Nature and significance of endoleaks and endotension: summary of opinions expressed at an international conference

OBJECTIVE: Endoleaks and endotension are critically important complications of some endovascular aortic aneurysm repairs (EVARs). For the resolution of controversial issues and the determination of areas of uncertainty relating to these complications, a conference of 27 interested leaders was held on November 20, 2000. METHODS: These 27 participants (21 vascular surgeons, five interventional radiologists, one cardiologist) had previously answered 40 key questions on endoleaks and endotension. At the conference, these 40 questions and participant answers were discussed and in some cases modified to determine points of agreement (consensus), near consensus (prevailing opinion), or disagreement. RESULTS: Conference discussion added two modified questions for a total of 42 key questions for the participants. Interestingly, consensus was reached on the answers to 24 of 42 or 57% of the questions, and near consensus was reached on 14 of 42 or 33% of the questions. Only with the answers to four of 42 or 10% of the questions was there persistent controversy or disagreement. CONCLUSION: The current endoleak classification system with some important modifications is adequate. Types I and II endoleak occur after 0 to 10% and 10% to 25% of EVARs, respectively. Many (30% to 100%) type II endoleaks will seal and have no detrimental effect, which never or rarely occurs with type I endoleaks. Not all endoleaks can be visualized with any technique, and increased pressure (endotension) can be transmitted through clot. Aneurysm pulsatility after EVAR correlates poorly with endoleaks and endotension. An enlarging aneurysm after EVAR mandates surgical or interventional treatment. These and other conclusions will help to resolve controversy and aid in the management of these vexing complications and should also point the way to future research in this field.     

The significance and management of different types of endoleaks

Development of endovascular abdominal aortic aneurysm repair (EVAR) has been accompanied by previously unencountered complications. The most challenging but least understood of these complications is the incomplete seal of the endovascular graft (endoleak), a phenomenon that has a variety of causes. An important consequence of endoleakage may be persistent pressurization of the aneurysm sac, which may ultimately lead to post-EVAR rupture. Data of 110 European centers were recorded in a central database (EUROSTAR). Patient, anatomic characteristics, and operative and device details were correlated with the occurrence of different types of endoleaks. Outcome events during follow-up, particularly expansion of the aneurysm, incidence of conversion to open repair, and post-EVAR rupture were assessed in the different categories of endoleaks and in a group of patients without any endoleak. Type I and III endoleak were associated with an increased frequency of open conversions or risk of rupture of the aneurysm. Device-related endoleaks also correlated with an increased need for secondary interventions. These types of endoleaks need to be treated without delay, and when no other possibilities are present, an open conversion to avert the risk of rupture should be considered. Type II endoleaks do not pose an indication for urgent treatment. However, they may not be harmless, because there was a frequent association with enlargement of aneurysm and reinterventions. Our findings suggest that more frequent surveillance examinations are indicated than in patients without collateral endoleak. The indication for intervention is primarily dictated by documented expansion of the aneurysm.     

A canine model to study the significance and hemodynamics of type II endoleaks

OBJECTIVE: The clinical significance of Type 2 endoleak after endovascular repair of abdominal aortic aneurysms (AAA) remains incompletely delineated. This study describes the development of a novel canine model that allows for continuous monitoring of intraaneurysmal pressure in the setting of Type 2 endoleak. METHODS: Infrarenal AAA were created in 10 mongrel dogs by implanting a prosthetic aneurysm containing an intraluminal, solid-state, strain gauge pressure transducer which is able to measure pressures in both solid and liquid media. A segment of native aorta with two or more patent side branch vessels was reimplanted into the prosthetic aneurysm using a Carrel patch. Four animals had two lumbar vessels implanted; two had two lumbar vessels and the caudal mesenteric artery implanted, and four control animals had no vessels reimplanted. Retrograde flow in the aneurysmal side branches caused a Type 2 endoleak after the aneurysm was excluded from antegrade flow by deploying a stent graft. Both systemic and intra-sac pressures were measured daily for up to 90 days after endovascular exclusion and indexed to systemic pressure. Endoleak patency and flow were assessed with digital subtraction angiography, duplex ultrasound, and cine-magnetic resonance angiography (MRA). Histological characterization of the intraaneurysmal contents was performed. RESULTS: Before endovascular exclusion, the systolic, mean arterial, and pulse pressure within the aneurysmal sac closely matched that of the systemic circulation (systolic, 0.96 +/- 0.22; mean, 0.94 +/- 0.21; pulse pressure, 0.97 +/- 0.22) (R value, 0.97). Endovascular exclusion in animals with no collateral side branch vessels resulted in no endoleak and significantly reduced intraaneurysmal pressure when compared to systemic pressure, with systolic, mean arterial, and pulse pressure 0.172 +/- 0.05, 0.137 +/- 0.05, and 0.098 +/- 0.02, respectively (P < 0.001). In animals with Type 2 endoleaks, the pressures were lower than systemic pressure, but statistically significant in their difference from the control group. The systolic pressure of those with Type 2 endoleaks was 0.702 +/- 0.048; mean arterial pressure was 0.784 +/- 0.028, and pulse pressure was 0.406 +/- 0.031 when indexed to systemic pressure (P < 0.001). Cine-MRA and Duplex ultrasound documented persistent patency of the Type 2 endoleaks throughout the study period in animals with multiple side branches. CONCLUSION: Intraaneurysmal pressure in the setting of Type 2 endoleaks may be accurately determined using this canine model. Intraaneurysmal pressure is maintained at a significant level in the context of this retrograde collateral perfusion, suggesting that persistent Type 2 endoleaks are of clinical significance. This model may serve to allow further evaluation and characterization of Type 2 endoleaks.     

胸主动脉夹层腔内隔绝术后内漏的分型及意义

目的 探讨胸主动脉夹层腔内隔绝术后内漏的分型及其意义。方法 97例主动脉夹层行腔内隔绝术。移植物释放定位成功后进行主动脉DSA，术后7－10天行螺旋CT，分别评估内漏的来源及量的多少，决定内漏的处理。近端多量内漏时，在近端附加延伸移植物置入，少量内漏暂不处理；移植物针孔内漏暂不处理；远端内漏根据量的多少决定处理方式。结果 12例近端内漏中，10例多量内漏经附加延伸移植物将内漏封闭，2例少量近端内漏未处理。5例远端反流及针孔内漏均在观察中。结论 根据内漏的来源，可将内漏分成4型，正确分型将有利于判断、处理以及规范化统计比较。     

���������в�ǻ�ڸ���������©�ķ��ͼ�����

目的探讨胸主动脉夹层腔内隔绝术后内漏的分型及其意义.方法 97例主动脉夹层行腔内隔绝术.移植物释放定位成功后进行主动脉DSA,术后7～10天行螺旋CT,分别评估内漏的来源及量的多少,决定内漏的处理.近端多量内漏时,在近端附加延伸移植物置入,少量内漏暂不处理;移植物针孔内漏暂不处理;远端内漏根据量的多少决定处理方式.结果 12例近端内漏中,10例多量内漏经附加延伸移植物将内漏封闭,2例少量近端内漏未处理.5例远端反流及针孔内漏均在观察中.结论根据内漏的来源,可将内漏分成4型.正确分型将有利于判断、处理以及规范化统计比较.     

Algorithm for the diagnosis and treatment of endoleaks.

BACKGROUND: Endoluminal grafting of abdominal aortic aneurysms (AAA) has shown promising early results. However, endoleaks present a new and challenging obstacle to successful aneurysm exclusion. We report our experience with primary, persistent endoleaks and provide an algorithm for their diagnosis and management. METHODS: Over a 19-month period, 73 patients underwent endoluminal repair of their AAAs using a modular bifurcated endograft as part of a US FDA Investigational Device Exemption trial. Spiral computed tomography (CT) scanning was performed prior to discharge after repair to evaluate for complete aneurysm exclusion. If no endoleak was present on that initial CT scan, color-flow duplex scanning was performed at 1 month, with repeat CT scanning at 6 months and 1 year. If the initial CT scan revealed the presence of an endoleak, repeat CT scanning was performed at 2 weeks, 1 month, and 3 months, or until the endoleak resolved. Any patient with an endoleak that persisted beyond 3 months underwent angiographic evaluation to localize the source of the leak. RESULTS: At 1 month, 62 patients (85%) had successful aneurysm exclusion. The remaining 11 patients (15%) had primary endoleaks, 8 (11%) of which persisted beyond 3 months, prompting angiographic evaluation. In 2 patients the endoleak was related to a graft-graft or graft-arterial junction. One was from the endograft terminus in the common iliac artery and was successfully embolized, along with its outflow lumbar artery. The other required placement of an additional endograft component across a leaking graft-graft junction to successfully exclude the aneurysm. The remaining six endoleaks were due to collateral flow through the aneurysm sac. In 4 cases this was lumbar to lumbar flow fed by hypogastric artery collaterals to the inflow lumbar artery. In the remaining 2 patients the endoleak was found to be due to flow between a lumbar and inferior mesenteric artery. Resolution of the endoleak by coil embolization of the feeding hypogastric artery branch in 1 patient was unsuccessful due to rapid recruitment of another hypogastric branch. Two of the six collateral flow endoleaks have resolved spontaneously without treatment, while the remaining cases have been followed up without evidence of aneurysm expansion. CONCLUSION: Systematic postoperative surveillance facilitates proper diagnosis and treatment of endoleaks. This involves serial CT scans to detect the presence of endoleaks, followed by angiography to determine their etiology and guide treatment, if clinically indicated.     

Imaging modalities for the detection and management of endoleaks

Although endovascular aneurysm repair (EVAR) has shown promising initial results, there are unique complications to this procedure. Endoleaks, which do not occur after traditional surgical repair of abdominal aortic aneurysms, are detected in patients undergoing EVAR and are thought by some to be one of the limitations of this procedure. Endoleaks may continue to perfuse and pressurize the aneurysm sac, thereby conferring an ongoing risk of aneurysm enlargement and/or rupture. Because of this, accurate endoleak detection and classification is essential following EVAR. Surveillance of patients is critical to determine the long-term performance of the stent grafts. Although this is usually accomplished with contrast-enhanced spiral computed tomography scans performed at regular intervals, duplex ultrasonography exams; magnetic resonance angiography; and digital subtraction angiography all have a role in endoleak detection and classification. This article will cover imaging modalities used to detect endoleaks. In addition, we will cover which imaging exams should be performed to help with endoleak management.     

Glycemic Control of Surgical Patients. What is Correct,What is Not

Perioperative hyperglycemia is very common among critically ill patients with or without diabetes mellitus (DM). Perioperative elevated levels of blood glucose (BG) have been linked with increases in morbidity, infections, anastomotic failure, autoimmune dysfunction, and raised mortality and prolongation of hospitalization. A variety of different approaches have been taken for the control of BG in the perioperative period, and different methods of measurement have been proposed, among which, point of care (POC) meters, arterial blood gas analysis and venous plasma analysis prevail. The aim of this literature review was to provide evidence-based answers as to how BG levels should be monitored. We conclude that more conservative glycemic control is preferable to “tight glycemic control” (TGC), in order to avoid complications associated with episodes of hypoglycemia.