The influence of prototype testing in three-dimensional aortic models on fenestrated endograft design.

OBJECTIVE: The fenestrated Anaconda endograft (Vascutek/Terumo, Inchinnan, UK) is intended for the treatment of abdominal aortic aneurysms with an insufficient infrarenal landing zone. The endografts are custom-made with use of high-resolution, 1-mm-slice computed tomography angiography images. For every case, a nonsterile prototype and a three-dimensional (3D) model of the patient's aorta are constructed to allow the engineers as well as the physician to test-implant the device and to review the fit of the graft. The aim of this investigation was to assess the impact of 3D model construction and prototype testing on the design of the final sterile endograft. METHODS: A prospectively held database on fenestrated endovascular aortic repair patients treated at a single institution was completed with data from the Vascutek engineers' prototype test results as well as the product request forms. Changes to endograft design based on prototype testing were assessed and are reported for all procedures. RESULTS: Between April 1, 2013, and August 18, 2015, 60 fenestrated Anaconda devices were implanted. Through prototype testing, engineers were able to identify and report potential risks to technical success related to use of the custom device for the respective patient. Theoretical concerns about endograft fit in the rigid model were expressed in 51 cases (85.0%), and the engineers suggested potential changes to the design of 21 grafts (35.0%). Thirteen cases (21.7%) were eventually modified after the surgeon's testing of the prototype. A second prototype was ordered in three cases (5.0%) because of extensive changes to endograft design, such as inclusion of an additional fenestration. Technical success rates were comparable for grafts that showed a perfect fit from the beginning and cases in which prototype testing resulted in a modification of graft design. CONCLUSIONS: Planning and construction of fenestrated endografts for complex aortic anatomies where exact fit and positioning of the graft are paramount to allow cannulation of the aortic branches are challenging. In the current series, approximately one in five endografts was modified after prototype testing in an aortic model. Eventually, success rates were comparable between the groups of patients with a good primary prototype fit and those in which the endograft design was altered. Prototype testing in 3D aortic models is a valuable tool to test the fit of a custom-made endograft before implantation. This may help avoid potentially debilitating adverse events associated with misaligned fenestrations and unconnected aortic branches.

Degree of contralateral carotid stenosis improves preoperative risk stratification of patients with asymptomatic ipsilateral carotid stenosis.

OBJECTIVE: The benefit of carotid surgery in asymptomatic patients with high-grade internal carotid artery stenosis (ICAS) is subject of intense debate, and thus improved preoperative risk stratification is mandatory. This study aimed to investigate the predictive value of contralateral ICAS (cl-ICAS) for the preoperative clinical presentation of patients with ipsilateral ICAS (primary outcome). METHODS: This study was a post hoc analysis of a prospective cohort comprising 485 consecutive patients undergoing carotid endarterectomy for high-grade ICAS. Patients were classified by their clinical presentation, ie, asymptomatic (n = 213) or symptomatic (within 6 months of surgery; n = 272, comprising both transient ischemic attack [TIA; n = 163] and stroke [n = 109]). We investigated the association of cl-ICAS with the primary outcome in adjusted regression models. RESULTS: Mean ipsilateral degrees of ICAS were similar in both groups (84% ± 10% vs 84% ± 11%; P = .92), whereas contralateral degrees were significantly higher in the symptomatic group (29% ± 34% vs 38% ± 39%; P = .008). After multivariable regression analysis, cl-ICAS >60% conferred a three times higher preoperative stroke risk (odds ratio, 3.31; 95% confidence interval, 1.98-5.54; P < .001). Inclusion of cl-ICAS significantly improved (P = .001) ipsilateral combined TIA and stroke risk prediction based on established risk factors (area under the curve, 0.66; 95% confidence interval, 0.60-0.72; P < .001). CONCLUSIONS: Our study identifies a high contralateral degree of ICAS as an independent predictor of preoperative ipsilateral TIA and stroke in patients with ipsilateral high-grade ICAS. Therefore, such patients might rather benefit from elective carotid surgery and intensive postoperative medical care.

Ratio of Apolipoprotein A-II/B Improves Risk Prediction of Postoperative Survival After Carotid Endarterectomy.

BACKGROUND AND PURPOSE: Even in patients with high-grade carotid stenosis, cardiovascular morbidity causes more deaths than strokes do. Despite successful low-density lipoprotein (LDL) cholesterol lowering, a significant risk of atherosclerotic cardiovascular disease remains, eventually rendering other lipid or lipoprotein ratios more efficient treatment targets. This study aimed to investigate the predictive value of the ratio of serum apolipoprotein A-II/B for overall mortality (primary outcome) of carotid surgery patients. METHODS: This single-center, nonrandomized, prospective cohort study comprised 327 consecutive patients undergoing carotid endarterectomy for high-grade internal carotid artery stenosis. Baseline lipoprotein concentrations were measured, and patients were observed for the occurrence of the primary outcome until the census date (January, 2003 to January, 2012; median follow-up, 102.3 months). RESULTS: The ratio of apolipoprotein A-II/B (hazard ratio, 0.74 per SD; confidence interval, 0.60-0.91; P=0.004) showed the highest association with the primary outcome compared with other lipid-risk parameters, significantly improving a prognostic model based on major cardiovascular risk factors, including LDL, high-density lipoprotein, and triglycerides in terms of overall performance, calibration, and discrimination. This led to a significantly improved reclassification of 8.9% of all patients (net reclassification improvement, 0.137; P=0.006 and integrated discrimination improvement, 0.041; P<0.001) and of 13.6% of patients with a serum baseline concentration of <100 mg/dL LDL (net reclassification improvement, 0.270; P=0.030 and integrated discrimination improvement, 0.061; P=0.002). CONCLUSIONS: Apolipoprotein A-II/B significantly improves risk prediction of overall survival, also in carotid surgery patients with lower LDL levels. Consequently, this ratio might provide an efficient diagnostic tool and eventually a treatment target for actual lipid-lowering therapies, which has to be addressed in future randomized controlled trials.