Revascularização cirúrgica do miocárdio com enxerto composto de artérias torácica interna esquerda e radial: comparação do fluxo sangüíneo para artéria coronária esquerda com a técnica convencional

Abstract

Background: Composite grafting techniques for coronary artery bypass grafts (CABG) have been widely used. However, it remains unclear whether this technique provides similar blood flow to the left coronary artery when compared to the conventional alternative. We sought to compare the total blood flow to the left coronary branches that are revascularized with left internal thoracic (LITA) and radial artery (RA) grafts using composite and non-composite techniques.Method: A total of 42 patients were randomly assigned to three groups according to the CABG technique to be used: Group A or composite LITA-RA in a Y format (n=14); Group B or modified composite LITA-RA intercoronary graft with RA and LITA to RA at the left anterior descending artery (LADn=14)]; and Group C or pedicled LITA to the LAD and aortocoronary RA (n=14). The patients were submitted to postoperative blood flow velocity analysis using a 0.014 inch 12 MHz Doppler flowire. Coronary flow reserve (CFR) was calculated by determining the average hyperemic peak velocity (APV) after an injection of adenosine.Results: Proximal LITA baseline APV was 28.4 ± 4.8 cm/s in group A, 34.4 ± 7.9 cm/s in group B (p=0.0384 x C) and 25.8 ± 8.6 cm/s in group C. The CFR was 2.1 ± 0.4, 2.0 ± 0.3 and 2.0 ± 0.4 in groups A, B and C respectively (p=0.7208 A, B x C). The total Q to LCA branches was 110 ± 30 in group A, 145 ± 59 in B and 133 ± 58 mL/min in C (p=0.3232 A, B x C).Conclusions: The LITA-RA composite graft maintains an adequate CFR and conveys similar blood flow to the left coronary artery branches when compared with conventional CABG technique. The utilization of two internal thoracic arteries has given benefits [2], but this can be associated with a greater morbidity in obese and diabetic patients [3].The radial artery (RA), in spite of its easy dissection and handling, initially demonstrated unfavorable results as evidenced by cineangiography. However, with modifications in the surgical dissection technique, in the preparation and handling of the graft, the RA was safely reintroduced for the treatment of coronary artery disease [4]. This graft now gives good results over the long term [5][6][7].With experience, it seemed evident that the different sizes between the wall of the RA and the wall of the ascending aorta could compromise the proximal anastomosis of the graft.Based on works of anastomosis of the right internal thoracic artery (RITA) in the LITA [8][9][10], some surgeons started to anastomose the RA proximally to the left internal thoracic artery, to revascularize the branches of the left coronary artery (LC) [11] giving the same results in the postoperative period when compared to the RITA under the same conditions [12,13] or the RA anastomosed proximally to the aorta [7].In composite arterial grafts, all the blood flow (Q) distributed to the revascularized arteries is from the LITA. This can lead to the question about if the blood flow available from the LITA is enough to irrigate the myocardium or, if in the composite arterial grafting techni...