Stress distribution in the walls of major arteries: implications for atherogenesis.

Background: There is a correlation between the sites of atheroma development and stress points in the arterial system. Generally, pulse pressure results in stresses acting on the vascular vessel, including longitudinal stress, radial or normal stress, tangential stress or hoop stress and shear stress. This paper explores the relationship between arterial wall shear stress and pulsatile blood pressure with the aim of furthering the understanding of atherogenesis and plaque progression.

Major gaps in human evidence for structure and function of the vasa vasora limit our understanding of the link with atherosclerosis.

Atherosclerosis is the major pathology causing death in the developed world and, although risk factor modification has improved outcomes over the last decade, there is no cure. The role of the vasa vasora (VV) in the pathogenesis of atherosclerotic plaque is unclear but must relate to the predictability of diseased sites in the arterial tree. VV are small vessels found on major arteries and veins which supply nutrients and oxygen to the vessel wall itself while removing waste.

Long-term Outcomes of the Western Australian Trial of Screening for Abdominal Aortic Aneurysms: Secondary Analysis of a Randomized Clinical Trial.

Importance: Mortality from ruptured abdominal aortic aneurysms (AAAs) remains high. The benefit of screening older men for AAAs needs to be assessed in a range of health care settings.

Objective: To assess the influence of screening for AAAs in men aged 64 to 83 years on mortality from AAAs.

Stress and strain behaviour modelling of the carotid bifurcation.

Background: The aim of this study is to investigate the biomechanical stress and strain behaviour within the wall of the artery and its influence on plaque formation and rupture using computational fluid dynamics (CFD).

Methods: A three-dimensional finite-element model of the carotid bifurcation was generated to analyse the wall stress and strain behaviour. Both single-layer and multilayer models were created and structural analysis was compared between these two types of models.

Guidelines for patient selection and performance of carotid artery stenting.

Background: The endovascular treatment of carotid atherosclerosis with carotid artery stenting (CAS) remains controversial. Carotid endarterectomy remains the benchmark in terms of procedural mortality and morbidity. At present, there are no consensus Australasian guidelines for the safe performance of CAS.

Computed tomography virtual intravascular endoscopy in the evaluation of fenestrated stent graft repair of abdominal aortic aneurysms.

Background: This study aimed to investigate the diagnostic value of computed tomography virtual intravascular endoscopy (VIE) in the follow-up of patients with abdominal aortic aneurysm (AAA) treated with fenestrated stent grafts.

Methods: A total of 19 patients (17 males and 2 females; mean age: 75 years) with AAA undergoing fenestrated stent grafts were retrospectively studied. Pre- and post-fenestration computed tomography data were reconstructed for the generation of VIE images of aortic ostia and fenestrated stents and compared with two-dimensional axial and multiplanar reformation (MPR) images.

Experimental measurement and mathematical modeling of pulsatile forces on a symmetric, bifurcated endoluminal stent graft model.

The objective of this study was to measure the pulsatile forces acting on a symmetric, bifurcated endoluminal stent graft to validate a computational fluid dynamics (CFD) and analytic model so that they can be used for various graft dimensions. We used a load cell to measure the force owing to the movement of an acrylic model of a bifurcated stent graft under pulsatile flow. This was then simulated with a CFD and analytic model.

Type II endoleaks: when is intervention indicated and what is the index of suspicion for types I or III?

One of the principal reasons for failure of endovascular aneurysm repair (EVAR) is the occurrence of endoleaks, which regardless of size or type can transmit systemic pressure to the aneurysm sac. There is little debate that type I endoleaks (poor proximal or distal sealing) are associated with continued risk of aneurysm rupture and require treatment. Similarly, with type III endoleak, there is agreement that the defect in the device needs to be addressed; however, what to do with type II endoleaks and their effect on long-term outcome are not so clear.

Multislice CT angiography of fenestrated endovascular stent grafting for treating abdominal aortic aneurysms: a pictorial review of the 2D/3D visualizations.

Fenestrated endovascular repair of an abdominal aortic aneurysm has been developed to treat patients with a short or complicated aneurysm neck. Fenestration involves creating an opening in the graft fabric to accommodate the orifice of the vessel that is targeted for preservation. Fixation of the fenestration to the renal arteries and the other visceral arteries can be done by implanting bare or covered stents across the graft-artery ostia interfaces so that a portion of the stent protrudes into the aortic lumen.

A laparoscopic endovascular aortobifemoral conduit that can be retained as a long-term bypass: a solution for patients with inadequate iliac access.

Purpose: To present a laparoscopic technique for placing a partially stented aortobifemoral (ABF) conduit that can be used for more proximal endovascular manipulations and then be retained as a permanent bypass of occlusive iliac disease.

Technique: Ethical approval was obtained to use a fresh frozen cadaver. The left common iliac artery, distal aorta, and proximal right common iliac artery were dissected laparoscopically.

3D stereoscopic visualization of fenestrated stent grafts.

The purpose of this study was to present a technique of stereoscopic visualization in the evaluation of patients with abdominal aortic aneurysm treated with fenestrated stent grafts compared with conventional 2D visualizations. Two patients with abdominal aortic aneurysm undergoing fenestrated stent grafting were selected for inclusion in the study. Conventional 2D views including axial, multiplanar reformation, maximum-intensity projection, and volume rendering and 3D stereoscopic visualizations were assessed by two experienced reviewers independently with regard to the treatment outcomes of fenestrated repair.

Multislice CT angiography in the follow-up of fenestrated endovascular grafts: effect of slice thickness on 2D and 3D visualization of the fenestration stents.

Purpose: To investigate the effect of multislice computed tomography (CT) protocols on the visualization of target vessel stents in patients with abdominal aortic aneurysm (AAA) treated with fenestrated endovascular grafts.

Methods: Twenty-one patients (19 men; mean age 75 years, range 63-86) undergoing fenestrated endovascular repair of AAA were retrospectively studied. Multislice CT angiography was performed with several protocols, and the section thicknesses used in each were compared to identify any relationship between slice thickness and target vessel stents visualized on 2-dimensional (2D) axial, multiplanar reformatted (MPR), and 3-dimensional (3D) virtual intravascular endoscopy (VIE) images.

Modeling of antegrade and retrograde flow into a branch artery of the aorta: implications for endovascular stent-grafting and extra-anatomical visceral bypass.

Purpose: To compare antegrade and retrograde flow characteristics in a branch of a conduit under typical pulsatile pressure and flows, seeking an answer to the question: "Does it matter whether inflow to a branch vessel is antegrade or retrograde?"

Methods: A model was built to simulate an abdominal aorta with a branch designed to approximate a typical renal artery. Experiments were conducted to measure the flow rates from 40- and 200-mm-long inflow conduit tubes simulating a branch with antegrade and retrograde inflow configurations. For the base case with a flush origin of the branch, the pressure difference between the main conduit and branch vessel was adjusted so that the average branch flow rate was 1.

CT virtual intravascular endoscopy in the visualization of fenestrated stent-grafts.

Purpose: To report the diagnostic value of computed tomographic (CT) virtual intravascular endoscopy (VIE) in the assessment of patients with abdominal aortic aneurysm (AAA) treated with fenestrated endovascular grafts.

Methods: Eight patients (7 men; mean age 76 years, range 70-82) with AAAs unsuitable for open surgery or conventional endovascular repair had fenestrated endovascular grafts implanted. Both pre- and post-fenestration multislice CT data were used to generate VIE images of the visceral artery ostia and the side branch fenestrated stents.

Large iliac arteries: a high-risk group for endovascular aortic aneurysm repair.

Purpose: To examine if the presence of large iliac arteries is a potential risk factor for the development of a type Ib endoleak (iliac sealing zone) or need for iliac artery-related secondary intervention in patients undergoing endovascular abdominal aortic aneurysm repair.

Methods: The medical notes and all preoperative and postoperative plain abdominal radiographs and computer tomographic scans were reviewed for a consecutive series of 100 patients (89 men; mean age 75 years, range 56-91) with large iliac arteries (mean 19.7 mm, range 16-22) who had Zenith endovascular stent-grafts inserted for management of aortoiliac aneurysmal disease from January 1999 until September 2002.

Treatment of infrarenal abdominal aortic aneurysms with oversized (36-mm) Zenith endografts.

Purpose: To evaluate the outcome of treating infrarenal abdominal aortic aneurysms with unfavorable necks using the 36-mm Zenith endograft.

Methods: The indication for use of the 36-mm endograft for infrarenal aortic aneurysm was a minimum 20-mm-long sealing zone and a diameter >28 mm at any point but <34 mm, varying more than 3 mm in contour. A series of 67 patients (64 men; mean age 76.

Short to midterm outcomes of fenestrated endovascular grafts in the treatment of abdominal aortic aneurysms: a systematic review.

Purpose: To perform a systematic review of the short to midterm outcomes of fenestrated endovascular grafts in patients with abdominal aortic aneurysms (AAA).

Methods: A search of PubMed and Medline databases for English-language literature was performed to find studies published between 1999 and 2006. Studies investigating the short to midterm results of fenestrated endovascular grafts for AAA were analyzed for clinical outcomes and postprocedural complications.

A laparoscopic access technique for endovascular procedures: surgeon training in an animal model.

Purpose: To present a laparoscopic technique for placing a transperitoneal conduit in the common iliac artery (CIA) or distal aorta to circumvent stenosed or occluded iliac systems and to assess the success of this laparoscopic access in a live animal model.

Technique: A porcine model was used owing to similarities in anatomy and size of the pig aorta to the human common iliac artery (CIA). Ethical approval was obtained, and the technique was developed in 8 animals under general anesthesia.

Outcomes of fenestrated endografts in the treatment of abdominal aortic aneurysm in Western Australia (1997-2004).

Purpose: To describe a 7-year experience with abdominal aortic aneurysm (AAA) repair using fenestrated Zenith endovascular endografts.

Methods: Six endovascular surgeons from 7 medical centers in Perth, Western Australia, contributed data to this retrospective study of 58 AAA patients (51 men; mean age 75.5+/-8.

Value of diffusion-weighted MRI during carotid angioplasty and stenting.

Introduction: The incidence of neurological injury following carotid angioplasty and stenting is of great interest to those advocating it as an alternative to endarterectomy in the management of critical carotid stenosis. A significant inter-observer variation exists in determining the presence or absence of a neurological deficit following the procedure objective imaging would be advantageous. In this study, we sought to assess diffusion weighted MRI as a diagnostic tool in evaluating the incidence of neurological injury following carotid angioplasty and stenting (CAS).

Movement and dislocation of modular stent-grafts due to pulsatile flow and the pressure difference between the stent-graft and the aneurysm sac.

Purpose: To investigate the stability and movement of modular aortic stent-grafts subjected to oscillating forces from pulsatile blood flow, with particular reference to the thoracic aorta.

Methods: Analytical mathematical modeling was used to understand the forces on modular grafts. In a benchtop experiment, a transparent acrylic box was filled with water to mimic an aneurysm.