Alterations of blood flow pattern after triple stent endovascular treatment of saccular abdominal aortic aneurysm: a porcine model / Alterações do padrão do fluxo sanguíneo após tratamento endovascular do aneurisma sacular da aorta abdominal com triplo stent: modelo em suínos

ABSTRACT Objective: to determine the blood flow pattern changes after endovascular treatment of saccular abdominal aortic aneurysm with triple stent. Methods: we conducted a hemodynamic study of seven Landrace and Large White pigs with saccular aneurysms of the infrarenal abdominal aorta artificially produced according to the technique described. The animals were subjected to triple stenting for endovascular aneurysm. We evaluated the pattern of blood flow by duplex scan before and after stent implantation. We used the non-paired Mann-Whitney test for statistical analysis. Results: there was a significant decrease in the average systolic velocity, from 127.4cm/s in the pre-stent period to 69.81cm/s in the post-stent phase. There was also change in the flow pattern from turbulent in the aneurysmal sac to laminate intra-stent. Conclusion: there were changes in the blood flow pattern of saccular abdominal aortic aneurysm after endovascular treatment with triple stent.

RESUMO Objetivo: determinar as alterações do padrão do fluxo sanguíneo após tratamento endovascular do aneurisma sacular de aorta abdominal com triplo stent. Métodos: estudo hemodinâmico de sete suínos das raças Landrace e Large White portadores de aneurismas saculares de aorta abdominal infrarrenal artificialmente produzidos segundo técnica descrita. Os animais foram submetidos a implante de triplo stent para correção endovascular do aneurisma e reavaliados por duplex scan quanto ao padrão do fluxo sanguíneo antes e após o implante dos stents. A análise estatística foi realizada com o teste Mann-Whitney não pareado. Resultados: verificou-se uma queda significativa da velocidade sistólica média de 127,4cm/s na fase pré-stent para 69,81cm/s na fase pós-stent. Houve ainda mudança no padrão do fluxo de turbilhonar no saco aneurismático para laminar intrastent. Conclusão: o estudo demonstrou alterações do padrão do fluxo sanguíneo do aneurisma sacular de aorta abdominal após tratamento endovascular com triplo stent.

Endovascular repair of a juxtarenal saccular aneurysm using the Multilayer Flow Modulator: report of the first case performed in a Public Hospital in Brazil / Tratamento de aneurisma de aorta sacular justarrenal com Multilayer Flow Modulator: relato do primeiro caso realizado em Hospital Público no Brasil

Endovascular treatment of abdominal aortic aneurysms (AAA), involving the exits of the renal and visceral arteries still constitutes a considerable challenge. Many different techniques have been developed over the years in attempts to surmount the difficulties presented by these cases. Techniques that have gained prominence include fenestrated or branched stents, methods involving parallel prostheses, such as the chimney, periscope and sandwich techniques, and, more recently, flow modulation with Multilayer stents. We describe a case of a complex juxtarenal saccular AAA with a high surgical risk, both according to cardiological assessment and because the patient had a difficult airway caused by a total laryngectomy for early stage laryngeal neoplasm. In view of the technical simplicity of using Multilayer stents, the presence of chronic obstructive aortoiliac disease, ostial stenosis of the renal artery and a small diameter suprarenal aorta, options involving fenestrated/branched stents and techniques involving parallel prostheses were ruled out, because of the need for multiple accesses. In view of the dilemma it presented, we describe this case as a therapeutic challenge and present the treatment option employed, which has been successful over the short term...

O tratamento endovascular de aneurismas de aorta abdominal (AAA), envolvendo a saída das artérias renais e viscerais, constitui ainda um importante desafio. Diversas técnicas foram desenvolvidas ao longo do tempo para contornar as dificuldades oferecidas por esta situação, destacando-se as endopróteses fenestradas ou ramificadas, as técnicas envolvendo próteses paralelas, como Chaminé, Periscópio e Sanduíche, e, mais recentemente, a utilização da modulação de fluxo por stent multicamadas Multilayer. Apresentamos um caso de AAA sacular complexo justarrenal e com alto risco cirúrgico pela avaliação cardiológica e por apresentar via aérea difícil, em decorrência de laringectomia total por antecedente de neoplasia de laringe. Devido à facilidade técnica do uso do Multilayer, à presença de doença obstrutiva crônica aorto-ilíaca, à estenose ostial renal e ao diâmetro limitado da aorta suprarrenal, descartaram-se as opções envolvendo endopróteses fenestradas/ramificadas ou técnicas envolvendo próteses paralelas, pela necessidade de diversos acessos para a execução. Diante do dilema imposto, apresentamos este caso como desafio terapêutico e com uma opção de tratamento bem sucedida, em curto prazo...

Endovascular Stent-Graft Placement and Secondary Intervention for Abdominal Aortic Aneurysm in a Patient who had a Previously Inserted Iliac Stent

Endovascular repair of abdominal aortic aneurysm is associated with low morbidity and mortality rates when compared to open surgery, and this can be used in patients who are at a high risk for open surgical repair. Also, secondary intervention is an important for achieving intermediate and long term success of endovascular repair of abdominal aortic aneurysm as this can resolve complications. We report here on endovascular stent-graft placement and a secondary interventional procedure in the abdominal aortic aneurysm of a patient who had a previously inserted iliac stent.

Multi-detector CT angiography for the assessment of anterior spinal artery and artery of Adamkiewicz patency in patients suspected of having thoracic aortic pathology / 老年心脏病学杂志（英文版）

Objective To evaluate the visualization of the anterior spinal artery (ASA) and the artery of Adamkiewicz (AKA) as well as the affecting factors for the detection rate using multidetector row CT (MDCT). Methods Ninety-nine consecutive patients (31 women and 68 men; age range, 25-90 years; average age 61.3 years) with suspicion for thoracic aortic lesions necessitating surgical intervention (31 aortic aneurysm, 45 dissection, 5 intramural hematoma, and 18 normal), underwent 16-slice MDCT angiography from the aortic arch to the aortic bifurcation. Transverse sections, multiplanar reformations (MPR) and thin maximum intensity projections (MIP) were used to assess the ASA and AKA. The level of the ASA and AKA origins and CT acquisition parameters were recorded. The contrast-to-noise ratio (CNR) of the image, an index of the mass of the T11 body (vertebral mass index), the subcutaneous fat thickness,and the CT value within the aortic arch and at the T11 level were measured. The detection of the ASA and AKA was evaluated relative to the acquisition parameters, scan characteristics, and aortic lesion type. Differences were assessed with Wilcoxon rank-sum and t tests. Results The ASA was visualized in 51 patients (52%) and the AKA in 18 patients (18 %). The ASA was identified in 36/67 (54%)patients with 1.25 mm thickness and in15/32 (47%) patients with 2.5-3.0 mm thickness. This difference did not achieve significance (P=0.13). The detection rate of the ASA and the AKA was influenced by vertebral mass index and the CNR (P＜0.05). The amount of subcutaneous fat affected the detection rate of the ASA (P＜0.05) but not the AKA. In CT scans with ASA detection, the mean CT values in the aorta at the arch and at T11 were 360 and 358 HU, respectively; whereas in CT scans without ASA detection, the CT values in the aorta at the arch and at T11 were lower (297 and 317 HU, respectively; both P＜0.05). Conclusion The ASA and AKA were less frequently detected in our cohorts than previous reports. The visualization of the ASA and AKA was significantly affected by aortic enhancement, the vertebral mass index, and the CNR.

Aortocaval Fistula Complicating Abdominal Aortic Aneurysm: A Case Report

Aortocaval fistula is a rare complication arising from an abdominal aortic aneurysm. A typical feature observed during the arterial phase of contrast-enhanced CT scanning in such patients is simultaneous enhancement of the dilated inferior vena cava and aorta. Awareness of the specific radiologic features of aortocaval fistula may facilitate diagnosis when the condition is unsuspected clinically. We report a case of aortocaval fistula secondary to abdominal aortic aneurysm, and review the previous literature.

Clinical Application of Stent-Graft Using Gianturco Stent and Poly-tetra-fluoro ethylene (PTFE) in AorticAneurysm

PURPOSE: To evaluate the effectiveness of treatment of aortic aneurysm with endoluminal stent-grafts usingGianturco stent and poly-tetra-fluoro ethylene (PTFE). MATERIALS AND METHODS: In ten patients with aorticaneurysm, eleven procedures were performed using tubular (n=7) or bifurcated (n=4) Gianturco Z-stents covered withPTFE to treat aortic disease (six atherosclerotic aortic aneurysms, four pseudoaneurysms of abdominal aorta inthree patients with Behcet's disease, and one penetrating atherosclerotic ulcer). Spiral CT angiography was usedfor follow-up from 14 days to 31 months (mean, 12 months). The effectiveness of stent-grafts was evaluated duringfollow-up. RESULTS: In all cases, implantation of stent-grafts was technically successful ; in five, perigraftleakage was detected on completion of aortography. On initial post-procedural CT images obtained 4 - 24 days afterinsertion of the stent-graft, complete thrombosis of the aneurysm was seen in seven cases and perigraft leakage infour. Two of the four cases in which leakage was seen on initial CT improved spontaneously during follow-up.Procedure-related thromboembolism occurred in one case, which was managed by thrombolytic therapy without residualsequelae. During follow-up CT, the size of aortic aneurysms of atherosclerotic disease did not change. Thepseudoaneurysms of Behcet's disease decreased and eventually completely disappeared, with only residual periaorticsoft tissue. CONCLUSION: For the treatment of aortie diseases, stent grafting using a Gianturco stent and PTFE isclinically feasible, safe, and effective.

Endovascular Treatment of Abdominal Aortic Aneurysm by Bifurcated Stent Graft

PURPOSE: To evaluate the effectiveness and safety of endoluminal bifurcated stent graft for the treatment of AAA. MATERIALS AND METHODS: Between August 1997 and August 1998, 20 patients with AAA underwent treatment involving the use of a bifurcated stent graft. Fourteen in whom the aneurysm involved only bifurcation and six patients in whom the common iliac arteries were involved. For one patient, a stent with a short proximal neck measuring 12 mm was used. The stent graft was inserted by means of a unilateral surgical femoral arteriotomy. After the procedure, follow up involving CT and aortography was performed between month 3 and month 12. RESULTS: The primary success rate with the first trial was 79 percent (15 of 19 patients), and the overall success rate was 84 percent; one perigraft leak was successfully corrected. In one case, technical failure occurred due to a tortuous iliac vessel and spasm. Procedure-related complications occurred in 16% of patients (3 of 19), one of whom died due to acute renal failure following a contrast overdose. CONCLUSION: Endovascular treatment of infrarenal AAA by means of a bifurcated stent graft was effective and safe. In particular, if the proximal neck measured more than 1cm, any AAA could be treated using bifurcated stent graft. Further investigation of the outcome and complications arising during long-term follow-up are needed, however.

A Suggestion of New Integrated Prognostic Factor for Aortic Aneurysm: Ta n gential Stress Index

PURPOSE: To construct a useful index for use as a prognostic factor in cases of aortic aneurysm. MATERIALS AND METHODS: Using CT or EBT, we studied nine ruptured aortic aneurysms, 40 unruptured aneurysms, and 42 normalaortas, measuring aortic diameter and wall thickness. Systolic, mean or diastolic blood pressure was used as apressure parameter. Tangential stress(TS) and the tangential stress index ( TSI) were calculated by modified Laplace's law. RESULTS: Average diastolic TS's (TSI's) were 1938 (4.13), 905 (1.84) and 554 (0.94) in rupturedaneurysm, unruptured aneurysm and normal groups, respectively (p<0.01). ROC curves of diastolic TS and TSI wereseen in a "useful study" zone. With a threshold of 1230 (2.90) for TS (TSI), the sensitivity and thespecificity for differentiation of ruptured and unruptured aneurysms were 100% (100%) and 75% (88%), and thepositive and the negative predictive values were 47% (64%) and 100% (100%), respectively (p<0.01). Amongsystolic, mean and diastolic TS 's and TS I 's, the diastolic TSI showed the highest specificity at its maximalsensitivity. CONCLUSION: Diastolic TSI is a more accurate prognostic factor for aortic aneurysm.

Aortic Arch Aneurysm: CT and MR Features

PURPOSE: The purpose of this study was to evaluate the CT and MR features of aortic arch aneurysms and todetermine the differences between involved segments and morphologic types according to their causes. MATERIALS AND METHODS: Twenty-nine patients with aortic arch aneurysms who underwent CT scanning(n=24) and/or MR imaging(n=16)were retrospectively evaluated. The aneurysms were analyzed with respect to location of involved segment,morphology, direction and size, and morphologic differences between aneurysms were compared according to causes. RESULTS: The causes of arch aneurysms were atherosclerosis in 25 patients(86%), trauma in three (10%) and infection in one (4%). Arch aneurysms were frequently located at the arch only(n=17,59%), ascending aorta toarch(n=6,21%), arch to descending aorta(n=4,14%), or ascending aorta to descending aorta(n=2,7%). The shape of theaneurysm was fusiform in 15 patients and saccular in 14. Atherosclerotic aneurysms(n=25) were fusiform in 15patients and saccular in ten. Arch aneurysms due to trauma and infection(n=4) were saccular. MRI was more helpfulthan CT scanning involved site, direction, and morphology of the aneurysm. CONCLUSION: Bothe CT scanning and MRIeasily diagnose arch aneurysms, though MRI is a very useful imaging modality for evaluating involved aorticsegments and morphologic types. Aortic arch aneurysms are either fusiform or saccular. Most saccular aneurysmsinvolve the aortic arch, whereas the involvement of fusiform aneurysms is more varied. Atherosclerosis is the mostcommon cause of both fusiform and saccular arch aneurysms.

Various Complications of Abdominal Aortic Aneurysm: CT Findings

PURPOSE: To evaluate on abdominal CT the type and incidence of various complications of abdominal aortic aneurysm (AAA). MATERIALS AND METHODS: Twenty six suspected cases of AAA were confirmed by operation(n=21) and by CT(n=5). The etiology, size, shape and incidence of various complications of AAA were then retrospectively evaluated. In addition, post-operative complications were also evaluated in five cases. RESULTS: The etiology ofthe aneurysm was atherosclerotic in 18 cases and mycotic in three ; it showed the presence of Behcet disease in three cases, of tuberculosis in one, and of Marfan syndrome in one. Among the 18 fusiform AAA, the mean maximum diameter of ruptured AAA(7.5+/-3.3cm, n=3) was significantly larger than that of unruptured AAA(4.9+/-1.6cm, n=15)(p<0.05). The saccular type was much more likely to rupture than the fusiform type(p<0.00001). Out of the eight saccular AAA, seven ruptured ; their mean maximum diameter was 3.9+/-1.3cm This was significantly smaller than that of ruptured fusiform aneurysm(p<0.05). The most common complication was rupture, and occurred ten of 26 cases(38%). Others included hydronephrosis in three cases, bowel infarction in one, and perianeurysmal retroperitoneal fibrosis in one case. Various post-operative complications developed in five patients ; these comprised periprosthetic pseudoaneurysm with hematoma (two cases), bowel ischemia (one), focal renal infarction(one), and secondary aorticoduodenal fistula (one). CONCLUSION: The most common complication of AAA was rupture, the rate of which was much higher in the saccular type with smaller size than the fusiform type. Other various and uncommon complications were observed. CT was helpful in detecting complications arising from AAA and in planning its treatment.

Various Complications of Abdominal Aortic Aneurysm: CT Findings

PURPOSE: To evaluate on abdominal CT the type and incidence of various complications of abdominal aortic aneurysm (AAA). MATERIALS AND METHODS: Twenty six suspected cases of AAA were confirmed by operation(n=21) and by CT(n=5). The etiology, size, shape and incidence of various complications of AAA were then retrospectively evaluated. In addition, post-operative complications were also evaluated in five cases. RESULTS: The etiology ofthe aneurysm was atherosclerotic in 18 cases and mycotic in three ; it showed the presence of Behcet disease in three cases, of tuberculosis in one, and of Marfan syndrome in one. Among the 18 fusiform AAA, the mean maximum diameter of ruptured AAA(7.5+/-3.3cm, n=3) was significantly larger than that of unruptured AAA(4.9+/-1.6cm, n=15)(p<0.05). The saccular type was much more likely to rupture than the fusiform type(p<0.00001). Out of the eight saccular AAA, seven ruptured ; their mean maximum diameter was 3.9+/-1.3cm This was significantly smaller than that of ruptured fusiform aneurysm(p<0.05). The most common complication was rupture, and occurred ten of 26 cases(38%). Others included hydronephrosis in three cases, bowel infarction in one, and perianeurysmal retroperitoneal fibrosis in one case. Various post-operative complications developed in five patients ; these comprised periprosthetic pseudoaneurysm with hematoma (two cases), bowel ischemia (one), focal renal infarction(one), and secondary aorticoduodenal fistula (one). CONCLUSION: The most common complication of AAA was rupture, the rate of which was much higher in the saccular type with smaller size than the fusiform type. Other various and uncommon complications were observed. CT was helpful in detecting complications arising from AAA and in planning its treatment.