VASCULAR DISEASE MANAGEMENT
May 2015, Vol. 12, No. 5
CFD Analysis to Evaluate Hemodynamic Parameters in a Growing Abdominal Aortic Aneurysm
Vincenzo Filardi, PhD
From University of Messina, Italy.
ABSTRACT: Objective: Previous works have shown that maximum diameter is not a reliable determinant of abdominal aortic aneurysm (AAA) rupture; however, it is currently the most widely accepted indicator. Wall stress may be a better indicator, and promising patient-specific results from structural models using static pressure have been published. The purpose of this study is to investigate changes in internal static pressure, blood flow, and wall shear stress (WSS) when the AAA increases in diameter from 10 mm to 50 mm. Understanding how these stresses are distributed and which factors influence their distribution is critical in evaluating the potential for rupture. Methods: Three male patients, affected by AAA at different stages, were selected to reproduce the growing process of an aneurysm. The information collected was focused on the geometry of the AAA lumen, material property of the wall, and flow conditions at the model boundaries. All patients were scanned with a spiral computed tomography scanner, and the obtained data were imported in a finite element code software. A linear law was speculated to predict the growth of the aneurysm from 10 mm to 50 mm diameter. Five representative finite element models were created and imported in a computational fluid dynamics code to perform fluid dynamics analyses. Patient informed consent and IRB approval were obtained. Results: The results of fluid dynamics analyses evidenced peaks of pressure aging from about 17 MPa for a diameter of 10 mm, to 19 MPa for a diameter of 50 mm. Depression zones can be identified under the neck of the aneurysms. Pressure distribution decreases from the borders to the center. Vectors of fluid velocity localized on the whole artery evidence peaks from 3.08 m/s for a diameter of 10 mm to 2.66 m/s for a diameter of 50 mm. Analyses show flow separation streamlines regions on the neck of the aneurysm, in which recirculation eddies are formed, while separation domains of velocity vectors can be easily individuated between center and periphery of the aneurysm, in which pressure radially increases while velocity decreases. Wall shear stress registered on the top of the caps of the five AAAs show values ranging from 0.15 to 0.50 Pa. Conclusions: Knowledge of the regional distribution of wall thickness and failure properties in an AAA can help in understanding its natural history, developing methods to predict rupture risk, and designing vascular prostheses.
Endovascular Treatment of Popliteal Artery Entrapment Syndrome: Technical Aspects and Results of Endovascular Treatment With Surgical Release of Popliteal Artery
Ugur Ozkan, MD; Merve Ozen, MD; Gurkan Ozkoc, MD
From the Baskent University Faculty of Medicine, Adana, Turkey.
ABSTRACT: Objectives: There is no standardized endovascular technique for treatment of popliteal artery entrapment syndrome (PAES). We retrospectively evaluated technical aspects and results of endovascular treatment with surgical releasing of popliteal artery for PAES. Methods: Five patients (all male; mean age, 33 years; range, 21 to 55 years) who underwent endovascular recanalization combined with surgical releasing of popliteal artery for PAES in a 3-year period were reviewed retrospectively. Balloon angioplasty was used for all patients, and manual aspiration thrombectomy was used when required to remove thrombus to restore blood flow in the popliteal artery. Musculotendinous resection and popliteal artery release was performed surgically in all patients after the endovascular treatment. Results: Endovascular techniques and surgical decompression were successful in all patients with an initial technical success rate of 100%. Primary and secondary patency rates were 60% and 60% respectively at a median follow-up of 64 months (range, 41-100 months). Three of 5 patients had an uneventful long-term follow-up. After treatment, thrombosis of the popliteal artery was observed in 2 patients, one of whom underwent endovascular treatment again at 4 and 18 months. That patient presented with a delayed thromboembolic occlusion in follow-up. Another patient with rethrombosis of the popliteal artery refused additional endovascular intervention and underwent bypass surgery. Conclusions: Endovascular treatment with surgical decompression of popliteal artery is a potential alternative treatment for PAES that is less invasive and offers an alternative to conventional bypass surgery, especially for young patients.
Mark Fillinger, MD, Discusses Study Results for the Aorfix Abdominal Aortic Aneurysm Stent
Interview by Jennifer Ford
Michel S. Makaroun, MD Details the Gore Suite of Aortic Branch Stent Grafts
Interview by Jennifer Ford
* Articles are subject to change at the editor’s discretion.