Color-flow duplex ultrasound scan versus computed tomographic scan in the surveillance of endovascular aneurysm repair.

OBJECTIVE: The purpose of this study is to compare both computed tomographic scan (CT) and color flow duplex ultrasound scanning (CDU) as surveillance modalities for clinically significant endoleaks and to evaluate concordance in abdominal aortic aneurysm (AAA) diameter measurements in patients after endovascular aneurysm repair (EVAR) in a busy hospital vascular laboratory. METHODS: We conducted a retrospective review of all patients who underwent endovascular repair of abdominal aortic aneurysms between February 1996 and November 2002 and had same-day CT and CDU studies. Ninety-seven patients enrolled in phase II clinical studies of Ancure devices had long-term follow-up with both modalities. The other patients underwent simultaneous studies, usually only at the 1-month postoperative visit. Peripheral vascular studies were performed by two certified vascular technicians; all CT scans were reviewed by one vascular surgeon. CT was used as the standard against which the sensitivity, specificity, negative predictive value, and positive predictive value of CDU in endoleak detection was determined. Statistics were performed by using the paired t test; a P value <.05 was considered significant. Kappa statistic was used to assess the correlation between CDU and CT in identifying endoleaks. The correlation between CT and CDU in AAA size measurements as well as in serial size measurements was also determined. RESULTS: Four hundred ninety-five same-day CT and CDU examinations were reviewed in 281 patients. Patients had an average follow-up of 34.6 months (range, 1 to 72 months). Thirty-five leaks were identified among the patients studied (12.4% overall). In comparison with CT, diagnosis of endoleak with ultrasound scanning was associated with a sensitivity of 42.9%, specificity of 96.0%, positive predictive value of 53.9%, and negative predictive value of 93.9%. The correlation between the two modalities was modest (kappa statistic 0.427). The minor axis transverse diameter as measured by ultrasound and CT scans (4.81 +/- 1.1 cm on CT and 4.55 +/- 1.1 cm on ultrasound) correlated closely (r =.93, P <.001.) Seventy percent of paired studies differed by < or =5 mm. Changes in aneurysm size throughout follow-up were -.29 +/-.71 cm on CT scan -.34 +/-.57 cm on duplex ultrasound scan. The correlation coefficient was.65 (P <.001). There was no significant difference in the change as measured by either modality on the paired t test. CONCLUSIONS: Although CDU demonstrates a high degree of correlation with CT scan in determining aneurysm size change over time, it has a low sensitivity and positive predictive value in endoleak detection. In the hospital vascular laboratory at a large tertiary care center, CDU cannot effectively replace CT scan in surveillance after EVAR.

Does endograft support alter the rate of aneurysm sac shrinkage after endovascular repair?

PURPOSE: To test the hypothesis that stent-graft support influences sac shrinkage independent of endoleak rates after endovascular repair of abdominal aortic aneurysms (AAA). METHODS: Ninety AAA patients underwent treatment with bifurcated endoluminal devices at our institution between October 1996 and February 1999. Fifty-two patients were treated using a nonsupported (NS) Ancure endograft and 38 using a fully supported (FS) Excluder endograft. Computed tomographic (CT) scans were obtained during the first postoperative month and at 6, 12, and 24-month intervals. Aneurysm diameter was measured as the minor axis of the largest AAA axial slice on the CT scan. Six, 12, and 24-month sac sizes were compared to the first postoperative evaluation. RESULTS: Successful endoluminal graft placement was accomplished in all patients. The two groups were matched for age, anatomical criteria, and comorbidities except for baseline AAA size: the mean diameter was 5.4 cm in the NS group and 5.0 cm for the FS group (p<0.01). Endoleak rates were 25% (13/52) in the NS group and 18% (7/38) in the FS group (p<0.05) at 1 month. All endoleaks that did not resolve spontaneously at 6 months were treated. Initial endoleak status did not affect the sac shrinkage rates at the 12 and 24-month evaluations. At 2 years, the NS group had greater shrinkage of the sac (1.2 cm) versus the FS cohort (0.3 cm, p<0.05). In addition, more patients in the NS group had sac shrinkage >or =5 mm (83% versus 18%, p<0.05). CONCLUSIONS: Despite a higher endoleak rate, the nonsupported Dacron Ancure endografts were associated with greater sac shrinkage at up to 24 months following implantation.

Can the internal iliac artery be safely covered during endovascular repair of abdominal aortic and iliac artery aneurysms?

Aneurysmal involvement of the common iliac (CIA) or the internal iliac arteries (IIA) have been relative contraindications for safe endovascular aortic aneurysm (AAA) repair. Our goal was to review our experience in dealing with this problem by performing permanent coverage of one or both IIA during endoluminal repair of aneurysms of the aortoiliac region and to develop a safe, durable strategy. Of the 228 consecutive patients who had endoluminal repair of abdominal aortic (AAA) and iliac artery (IAA) aneurysms between 4/1999 and 4/2001 at our institution, 49 patients underwent coverage and/or coil embolization of one or both IIA during repair because of complex aortoiliac anatomy. These patients were evaluated prospectively for short-term adverse outcome. The results showed that CIA or IIA aneurysms can be managed safely during endoluminal repair of AAA. The IIA can be covered or embolized with minimum adverse consequences in patients who have inadequate CIA for deployment of the aortic or iliac endograft. Unilateral IIA occlusion is well tolerated. We advocate that whenever bilateral IIA occlusion is necessary during endovascular aneurysm repair, one of the IIAs should be revascularized if it is not aneurysmal.