How safe is internal iliac artery embolisation prior to EVAR? A 10-year retrospective review.

PURPOSE: Internal iliac artery (IIA) embolisation is commonly performed prior to endovascular aneurysm repair (EVAR) of aortoiliac aneurysms to prevent type 2 endoleaks via the internal iliac arteries. The safety of this procedure is controversial due to the high incidence of pelvic ischaemic complications. METHODS: We undertook a retrospective review of all patients undergoing IIA embolisation before EVAR from 2002 to 2012, to determine incidence of, and factors associated with pelvic ischaemia. RESULTS: Eight of 25 patients (32 %) experienced new-onset ischaemia, including erectile dysfunction (4 %), and buttock claudication (28 %) that persisted >6 months in only four patients (16 %). Both bilateral IIA embolisation and a shorter time interval to EVAR correlate with increased risk (p = 0.006 and p = 0.044). No co-morbidities or demographic factors were predictive. CONCLUSIONS: We conclude that IIA embolisation remains a beneficial procedure, however, to minimise the risk of buttock claudication we advise against both bilateral IIA embolisation and short time intervals between embolisation and subsequent EVAR.

A three-dimensional finite element model of an adherent eukaryotic cell.

Mechanical stimulation is known to cause alterations in the behaviour of cells adhering to a substrate. The mechanisms by which forces are transduced into biological responses within the cell remain largely unknown. Since cellular deformation is likely involved, further understanding of the biomechanical origins of alterations in cellular response can be aided by the use of computational models in describing cellular structural behaviour and in determining cellular deformation due to imposed loads of various magnitudes. In this paper, a finite element modelling approach that can describe the biomechanical behaviour of adherent eukaryotic cells is presented. It fuses two previous modelling approaches by incorporating, in an idealised geometry, all cellular components considered structurally significant, i.e. prestressed cytoskeleton, cytoplasm, nucleus and membrane components. The aim is to determine if we can use this model to describe the non-linear structural behaviour of an adherent cell and to determine the contribution of the various cellular components to cellular stability. Results obtained by applying forces (in the picoNewton range) to the model membrane nodes suggest a key role for the cytoskeleton in determining cellular stiffness. The model captures non-linear structural behaviours such as strain hardening and prestress effects (in the region of receptor sites), and variable compliance along the cell surface. The role of the cytoskeleton in stiffening a cell during the process of cell spreading is investigated by applying forces to five increasingly spread cell geometries. Parameter studies reveal that material properties of the cytoplasm (elasticity and compressibility) also have a large influence on cellular stiffness. The computational model of a single cell developed here is proposed as one that is sufficiently complex to capture the non-linear behaviours of the cell response to forces whilst not being so complex that the parameters cannot be specified. The model could be very useful in computing cellular structural behaviour in response to various in vitro mechanical stimuli (e.g. fluid flow, substrate strain), or for use in algorithms that attempt to simulate mechanobiological processes.