materials used for LAD in terms of TTFM parameters have been reported [5]. The purpose of this study was to explore the differences in different conduit materials used for LAD in terms of parameters such as the pulse index (PI), mean graft flow (MGF) and diastolic flow fraction (DF) measured by TTFM.…”

Transit time flow measurement of coronary bypass grafts before and after protamine administration

“…DF decreased post-protamine for arterial grafts but was unchanged for venous grafts and BF was unchanged for both graft types. Of note, reports on flows in arterial vs. venous conduits usually report higher flows in venous conduits [16], but this is not always true when comparing the radial artery to venous grafts [17]. We did not differentiate between radial grafts and other arterial grafts which might have yielded slightly different results.…”

Intraoperative graft flow profiles in coronary artery bypass surgery: A meta‐analysis

“…We found grafts in OPCABG to have lower MGF than in ONCABG. Amin et al found comparable values for PI in the crude comparison, irrespective of surgical technique. In our analysis, no difference was found in PI between OPCABG and ONCABG.…”

“…Our findings are consistent with previous observational studies. Amin et al reported an overall lower MGF in arterial conduits, compared with venous grafts (43.6 ± 31.4 vs 48.2 ± 33.6 mL/min; P ‐value .11). Cetin et al showed that MGF graft flow was lower in LITA grafts than in venous grafts (41.6 ± 2.3 vs 45.8 ± 2 mL/min).…”