The impact of the degree competitive flow on bypass graft occlusion.

Transcription

1 The impact of the degree competitive flow on bypass graft occlusion. Poster No.: C-2651 Congress: ECR 2013 Type: Authors: Keywords: Scientific Exhibit I. Menkov, I. Zheleznyak, S. Rud, G. E. Trufanov; St. Petersburg/ RU Obstruction / Occlusion, Grafts, Contrast agent-intravenous, CT- Angiography, Cardiac Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 9

2 Purpose Coronary artery disease (CAD) is leading cause of mortality working-age population in the world. Coronary artery bypass graft in patients with multivessel coronary artery disease is mandatory surgical technique that can provide complete revascularization by using arterial conduits and saphenous vein grafts. However, the effective functioning time of arterial and venous grafts is different. In the first few years after surgery the most important role plays factors, which influence on the blood flow velocity in the graft: the quality of the anastomosis site, presence of significant stenosis (>50% reduction in lumen diameter, >75% reduction area vessel) or occlusion vessel segments distal to the anastomosis, recipient vessel's diameter (recipient - vessel is received the graft) (Fig. 1). Also, one of the main causes of bypass graft failure can be competitive flow, which observed near the end-to-side anastomosis region. The concept of competitive flow consists in the following: vessel segments distal to the anastomosis receive the blood flow both from the native artery and the graft that provides a reason to the occlusion or narrowing of the bypass graft supplying this coronary vessel by high blood flow velocity in the proximal segment of this artery (Fig. 2). Multidetector computed tomography coronary bypass angiography has become an important imaging modality for the non-invasive assessment of CAD. Images for this section: Page 2 of 9

3 Fig. 1: Distal vessel segment mainly receive the blood flow from the graft. The graft is functioning normally. Page 3 of 9

4 Fig. 2: Distal vessel segment mainly receive the blood flow from the proximal segment of native coronary artery that provides a reason to the reduction of blood flow in the graft. Page 4 of 9

5 Methods and Materials The aim of this study is research the impact of the degree of stenosis proximal segments native coronary arteries on bypass graft occlusion. A total of 57 patients (46 men, 66±12 years), were examined by a 64-slice computed tomography coronary bypass angiography, using the following scan parameters: 400 ms gantry rotation time, detector collimation 64#0.5 mm, tube voltage kv, the pitch The mean interval between bypass surgery and CT angiography was 3,8±2,1 years (range 0,5-6 years). The degree of stenosis was measured in relation the average area of the vessel proximal and distal to the stenosis to the place with most narrowing vessel. If the patient's heart rate exceeded 65 beats/min, oral beta-blocking medication (50 or 100 mg metoprolol) was administered one hour before examination, unless contraindicated. All grafts were divided into groups according to the presence of graft failure and grafts type (arterial or venous). Then the group with graft failure was divided by the degree of stenosis proximal segments of the native coronary artery, ranging from 50% to 100% with 10% increment. Comparison between different groups was calculated using Pearson's nonparametric test. Results Sufficient image quality for the assessment of bypass grafts by MSCT was demonstrated in 55 patients (96.5%) (Fig. 3). In 2 patients image quality was insufficient owing to motion artifacts related to atrial fibrillation. 34 patients (59.7%) with 42 graft's occlusions were available for evaluation (14 arterial grafts and 28 venous grafts) (Fig. 4, 5). The frequency of graft occlusion in arterial graft group was: 50-60% stenosis - 3; 60-70% - 6; 70-80% - 2; 80-90% - 2; % -1, invenous graft group was: 50-60% - 6; 60-70% - 11; 70-80% - 5; 80-90% - 3; % - 3. The strong inverse correlation was found between the degree of native coronary artery stenosis and grafts occlusion (r = -0.8; p <0.05). Images for this section: Page 5 of 9

6 Fig. 3: CT bypass angiography. VRT-reconstruction, curved and orthogonal MPRreconstruction. 85% stenosis of the proximal segment of the left anterior descending artery (1). Arterial graft to the left anterior descending artery is functioning normally (2). Page 6 of 9

7 Fig. 4: CT bypass angiography. VRT-reconstruction, curved and orthogonal MPRreconstruction. Occlusion of saphenous vein graft to the posterior descending artery. The mark of the proximal graft anastomosis on the ascending aorta (1). The mark of the distal graft anastomosis on the posterior descending artery (2). 71% stenosis of the proximal segment of the right coronary artery. Page 7 of 9

8 Fig. 5: CT bypass angiography. VRT-reconstruction, curved and orthogonal MPRreconstruction. Occlusion of arterial graft to the left anterior descending artery (arrow). 60% stenosis of the proximal segment of the left anterior descending artery. Page 8 of 9

9 Conclusion CT bypass angiography allows to evaluate patency of the native coronary artery and bypass grafts and helps to identify the main causes of bypass graft occlusion. The risk of grafts occlusion increases with decreasing of the degree stenosis of proximal segments native coronary arteries. In the late postoperative period the competitive flow is one of the main predisposing factors for graft occlusion. References 1. Hata, M. Long-term patency rate for radial artery vs. saphenous vein grafts using same-patient materials / M. Hata, I. Yoshitake, S. Wakui // Circ. J Vol. 75, N 6. - P Kawamura, M. Patency rate of the internal thoracic artery to the left anterior descending artery bypass is reduced by competitive flow from the concomitant saphenous vein graft in the left coronary artery. / M. Kawamura, M. Buerke, Y.S. Lee [et al.] // Eur. J. Cardiothorac. Surg Vol. 34, N 4. - P Ko, Y.G. Assessment of coronary artery bypass graft patency by multislice computed tomography / Y.G. Ko, D.H. Choi, Y.S. Jang [et al.] // Yonsei. Med. J Vol. 44, N 3. - P Lau, G.T. Lumen loss in the first year in saphenous vein grafts is predominantly a result of negative remodeling of the whole vessel rather than a result of changes in wall thickness / G.T. Lau, P.G. Bannon, L.J. Ridley // Circulation Vol. 114, N 1. - P Sabik, J.F.I. Does competitive flow reduce internal thoracic artery graft patency? / J.F.I. Sabik, B.W. Lytle, E.H. Blackstone [et al.] // Ann. Thorac. Surg Vol. 76, N 5. - P Personal Information Page 9 of 9