Robert S. Poston, Junyan Gu, Nick Burris, Charles White.
University of Maryland School of Medicine, Baltimore, MD, USA.
OBJECTIVE: Minimally invasive grafting of multiple coronary arteries (mini-CABG) typically utilizes the left internal mammary artery (LIMA) and one additional conduit. It is understood that choosing the radial artery (RA) vs. right IMA (RIMA) does not substantially change acute patency but alters the risk of postoperative spasm. We used multidetector computed tomography (MDCT), an established technique for defining graft patency, as a novel way to quantify the difference in the risk of spasm for RA vs. RIMA conduits following mini-CABG.
METHODS: We prospectively analyzed consecutive mini-CABG cases performed off-pump between 2/06 and 12/07 using the LIMA and either RIMA (n=32) or RA (n=50). RA were grafted only onto coronary targets with >80% stenosis. Conduit diameter was determined intraoperatively using catheter-based optical coherence tomography (OCT) and again on day4 with 64 channel-MDCT. Grafts were defined as "patent" when contrast was present throughout its length and "spastic" when the minimum diameter of the graft was less than the target coronary diameter .
RESULTS: There were no significant clinical differences between the RA vs. RIMA groups. MDCT on day4 showed all grafts patent except one RA and one RIMA. Baseline RIMA diameter (2.6±0.6mm) did not significantly change on day4. RA diameter remained unaffected between these two measurements in 15 RA grafts (30%) and showed modest change (not sufficient to diagnose spasm) in 16 RA (32%). Spasm was diagnosed in 19 RA (38%) due to an angiographic “string-sign” in 6 and focal narrowing in 13, resulting in significantly lower Fitzgibbon A patency rates for the RA vs. RIMA group (60 vs. 97%, p=0.02).
CONCLUSIONS: RA or RIMA yield excellent early patency when used as bypass conduits for mini-CABG. However, using a highly sensitive method for diagnosing spasm that compares conduit diameter intraoperatively (OCT) versus postoperatively (MDCT), we noted that RA graft spasm is more prevalent than might have been anticipated, even without significant competitive flow from the native coronary. RIMA harvest/grafting increases the complexity of mini-CABG but reduces this risk. 
Back to 2008 Annual Meeting
Back to Program Outline