Abstracts: Suppl. 2 to Vol. 11 (September 15, 2010)

Abstracts/Interactive CardioVascular and Thoracic Surgery S63 Interactive CardioVascular and Thoracic Surgery Abstracts – 24th EACTS Objectives: Competitive flow is accepted as an important cause of occlusion of arterial grafts. Reopening of graft lumen has also been reported, but details remain unknown. We sought to delineate the effect of competitive flow on the long-term clinical results and the fate of bypass grafts. Methods: Clinical records and angiograms of 3092 bypass grafts in 799 patients who underwent off-pump coronary artery bypass grafting (CABG) using the internal thoracic artery (ITA) and radial artery, without aortic manipulation, since 2000 were examined. Dominant flow direction was graded as antegrade, competitive, and no flow (=occlusion). Late angiography was performed for 512 bypass grafts in 139 patients. The follow-up period was 54±30 months. Results: The early graft patency rate was 98.1% (3032/3092). The rate of antegrade flow was 91.6% (2831/3092), while competitive flow was detected in 6.5% (201/3092). In univariate and multivariate analyses, territory of circumflex artery [hazard ratio (HR)=3.3, P<0.0001] and right coronary artery (HR=4.3, P<0.0001), female (HR=1.6, P=0.01), number of targets per in-situ ITA (HR=1.6, P<0.0001), 51–75% stenosis (HR=14.3, P<0.0001), distal end of the graft (HR=13.8, P<0.0001), and composite graft (HR=4.7, P=0.01) were identified as significant predictors of competitive or no flow. The actuarial patency rates of bypass grafts with antegrade flow were significantly higher than those with competitive flow (88.1% at five years and 73.5% at eight years, vs. 27.6% and 11.5%, P<0.0001). Reopening of the graft lumen associated with progression of native stenosis was not seen in the present series. Conclusions: Functional recovery of an occluded graft was considered extremely rare. Competitive flow should be avoided by appropriate graft arrangement and patient selection to achieve the advantages of arterial grafts. 002 THE IMPACT OF COMPETITIVE FLOW ON DISTAL CORONARY FLOW AND ON GRAFT FLOW DURING CORONARY ARTERY BYPASS SURGERY N. Tsirikos Karapanos, S.H. Suddendorf, Z. Li, L.D. Joyce, S.J. Park Cardiovascular Surgery, Mayo Clinic, Rochester, MN, USA Objectives: To determine the effect of competitive flow (LAD-CF) to the graft flow (LIMA-GF) and to the distal coronary flow (LAD-DF), we performed a quantitative coronary blood flow analysis in a swine model of a left internal mammary artery (LIMA) to left anterior descending (LAD) coronary artery. Methods: In seven swine, a LIMA-to-LAD coronary artery bypass graft (CABG) was performed on the beating heart. Blood flow was measured in the LAD proximally and distally of the LIMA-to-LAD anastomosis (LAD-CF and LAD-DF, respectively), in the LIMA (LIMA-GF) and in the pulmonary artery (cardiac output, CO) along with the LIMA pulsatility index (PI) and the left ventricular pressure (LVP). Baseline (before CABG) measurements of CO, LVP, LAD-CF and LAD-DF were followed by post-CABG simultaneous measurements of all parameters at five levels of competitive flow: LAD-CF=100%, 75%, 50%, 003 LEFT INTERNAL MAMMARY ARTERY IN CORONARY ARTERY BYPASS GRAFTING: DOES SIZE MATTER? M. Poullis, P. Sastry Surgery, Liverpool Heart and Chest Hospital, Liverpool, UK Objectives: Evidence points to the prognostic superiority of anastomosing the left internal mammary artery (LIMA) to the left anterior descending (LAD). However, the harvested LIMA is occasionally discarded as a conduit based on a subjective assessment of its small luminal diameter and presumed diminished flow. Our hypothesis is that LIMA diameter may be a flow limiting factor in revascularising the LAD, implying some LIMAs are too small to use. Methods: We created a mathematical model of a LIMA to LAD anastomosis, utilising the principles of fractional flow reserve (FFR). The pressure gradient down the LIMA has to be <19 mmHg to allow an FFR >0.75. A LIMA mean perfusion pressure of 80 mmHg, and a CVP of 5 mmHg were utilised. The threshold for sufficient flow down the LAD during exercise has been established to be 80 ml/min, and during rest to be 40 ml/min. The Reynolds number was found to be in the range 500–750, indicating laminar flow, allowing use of Poiseuille’s formula to calculate the blood flow for a matrix of LIMA lengths and diameters. Results: The calculations indicate that any LIMA of internal diameter >2.0 mm will provide satisfactory flow rates both at rest and during exercise, even with LIMA lengths up to 20 cm. Conclusions: LIMA diameter and length have a significant influence on LIMA to LAD flow rates, and in combination can potentially be flow-limiting. A clinical study is needed to confirm or refute these theoretical calculations. 004 ENDOTHELIUM-DEPENDENT AND ENDOTHELIUM-INDEPENDENT VASODILATOR RESPONSE OF LEFT AND RIGHT INTERNAL THORACIC ARTERIES USED AS A COMPOSITE Y-GRAFT D. Glineur, G. El Khoury, C. Hanet Cardio Vascular, Cliniques Universitaire St. Luc, Brussels, Belgium Objectives: The manner in which a blood vessel is harvested for use as a coronary graft may be important in maintaining a viable and functional endothelial lining. Internal thoracic artery (ITA) composite Y-grafts are characterised by the connection of an in-situ left ITA with preserved innervation and lymphatics and of a free right ITA. Methods: To determine whether endothelial function differs between left and right ITA segments in a Y-graft configuration, 11 patients were studied three years after surgery. The endothelium-dependent vasodilator substance P was selectively infused (1.4 up to 22.4 pmol/min in doubling dose increments) in the ostium of ITA Y-grafts. A maximal endothelium-independent Monday A.M. 001 A 10-YEAR CLINICAL AND ANGIOGRAPHIC FOLLOW-UP OF COMPETITIVE FLOW IN SEQUENTIAL AND COMPOSITE ARTERIAL GRAFTS H. Nakajima1, J. Kobayashi1, K. Toda1, T. Fujita1, Y. Shimahara1, S. Kitamura2 1Cardiovascular Surgery, National Cardiovascular Center, Osaka, Japan; 2National Cardiovascular Centre, Osaka, Japan 25% and 0% after gradually snaring down a snare placed proximally of the LAD-CF flow probe. Results: Baseline CO and LVP remained unchanged post-CABG. LAD-DF was reduced significantly post CABG (–32%, P<0.001). Gradual reduction of the LAD-CF (at 75%, 50%, 25% and 0%) resulted in significant increase of LIMA-GF (+38%, +63%, +113%, +225% with P<0.01 at all LAD-CF levels), reduced PI (6.8, 5.7, 4.1, 3.1, 2.5) and simultaneous increase of LAD-DF (+8% P=NS, +8% P=NS, +12% P<0.05, +44% P<0.01). Conclusions: Decreasing competitive flow has a positive impact, not only by increasing the graft flow and decreasing the PI, but also by increasing the distal coronary flow. In addition to the best of our knowledge, this is the first study where blood flow is measured in all the components of the LIMA-to-LAD anastomosis. Abstracts 001—054-I Benefits and limitations of composite arterial coronary revascularisation Monday 13 September 2010 0 (...truncated)