Endovascular repair of abdominal aortic aneurysms: CTA evaluation of contraindications

Endovascular aortic aneurysm repair (EVAR) is considered an acceptable alternative to open surgery in selected patients. Its feasibility depends mainly on anatomic factors that represent the important predictors of success and the most important exclusion criteria. Poor anatomic patient selection is generally associated with a higher risk for procedural complications and compromised long-term outcomes. Therefore pretreatment imaging is crucial for evaluating patient suitability for EVAR. Multidetector computed tomographic angiography represents the current standard of reference in the evaluation of the abdominal aorta and iliac axis anatomy because it provides all the details needed for selection of patients who are suitable for endograft and the choice of the appropriate device. This report identifies and reviews computed tomographic angiographic anatomic contraindications for EVAR.     

Infected abdominal aortic aneurysms

We report five cases of infected abdominal aortic aneurysm managed at the St. Thomas Hospital between 1975 and 1985. Two patients died, one before operation, and another during surgical repair of aneurysmal rupture. Three patients survived, all of whom had primary repair of the aorta or in situ Dacron graft reconstruction. One patient is still living nine years after operation. The availability of organism-specific antibiotic agents has enabled us to use the in situ reconstruction method to successfully manage these patients without increased morbidity or mortality from recurrent infection. A high index of suspicion, prompt surgical resection, and aggressive specific antibiotic therapy are necessary for patient survival.     

Management of abdominal aortic aneurysms

Rupture of an abdominal aortic aneurysm (AAA) remains a common vascular catastrophe in all emergency departments. Currently, the natural history of AAAs indicates that risk of rupture increases considerably when the aneurysm is greater than 5 cm in diameter. Appropriate management of aneurysms is elective repair for patients with a good operative risk whose aneurysm is between 5 and 6 cm. For patients with a serious medical comorbidity, the threshold for AAA repair is usually 6 cm. Surgical management is generally safe with extraordinarily durable results. Another current option is an investigational endovascular stent graft, but the long-term outcome for these new devices remains unknown. In addition, optimal medical management should include careful control of hypertension and smoking cessation. The current prognosis for healthy patients who undergo elective aneurysm repair is excellent.     

Imaging of abdominal aortic aneurysms

Given the high rate of morbidity and mortality associated with abdominal aortic aneurysms (AAAs), accurate diagnosis and preoperative evaluation are essential for improved patient outcomes. Ultrasonography is the standard method of screening and monitoring AAAs that have not ruptured. In the past, aortography was commonly used for preoperative planning in the repair of AAAs. More recently, computed tomography (CT) has largely replaced older, more invasive methods. Recent advances in CT imaging technology, such as helical CT and CT angiography, offer significant advantages over traditional CT. These methods allow for more rapid scans and can produce three-dimensional images of the AAA and important adjacent vascular structures. Use of endovascular stent grafts has increased recently and is less invasive for the repair of AAAs in selected cases. Aortography and CT angiography can precisely determine the size and surrounding anatomy of the AAA to identify appropriate candidates for the use of endovascular stent grafts. Helical CT and CT angiography represent an exciting future in the preoperative evaluation of AAAs. However, this technology is not the standard of care because of the lack of widespread availability, the cost associated with obtaining new equipment, and the lack of universal protocols necessary for acquisition and reconstruction of these images.     

Endovascular repair of abdominal aortic aneurysms

Abdominal aortic aneurysms increasingly are being repaired with an endovascular procedure, which is less invasive compared to traditional approaches. Decreased hospitalization is one of several advantages of the endovascular approach; however, there also are significant disadvantages that the patient should consider carefully. Complications of the endovascular approach are the same as with open procedures, and there is added potential for endoleaks (ie, leakage of the graft). The patient must be involved in an imaging surveillance program for life to continually assess the graft's durability. Endovascular repair of abdominal aortic aneurysms is a rapidly developing technology. Research is ongoing and emphasizes smaller deployment devices and stronger graft materials. AORN J 77 (March 2003) 631-642.     

Endoluminal treatment of abdominal aortic aneurysms

BACKGROUND: We report our preliminary results with endovascular treatment of abdominal aortic aneurysms (AAA). METHODS: Between October 1998 and June 2000, 64 patients (62 male, two female; mean age = 70 years) underwent endovascular repair of AAA. Different types of prostheses were used, both bifurcated (n = 58) and straight (n = 6). We performed duplex sonography and spiral computed tomographic angiography (CTA) at discharge and at 3, 6, 12, and 18 months. Follow-up ranged from 1 to 20 months. RESULTS: All procedures were successful, except for three immediate and one late surgical conversions (6.2%). One patient died 14 days after immediate surgical conversion. At discharge, CTA showed 13 endoleaks: three resolved spontaneously, six persisted during follow-up, and four (one angioplasty and three embolizations) were treated successfully. Stenosis of an iliac branch occurred in one patient after 3 months and was successfully treated by angioplasty. Late endoleaks were detected by imaging follow-up in four cases, three at 1 year and one at 6 months, requiring deployment of distal extender cuffs (n = 2), a proximal cuff (n = 1), and lumbar embolization (n = 2). CONCLUSION: Our preliminary experience supports the efficacy of endovascular repair in selected patients, but strict and accurate follow-up is required.     

Evaluation for abdominal aortic aneurysms is justified in patients with thoracic aortic aneurysms

Aortic aneurysms are a significant cause of mortality, and the presence of multiple aneurysms may affect treatment plans. The purpose of this study was to determine the frequency of abdominal aortic aneurysms (AAAs) in patients with thoracic aortic aneurysms (TAAs) and to establish whether patient specific factors, such as gender and comorbidities, influenced the frequency of AAAs, thereby indicating if and when abdominal aortic evaluation is justified. Electronic medical records were reviewed from 1000 patients with a computed tomography (CT) angiogram of the chest and abdomen and a clinical diagnosis of TAA from Cardiac Surgery clinic between 2008 and 2013. 538 patients with history of aortic intervention, dissection, rupture or trauma were excluded. The frequency of AAAs among the 462 remaining patients was established, and statistical analysis was used to elucidate differences in frequency based on age, gender, comorbidities, and TAA location. Overall, 104 of 462 (22.5 %) patients with a TAA also had an AAA. There were significant differences in the frequency of AAA based on TAA location, age, and comorbidities. The following comorbidities showed positive associations with AAA using logistic regression analysis: age ≥65 (P < 0.0001; OR 30.1; CI 7.14–126.61), smoking history (P < 0.0001; OR 4.1; 2.35–7.30), and hypertension (P = 0.024; OR 2.1; CI 1.11–4.16). Aneurysms in the proximal/mid descending (P < 0.0001; OR 4.96; CI 2.32–10.61) and diaphragm level (P < 0.0001; OR 38.4; CI 14.71–100.15) of the aorta also showed a positive association with AAAs when adjusted for age and gender. AAA screening in patients with TAA is a reasonable, evidence-based option regardless of the TAA location, with the strongest support in patients >age 55, with systemic hypertension, a smoking history and/or a TAA in the descending thoracic aorta.     

Endoluminal repair of infrarenal abdominal aortic aneurysms

Endoluminal repair of abdominal aortic aneurysms (AAA) offers an attractive alternative to open surgical repair. Early experience has shown that endoluminal repair can be performed safely, with low morbidity and mortality rates. Data from non-randomised studies have demonstrated that the endoluminal technique has certain advantages when compared with open repair in carefully selected patients. These include shorter hospital stay, decreased use of intensive-care beds and lower blood loss. The major drawback to endoluminal repair is the durability of the stent grafts. Registers of endoluminal devices have shown that, even after successful repair, new endoleaks may occur after apparently successful deployment and the transverse diameter of the aneurysm may continue to expand, even in the absence of an endoleak. Some of the devices have developed problems with the integrity of either the stent or its graft covering, which could result in aneurysm rupture. Manufacturers have recently been criticised for not releasing data on adverse events. No randomised trials comparing endoluminal with open repair of infrarenal AAA have yet been performed, however, financial support has recently been granted for a multicentre UK study (endovascular aneurysm repair — EVAR). This trial will randomise patients who are deemed fit for operation to either open repair or endovascular repair (EVAR 1) and patients regarded as unfit to best medical treatment, or best medical treatment with endovascular repair (EVAR 2).     

Understanding the pathogenesis of abdominal aortic aneurysms

An aortic aneurysm is a dilatation in which the aortic diameter is ≥3.0 cm. If left untreated, the aortic wall continues to weaken and becomes unable to withstand the forces of the luminal blood pressure resulting in progressive dilatation and rupture, a catastrophic event associated with a mortality of 50–80%. Smoking and positive family history are important risk factors for the development of abdominal aortic aneurysms (AAA). Several genetic risk factors have also been identified. On the histological level, visible hallmarks of AAA pathogenesis include inflammation, smooth muscle cell apoptosis, extracellular matrix degradation and oxidative stress. We expect that large genetic, genomic, epigenetic, proteomic and metabolomic studies will be undertaken by international consortia to identify additional risk factors and biomarkers, and to enhance our understanding of the pathobiology of AAA. Collaboration between different research groups will be important in overcoming the challenges to develop pharmacological treatments for AAA.     

Fenestrated endografts for complex abdominal aortic aneurysms

The treatment of aortic aneurysm disease using endovascular stent grafts has evolved over the past 20 years. Extending this approach to aneurysms involving the visceral aorta has required development of fenestrated endografts. By creating branches to accommodate visceral vessels, the proximal landing zone can be chosen based on the adequacy of the aortic wall, rather than the constraints of visceral vessels. This allows for a more stable repair, and permits a minimally invasive approach in even very complex aneurysms. As the technology becomes more widespread, the use of these grafts has emerged from an experimental form to standard of care in some jurisdictions. Thus, many patients who might have previously been considered high risk for aneurysm repair are now candidates for surgery. This article outlines the basic concepts behind the development of fenestrated endografts, their current use, and the future of the technology.     

多学科联合治疗破裂性腹主动脉瘤

目的 探讨提高破裂性腹主动脉瘤救治成功率的途径和方法。方法 通过胸腹联合切口阻断瘤体近远端和自体血回输等技术，救治破裂性腹主动脉瘤患者12例。结果术后存活8例，手术成功率为67％。2例在术中因休克时间过长而死亡。另2例在术后两周内因并发肾功能衰竭和弥漫性血管内凝血等严重并发症而死亡。结论 对破裂性腹主动脉瘤及早诊断并手术、术中缩短手术时间、尽量回输自体内、减少异体血输注量，是提高救治成功率的必要保证。     

Imaging of abdominal aortic aneurysms after endoluminal repair

The recently published clinical trials of endoluminal repair of aortic aneurysms underline the need for a close imaging follow-up of patients undergoing these procedures. This article discusses the role of different imaging modalities in the evaluation of these patients.     

Emerging strategies to treat ruptured abdominal aortic aneurysms

Population screening programmes and a falling population prevalence of smoking have led to a declining incidence of ruptured abdominal aortic aneurysms in men. However, ruptured abdominal aortic aneurysms remain a common vascular surgical emergency, with an increasing proportion of ruptures being in women. About one quarter of the ruptures have a juxta-renal aneurysm and are more challenging to repair using endovascular technologies. Endovascular technologies may not reduce the overall mortality, compared with open surgical repair, but appear to offer early benefits with respect to patient quality of life at acceptable cost. Challenges over the next 5 years include widening the access to repair, developing an accurate bedside risk scoring tool, as well as optimising strategies for pre-operative resuscitation, standardising peri-operative care and the management of post-operative complications.     

Automatic aortic root landmark detection in CTA images for preprocedural planning of transcatheter aortic valve implantation

Transcatheter aortic valve implantation is currently a well-established minimal invasive treatment option for patients with severe aortic valve stenosis. CT Angiography is used for the pre-operative planning and sizing of the prosthesis. To reduce the inconsistency in sizing due to interobserver variability, we introduce and evaluate an automatic aortic root landmarks detection method to determine the sizing parameters. The proposed algorithm detects the sinotubular junction, two coronary ostia, and three valvular hinge points on a segmented aortic root surface. Using these aortic root landmarks, the automated method determines annulus radius, annulus orientation, and distance from annulus plane to right and left coronary ostia. Validation is performed by the comparison with manual measurements of two observers for 40 CTA image datasets. Detection of landmarks showed high accuracy where the mean distance between the automatically detected and reference landmarks was 2.81 ± 2.08 mm, comparable to the interobserver variation of 2.67 ± 2.52 mm. The mean annulus to coronary ostium distance was 16.9 ± 3.3 and 17.1 ± 3.3 mm for the automated and the reference manual measurements, respectively, with a mean paired difference of 1.89 ± 1.71 mm and interobserver mean paired difference of 1.38 ± 1.52 mm. Automated detection of aortic root landmarks enables automated sizing with good agreement with manual measurements, which suggests applicability of the presented method in current clinical practice.     

Use of endoluminal aortic stent-grafts for the repair of abdominal aortic aneurysms

Abdominal aortic aneurysms affect approximately 1.5% of the United States population. Randomized trials recommend repair when the maximal aneurysm diameter is 5.5 cm or greater. Since the first report of this technique in 1991, endovascular repair has become the preferred method for elective therapy of AAA disease. This has been a direct result of reported decreased hospital length of stay, reduced patient recovery time and improved survival. The application of endovascular aneurysm repair (EVAR) requires a thorough understanding of aneurysm anatomy, which is critical for appropriate patient selection. In particular the surgeon must be familiar with device-related criteria for proximal fixation and distal fixation as well as access vessels size, tortuosity, and calcification which can often be the limiting factor in the application of EVAR. Although the reported results of EVAR indicate significant advantages when compared with conventional open repair, it is critical to have an understanding of the particular complications associated with EVAR. The development of endoleaks, reports of stent migration and stent fracture as well as the development of limb stenosis and/or occlusion have been reported in up to 20% of patients treated with EVAR and thus necessitate appropriate long-term surveillance protocols.     

腹主动脉瘤腔内隔绝术围手术期护理

总结了8例腹主动脉瘤(AAA)腔内隔绝术(EVE)的围手术期护理,主要内容是:术前做好入院指导及心理护理,调整心理状态以适应手术,防止腹主动脉瘤破裂;术中注意观察患者尿量及双下肢皮肤温度、足背动脉的搏动情况;术后做好体位护理及呼吸道护理,各种管道的护理观察,做好并发症的观察及护理.结果8例移植物全部成功置入,术后出现腹膜后出血1例,黑便1例,发热3例,经及时治疗与护理病情恢复良好,无1例出现肾功能衰竭及下肢血栓形成.患者均在术后2周内康复出院.认为尽管腹主动瘤腔内治疗系微创手术,但其本身亦有一定的并发症,加强围手术期护理,预防并及时处理并发症是提高手术成功率,保障患者痊愈的重要环节.