腔内血栓降低大鼠腹主动脉瘤壁残余应力对瘤壁保护作用的评价

目的：用测量张开角的方法研究大鼠单纯腹主动脉瘤（AAA）和腔内血栓AAA模型的应力分布，对比两种模型瘤壁的顺就生，评估腔内血栓对瘤壁的保护作用。方法：用猪弹力蛋白酶灌注Wistar大鼠腹主动脉建立梭形肾下AAA模型，相似的方法并机械破坏内腹建立腔内血栓AAA模型，测量并对比单纯AAA和腔内血栓AAA动脉环的蠕变速度，残余应力，对比两组AAA同一瘤体不同部位的残余应力，动脉环内径和瘤壁厚度。结果：单纯AAA模型建立的成功率90%，腔内血栓AAA模型建立的成功率为60%，单纯AAA动脉环蠕变速度较腔内血栓AAA慢，单纯AAA入口和出口的残余应力值最大，内径和瘤壁厚度最小；腔内血栓AAA的残余应力分布规律相似，但总体残余应力较低。结论：残余应力量化反映AAA瘤壁的顺应性，腔内血栓AAA较单纯AAA的顺应性大；单纯AAA和腔内血栓AAA入口和出口附近应力最大，腔内血栓通过降低血管的残余应力对AAA起保护作用。     

主动脉扩张病腔内治疗——腹主动脉瘤的无创检查

腹主动脉瘤是血管外科比较常见的动脉扩张性疾病，是由于腹主动脉局限性退化扩张，最终无法承受血流冲击导致瘤壁破裂的一种高危性疾病，90％以上的动脉瘤破裂者发生猝死。在得到诊断的症状性腹主动脉瘤中，2年内自然破裂率达到50％。而随着人类的寿命的不断延长，它已经逐渐成为危害老年人生命健康的重要疾病。据报道，在澳洲大于65岁的老年男性腹主动脉瘤患者中，最大直径大于3cm的患者超过了7．2％。如何在早期发现并正确诊断的同时避免不必要的检查创伤，也是摆在临床医生面前的一大课题。腹部X平片，曾经是诊断腹主动脉瘤的常用诊断方法，但由于其只能发现腹主动脉瘤瘤体巨大或瘤壁钙化较明显的患者，并且无法显示血流动力学的改变和进行参数的测量，故诊断率低，临床应用有限。     

国产血管内裸支架介入治疗假性腹主动脉瘤的研究

目的 探讨国产血管内支架对假性腹主动脉瘤的治疗作用。方法 健康杂种犬32条均分为4组（组Ⅰ-Ⅳ）,对照组为组I,实验组按腹主动脉前壁切开长度不同分为组Ⅱ-Ⅳ。外科方法建立腹主动脉瘤模型后行介入治疗并行影像学和肉眼检查。结果 影像学检查：组I即对照组瘤腔非;组Ⅱ瘤腔已闭合;组Ⅲ残留一小瘤腔;组Ⅳ显示一大的瘤腔,支架无移位。肉眼检查显示：组I：腹主动脉破裂口存在;组Ⅱ：腹主动脉破裂口已被支架和新生内膜完全覆盖,瘤腔内充满条索状机化物;组Ⅲ：破裂口几乎被支架和新生内膜所覆盖,仅遗留有一直径约1．0cm的小瘤腔,但瘤壁呈向心性增厚;组Ⅳ：破裂口仅部分被支架和新生内膜所覆盖,中央处遗留有直径1．0－1．5cm破裂口未被新生内膜覆盖,仍有一大瘤腔。结论 国产网孔面积为4．3mm^2的镍钛形状记忆合金血管内裸支架,对瘤腔入口≤1cm的腹主动脉瘤有治疗作用;瘤腔入口＞1cm但≤2cm可防止动脉瘤继续扩张和迟发破裂;瘤腔入口≥3cm则无任何治疗作用。     

人类腹主动脉瘤三维模型的有限元应力分析

目的 应用有限元的方法分析人类腹主动脉瘤(AAA)瘤壁应力分布，分析可能发生的破裂部位和生长方向，预测AAA的破裂风险。方法螺旋CT扫描AAA获得断层图像，用图形合成软件构建AAA几何模型，设定瘤壁组织生物力学参数和边界条件，使用有限元分析的方法分析个体化AAA瘤壁的应力分布。结果本例AAA应力峰值位于远端分叉部位，瘤体应力峰值位于后壁，均小于瘤壁的承受极限。结论AAA应力模型有助于分析个体化AAA的破裂部位和生长方向，但该模型仍需要进一步完善。     

不同内径腹主动脉瘤腔内血流状况分析

目的　观察不同内径腹主动脉瘤腔内血流情况。方法　应用二维彩色多普勒超声观察不同内径和形状腹主动脉瘤患者 (2 0例 )和通过牛颈外静脉移植法 (3例 )及补片法 (3例 )制作不同内径和形状的腹主动脉瘤模型的动脉瘤腔内血流。结果　在人体中 ,动脉瘤内径≤ 3 .0cm有 5例 ,其中 4例为层流 ,动脉瘤形态为梭形。动脉瘤内径 >3 .0cm有 15例 ,其中 14例出现湍流。 3例牛颈静脉移植法建立的模型 ,当内径≤ 1.5cm时 ,血流表现为层流 ,动脉瘤形态为梭形。内径 >1.5cm时 ,动脉瘤腔内出现湍流和逆流。 3例牛颈静脉补片法建立的模型 ,在动脉瘤腔内近凸起部位出现湍流和逆流。结论　随着动脉瘤内径的增大和形状的改变 ,瘤腔内的血流更为复杂 ,可能会对动脉瘤的生长、破裂及血栓形成产生进一步的影响。     

正常人降主动脉壁及髂总动脉壁周向张力及平均应力分析

体中段平面及髂总动脉处有创测压,测量收缩压、舒张压、平均压,MRI下测量动脉内径、壁厚.通过公式计算得出动脉壁周向张力与平均应力,以自身不同部位对照.结果:收缩压自胸主动脉至髂总动脉逐渐升高(P<0.01),舒张压胸主动脉与腹主动脉相差不明显(P>0.05),髂总动脉较胸主动脉与腹主动脉低(P<0.01),平均动脉压肾下腹主动脉最高(P<0.01).自胸主动脉至髂总动脉动脉内径逐渐缩小(P<0.01),管壁亦逐渐变薄(P<0.01).动脉壁周向张力自胸主动脉至髂总动脉逐渐减少(P<0.01).肾下腹主动脉平均应力大于其它动脉(P<0.01),且在一个心动周期中变化幅度最大.结果 肾下腹主动脉处平均应力大于肾上腹主动脉、胸主动脉和髂总动脉,且在一个心动周期中变化幅度最大,可能是造成肾下腹主动脉易于受损而形成动脉瘤的原因.     

腹主动脉瘤的无创检查

腹主动脉瘤是血管外科比较常见的动脉扩张性疾病,是由于腹主动脉局限性退化扩张,最终无法承受血流冲击导致瘤壁破裂的一种高危性疾病,90%以上的动脉瘤破裂者发生猝死.在得到诊断的症状性腹主动脉瘤中,2年内自然破裂率达到50%.而随着人类的寿命的不断延长,它已经逐渐成为危害老年人生命健康的重要疾病.据报道,在澳洲大于65岁的老年男性腹主动脉瘤患者中,最大直径大于3 cm的患者超过了7.2%.如何在早期发现并正确诊断的同时避免不必要的检查创伤,也是摆在临床医生面前的一大课题.腹部X平片,曾经是诊断腹主动脉瘤的常用诊断方法 ,但由于其只能发现腹主动脉瘤瘤体巨大或瘤壁钙化较明显的患者,并且无法显示血流动力学的改变和进行参数的测量,故诊断率低,临床应用有限.目前在诊断和动态监测腹主动脉瘤方面已很少使用.随着影像学技术的发展,腹主动脉瘤的诊断方法 有了长足的进步.在非侵入性诊断中,超声、CT、MRI成为当前常用的三种主要诊断方法 .     

腹主动脉瘤发病研究新进展

过去一直认为腹主动脉瘤 (ＡＡＡ)主要是因动脉壁粥样硬化后致动脉壁薄弱 ,薄弱处在经受动脉压力冲击后动脉壁扩张 ,最后膨胀成为腹主动脉瘤。近年来基因和生化研究等方面的进展使这一传统概念受到了强烈的冲击 ,甚至有人认为在腹主动脉瘤病人中动脉硬化为继发性或伴发的 ,这些研究表明腹主动脉瘤与基因、环境和生化因素等致主动脉组织代谢发生改变有关。一、临床发现如果说动脉壁的瘤样扩张为动脉粥样硬化所致 ,在弥漫性动脉硬化的病人中应常见周围动脉瘤和主动脉瘤共存 ,然而临床所见却非如此。另外病人因动脉粥样硬化致股浅动脉、远端动…     

腹主动脉瘤破裂并发主动脉-下腔静脉瘘术后妊娠的处理(附一例报告)

腹主动脉瘤破裂并发主动脉-下腔静脉瘘发生率约占腹主动脉瘤手术的1%。我们于1984年6月为一女性青年作动静脉瘘口修补,在腹主动脉瘤近、远端分别切断腹主动脉和双侧髂总动脉,切开瘤后壁,在瘤腔内作真丝人造血管移植术,恢复腹主动脉到两侧髂总动脉血流。术后于1985年10月结婚,婚后数月妊娠。在妊娠初4个月,自觉良好,能从事轻体力劳动。但5个月后,自感下肢行走乏力,工作疲倦。在本院产科检查:腹部膨隆,     

腹主动脉瘤的诊治进展

腹主动脉瘤的病因主要是动脉粥样硬化 ,约占 95 %左右 ,其他为创伤性、感染性、动脉壁中层退行性变、先天性、非感染性主动脉炎及梅毒等。临床上最多见的是肾动脉水平以下的腹主动脉瘤 ,称为肾下腹主动脉瘤。病变位于肾动脉水平以下 ,髂动脉以上的腹主动脉 ,若瘤体近远端都有一段主动脉壁较为正常的 ,这成为手术或介入治疗的有利条件 ,但是也有约 3 2 %的病例同时合并髂动脉瘤。腹主动脉瘤病人 60岁以上老年男性多见 ,我院资料统计 ,平均为 70 .2岁 ,男女比例为 5 .93∶1。常见的症状有搏动性膨胀性腹部肿块 ,其次为腹痛 ,多位于脐周及中上…     

Endovascular Repair of a ruptured abdominal aortic and iliac artery aneurysm with an acute iliocaval fistula secondary to lymphoma

Abdominal aortic aneurysms (AAA) are common and generally asymptomatic unless rupture occurs. A 3 to 4-cm AAA has a 1-2% risk of rupture over 5 years. We present the case of an 85-year-old male with a history of chronic lymphocytic leukemia, a 3-cm infrarenal AAA, and a 2-cm right common iliac artery aneurysm whose AAA ruptured and who developed an acute iliac artery–to–vena cava fistula secondary to eroding adenopathy from an aggressive low-grade lymphoma. Initially, an open repair was attempted but access to the aorta was not possible because of complete encasement of the infrarenal and suprarenal aorta with tumor that was clinically invading the aortic wall. Secondary tumor invasion into the aorta is a rare complication. An endovascular repair was accomplished with successful exclusion of both the aneurysm and the iliocaval fistula. Endovascular repair provides a valuable alternative in the "hostile abdomen" when standard open repair may be hazardous or impossible.     

Wall Stress Studies of Abdominal Aortic Aneurysm in a Clinical Model

To estimate when an abdominal aortic aneurysm (AAA) may rupture, it is necessary to understand the forces responsible for this event. We investigated the wall stresses in an AAA in a clinical model. Using CT scans of the AAA, the diameter and wall thickness were measured and the model of the aneurysm was created. The wall stresses were determined using a finite element analysis in which the aorta was considered isotropic with linear material properties and was loaded with a pressure of 120 mmHg. The AAA was eccentric with a length of 10.5 cm, a diameter of 2.5 to 5.9 cm, and a wall thickness of 1.0 to 2.0 mm. The aneurysm had specific areas of high stress. On the inner surface the highest stress was 0.4 N/mm2 and occurred along two circumferentially oriented belts--one at the bulb and the other just below. The stress was longitudinal at the anterior region of the bulb and circumferential elsewhere, suggesting that a rupture caused by this stress will result in a circumferential tear at the anterior portion of the bulb and a longitudinal tear elsewhere. In the mid-surface the highest stress was 0.37 N/mm2 and occurred at two locations: the posterior region of the bulb and anteriorly just below. The stress was circumferential, suggesting that the rupture caused by this stress will produce a longitudinal tear. The location and orientation of the maximum stress were influenced more by the tethering force than by the wall thickness, luminal pressure, or wall stiffness. In conclusion, the rupture of an AAA is most likely to occur on the inner surface at the bulb. Such analytical approaches could lead to a better understanding of the aneurysm rupture and may be instrumental in planning surgical interventions.     

Wall stress distribution on three-dimensionally reconstructed models of human abdominal aortic aneurysm

PURPOSE: Abdominal aortic aneurysm (AAA) rupture is believed to occur when the mechanical stress acting on the wall exceeds the strength of the wall tissue. Therefore, knowledge of the stress distribution in an intact AAA wall could be useful in assessing its risk of rupture. We developed a methodology to noninvasively estimate the in vivo wall stress distribution for actual AAAs on a patient-to-patient basis. METHODS: Six patients with AAAs and one control patient with a nonaneurysmal aorta were the study subjects. Data from spiral computed tomography scans were used as a means of three-dimensionally reconstructing the in situ geometry of the intact AAAs and the control aorta. We used a nonlinear biomechanical model developed specifically for AAA wall tissue. By means of the finite element method, the stress distribution on the aortic wall of all subjects under systolic blood pressure was determined and studied. RESULTS: In all the AAA cases, the wall stress was complexly distributed, with distinct regions of high and low stress. Peak wall stress among AAA patients varied from 29 N/cm(2) to 45 N/cm(2) and was found on the posterior surface in all cases studied. The wall stress on the nonaneurysmal aorta in the control subject was relatively low and uniformly distributed, with a peak wall stress of 12 N/cm(2). AAA volume, rather than AAA diameter, was shown by means of statistical analysis to be a better indicator of high wall stresses and possibly rupture. CONCLUSION: The approach taken to estimate AAA wall stress distribution is completely noninvasive and does not require any additional involvement or expense by the AAA patient. We believe that this methodology may allow for the evaluation of an individual AAA's rupture risk on a more biophysically sound basis than the widely used 5-cm AAA diameter criterion.     

Reduced aortic wall stress in diabetes mellitus.

OBJECTIVE: Most risk factors are similar for abdominal aortic aneurysm (AAA) and atherosclerosis, e.g. smoking, male gender, age, high blood pressure, hyperlipidemia. Diabetes mellitus however, is a risk factor for atherosclerosis, but diabetic patients seldom develop AAA. The reason for this discrepancy is unknown. Increased aortic wall stress seems to be an etiologic factor in the formation, growth and rupture of AAA in man. The aim of our study was to study the wall stress in the abdominal aorta in diabetic patients compared with healthy controls. METHODS: 39 patients with diabetes mellitus and 46 age - and sex matched healthy subjects were examined with B-mode ultrasound to determine the lumen diameter (LD) and intima-media thickness (IMT) in the abdominal aorta (AA) and the common carotid artery (CCA). Diastolic blood pressure (DBP) was measured non-invasively in the brachial artery. LaPlace law was used to calculate circumferential wall stress. RESULTS: Age, DBP, and LD in the abdominal aorta were not significantly different in the diabetic patients compared to controls. IMT in the AA was larger in the diabetic patients, 0.89+/-0.17 vs 0.73+/-0.11 mm (p<.001). Accordingly aortic wall stress was reduced in the diabetics, 7.8+/-1.7 x 10(5) vs 9.7+/-1.9 x 10(5)dynes/cm(2) (p<.001). CONCLUSIONS: Wall stress in the abdominal aorta is reduced in diabetes mellitus. This is mainly due to a thicker aortic wall compared to healthy controls. The reduced aortic wall stress coincides with the fact that epidemiological studies have shown a decreased risk of aneurysm development in diabetic patients.     

Chronic contained rupture of an abdominal aortic aneurysm

The operative treatment of chronic contained rupture of a saccular abdominal aortic aneurysm (AAA) with retroperitoneal haematoma is reported. A 62-year-old man presented with a painless abdominal mass and intermittent claudication. He had an episode of severe abdominal pain about 2 years before admission. A giant retroperitoneal neoplasm was initially suspected, based on computed tomography. However, magnetic resonance imaging, angiography and colour Doppler sonography demonstrated chronic contained rupture of an AAA. A punched-out oval defect (width 3.5 cm × length 4.5 cm) that was thought to connect the thrombosed aneurysm to an organized retroperitoneal haematoma was discovered in the posterior wall of the bifurcation of the aorta at laparotomy. An infrarenal aortobiexternal iliac Y-graft with bypass to the left femoral artery was placed without removing the aneurysm or haematoma. Recovery was uneventful. The retroperitoneal haematoma appeared smaller on computed tomography about 1 year after operation. This case fulfulled the criteria for chronic contained rupture of an AAA proposed by Jones and associates.     

二甲双胍激活AMPK/mTOR信号通路抑制大鼠腹主动脉瘤形成

目的:研究二甲双胍(MET)通过AMPK/mTOR信号通路抑制人腹主动脉瘤(AAA)的发展机制.方法:40只雄性SD大鼠,体重(200±20)g,被分成4组:正常对照组(Control)、MET+AAA组、AAA组和C.C+AAA组,每组10只.通过腹主动脉腔内灌注猪胰弹性蛋白酶建立大鼠AAA模型.AMPK激活剂MET...     

Case report of a hybrid endovascular approach to an abdominal aortic dissection with retrograde thoracic extension and infrarenal aneurysm

Spontaneous abdominal aortic dissection (AAD) with retrograde thoracic extension is an extremely rare occurrence with a high mortality. Abdominal aortic dissection can be associated with an abdominal aortic aneurysm (AAA) and the presence of an AAD with an AAA mandates surgical intervention because of a high rate of rupture. We present the case of a 53-year-old woman with a spontaneous AAD that extended retrograde into the thoracic aorta with a concomitant supraceliac intimal tear and an infrarenal AAA repaired electively with a hybrid approach using a supraceliac stent graft and an open infrarenal aortobiiliac graft. This hybrid approach provided an excellent outcome of this rare and complex vascular pathology.     

237例肾动脉水平以下腹主动脉瘤手术治疗经验

目的提高腹主动脉瘤手术的安全性。方法总结了自１９６０年１月到１９９６年１２月２３７例肾动脉水平以下腹主动脉瘤切除人造血管移植手术治疗的经验。结果随着腹膜后途径的应用,动脉瘤近端血流控制、动脉瘤切除以及缝合修补等方法的改进,使手术的危险性明显降低,手术时间缩短（２～３ｈ）。随访２２７例,手术死亡率低（３．８％）。５年存活率达７４．４％。结论手术技术和麻醉监护的进步,使腹主动脉瘤修补手术变得更迅速、安全和方便。