Intimal hyperplasia and hemodynamic factors in arterial bypass and arteriovenous grafts: a review

Stenosis at the graft–vein junction caused by intimal hyperplasia (IH) is the major cause of failure of vascular access grafts used for hemodialysis. There is a strong relationship between hemodynamic factors and formation of IH. The hemodynamic pattern and the location of IH are different in arterial bypass grafts (ABGs) compared with arteriovenous grafts (AVGs). In an ABG, end-to-side anastomosis of the expanded polytetrafluoroethylene graft and artery produces hemodynamic changes around the junction. IH develops at the arterial floor and the toe and heel of the distal anastomosis. Low shear stress and oscillating shear forces at the arterial floor and the heel plus a high wall sheer stress (WSS) gradient at the toe probably promote IH development. Compliance mismatch between the graft and artery causes turbulence that may contribute to IH formation. The blood flow rate in AVGs is 5–10 times greater than that in ABGs. High flow causes turbulence that injures endothelial cells and eventually results in IH. The peak WSS in AVGs is about 6N/m², much higher than that in ABGs. Excessively high WSS may effect IH formation in AVGs. Several venous cuff or patch anastomotic designs have been used in attempts to regulate hemodynamic factors in grafts. In ABGs, these designs appear to help decrease IH formation. In AVGs, however, they generally have not improved patency rates. In a high-flow system such as an AVG, more drastic changes in anastomotic design may be required.     

血液回收对非体外循环冠状动脉旁路移植患者红细胞和血液粘度的影响

目的观察血液回收技术对非体外循环冠状动脉旁路移植患者红细胞、血小板和血液粘度的影响。方法2005年8月~2007年10月间,共完成46例非体外循环冠状动脉旁路移植术,随机分为实验组(血液回收组)和对照组(不使用血液回收机组),每组23例。观察两组用血液制品的数量和术后24h的引流量,比较两组术前和术后24h的红细胞计数、血红蛋白、红细胞压积、血小板计数、低切全血粘度和高切全血粘度。结果实验组用浓缩红细胞和血浆的量明显少于对照组,两组术后24h引流量、术前和术后24h的红细胞计数、血红蛋白、红细胞压积、血小板计数、低切全血粘度和高切全血粘度之间的差异无显著性意义。结论血液回收技术在非体外循环冠状动脉旁路移植患者中能减少输血,对红细胞、血小板和血液粘度无不利影响。     

Morphological inspection of 80 consecutive Gyro pumps after cardiopulmonary bypass

 We have been using the Gyro centrifugal pump C1E3 for cardiopulmonary bypass in anticipation of high efficiency, low hemolysis, and antithrombogenicity of this pump. However, the clinical evaluation of this pump remains to be clarified, because it has been a short time since the pump appeared in clinical situations. The aim of the present study is to inspect and analyze the Gyro pumps morphologically after clinical use. We examined 80 consecutive pumps after cardiopulmonary bypass for 186 ± 67 min with a mean flow rate of 2.52 ± 0.22 l/min/m² at a mean rotational speed of 2485 ± 81.1 rpm. Although no abnormal findings were present in 79 pumps, one pump was found to contain effusion at the connection between the impeller body and the shaft. The extudate was supposed to be blood, based upon the results of X-ray spectrometer analysis. The cause was determined to be the upward deviation of the shaft off the impeller body. Scanning electron microscopy showed scratches on a part of the bottom housing and a smooth surface of both the male and female pivots of the pump. Surface profile measurement revealed that the deformity of the female pivots was 0.14 mm (top) and 0.05 mm (bottom). These observations suggest that the floating force and vibration by the rotating impeller acted on the joint zone between the alumina ceramic shaft and the polycarbonate impeller body, resulting in dissection of the adhesive agent from the polycarbonate. Although this abnormality may be rare, the structural design still may need to be improved. Received: November 9, 2001 / Accepted: February 4, 2002     

非体外循环冠状动脉搭桥术临床分析——附21例报告

目的评价非体外循环心脏不停跳冠状动脉搭桥术的临床价值及意义。方法回顾分析21例非体外循环冠状动脉搭桥术的临床资料,对手术方法及围手术期治疗进行分析总结。结果全组无术中需转体外循环,无围手术期急性心肌梗死,无死亡病例。术后心绞痛全部缓解,住院天数12~21d,平均14.53d。结论非体外循环冠状动脉搭桥术安全可行,且可减少输血,减轻手术创伤与并发症。远期效果有待观察。     

常规与微创冠脉搭桥术围手术期血浆S100-B蛋白水平的相关研究

目的: 通过测定体外循环和非体外循环条件下冠脉搭桥术患者血浆S100-B蛋白水平的变化，比较2种手术方式对脑损伤程度有无不同，探讨术中影响血浆S100-B蛋白水平变化的相关因素。方法: 30例择期行冠脉搭桥术的患者，分为体外循环组（CPB group，A组）和微创非体外循环组（non-CPB group，B组）,每组均为15例。于术前、麻醉后、主动脉侧壁钳开放时、术毕时、术后2 h、6 h、12 h和24 h采血测血浆S100-B蛋白浓度。结果： （1） 两组患者血浆S100-B蛋白浓度均在升主动脉侧壁钳开放时显著高于术前，且A组患者血浆S100-B蛋白浓度峰值是B组的3倍多（2.32±0.26 μg/L和0.71±0.14 μg/L）,之后逐渐降低，到术后24 h基本接近正常。（2） 术中患者血浆S100-B蛋白升高水平与体外循环转机时间或心表手术操作时间呈正相关（A组：r＝0.659，P＜0.05;B组：r＝0.584, P＜0.05）。结论： 血浆S100-B蛋白水平可以用来评价2种冠脉搭桥术对脑的损伤程度，术后连续检测对于诊断脑损伤并及时采取相应预防措施具有重要价值;非体外循环微创冠脉搭桥术较常规体外循环下手术更能够有效降低对脑损伤的程度和术后出现神经功能障碍的风险。     

Regional left ventricular function in the three main coronary artery territories at rest and during exercise

Summary Twenty consecutive patients (mean age 51.6 years) with persistent severe angina pectoris underwent aorto-coronary bypass surgery receiving an overall of 60 anastomosis. On an average, 9.4±1.5 months p.o. first pass radionuclide ventriculograms (18 to 24 mCi 99 m Technetium-Pertechnetate i.v.) were performed at rest and after excerise. Besides measurement of global ejection fraction (GEF), regional ejection fraction (REF) was assessed employing for the first time a new technique: each RAO-view of p.o. radionuclide left ventriculogram was subdivided into three regions according to supply of the three main coronary arteries and their branches as visualized on pre-operative coronary angiogram.GEF improved after maximum exercise in 13 cases by 8.1% points (from 50.4 to 58.5%), remained unchanged three times and decreased four times by 7.1 points (from 51.6 to 44.5%; all changesp<0.05).In completely revascularized regions (n=35) REF improved 24 times by 9.7 points (from 51.1 to 60.8%), did not differ from rest REF six times and decreased in three case by 7.3 points (from 48.6 to 41.3%; all changesp<0.05). Completely revascularized regions responded to exercise like normally perfused areas (increase 7.8 points (from 50.6 to 58.4%;n=7;p<0.05).REF deteriorated in incompletely revascularized regions (n=9) six times by 12.8 points (from 58.0 to 45.2%), remained unchanged twice and improved once by 4.5 points. Total group's REF decreased by 7.3 points (from 56.8 to 49.5%;p<0.05). Exercise REF of incompletely revascularized regions was highly significant inferior to that of completely revascularized regions (49.5 to 58.4%;p<0.01).GEF is a weighted balance of the three regional ejection fractions. The most important parameter is REF of LAD territory.     

Inhibition of heparin/protamine complex-induced complement activation by Compstatin in baboons

Complement activation products are major components of the inflammatory response induced by cardiac surgery and cardiopulmonary bypass which contribute to postoperative organ dysfunction, fluid accumulation, and morbidity. Activation of the complement system occurs during extracorporeal circulation, during reperfusion of ischemic tissue, and after the formation of heparin-protamine complexes. In this study we examine the efficacy of Compstatin, a recently discovered peptide inhibitor of complement, in preventing heparin/protamine-induced complement activation in baboons. The study was performed in baboons because Compstatin binds to baboon C3 and is resistant to proteolytic cleavage in baboon blood (similar to humans); Compstatin inhibits only the activation of primates' complement system. After testing various doses and administration regimens, Compstatin produced complete inhibition at a total dose of 21 mg/kg when given as a combination of bolus injection and infusion. Compstatin completely inhibited in vivo heparin/protamine-induced complement activation without adverse effects on heart rate or systemic arterial, central venous, and pulmonary arterial pressures. This study indicates that Compstatin is a safe and effective complement inhibitor that has the potential to prevent complement activation during and after clinical cardiac surgery. Furthermore, Compstatin can serve as the prototype for designing an orally administrated drug.     

深低温体外循环对犬趾蹼微循环指标的研究

本研究表明,深低温体外循环时,犬趾蹼微循环发生的变化与温度有关。平均动脉压(MAP)的变化不能反映组织灌注的优劣情况。毛细血管内的血流速度与灌注流量的高低有关。     

人TFPI基因转染对兔移植静脉血栓形成和近期通畅率的影响

目的： 为减少冠状动脉旁路移植术后血栓形成，探讨人组织因子途径抑制因子(TFPI)基因转染对兔移植静脉血栓生成的影响。方法：构建真核表达质粒pCMV-(Kozak)TFPI。采用阳离子脂质体和腔内加压灌注法，转染移植静脉内皮细胞。RT-PCR、Western blotting和免疫组化法检测外源基因在兔移植静脉中的表达。病理标本、扫描电镜观察移植静脉血栓形成情况，血管多普勒观测其通畅率。结果：移植静脉中有人TFPI基因和蛋白表达。静脉移植术后3 d，基因转染组、空载体和空白对照组分别有1条、8条和7条移植静脉发生血栓，术后30 d，以上各组分别有0条、5条和5条移植静脉完全闭塞，前者静脉血栓发生率和闭塞率均低于后两者(P<0.05)。扫描电镜显示两对照组内皮表面有红细胞和血小板黏附、聚集，而转染组基本正常。结论：人TFPI基因干预，减少了兔移植静脉血栓形成，提高了近期通畅率。     

Serum levels of IL-1, IL-6 and tumour necrosis factors in patients undergoing coronary artery bypass grafts or cholecystectomy.

Plasma levels of biologically active IL-1, tumour necrosis factor (TNF) and IL-6 were measured before, during and after coronary artery bypass graftings (CABG) (n = 9) and cholecystectomy (CHO, n = 9), and in normal controls (nine healthy volunteers). Mean pre-operative IL-1 concentration in four of the nine CABG patients was 0.452 + 0.03 ng/ml, significantly (P less than 0.001) higher than that of the other five (0.045 +/- 0.009 ng/ml), CHO patients (0.035 +/- 0.005 ng/ml) and controls (0.029 +/- 0.008 ng/ml). Three of the four patients with high pre-operative IL-1 had functional capacity IV, while the other five had functional capacity IIa or IIb. Slight IL-1 elevation after anaesthesia, followed by reduction after initiation of bypass, elevation on completion of surgery and reduction to basal levels after 7 days was found in patients undergoing CABG. Mean basal TNF levels of CABG and CHO patients did not differ, but were higher than those of controls (2.85 +/- 0.5 ng/ml for CABG, 2.05 +/- 0.06 ng/ml for CHO, 0.72 +/- 0.07 ng/ml for normals, P less than 0.001). A unique kinetics of release during CABG was observed also for TNF. Mean pre-operative IL-6 levels were normal (50 +/- 3 ng/ml for CABG, 50 +/- 0.5 ng/ml for CHO and 65 +/- 10 ng/ml for controls). Gradual elevation to a mean peak of 725 +/- 100 ng/ml on completion of CABG was observed as compared with 275 +/- 50 ng/ml in CHO (P less than 0.01). On the seventh post-operative day mean IL-6 levels returned to normal. Two patients with post-operative low-grade fever (38 degrees C) had high, late cytokine levels. One of these two patients had leucocytosis, sterile discharge from the operative wound and was diagnosed as suffering from the Dressler syndrome. In this study elevated cytokine values and unique kinetics of release into the serum were found in patients undergoing CABG.