Boonprasit Kritpracha

Aortic diameter is an insensitive measurement of early aneurysm expansion after endografting.

Purpose: To determine the sensitivity of various methods of diameter measurement to detect abdominal aortic aneurysm (AAA) size change following endovascular grafting. Methods: Sixty-eight patients (59 men; mean age 68 years, range 47–84) with 3-dimensional reconstruction of 196 computed tomography (CT) studies (68 preoperative, 128 follow-up) were studied. Implanted devices included 50 bifurcated and 18 straight stent-grafts. All diameter measurements were obtained from reformatted CT slices perpendicular to the center of blood flow. Three diameter measurements were made for each study: (1) transverse (TR), (2) anteroposterior (AP), and (3) maximum diameter in any orientation (Dmax). Volume measurements were calculated from the lowest main renal artery to the aortic bifurcation. Changes in diameter and volume were determined by subtracting follow-up measurements from preop measurements. Diameter and volume changes >5 mm and 10%, respectively, were considered significant. Results: AAA volume significantly increased in 20 (15%) studies, decreased in 84 (66%), and remained unchanged in 24 (19%). Agreement between methods of diameter measurement (TR, AP, Dmax) and volume change were 35%, 15%, and 25% for volume increase >10%, respectively, and 70%, 88%, and 74%, respectively, for volume decrease >10%. The orientation of maximum diameter varied in individual serial exams in 19 (28%) patients. Three of 12 patients with a study showing volume increase failed to demonstrate endoleak. Conclusions: Diameter measurements were not sensitive in detecting enlarging AAA after endografting. Volume measurement determined by 3D reconstruction is the preferred method for early diagnosis of patients with enlarging AAA that may indicate increased risk of rupture after aortic endografting.

Predictive factors for limb occlusions after endovascular aneurysm repair

OBJECTIVE Greater flexibility and smaller sizes for introducer sheaths in the newest stent grafts increase the feasibility of endovascular aneurysm repair but raise concerns about long-term limb patency. The aim of the study was to determine the incidence of and predictive factors for limb occlusion after use of the Endurant stent graft (Medtronic Inc, Minneapolis, Minn) for abdominal aortic aneurysm. METHODS The Endurant Stent Graft Natural Selection Global Postmarket Registry (ENGAGE) prospectively included 1143 patients treated with bifurcated devices who were observed for up to 2 years. Limb occlusions were evidenced by computed tomography, angiography, or ultrasound. To predict stent graft limb occlusion, a two-step model-building technique was applied. We first identified predictors from a total of 47 covariates obtained at baseline and in the periprocedural period. Subsequently, we reduced the set of potential predictors to key factors that are clinically meaningful. To handle large numbers of covariates, we used the Classification And Regression Tree (CART) method. RESULTS Forty-two stent graft limbs occluded in 39 patients (3.4% of the patients). At 2 years, the rate of freedom from stent graft limb occlusion calculated by Kaplan-Meier plot was 97.9% (standard error [SE], 0.33%). Of the 42 occlusions, 13 (31%) were observed within 30 days and 30 (71%) within 6 months. The strongest independent predictors were distal landing zone on the external iliac artery, external iliac artery diameter ≤10 mm, and kinking. High-risk vs low-risk patients were identified according to a decision tree based on the strongest predictors. Freedom from stent graft limb occlusion was 96.1% (SE, 0.64%) in high-risk patients vs 99.6% (SE, 0.19%) in low-risk patients. CONCLUSIONS After Endurant stent grafting, the incidence of limb occlusion was low. Classifying patients as high risk vs low risk according to the algorithm used in this study may help define specific strategies to prevent limb occlusion and improve the overall results of endovascular aneurysm repair using the latest generation of stent grafts.

Post-endograft abdominal aortic aneurysm shrinkage varies among hospitals: observations from multicenter trials.

Purpose: To evaluate differences in abdominal aortic aneurysm (AAA) shrinkage among hospitals following protocol-driven patient selection and using endografts from a single manufacturer. Methods: Standardized inclusion criteria for the Talent endograft multicenter trials included AAA diameter ≥40 mm and proximal neck limits of length ≥5 mm, diameter 14 to 32 mm, and angle ≤60°. AAA reporting standards categories were used to classify distal aorta and common iliac artery involvement. Serial computed tomographic scans through 12-month follow-up were examined by independent core laboratory review. Significant shrinkage was defined as a ≥5-mm decrease in the AAA largest minor axis diameter. Trial sites with >10 complete study cases were selected for stepwise logistic regression analysis. In the 13 trial sites meeting this criterion, 323 patients (mean age 74; 93% men) were treated for aneurysms with a mean pretreatment diameter of 53 mm. Results: At 12 months, significant AAA shrinkage occurred in 192 (59%) cases. The AAA shrinkage rate was 71% to 82% at 3 sites, 60% to 64% at 4 sites, 45% to 50% at 4 sites, and 35% and 27% at the 2 remaining sites. In the multivariate analysis, the hospital site showed a strong, independent association with aneurysm shrinkage (p<0.04). Neck and pretreatment AAA diameters were also found to be important factors (p<0.04). Age, gender, AAA classification, neck length, and angle were not significant correlates. Sixty-four (20%) endoleaks (29 type I, 34 type II, and 1 type III) were observed. The incidence of proximal endoleak was significantly different among sites (p<0.001) and highest in the 3 sites with the lowest AAA shrinkage rate. Conclusions: AAA shrinkage rates vary significantly among hospitals using the same endograft and protocol-defined patient selection criteria. Site-specific factors appear to be an important variable leading to successful endograft repair, as defined by post-endograft aneurysm shrinkage.

Internal Iliac Artery Occlusion Using a Stent-Graft Tunnel during Endovascular Aneurysm Repair: A New Alternative to Coil Embolization

Purpose: To report a new endovascular technique for internal iliac artery (IIA) occlusion during stent-graft treatment in patients with aortoiliac aneurysm. Technique: Stent-grafts measuring 20 to 28 mm in diameter and 37.5 mm long were deployed at the iliac bifurcation to occlude the IIA at its origin. Subsequent deployment of an aortic bifurcation endograft with ipsilateral extension into the external iliac artery was through this iliac stent-graft tunnel. This approach has been used in 5 patients with abdominal aortic aneurysm and common iliac artery aneurysm (n = 4) or isolated iliac artery aneurysm. Proximal IIA occlusion was achieved in all cases with no distal type I endoleak. IIA patency on the side opposite to the tunnel procedure was preserved in each case. No patient described new onset of pelvic ischemic symptoms. Over a mean 10-month follow-up (range 1–12), there was no secondary procedure required for type I endoleak. Three patients had a CIA aneurysm diameter change of −1, −4, and 0 mm at 1 year. Conclusions: This new method for IIA occlusion at its origin without coil embolization may prove to be a useful adjunct to endovascular aortoiliac aneurysm repair. The technique is simple, rapid, and may minimize the risk of pelvic ischemia.