Hybrid endovascular repair in aortic arch pathologies: a retrospective study

The aortic arch presents specific challenges to endovascular repair. Hybrid repair is increasingly evolving as an alternative option for selected patients, and promising initial results have been reported. The aim of this study was to introduce our experiences and evaluate mid-term results of supra aortic transpositions for extended endovascular repair of aortic arch pathologies. From December 2002 to January 2008, 25 patients with thoracic aortic aneurysms and dissections involving the aortic arch were treated with hybrid endovascular treatment in our center. Of the 25 cases, 14 were atherosclerotic thoracic aortic aneurysms and 11 were thoracic aortic dissection. The hybrid repair method included total-arch transpositions (15 cases) or hemi-arch transpositions (10 cases), and endovascular procedures. All hybrid endovascular procedures were completed successfully. Three early residual type-I endoleaks and one type-II endoleak were observed. Stroke occurred in three patients (8%) during the in-hospital stage. The perioperative mortality rate was 4%; one patients died post-operatively from catheter related complications. The average follow-up period was 15 ± 5.8 months (range, 1-41 months). The overall crude survival rate at 15 months was 92% (23/25). During follow-up, new late endoleaks and stent-raft related complications were not observed. One case (4%) developed a unilateral lower limb deficit at 17 days and was readmitted to hospital. In conclusion, the results are encouraging for endovascular aortic arch repair in combination with supra-aortic transposition in high risk cases. Aortic endografting offers good mid-term results. Mid-term results of the hybrid approach in elderly patients with aortic arch pathologies are satisfying.     

Transfusion Cost Containment for Abdominal Surgery with Neural Networks

Typing and crossmatching blood is a significant cost for most hospitals, regardless of whether the blood is actually transfused. Many hospitals have implemented a Maximum Surgical Blood Order Schedule, MSBOS, to control over-ordering of blood units for surgery. The research presented in this article examines the use of neural networks for predicting the quantity of blood required by individual patients undergoing abdominal surgery (e.g. splenectomy). A comparison is made between the neural network predictions at a particular hospital versus the current MSBOS methodology for ordering surgical blood, by using the crossmatch to transfusion ratio. Results from the neural network transfusion predictions for the abdominal aortic aneurysm (AAA) surgery imply that neural networks can significantly improve the transfusion efficiency of hospitals. However, further examination of neural network capabilities for predicting the transfusion needs of patients undergoing other types of abdominal surgeries indicates that for operations other than the AAA, neural networks tend to under-predict the transfusion requirements of ten percent of the patients. Even if not used to limit over-ordering of blood for surgical transfusions, neural networks may be used as an intelligent decision support system to evaluate the current efficiency of hospital transfusion practices and to indicate beneficial changes to current MSBOS values.     

Contrast-enhanced abdominal echo planar imaging: Dynamic signal-intensity changes following intravenous injection of gadolinium-DOTA

Objectives: After I.V. administration of gadolinium-DOTA, the early contrast enhancement pattern and related signal-intensity (SI) changes in normal abdominal organs (kidney, spleen, liver) are evaluated over the first 4 min by using ultrafast spin-echo echo planar imaging (SE-EPI). Methods: On a 1.5-T magnetic resonance unit ultrafast EPI of the upper abdomen was performed in 12 patients in order to show the contrast enhancement pattern and related measurable SI changes onT ₁ andT ₂-weighted (w) images over the first 4 min after I.V. bolus injection of 0.1 mmol kg^–1 gadolinium (Gd)-DOTA in the spleen, liver, renal cortex, and renal medulla. A TR/TE of 500/44 or 45 ms inT ₁w SE-EPI and a TR/TE of 2000/80 or 100 ms inT ₂-w SE-EPI were used. Results: Typical time-dependent SI changes were noticed onT ₁w images: Subsequent to a SI increase in the renal cortex (starting 7 s after the I.V. injection of Gd-DOTA) SI increased first in the outer renal medulla (6 s later) and then in the inner renal medulla (21 s later). A SI increase was observed in the spleen (starting after 15 s) and in the liver (starting 7 s later). OnT ₂-w images, a SI decrease in the renal cortex (starting after 14 s) was followed by migration of a dark band from the outer (after 46 s) to the inner medulla (after 70 s). Only minimal changes were noticed in the spleen and liver. Conclusions: Ultrafast SE-EPI following I.V. bolus injection of Gd-DOTA enables the observation of the very early contrast agent kinetics in various abdominal organs. The associated SI changes onT ₁- andT ₂- SE EPI are related to organ perfusion and contrast agent tissue concentration and biodistribution.Additional reprints of this chapter may be obtained from the Reprints Department, Chapman & Hall, One Penn Plaza, New York, NY 10119.     

不同破口位置对主动脉夹层真假腔内压力及肾肠灌注的影响

为提高主动脉夹层疾病的治疗效果,针对主动脉夹层疾病,研究主动脉夹层内的血流动力学变化,尤其是不同破口位置下,夹层患者的肾肠等器官的灌注情况及产生的影响.利用3D打印技术制作不同破口位置的主动脉夹层模型,通过实验方法进行主动脉夹层内血流模拟,并对主动脉夹层模型真假腔内的压力及肾肠支脉的压力进行测量,辅以超声技术进行观测.不同破口位置下,真假腔压力都会随不同基准压力(15 960、21 280、26 600 Pa)的升高而增大,在3种基准压力水平(15 960、21 280、26 600 Pa)下,模型B肠系膜动脉压力明显高于模型A肠系膜动脉压力.真假腔压力会随不同基准压力的升高而增大,压力极差变化更加剧烈,管壁的负担加重,夹层破裂风险更大.降压手段支持下,模型B有可能出现肠器官灌注不良状态,即因低灌出现脏器缺血情况.     

人参皂苷Rg1治疗性给药的抗心肌肥厚作用

目的 观察人参皂苷Rg1 治疗性给药对缩窄腹主动脉所致大鼠左心室肥厚的影响。 方法 SD 大鼠随机分为假手术组、模型组、Rg1 (3.75,15 mg/kg) 组以及左旋精氨酸(L-arg) 200 mg kg组。后4 组用腹主动脉缩窄术(AAC) 造模, 手术3周后腹腔注射给药共4 周。给药末监测大鼠血流动力学, 称心脏质量以计算左室肥厚指标(即左室肥厚指数, LVHI =左室重 体重) 和左室重 右室重(LVW/VW), 用实时荧光定量PCR (Real-Time PCR) 法检测心房利钠因子(ANF) 和钙调神经磷酸酶(CaN) mRNA 的表达。 结果 与假手术组比较,模型组的血压、左室内收缩压、左室舒张期末压、LVHI 和LVW/RVW 均显著升高, ±dp/d tmax 降低,ANF 和CaN mRNA 表达明显上调。Rg1 和L-arg给药不影响血压及左室内收缩压, 但显著降低左心室舒张期末压(LVEDP) 而增加±dp/dtmax, 并使LVHI 和LVW/RVW 减低, ANF 和CaN mRNA 表达下调。 结论 Rg1 具有抗压力超负荷所致左心室肥厚作用, 并可能与其抑制CaN 信息通路有关。     

Blood flow and coherent vortices in the normal and aneurysmatic aortas: a fluid dynamical approach to intra-luminal thrombus formation

Abdominal aortic aneurysms (AAAs) are frequently characterized by the development of an intra-luminal thrombus (ILT), which is known to have multiple biochemical and biomechanical implications. Development of the ILT is not well understood, and shear–stress-triggered activation of platelets could be the first step in its evolution. Vortical structures (VSs) in the flow affect platelet dynamics, which motivated the present study of a possible correlation between VS and ILT formation in AAAs. VSs educed by the λ₂-method using computational fluid dynamics simulations of the backward-facing step problem, normal aorta, fusiform AAA and saccular AAA were investigated. Patient-specific luminal geometries were reconstructed from computed tomography scans, and Newtonian and Carreau–Yasuda models were used to capture salient rheological features of blood flow. Particularly in complex flow domains, results depended on the constitutive model. VSs developed all along the normal aorta, showing that a clear correlation between VSs and high wall shear stress (WSS) existed, and that VSs started to break up during late systole. In contrast, in the fusiform AAA, large VSs developed at sites of tortuous geometry and high WSS, occupying the entire lumen, and lasting over the entire cardiac cycle. Downward motion of VSs in the AAA was in the range of a few centimetres per cardiac cycle, and with a VS burst at that location, the release (from VSs) of shear-stress-activated platelets and their deposition to the wall was within the lower part of the diseased artery, i.e. where the thickest ILT layer is typically observed. In the saccular AAA, only one VS was found near the healthy portion of the aorta, while in the aneurysmatic bulge, no VSs occurred. We present a fluid-dynamics-motivated mechanism for platelet activation, convection and deposition in AAAs that has the potential of improving our current understanding of the pathophysiology of fluid-driven ILT growth.     

Bio-Multifunctional Hydrogel Patches for Repairing Full-Thickness Abdominal Wall Defects

Developing bio-multifunctional patches with natural extracellular matrix-like structures, excellent high adhesion in the wet state, self-healing ability, antibacterial activity, and favorable cell responses for accelerating tissue healing is highly desirable in clinical applications. Herein, bio-multifunctional composite hydrogels are developed by coupling carboxymethyl chitosan and 4-arm poly (ethylene glycol) aldehyde for full-thickness abdominal wall defect repair. The prepared hydrogels exhibit excellent self-healing and mechanical properties, high adhesion in the wet state, and significant antibacterial ability. In vitro cellular experiments show that the hydrogels combined with recombinant bovine basic fibroblast growth factor remarkably promote cell proliferation and then accelerate full-thickness abdominal wall defect repair in a rat model. The histomorphological evaluation shows that compared to the commercial polypropylene mesh used clinically, the designed hydrogel patches facilitate an increase in the thickness and integrity of the abdominal wall tissue by upregulating the production of Ki67, enhancing the formation of collagen, inducing neovascularization, and inhibiting inflammation by reducing the expression of IL-6, TNF-α, and IL-1β. The results demonstrate that this novel bio-multifunctional hydrogel patch holds great potential for the treatment of full-thickness abdominal wall defects.     

Thrombosed hemodialysis access as an unusual source of emboli in the upper extremity of a kidney transplant recipient

Arteriovenous fistula (AVF) is no longer used in kidney transplant recipients. However, there is no consensus regarding whether or not to ligate a well‐functioning AVF after successful kidney transplantation, particularly in patients with well and stably functioning kidney transplants. Most AVFs without complications are left in situ and more than one‐third of native AVFs close spontaneously. The currently accepted policy toward thrombosed AVFs is retention within the patient's extremity without treatment. These thrombosed AVFs seldom cause serious problems. However, when combined with aneurysmal dilatation of the proximal vein adjacent to the arterial anastomotic area, the AVF could act as the source of distal arterial emboli. This is very similar clinical scenario to that observed in embolization from a peripheral arterial aneurysm. Here we describe a case report of upper extremity ischemia following massage of a thrombosed aneurysmal AVF. The patient was successfully treated with a combination of catheter‐directed thromboaspiration, thrombolysis, and surgical repair of the thrombosed AVF. To the best of our knowledge, this is the first report of upper extremity embolism after massage of a thrombosed aneurysmal AVF involving this combined treatment.     

Association of the C-Reactive Protein Gene (CRP) rs1205 C>T Polymorphism with Aortic Valve Calcification in Patients with Aortic Stenosis

Elevation in C-reactive protein (CRP) levels have been shown in patients with aortic valve stenosis (AS). Minor allele of the CRP gene (CRP) rs1205 C>T polymorphism has been associated with lower plasma CRP concentrations in cohorts of healthy and atherosclerotic patients. Considering the existing similarities between atherosclerosis and AS, we examined the effect of CRP rs1205 C>T polymorphism on the AS severity. Three hundred consecutive Caucasian patients diagnosed with AS were genotyped for the rs1205 C>T polymorphism using the TaqMan assay. Severity of the AS was assessed using transthoracic echocardiography. The degree of calcification was analyzed semi-quantitatively. Carriers of the rs1205 T allele were characterized by elevated serum CRP levels (2.53 (1.51–3.96) vs. 1.68 (0.98–2.90) mg/L, p < 0.001) and a higher proportion of the severe aortic valve calcification (70.4% vs. 55.1%, p = 0.01) compared with major homozygotes. The effect of CRP rs1205 polymorphism on CRP levels is opposite in AS-affected than in unaffected subjects, suggesting existence of a disease-specific molecular regulatory mechanism. Furthermore, rs1205 variant allele predisposes to larger aortic valve calcification, potentially being a novel genetic risk marker of disease progression.