John A. Brennan

Endotension after endovascular aneurysm repair: definition, classification, and strategies for surveillance and intervention.

In the ongoing evolution of a categorization system for endoleak, the authors propose the term endotension to define persistent or recurrent pressurization of the aortic aneurysm sac after endovascular repair. Endotension is evidence that the aneurysm remains at risk of rupture and should, therefore, be considered an indication for secondary intervention. Management strategies and a grading system for endotension are offered.

Longitudinal aneurysm shrinkage following endovascular aortic aneurysm repair: a source of intermediate and late complications.

PURPOSE To report the incidence of delayed complications following endovascular abdominal aortic aneurysm (AAA) repair and the relationship of these sequelae to morphological changes in the sac and endograft. METHODS Twenty-six AAA patients treated with Vanguard endografts had completed > or = 1-year follow-up. Postoperative angiograms and spiral computed tomographic (CT) scans with 3-dimensional reconstruction were compared to the 1-year images to determine morphological changes in the aneurysm sac and the endograft. These changes were then related to complications occurring between 1 and 12 months postoperatively in the study group. RESULTS Comparison of angiograms uncovered endograft buckling in 18 (69%) patients and acutely angled or kinked endografts in 10 (38%). Measurements from the CT scans found that undistorted endografts had a mean change in sac length of +6.6 mm. Mean sac length change in buckled endografts was -3.1 mm, while kinked endografts displayed a mean change of -6.2 mm (p < 0.002, Students t-test). Five (19%) patients, all with distorted endografts, demonstrated late (1 to 12 months) complications (4 endoleaks and 1 graft limb thrombosis) owing to component separation, distal stent migration, and acute angulation. No movement in the proximal stent was observed. Elongation of the endograft (flow line measurement) was observed in one tube graft only. CONCLUSIONS In this study, longitudinal shrinkage of the sac following endovascular aortic aneurysm repair led to buckling or kinking of the endograft within 1 year in 69% of patients. This appears to be an important source of delayed complications.

Fenestrated endovascular repair for juxtarenal aortic aneurysm.

The outcome of fenestrated endovascular aneurysm repair (F‐EVAR) was evaluated.

Detection of Endoleak with Enhanced Ultrasound Imaging: Comparison with Biphasic Computed Tomography

Purpose: To compare unenhanced and enhanced ultrasound imaging to biphasic computed tomography (CT) in the detection of endoleak after endovascular abdominal aortic aneurysm (AAA) repair. Methods: Fifty-three patients (44 men; mean age 70 years) were examined during 96 follow-up visits after endovascular AAA repair. All patients had color Doppler and power Doppler ultrasound studies performed before and after the administration of an ultrasound contrast agent. Biphasic (arterial and delayed) CT was performed on the same day, and the ultrasound and CT studies were independently scored to record the presence or absence of endoleak and the level of confidence in the observation. Results: The sensitivity of the ultrasound techniques to detect endoleak improved with the use of ultrasound contrast media, ranging from a low of 12% with unenhanced color Doppler to 50% with enhanced power Doppler. However, the enhanced power Doppler failed to detect 9 type II endoleaks identified by CT (86% negative predictive value for endoleak). There were only 2 graft-related endoleaks in the study; one was diagnosed from the ultrasound image, but the other had nondiagnostic ultrasound scans because of poor views. Conclusions: Ultrasound scanning with or without contrast enhancement was not as reliable as CT in diagnosing type II endoleak. CT imaging remains our surveillance modality of choice.

Early Results of Fenestrated Endovascular Repair of Juxtarenal Aortic Aneurysms in the United Kingdom

Background— Fenestrated endovascular repair of abdominal aortic aneurysms has been proposed as an alternative to open surgery for juxtarenal and pararenal abdominal aortic aneurysms. At present, the evidence base for this procedure is predominantly limited to single-center or single-operator series. The aim of this study was to present nationwide early results of fenestrated endovascular repair in the United Kingdom. Methods and Results— All patients who underwent fenestrated endovascular repair between January 2007 and December 2010 at experienced institutions in the United Kingdom(>10 procedures) were retrospectively studied by use of the GLOBALSTAR database. Site-reported data relating to patient demographics, aneurysm morphology, procedural details, and outcome were recorded. Data from 318 patients were obtained from 14 centers. Primary procedural success was achieved in 99% (316/318); perioperative mortality was 4.1%, and intraoperative target vessel loss was observed in 5 of 889 target vessels (0.6%). The early reintervention (<30 days) rate was 7% (22/318). There were 11 deaths during follow-up; none were aneurysm-related. Survival by Kaplan–Meier analysis was 94% (SE 0.01), 91% (0.02), and 89% (0.02) at 1, 2, and 3 years, respectively. Freedom from target vessel loss was 93% (0.02), 91% (0.02), and 85% (0.06), and freedom from late secondary intervention (>30 days) was 90% (0.02), 86% (0.03), and 70% (0.08) at 1, 2, and 3 years. Conclusions— In this national sample, fenestrated endovascular repair has been performed with a high degree of technical and clinical success. Late survival and target vessel patency are satisfactory. These results support continued use and evaluation of this technique for juxtarenal aneurysms, but illustrate the need for a more robust evidence base.

Heterogeneity of tensile strength and matrix metalloproteinase activity in the wall of abdominal aortic aneurysms.

Purpose: To measure the tensile strength of the aneurysm wall and the matrix metalloproteinase (MMP) activity in similar samples of aortic tissue. Methods: Detailed mechanical testing was conducted on 124 standardized specimens of aneurysm wall harvested from 24 patients undergoing elective aneurysm repair. The intrasac pressure required to cause aneurysm rupture was calculated based upon the Law of Laplace. In addition, MMP-2 and 9 were assayed from these specimens. Sixty specimens of nonaneurysmal aorta from 6 cadaveric organ donors served as controls. Intrasubject and intersubject variations were analyzed. Results: In the aneurysm specimens, the Youngs modulus was 1.80times106 N/m2, the load at break was 6.36 N, the strain at break was 0.30, the ultimate strength was 0.53times106 N/m2, and the MMP activity was 312 for MMP-2 and 460 for MMP-9. In the controls, the circumferential measurements were a Youngs modulus of 1.82times106 N/m2, a load at break of 5.43 N, strain at break of 0.29, ultimate strength of 0.61times106 N/m2, and MMP activity of 395 for MMP-2 and 2019 for MMP-9. Longitudinal measurements in controls were a Youngs modulus of 1.38times106 N/m2, a load at break of 11.39 N, a strain at break of 0.33, and ultimate strength of 1.30times106 N/m2. Intra and intersubject variation of all parameters was very high. Based upon the lowest measured tensile strength for each aneurysm, the intrasac pressure required to cause rupture varied from 142 to 982 mmHg. Conclusions: Localized “hot spots” of MMP hyperactivity could lead to focal weakening of the aneurysm wall and rupture at relatively low levels of intraluminal pressure. These data suggest that tensile strength of the sac is just as important as intrasac tension in determining the risk of rupture. Moreover, these observations may explain why some small aneurysms rupture and larger aneurysms do not. Assessment of rupture risk based on computation or measurement of wall stress may be subject to error and inaccuracy due to variations in wall tensile strength.

Use of contrast-enhanced ultrasound in follow-up after endovascular aortic aneurysm repair

PURPOSE To investigate the use of contrast-enhanced ultrasound in the detection of endoleak after endovascular repair of abdominal aortic aneurysm. MATERIALS AND METHODS Eighteen patients underwent follow-up on 20 occasions after endovascular aortic aneurysm repair by arterial-phase contrast-enhanced spiral computed tomography (CT). All patients had unenhanced color Doppler ultrasound and Levovist-enhanced ultrasound on the same day. The ultrasound examinations were reported in a manner that was blind to the CT results. CT was regarded as the gold standard for the purposes of the study. RESULTS There were three endoleaks shown by CT. Unenhanced ultrasound detected only one endoleak (sensitivity, 33%). Levovist-enhanced ultrasound detected all three endoleaks (sensitivity, 100%). Levovist-enhanced ultrasound indicated an additional six endoleaks that were not confirmed by CT (specificity, 67%; positive predictive value, 33%). In one of these six cases, the aneurysm increased in size, which indicates a likelihood of endoleak. Two of the remaining false-positive results occurred in patients known to have a distal implantation leak at completion angiography. CONCLUSION In this small group of patients, contrast-enhanced ultrasound appears to be a reliable screening test for endoleak. The false-positive results with enhanced ultrasound may be due to the failure of CT to detect slow flow collateral pathways. Although the number of patients in this study is small, enhanced ultrasound may be more reliable than CT in detecting endoleak.

Aortic Side Branch Embolization before Endovascular Aneurysm Repair: Incidence of Type II Endoleak

PURPOSE To assess the feasibility of embolization of aortic side branches and its impact on the incidence of type II endoleak after endovascular aneurysm repair. MATERIALS AND METHODS Endovascular aneurysm repair was performed in 74 patients. Aortic side branch vessels were evaluated on the preoperative angiogram and computed tomography (CT) and, where embolization of lumbar and inferior mesenteric vessels was considered technically possible, this was attempted prior to endovascular repair. Follow-up CT was used to assess the presence of type II endoleak. RESULTS Seventy-two patients were followed up for longer than 1 month. Embolization was attempted in 25 cases, successfully in 10, with partial success in 11, and failure in four. Twenty patients with successful or partly successful preoperative embolization were discharged and followed-up. Four (20%) had demonstrable type II endoleak during follow-up, with two of these persisting at latest follow-up. Of 43 patients without previous embolization, there were 10 (23.3%) type II endoleaks during the follow-up period, four of these persisting. In cases with type II endoleak, mean sac diameter change was -0.5 mm in the cases with previous embolization and +3.1 mm without. The mean period to onset of type II endoleak was 6.9 months without, and 15.3 months with, previous embolization. CONCLUSION Although the cohort size is below a level that would confer significance, the trend of these findings is such as to suggest a lack of influence of aortic side branch embolization on the incidence of type II endoleak during the follow-up period.

Endoluminal repair of internal carotid artery aneurysm: A feasible but hazardous procedure

PURPOSE The aim of this study was to report the repair of an aneurysm of the internal carotid artery using the endoluminal method. METHODS A 70-year-old male patient noted a swelling in the right side of his neck 22 years after endarterectomy of the right internal carotid artery. Duplex ultrasound confirmed the clinical diagnosis of aneurysm of the internal carotid artery. Further investigation included contrast-enhanced computed tomographic (CT) scanning and carotid angiography performed via a retrograde femoral approach. The aneurysm contained thrombus and was 3 cm in diameter and in length. It extended superiorly from a point 0.5 cm above the carotid bifurcation to a point estimated to be 2 cm from the base of the skull. Repair of the aneurysm was undertaken using the endoluminal method. A self-expanding endograft 8 mm in diameter and 4 cm in length was introduced through a 12F sheath in the common carotid artery. An on-table completion angiogram of the right-sided extracranial carotid arteries and the intracranial internal carotid artery and branches was obtained. RESULTS The completion angiogram and postoperative CT scan confirmed exclusion of the aneurysm sac from the circulation. The patient awoke from anesthesia with complete paralysis of the left arm. Recovery of movement commenced 1 hour later. A brain CT scan demonstrated the event to be an embolic stroke. Strength had returned by 7 days. Function of the arm was good 1 month after operation, but coordination for fine movements was lacking. At the 6-month follow-up, good arm function was maintained. A duplex ultrasound scan demonstrated not only continued exclusion of the aneurysm sac but occlusion of the endograft, also. CONCLUSIONS Endoluminal repair of aneurysms of the internal carotid artery is feasible but carries the risk of major morbidity as a result of peripheral embolization and early occlusion of the endograft.

Late complications after ligation and bypass for popliteal aneurysm

Ligation and bypass is standard treatment for popliteal aneurysm. This technique does not abolish collateral circulation to the aneurysm, which may continue to expand and/or rupture. This study assessed whether complete thrombosis of the aneurysm sac occurs after operation and examined the long‐term clinical outcome.