Two case reports of the right-sided aortic arch

Two cases of right aortic arch with the left subclavian artery as its last branch were found in cadavers of 66- and 80-year-old Japanese males during the 1995 and 1996 dissection for students at Tokyo Dental College. In both cases, the esophagus and trachea were surrounded by a vascular ring which consisted of the aortic arch and arterial ligament. The left common carotid artery arose from the ascending aorta as the first branch and crossed ventral to the trachea in a left cephalic direction. In The second branch of the aorta, which was the right common carotid artery, the aortic arch ran in a dorsal direction, passing between the esophagus and vertebra after branch out the right subclavian artery. The left subclavian artery arose dorsal to the esophagus, and there was an aortic diverticulum between the left subclavian artery and the descending aorta. The arterial ligament communicated between the left pulmonary artery and the arterial diverticulum. The trachea and esophagus were consequently encircled by the vascular ring. Both of the present cases were of the N-type, according to the classification by Adachi-Williams-Nakagawa (Group IIIB1 type by Stewart, 1964).     

基于CT图像胸主动脉夹层与正常胸主动脉内血流动力学模拟对比分析

目的通过对基于CT图像的血流动力学数值模拟获得的患有降主动脉夹层与正常胸主动脉内的血流动力学参数的比较,分析主动脉夹层内血液流动状态与动脉夹层疾病的关系,为阐明主动脉夹层疾病的发病机制提供理论依据。方法患者A为46岁男性,胸主动脉正常;患者B为33岁女性,患有通腔型降主动脉夹层,即通腔形式的DeBakeyⅢ型主动脉夹层。CT图像为DICOM格式,层间距为0.5mm,每片图像的平面分辨率为512×512,像素大小为0.5mm。应用医学图像后处理软件对通过临床获得的CT二维医学图像数据进行处理重构,得到正常和患有降主动脉夹层的胸主动脉三维立体模型并转化为可用于模拟计算的计算机辅助设计（CAD）模型。应用计算流体力学（CFD）软件模拟胸主动脉内血流情况,获得相关血流动力学参数。结果计算出胸主动脉在心动周期内不同时刻的血流动力学参数。结论在心动周期内患有动脉夹层胸主动脉内血流情况较正常胸主动脉内血流情况更为复杂,表现为管壁压力变化较大、夹层开口处出现多个漩涡等现象,表明主动脉夹层内复杂血流情况与主动脉夹层疾病的发病机制存在一定的关系。     

基于ABAQUS的升主动脉置换术术后血流数值模拟

目的:为研究人工升主动脉置换术治疗Stanford A型主动脉夹层后的血流动力学规律,采集临床CT图像,构建术后个性化主动脉流场几何模型。基于计算流体动力学对其进行数值模拟,得到术后流域壁面压力分布和流速分布两个力学指标,从而分析术后流域规律。方法:采集术后CT图像DICOM文件并应用影像后处理软件MIMICS进行三维重构及优化获得几何模型,再将该流域模型导入网格划分软件进行CFD网格划分,最后将网格文件导入ABAQUS/CFD模块进行多周期瞬态模拟。结果:通过模拟计算,得到术后主动脉在心动周期不同时刻的血流动力学参数。结论:血流动力学参数与边界条件密切相关。主动脉内复杂流场环境与心血管疾病存在一定联系。数值模拟可为人工血管置换术后病情发展提供参考。     

基于计算流体力学的Stanford B型主动脉夹层血流动力学分析

目的通过计算流体力学(computational fluid dynamics, CFD)分析Stanford B型夹层的血流动力学参数,从而有效全面评估疾病。方法基于1例复杂的Stanford B型主动脉夹层患者的增强CTA影像,构建三维模型和血流动力学的数值模拟研究,分析流场速度分布、夹层破口剖面速度分布以及壁面切应力。结果该病例在夹层入口、出口处的血液流速分别最高达到1.2、2 m/s,为进一步预测夹层破裂位置和评估夹层破裂风险提供依据。在夹层破口附近的假腔壁面形成明显的低壁面切应力区,与患者体内血栓位置相一致。结论 CFD能有效分析复杂主动脉夹层的血流动力学特征,获得主动脉弓部及其降主动脉的剪切力与主动脉夹层发生的相关性,有助于指导临床对主动脉进行功能学评估,进而预防疾病发生。     

猪动脉及心脏瓣膜内皮细胞的形态学特征

目的 探讨猪大、中动脉及心脏瓣膜内皮细胞的形态学特征,为血管的临床和实验研究积累资料。方法 动物在生理压下先后灌注肝素生理盐水和中性福尔马林溶液,取出升主动脉、主动脉弓,主动脉降部等大动脉和主动脉瓣;颈总动脉、胸廓内动脉、冠状动脉及其前后降支
等中动脉。标本按照电子显微镜常规处理,扫描电子显微镜下观察其内皮细胞的形态学特征。结果 在大、中动脉的直部,内皮细胞呈梭形,核区微隆起,其长轴与血流方向一致。在大动脉弯曲部和主动脉瓣,内皮细胞呈卵圆形,有丰富的微绒毛。在冠状动脉观察到多个白细胞黏附在
内皮表面。在右冠状动脉的后室间支,观察到一处细胞正处在更新状态。在胸廓内动脉、颈总动脉和冠状动脉观察到黏附在内皮表面且具有长突起的细胞,其胞体呈圆形、卵圆形、三角形等,突起数量2~6个不等。有的突起有分叉。结论 内皮细胞的形态、排列、微绒毛的长度、密度
和数量等随部位的不同而有差异,切应力可能是造成这些差异的重要因素之一。     

A schematic diagram showing the various components of the embryonic aortic arch complex in the retroesophageal right subclavian artery

A retroesophageal right subclavian artery, arising from the arch of the aorta as the terminal branch and passing dorsal to the esophagus, was found in five (1.2%) of 428 bodies donated for student dissection at Kumamoto University between 1993 and 2008. The presence of a retroesophageal right subclavian artery has been generally explained to be caused by the persistence of the normally eliminated part of the right dorsal aorta caudal to the seventh intersegmental artery and the disappearance of the normally patent right fourth aortic arch and the part of the right dorsal aorta cranial to the seventh intersegmental artery during the developmental process. However, the parts which remain or disappear are different in each case. With the aim of determining the portions eliminated or persisting and thereby gaining an understanding of the developmental process of the retroesophageal right subclavian artery in each instance, we made schematic diagrams showing the various components of the embryonic aortic arch complex as the prototype just before the anomaly occurred. Based on these diagrams, we conclude that immediately preceding the disappearance of the distal part of the right dorsal aorta and the dorsal part of the right sixth aortic arch, the third intersegmental artery was situated opposite to the fourth aortic arch and the seventh intersegmental artery was situated cranial to the point of junction of the right and left dorsal aortae.     

Extraordinary branching pattern of the aortic arch

A CT‐scan of a 75‐year‐old patient showed an aneurysm of the descending aorta with a maximum diameter of 4.8 cm involving the left subclavian artery. Due to the fact that the patient had several comorbidities including a severe chronic obstructive pulmonary disease he was treated only conservatively. However, there were several interesting findings on the CT‐scan: the branching pattern of the aortic arch revealed a left carotid artery arising as first side branch of the distal part of the ascending aorta. This vessel crosses the midline right in front of the trachea. Apart from that the patient did not have a brachiocephalic trunk: the right carotid artery arose as the first branch from the aortic arch and crossed the right subclavian artery anteriorly. Furthermore, the left subclavian seemed to arise from the descending aorta and not from the aortic arch. Clin. Anat. 26:1006–1007, 2013. © 2013 Wiley Periodicals, Inc.     

The Effect of Celiac and Renal Artery Outflows on Near-Wall Velocities in the Porcine Iliac Arteries

The effects of the outflow of aortic blood through the celiac and renal arteries on the flow field in the external iliac arteries were studied under steady and physiologically realistic pulsatile flow conditions. Laser Doppler velocimetry (LDV) measurements were made close to the medial, lateral, ventral, and dorsal walls of the external iliac branches of a clear, flow-through replica of a porcine aorta and its daughter vessels. The outflow from each branch of the replica was controlled so that the infrarenal aortic flow rate and the flow partition at the aortic trifurcation were the same for all experiments. LDV measurements were made with flow exiting through both the renal and celiac artery ostia, only the celiac ostium, and neither ostium. The steady flow results indicate that while the outflow through the renal arteries did not have a significant effect on near wall shear rate in the external iliac arteries, the flow through the celiac artery did. However, in pulsatile flow, three indices of near wall velocity in the iliac arteries were unaffected by celiac artery outflow, while a fourth showed a small effect that can be attributed to differences in minimum velocity. These results indicate that reliable simulations of blood flow in the external iliac arteries can be carried out without including the renal and celiac vessels, provided that the correct infrarenal flow wave is used. They also demonstrate that the flow field downstream of a region, such as a branch, that strongly alters the flow, can be nearly independent of the velocity field entering the region. © 2000 Biomedical Engineering Society. PAC00: 8719Uv, 8719Xx     

Time dependent non-Newtonian numerical study of the flow field in a realistic model of aortic arch

A three-dimensional time dependent numerical simulation was performed in a geometric model of aortic arch complete with a realistic aortic root and major branches originating from the arch, for a peak Reynolds number set at 2200 and Womersley number set at 20.4. The computational fluid dynamic analysis was aimed to provide spatial and temporal distribution of the shear stress all along the entire model together with the velocity patterns, related both to the non planar geometry of the aortic system here considered and to the pulsatility imposed on the numerical model to simulate physiologic conditions. A non-Newtonian evolving fluid was considered to account for the actual rheological nature of blood; a comparison on the incidence of wall shear stress, implementing a Newtonian fluid, was also made as reference. The spatial shear stress pattern, within the cardiac cycle, was shown to have higher values in correspondence to the inner wall of the aortic arch and the sites where the major vessels originated from the arch itself. The velocity patterns, on transversal sections of the aorta, resulted in highly skewed morphology. The resulting complex fluid dynamics, established in the aortic arch and in its branches, can be related to the possible endothelium response to mechanical stimuli, induced by wall shear stress, in the promotion of inflammatory events.     

Cardiovascular ochronosis

A 64-year-old man with alkaptonuric ochronosis required aortic valve replacement for severe aortic stenosis and single-vessel aortocoronary artery bypass grafting for a subtotally occluded obtuse marginal branch of the circumflex coronary artery. Operative findings included ochronosis of a partly calcified aortic valve and the aortic intima. The aortic valve and a punch biopsy specimen of the ascending aorta were removed at surgery and were studied with transmission electron microscopy and light microscopy. The ultrastructural studies of the aortic valve revealed intracellular and extracellular deposits of ochronotic pigment. A portion of the extracellular ochronotic pigment represented degenerated cells. Large deposits of extracellular ochronotic pigment were associated with areas of valvular calcification. Electron microscopic study of the aorta disclosed ochronotic pigment in macrophages and smooth-muscle cells. Aggregates of extracellular ochronotic pigment in the intima and media appeared to be in locations of necrotic cells. Light microscopy also showed intracellular and extracellular deposits of ochronotic pigment. Our study suggests that extensive extracellular deposits of ochronotic pigment in the aortic valve may serve as a stimulus for dystrophic calcification. This may play a role in the development of aortic valve calcification and aortic stenosis associated with alkaptonuric ochronosis. To our knowledge, this is the first ultrastructural study of the aortic valve and aorta in alkaptonuric ochronosis.