Algorithm for the diagnosis and treatment of endoleaks

Follow-up evaluation of endoluminally treated abdominal aortic aneurysms with duplex ultrasonography: validation with computed tomography

OBJECTIVE

A growing number of patients with abdominal aortic aneurysms are currently being offered endoluminal treatment. However, the incidence of endoleaks, stenosis, and thrombosis is around 25% to 30%. As a result, a strict post procedure imaging surveillance protocol is necessary. The purpose of this study was to compare duplex ultrasonography (DU) and computed tomography (CT) for the follow-up of endoluminally treated aortic aneurysms.

METHODS

A total of 89 patients were followed up with serial CT and DU at 1, 3, 6, 12, and 24 months after endoluminal treatment. Special attention was directed toward the presence of endoleaks and aneurysm diameter evolution. Preoperative CT and DU were also reviewed to assess aneurysm diameter correlation.

RESULTS

With DU, 14 type I and 21 type II endoleaks were identified. In one case the DU did not visualize a type II endoleak present on CT, and CT did not confirm three type II leaks identified with DU. There was only one false positive for type I endoleak with DU. The sensitivity of DU was 96% with a specificity of 94%, when compared with CT. A linear regression analysis of the diameters obtained with DU and CT revealed a good correlation. However, variability was high, indicating poor agreement. Regarding diameter evolution, the range was identical in 45%, and the trend was similar in 73%. However, in 9% of the cases, DU showed a decrease in diameter, whereas CT showed a significant increase.

CONCLUSION

DU is an accurate tool for the diagnosis of endoleaks, but is less valuable for diameter measurements, when compared with CT. Currently, DU is a useful tool, but CT remains a key part of the postoperative evaluation after endoluminal treatment of abdominal aortic aneurysms. At institutions where DU is used for follow-up, researchers should perform quality control studies to avoid potentially significant errors.

Endovascular stent-graft in abdominal aortic aneurysms: the relationship between patent vessels that arise from the aneurysmal sac and early endoleak

PURPOSE

To determine the association of patent sac branch vessels (lumbar and inferior mesenteric arteries [IMAs]) with early endoleak rate after stent-graft repair of abdominal aortic aneurysm (AAA).

MATERIALS AND METHODS

Pre- and postoperative computed tomographic (CT) angiograms in 158 patients who underwent stent-graft AAA repair were retrospectively reviewed to determine the preoperative patency of IMAs and other sac branch vessels (feeders) and presence or absence of immediate postoperative endoleak. Relationships of early endoleak rate with total branch vessel, IMA, and lumbar artery patency and graft type were evaluated.

RESULTS

There was a significant association between patency of sac feeders and rate of early endoleak, especially type 2. As total patent feeders increased from zero to three to four to six, total endoleak rate increased from 6% (one of 17) to 35% (30 of 86); type 2 endoleak rate, from 0% to 25%. IMA patency was significantly associated with total early endoleak rate. Increasing lumbar artery patency also was associated with significantly higher total and type 2 endoleak rates: With zero to three lumbar arteries, the total endoleak rate was 17% and type 2 endoleak rate was 13%, as compared with 60% and 50%, respectively, with more than six patent lumbar arteries.

CONCLUSION

Sac branch vessel patency is associated with significantly higher early total and type 2 endoleak rates after stent-graft repair of AAAs; thus, patent sac branches play an important role in the pathogenesis of endoleaks.

Elevated plasma levels of matrix metalloproteinase-9 in patients with abdominal aortic aneurysms: a circulating marker of degenerative aneurysm disease

PURPOSE

Matrix metalloproteinase-9 (MMP-9) is abundantly expressed in abdominal aortic aneurysms (AAAs), where it plays a pivotal role in connective tissue destruction. Elevated plasma concentrations of MMP-9 (MMP-9PL) also have been reported in patients with AAAs, but it is unclear if this can distinguish patients with AAAs from those with atherosclerotic occlusive disease (AOD). The purpose of this study was to further define the utility of elevated MMP-9PL levels in the diagnosis and evaluation of AAAs, and to examine if changes in MMP-9PL can be used as a functional biomarker of degenerative aneurysm disease.

MATERIALS AND METHODS

Peripheral venous blood was obtained from 25 patients with AAAs, 15 patients with AOD, and five normal control subjects. MMP-9PL levels were determined by an enzyme-linked immunosorbent assay. In four patients undergoing open AAA repair, MMP-9PL levels were directly compared with the amount of MMP-9 produced in aortic tissue. Six additional patients undergoing operative AAA repair were followed for 3-10 months to determine how treatment affected elevated MMP-9PL concentrations.

RESULTS

Mean (+/- SE) MMP-9PL was 36.1 +/- 7.7 ng/mL in normal control subjects, 54.7 +/- 10.5 ng/mL in patients with AOD, and 99.4 +/- 17.4 ng/mL in patients with AAAs (P < .05 versus normal control subjects and patients with AOD). Elevated MMP-9PL levels (> 87.8 ng/mL) were found in 12 of 25 (48%) patients with AAA but in only one of 15 (7%) patients with AOD (P < .05). MMP-9PL levels did not correlate significantly with either age, gender, or aneurysm diameter, although there was a trend toward the highest values in male patients with large AAAs. Production of MMP-9 in aneurysm tissues paralleled MMP-9PL levels, and elevated MMP-9PL levels decreased by 92.7% +/- 3.2% after surgical AAA repair.

CONCLUSIONS

Elevated MMP-9PL levels were observed in approximately one half of patients with AAAs and less than 10% of those with AOD (positive predictive value of 92.3%), but normal MMP-9PL levels had limited utility in excluding the presence of an aortic aneurysm (negative predictive value, 52%). MMP-9PL levels in patients with AAAs appeared to directly reflect the amount of MMP-9 produced within aneurysm tissue, and MMP-9PL levels decreased substantially after aneurysm repair. Measures of circulating MMP-9 may provide a biologically relevant marker of connective tissue metabolism in patients with AAAs.

Adverse consequences of internal iliac artery occlusion during endovascular repair of abdominal aortic aneurysms

OBJECTIVE

Embolization of the internal iliac artery (IIA) may be performed during endovascular abdominal aortic aneurysm (AAA) repair if aneurysmal disease of the common iliac artery precludes graft placement proximal to the IIA orifice. The IIA may also be unintentionally occluded because of iliac trauma or coverage by the endograft. The purpose of this study was to determine the incidence, etiology, and consequences of IIA occlusion during endoluminal AAA repair.

METHODS

Over 2 years, 96 patients have undergone endoluminal AAA repair. The details of the operative procedure, reasons for IIA occlusion, perioperative complications, and clinical follow-up were recorded.

RESULTS

The IIA was intentionally occluded in 15 patients (16%) to treat 13 common iliac artery aneurysms, one IIA aneurysm, and one external iliac artery aneurysm. The IIA was unintentionally occluded in 9 patients (9%), resulting from traumatic iliac dissection in 5 patients and coverage of the IIA by the endograft in the remaining 4 patients. Three patients had colon ischemia. One patient with a unilateral IIA occlusion had sigmoid infarction necessitating resection. The other two patients underwent intentional occlusion of one IIA followed by unintentional occlusion of the contralateral IIA because of a traumatic iliac dissection. Both had postoperative abdominal pain and distention; rectosigmoid ischemia was revealed through colonoscopy. Conservative treatment with bowel rest and broad-spectrum antibiotics was successful in both cases. Nondisabling hip and buttock claudication occurred in seven patients (32%) at 1 month but resolved by 6 months in three of these patients.

CONCLUSION

Embolization of the IIA for iliac aneurysmal disease and unintentional IIA occlusion due to trauma or graft coverage occurs in a considerable number of patients undergoing endoluminal AAA repair. Most patients with unilateral occlusion do not experience colon ischemia or disabling claudication. Therefore, unilateral embolization of the IIA is well tolerated and allows for the endoluminal treatment of patients with both an AAA and an iliac artery aneurysm, thereby expanding the number of patients who can be managed with an endovascular approach. Although acute, bilateral IIA occlusions should be avoided, significant consequences were not observed in our small series of patients.