The frequently observed de-endothelialization of venous coronary bypass grafts prepared using standard methods exposes subendothelial prothrombotic cells to blood components, thus endangering patients by inducing acute thromboembolic infarction or long-term proliferative stenosis. Our aim was to gain deeper histological and physiological insight into these relations. An intricate network of subendothelial cells, characterized by histological features specific for true pericytes, was detected even in healthy vessels and forms, coupled to the luminal endothelium, a second leaflet of the macrovascular intima. These cells, and particularly those in the venous intima, express enormous concentrations of tissue factor and can recruit additional amounts of up to the 25-fold concentration within 1 h during preincubation with serum (intimal pericytes of venous origin activate 30.71 ± 4.07 pmol coagulation factor x·min−1·10−6 cells; n = 15). Moreover, decoupled from the endothelium, they proliferate rapidly (generation time, 15 ± 2.1 h, n = 8). Central regions of atherosclerotic plaques, as well as of those of restenosed areas of coronary vein grafts, consist almost completely of these cells. In stark contrast with the prothrombogenicity of the intimal pericytes, intact luminal endothelium recruits high concentrations of thrombomodulin (CD 141) specifically within its intercellular junctions, activates Protein C rapidly (42 ± 5.1 pmol/min·106 venous endothelial cells at thrombin saturation; n = 15), can thus actively prevent coagulatory processes, and never expresses histologically detectable and functionally active tissue factor. Given this strongly prothrombotic potential of the intimal pericytes and their overshooting growth behavior in endothelium-denuded vascular regions, they may play important roles in the development of atherosclerosis, thrombosis, and saphenous vein graft disease.
CABG using both ITAs can be performed routinely with good clinical results and low mortality. Compared with single ITA grafting, sternal and bleeding complications were slightly increased. Diabetes mellitus, BITA grafting, duration of surgery but not obesity or COPD could be identified as independent risk factors for sternal complications. Dialysis-dependent renal failure, EF<30%, emergent cases, and the absence of BITA grafting were predictors for increased perioperative mortality.
The 30-day lethality was 1.6% in the BIMA group, 1.7% in the SIMA group in patients under 70, and 4.1% (BIMA) and 4.0% (SIMA) in patients over 70 (p = n.s.). A significantly higher blood loss was observed in the BIMA group (BIMA 979+/-708 ml, SIMA 790+/-575 ml, p<0.05). The rethoracotomy rate due to bleeding was significantly higher in patients with BIMA (4.1%) compared to those with SIMA (2.5%, p<0.05). In patients with a body mass index (BMI) of less than 27, no significant difference could be found (SIMA 2.8%, BIMA 3.4%, p = n. s.). Patients with a BMI >27 showed a significantly higher rethoracotomy rate (SIMA 2.2%, BIMA 4.9%). A higher incidence of sternal instabilities could be observed in the BIMA group (4.2%, p<0.05). Diabetes mellitus could not be identified as an independent risk factor for sternal complications (SIMA 2.9%, BIMA 5.0%, p = n. s.). COUCLUSION: CABG using both IMA's can be performed in nearly all patients as a routine method with good clinical results and low mortality. Bleeding in the BIMA group within 48 hours was increased. BMI >27 could be identified as a risk factor for sternal complications, but not diabetes mellitus or age over 70 years.
Regarding operative mortality, EuroSCORE II showed in this study a slightly higher discriminatory accuracy than EuroSCORE I. There were no significant differences in the calibration of the two model versions in "low-" and "moderate-risk" patients regarding early as well as mid-term mortality. Analyses in larger patient populations will contribute to further model improvement.
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