冠状动脉搭桥血流动力学数值模拟

目的深入研究缝合区附近的血流动力学特性,这对于了解内膜增生的发生机制以及提高冠状动脉搭桥畅通率有重要的指导与临床意义。方法通过运用三维重建软件和逆向工程软件从CT医学图像中重建出弯曲冠状动脉模型,并考虑移植管缝合到冠状动脉上时端口的变形。采用有限体积法数值研究的方法,模拟冠状动脉搭桥术中下游缝合区附近的血液流动的流场。结果临床上常出现内膜增生的位置都存在不正常的血流动力学现象,缝合前端和缝合后端都出现了严重的回流现象。结论在冠状动脉旁路移植术中,移值管远端应缝合到曲率较小的冠状动脉上。     

Numerical Simulation of Coronary Artery Bypass Graft with an Assistant Graft

The conventional bypass design is to implant a graft on the stenosed host artery allowing blood to flow bypass the stenotic artery. However, restenosis is a challenging problem which finally results in reoperation. The purpose of this paper is to propose a new bypass graft design of coronary artery with an assistant graft for the treatment of coronary artery stenosis. An additional assistant graft was employed in the new design compared with the conventional ETS anastomosis. Numerical simulations were performed by means of finite volume method using computational fluid dynamics （CFD） solver. Results demonstrated that the new anastomoses model provided a more smooth flow at the distal ETS anastomosis without any stagnation point on anastomotic bed and vortex formation in the heel region. Oscillatory shear index （OSI） and time-averaged wall shear stress gradient （TAWSSG） at the artery bed of the distal ETS anastomosis were reduced. The coronary artery bypass graft with an assistant graft is feasible to improve the local hemodynamics and diminish the probability of restenosis in the treatment of coronary artery stenosis.     

A Novel Coronary Artery Bypass Graft Design of Sequential Anastomoses

In this paper, the hemodynamics in a three-dimensional out-of-plane sequential bypass graft model is first investigated. Based on the advantageous flow characteristics observed within the side-to-side (STS) anastomosis in the sequential bypass graft simulation, a new CABG coupled-sequential anastomosis configuration is designed, entailing coupled STS and end-to-side (ETS) anastomotic components. In this new CABG design, the flow fields and distributions of various wall shear stress parameters within the STS and ETS anastomotic regions are studied, and compared to those of the conventional distal anastomosis, by means of computational fluid dynamics simulation of pulsatile Newtonian blood flow. Simulation results demonstrate that the new sequential anastomoses model provides: (i) a more uniform and smooth flow at the ETS anastomosis, without any stagnation point on the artery bed and vortex formation in the heel region of the ETS anastomosis within the coronary artery; (ii) a spare route for the blood flow to the coronary artery, to avoid re-operation in case of re-stenosis in either of the anastomoses; and (iii) improved distribution of hemodynamic parameters at the coronary artery bed and in the heel region of the ETS anastomosis, with more moderate shear stress indices. These advantages of the new design over the conventional ETS anastomosis are influenced by the occlusion ratio of the native coronary artery, and are most prominent when the proximal segment of the coronary artery is fully occluded. By varying the design parameters of the anastomotic angle and distance between the two anastomoses, the superior coupled STS–ETS anastomoses design is found to have the anastomotic angle of 30° and 30 mm distance between the two (STS and ETS) components.     

Patient-Specific Multiscale Modeling of Blood Flow for Coronary Artery Bypass Graft Surgery

We present a computational framework for multiscale modeling and simulation of blood flow in coronary artery bypass graft (CABG) patients. Using this framework, only CT and non-invasive clinical measurements are required without the need to assume pressure and/or flow waveforms in the coronaries and we can capture global circulatory dynamics. We demonstrate this methodology in a case study of a patient with multiple CABGs. A patient-specific model of the blood vessels is constructed from CT image data to include the aorta, aortic branch vessels (brachiocephalic artery and carotids), the coronary arteries and multiple bypass grafts. The rest of the circulatory system is modeled using a lumped parameter network (LPN) 0 dimensional (0D) system comprised of resistances, capacitors (compliance), inductors (inertance), elastance and diodes (valves) that are tuned to match patient-specific clinical data. A finite element solver is used to compute blood flow and pressure in the 3D (3 dimensional) model, and this solver is implicitly coupled to the 0D LPN code at all inlets and outlets. By systematically parameterizing the graft geometry, we evaluate the influence of graft shape on the local hemodynamics, and global circulatory dynamics. Virtual manipulation of graft geometry is automated using Bezier splines and control points along the pathlines. Using this framework, we quantify wall shear stress, wall shear stress gradients and oscillatory shear index for different surgical geometries. We also compare pressures, flow rates and ventricular pressure-volume loops pre- and post-bypass graft surgery. We observe that PV loops do not change significantly after CABG but that both coronary perfusion and local hemodynamic parameters near the anastomosis region change substantially. Implications for future patient-specific optimization of CABG are discussed.     

Human Saphenous Vein Coronary Artery Bypass Graft Morphology,Geometry and Hemodynamics

Coronary artery bypass graft (CABG) failure has been linked to graft hemodynamics, in particular wall shear stress. This study characterizes the morphology, geometry and wall shear stress patterns in human CABGs. The intimal thickness (IT) in 49 human saphenous vein CABGs was measured by digital light microscopy. The geometry of six saphenous vein CABGs was replicated by post-mortem infusion of Batsons #17 anatomical corrosion casting compound. Graft hemodynamics were evaluated in two flow models, fabricated from the casts, under steady (Re = 110) and pulsatile flow (Re = 110, = 2) conditions. Saphenous vein CABGs in situ for more than 2 months had, on average, the greatest IT on the hood and suture sites of the distal anastomosis. Floor thickening was highly variable and significantly less than IT at the hood, suture site and graft body. All casts showed an indentation along the floor and 5/6 casts displayed a sharp local curvature on the hood. In both flow models, a large increase in wall shear rate occurred on the hood, just proximal to the toe. The local geometry of the hood created this large spatial gradient in wall shear stress which is a likely factor in hood intimal hyperplasia.     

The Composite Aortic Wall Graft Technique: An Option for a Short Coronary Artery Bypass Graft

SUMMARY

During coronary artery bypass graft (CABG) surgery, the saphenous vein is sutured through its proximal segment to the aorta. Intimal hyperplasia is one of the possible causes of graft occlusion. Notably, blood turbulence can induce wall shear stress that may also play an important role in this process.

OBJECTIVE

We propose a new technique for performing proximal anastomosis to avoid CABG failure.

METHOD

An 80 kg pig was subjected to open heart surgery. Four stitches were placed in the anterior ascending aorta, which formed a 2 cm by 4 cm patch. This patch was isolated through the application of a tangential clamp that was oriented parallel to the axis of the aorta. After releasing the patch, which was held to the aorta through its cranial end pedicle, the rims were sutured to each other creating a conduit with a length of 4 cm and an internal diameter of 4 mm. The rest of the aortotomy was closed by placing a direct suture between its rims.

RESULT

This novel technique created an “in situ” aortic wall graft that was 4 cm long and characterized as being of uniform 4 mm caliber.     

Hemodynamics Simulation of Stenosed Coronary Bypass Graft

By means of FEM, the physiological blood flow in coronary bypass graft is simulated. The stenosis in coronary artery is involved in the graft model,and the deformation of graft end to allow the surgical suture with a smaller diameter coronary is taken into consideration. The flow pattern, secondary flow and wall shear stress in the vicinity of anastomosis are analyzed. It is shown that a zone of low wall stress and high wall stress gradient exists downstream the toe. The floor opposed to the anastomosis is an area of high wall stress and high wall stress gradient. Both the toe downstream and the anastomosis bottom floor are prone to intimal hyperplasia.     

冠状动脉搭桥体外循环湿备的技术改良

对冠状动脉搭桥术备体外循环的湿备模式进行改良,以达到即满足临床需要,又节省医疗资源的预期。采用储血器、微栓滤器、接头和管道连接并预充排气的湿备模式,术中根据需要再连接氧合器。232例冠状动脉搭桥术的患者,术中因血压偏低转为体外循环辅助下冠脉搭桥共7例,平均用时约2~3 min。此种改良湿备模式能更好地满足冠状动脉搭桥术备体外循环的需要,并可节约大量医疗资源。     

具有不同移植管-宿主动脉直径比的冠状动脉搭桥术的血流动力学仿真比较

为了说明移植管-宿主动脉直径比对冠状动脉搭桥术的流场及壁面切应力的影响，构造了三个具有不同移植管-宿主动脉直径比的冠状动脉搭桥术模型，三个模型的移植管直径分别小于、等于和大于宿主动脉的直径；利用有限单元数值模拟方法对三个模型中的生理性脉动血流进行了仿真分析；对流场、壁面切应力及其相关系数的时空分布进行了显示和比较。结果表明，大直径比的模型具有相对较大的纵向速度、大而均匀的壁面切应力以及小的壁面切应力梯度，从而在一定程度上改善了血流动力学；在搭桥术应用中采用大于或等于1的直径比是可取的。然而，在三个模型中，与壁面切应力相关的时间参数并没有显著差别。为了提高冠状动脉搭桥术的畅通率，设计新的缝合结构是很有必要的。     

Psychological Risk Factors for Increased Post-Operative Length of Hospital Stay Following Coronary Artery Bypass Graft Surgery

To date, researchers have examined the role of psychological factors in longer-term adaptation to coronary artery bypass graft surgery (CABG), but few have investigated the role of such factors in the immediate post-operative period. Thus, the current study examined psychological risk factors for increased post-operative length of hospital stay in 119 consecutive elective CABG patients (100 men and 19 women). When controlling for operative/post-operative factors, medical factors accounted for 24.5% of the variance. However, pre-operative psychological factors accounted for a further 4.4% of the variance, with increased depression and lower PTSD symptomatology identified as significant independent risk factors for longer post-operative length of hospital stay. Hence, while post-operative length of hospital stay is largely determined by medical factors, psychological factors also influence this outcome. Further research is required to replicate the current findings and to determine the mechanisms through which these variables may act.     

冠脉搭桥手术后患者不适症状与焦虑抑郁关系的研究

目的：研究冠状动脉旁路移植手术后患者不适症状与心理状态的关系。方法：采用问卷调查的方法（症状调查表，焦虑自评量表及抑郁自评量表对65例接受了冠状动脉旁路移植手术的患者进行调查。结果：不适症状量表总得分与心理状态SAS及SDS量表总标准分呈正相关。症状调查表分数越高，则心理问题越严重。结论：对CABG术后患者采取健康宣教、心理辅导甚至适当的使用药物能减轻患者的不适症状。     

右冠状动脉起源于左冠状窦的血流动力学分析

目的通过计算流体动力学(computational fluid dynamics,CFD)分析右冠状动脉起源于左冠状窦(anomalous origin of the right coronary artery from the left coronary artery sinus,AORL)的血流动力学参数,从而有效评估疾病。方法选取正常右冠状动脉(right coronary artery,RCA)和AORL两例个体病例,在Mimics软件中重建两个病例的血管模型,并将模型导入ANSYS CFX软件中进行血流动力学模拟计算,比较正常和AORL两种模型的血流动力学情况。结果 AORL模型右冠状动脉入口截面具有较小的血流量(9. 35 cm~3/s),有可能会导致右冠状动脉下游供血不足; AORL模型右冠状动脉急性拐角处的压力(13. 78 kPa)相比于正常模型右冠状动脉(14. 9 kPa)较低; AORL模型壁面剪切力(12. 83 Pa)大于正常模型(9. 74 Pa); AORL模型血管壁变形量较大。结论 AORL入口流速及拐角处压力均比正常RCA小,从而可能导致缺血症状发生。研究结果对临床上有效评估缺血等疾病具有理论指导意义。     

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。     

Native Coronary Artery and Grafted Artery Spasm Just after Coronary Artery Bypass Grafting: A Case Report

Native coronary artery spasm after coronary artery bypass grafting (CABG) is scarce. It frequently causes disastrous circulatory collapse. We report a 72-yr-old male, who experienced native coronary artery spasm and grafted artery spasm following CABG, which was successfully treated with coronary angiography and intracoronary injection of nitroglycerine.     

冠状动脉旁路移植围手术期抑郁、焦虑状况调查

目的调查行冠状动脉旁路移植术(CABG)的患者围术期抑郁、焦虑的发生率及相关因素.方法2005年7月至2006年5月,以连续行择期CABG术的73例患者为研究对象,分别在术前1周内和术后出院前1天使用ZUNG氏抑郁自评量表和焦虑自评量表进行评分.结果手术前共有21例(28.8%)阳性患者,其中11例患者存在抑郁状态,7例患者同时存在抑郁和焦虑状态,3例存在焦虑状态.手术后共有34例(46.6%)阳性患者,其中18例患者存在抑郁状态,13例患者同时存在抑郁和焦虑状态,3例存在焦虑状态.SDS标准分术后(47.9±10.0)高于术前(43.7±10.0, t=3.55,P=0.001), 焦虑评分术后(41.6±8.5)高于术前(39.3±7.4, t=2.20,P=0.031).术前发生抑郁焦虑的患者受教育少(8±3/10±3年, t=2.18,P=0.032),术后焦虑抑郁组中术前就存在抑郁焦虑的比例高(16/34对5/39,χ2＝10.391, P=0.001),术前多次心肌梗死的4例都在术后抑郁焦虑组(4/34比0/39,P=0.043);术前抑郁焦虑情绪对术后围手术期恢复没有影响.术后是否发生抑郁焦虑者住院时间没有显著差别.结论CABG患者围术期抑郁焦虑状态有较高的发生率,术后情绪更差.受教育程度低是术前情绪不良的危险因素,病情重是术后情绪不良的危险因素.     

桡动脉在冠状动脉旁路术中的应用解剖学研究

目的：为应用桡动脉作冠状动脉旁路术(coronary artery bypass grafting，CABG)的动脉桥提供解剖学依据。方法：观测了35具成人尸体的两侧桡动脉长度、外径、毗邻结构和可用于CABG的长度和外径。结果：桡动脉总长度为20．87cm，可用于CABG的长度为19．99cm；桡动脉上端外径为3．18mm，可用于CABG的桡动脉上端、中点、下端外径分别是2．66mm、2．28mm、2．29mm。结论：桡动脉有足够的长度和与冠状动脉相匹配的外径，可作为CABG的动脉桥。     

以桡动脉为移植体行冠状动脉旁路术的局解手术学研究

本文对104侧上肢桡动脉第一段和63例成人离体心脏之冠状动脉及其主要分支,根据临床应用进行了观测。结果:桡动脉长度为22.10±1.2cm;外径(下同):上端为3.00±0.6mm,下端为2.60±0.6mm。后降支(房室交点下1cm处)为2.41±0.4mm,左右心耳与肺劝脉交角下1cm处的前降支为3.83±0.6mm,右冠状动脉主干为3.79±0.7m。距离:自主动脉前窦上2cm至前降支中点的长度为6.61±0.5cm,经右冠状沟至房室交点的长度为11.80±1.5cm。测量数据提示:以桡动脉为移植体足以吻接任何冠状动脉。本文尚阐述和讨论了该术式的局解手术学基础和操作程序,对冠状动脉旁路术(CABO)中常用的几种移植体之利弊进行了评     

Symptoms of Traumatic Stress after Coronary Artery Bypass Grafting

Background: Traumatic stress symptoms have only recently been studied in association with medical treatment procedures. Purpose: The study examined associations of physical and psychological functioning during hospitalization to symptoms of traumatic stress after cardiac surgery. Methods: One hundred thirteen patients admitted for coronary artery bypass grafting participated in the study. Symptoms of traumatic stress were assessed one and six months after surgery, with the Impact of Event Scale. Preoperative stress and ruminative thinking, length of preoperative waiting, duration of surgery, and postoperative recovery indices (length of stay in the intensive care unit, cognitive functioning during intensive care, length of stay in the hospital) were examined. Results: Ten percent of the patients reported severe (> 19) symptoms of avoidance, and five percent reported severe symptoms of intrusion in both follow-ups. Hierarchical regression analyses showed that preoperative stress was positively associated to avoidance symptoms in both follow-ups (p < .01). Preoperative stress and ruminative thinking was positively associated to intrusion symptoms one month after surgery (p < .01). Disease related factors were not related to symptoms of traumatic stress during the postoperative period. Conclusion: This study highlights the role of preoperative surgery-related stress as a risk factor for traumatic stress in the postoperative period.     

冠状动脉搭桥术后谵妄的研究现状

冠状动脉搭桥手术越来越普遍,术后谵妄成为影响冠状动脉搭桥手术预后的一大难题。术后谵妄不仅影响患者心肺功能恢复,延长术后ICU滞留时间及住院时间,增加医疗负担,并且与术后并发症发生率及死亡率的增加密切相关。本文从谵妄的定义、易感因素、发病机制、术后评估、治疗几个方面做一综述,旨在总结以往研究经验,发掘围手术期实际有效的干预措施,提高临床医生对冠状动脉搭桥术后谵妄的认识和管理水平。