Superior Flow Pattern of Internal Thoracic Artery over Saphenous Vein Grafts during OPCAB Procedures

Abstract

The advantages of the use of the internal thoracic artery (ITA) over that of the saphenous vein (SV) for revascularization of the circumflex (Cx) or right coronary artery (RCA) are still debated. Serial intraoperative flow measurements were carried out in 306 consecutive patients (mean age 64 years, mean Euroscore 5.1) undergoing off-pump coronary artery bypass grafting (OPCAB). The LAD was grafted in 302 patients [293 ITA (97%), 9 SV], the Cx in 252 patients [117 ITA (46%), 135 SV], and the RCA in 260 patients [36 ITA (14%), 224 SV]. Averages of 3.7+/-1.0 distal anastomoses/patient were constructed. Mean pulsatile index (PI) was significantly better for the single ITA/Cx-grafts (2.8+/-1.9, n=92) than for the single SV/Cx-grafts (3.3+/-1.7, n=43, p<0.05), whereas the mean flow did not differ (28+/-22 and 31+/-25 mL/min respectively, p=ns). Accordingly, the mean PI was significantly better for the single ITA/RCA-grafts (2.2+/-1.2, n=36) than for the single SV/RCA-grafts (3.4+/-2.6, n=178, p<0.01), whereas the mean flow did not differ (30+/-16 and 32+/-22 mL/min respectively, p=ns). The incidence of perioperative myocardial infarction tended to be lower in patients receiving an ITA to either the Cx or the RCA than in those receiving a SV, but the difference did not reach statistical significance [2/92 of ITA/Cx (2.2%) vs. 2/43 of SV/Cx (4.6%), 1/36 of ITA/RCA (2.8%) vs. 8/178 of SV/RCA (4.5%)]. The internal thoracic artery provides superior flow properties than the SV to the Cx and RCA regions with reduced perioperative ischemia. Whether this advantage persists after adjusting for the grade of the proximal coronary stenosis needs further studies.