Escalation of Antithrombotic Therapy Should Be Considered in the Presence of Intraluminal Prosthetic Graft Thrombus Following Endovascular Aneurysm Repair

A hemodynamic study of blood flow models on various stent graft configurations during aorto-iliac reconstruction

PURPOSE

To compare the hemodynamic performance of three (Bottom Up non-ballet, Top-Down non-ballet, Top Down ballet) idealized stent graft configurations used during endovascular repair of abdominal aortic aneurysms, under the influence of various rheological models.

METHODS

Ten rheological models are assumed and a commercial finite volume solver is employed for the simulation of blood flow under realistic boundary conditions. An appropriate mesh convergence study is performed and five hemodynamic variables are computed: the time average wall shear stress (TAWSS), oscillatory shear index (OSI), relative residence time (RRT), endothelial cell activation potential and displacement force (DF) for all three configurations.

RESULTS

The choice of blood flow model may affect results, but does not constitute a significant determinant on the overall performance of the assumed stent grafts. On the contrary, stent graft geometry has a major effect. Specifically, the Bottom Up non-ballet type is characterized by the least favorable performance presenting the lowest TAWSS and the highest OSI, RRT and ECAP values. On the other hand, the Top Down ballet type presents hemodynamic advantages yielding the highest TAWSS and lowest OSI, RRT and ECAP average values. Furthermore, the ballet type is characterized by the lowest DF, although differences observed are small and their clinical relevance uncertain.

CONCLUSIONS

The effect of the assumed rheological model on the overall performance of the grafts is not significant. It is thus relatively safe to claim that it is the type of stent graft that determines its overall performance rather than the adopted blood flow model.

Editor's Choice -- European Society for Vascular Surgery (ESVS) 2024 Clinical Practice Guidelines on the Management of Abdominal Aorto-Iliac Artery Aneurysms

OBJECTIVE

The European Society for Vascular Surgery (ESVS) has developed clinical practice guidelines for the care of patients with aneurysms of the abdominal aorta and iliac arteries in succession to the 2011 and 2019 versions, with the aim of assisting physicians and patients in selecting the best management strategy.

METHODS

The guideline is based on scientific evidence completed with expert opinion on the matter. By summarising and evaluating the best available evidence, recommendations for the evaluation and treatment of patients have been formulated. The recommendations are graded according to a modified European Society of Cardiology grading system, where the strength (class) of each recommendation is graded from I to III and the letters A to C mark the level of evidence.

RESULTS

A total of 160 recommendations have been issued on the following topics: Service standards, including surgical volume and training; Epidemiology, diagnosis, and screening; Management of patients with small abdominal aortic aneurysm (AAA), including surveillance, cardiovascular risk reduction, and indication for repair; Elective AAA repair, including operative risk assessment, open and endovascular repair, and early complications; Ruptured and symptomatic AAA, including peri-operative management, such as permissive hypotension and use of aortic occlusion balloon, open and endovascular repair, and early complications, such as abdominal compartment syndrome and colonic ischaemia; Long term outcome and follow up after AAA repair, including graft infection, endoleaks and follow up routines; Management of complex AAA, including open and endovascular repair; Management of iliac artery aneurysm, including indication for repair and open and endovascular repair; and Miscellaneous aortic problems, including mycotic, inflammatory, and saccular aortic aneurysm. In addition, Shared decision making is being addressed, with supporting information for patients, and Unresolved issues are discussed.

CONCLUSION

The ESVS Clinical Practice Guidelines provide the most comprehensive, up to date, and unbiased advice to clinicians and patients on the management of abdominal aorto-iliac artery aneurysms.

A Retrospective Evaluation of Intra-Prosthetic Thrombus Formation After Endovascular Aortic Repair in Cook Zenith Alpha and Medtronic Endurant II Patients

OBJECTIVE

To investigate the occurrence of limb graft occlusion (LGO) and intra-prosthetic thrombus (IPT) formation in Zenith Alpha and Endurant II stent graft limbs.

METHODS

A single centre retrospective study was conducted on patients treated with the Zenith Alpha and Endurant II stent grafts between 2017 and 2019. All post-operative computed tomography angiography images were re-investigated for thrombus formation. Demographic, aneurysm, and stent graft data were collected and compared. LGO was defined as complete occlusion or significant stenosis (≥ 50% lumen diameter reduction). Logistic regression on pro-thrombotic risk factors was conducted. Freedom from LGO and overall limb IPT were compared using Kaplan-Meier analyses.

RESULTS

Seventy-eight Zenith Alpha and eighty-six Endurant II patients were studied. The median follow up was 33 (IQR 25, 44) months for Zenith Alpha patients and 36 (IQR 22, 46) months for Endurant II patients (p = .53). LGO was seen in 15% (n = 12) of Zenith Alpha patients and 5% (n = 4) of Endurant II patients (p = .032), and freedom from LGO was significantly higher among Endurant II patients (p = .024). The Zenith Alpha stent graft was an independent risk factor for LGO (OR 3.9, 95% CI 1.1 - 13.4; p = .032). Among Zenith Alpha patients, limb flare compression within the main body gate was over represented in LGO patients (p = .011). There was no difference in freedom from overall limb IPT between the stent graft systems. For Endurant II limbs, IPT was significantly less common in the integrated ipsilateral limbs (without ETLW/ETEW stent graft limbs) (p = .044). Main endograft body IPT was correlated with overall limb IPT (p = .035).

CONCLUSION

LGO was significantly more common among Zenith Alpha than Endurant II patients. Zenith Alpha limbs was an independent risk factor for LGO. There was no difference between stent grafts in overall limb IPT formation.