Successful endovascular treatment of a recurrent giant celiac artery aneurysm.

Visceral artery aneurysms are very rare and aneurysms of the celiac trunk are the rarest ones: they are in most cases asymptomatic and their detection is frequently incidental. In this article we report the case of a man affected by severe abdominal pain with a huge aneurysm of the celiac trunk, first successfully treated with coil embolization, but, after 10 months, another endovascular embolization was required for deployment of the metallic coils previously released, ahead into the fund of the sac with recanalization of the aneurysm. A second endovascular treatment was performed with other coils and Amplatzer-Plug. The high risk of rupture makes treatment of such aneurysms mandatory and surgery is still considered the gold standard therapy of VAA, but, due to its high morbidity and mortality risks, in the last years, it has been widely replaced by endovascular embolization. An effective endovascular embolization requires not only the complete filling of the aneurysmal sac, but also the complete vascular exclusion of its in-flow and out-flow tracts, to reduce the risk of its anterograde or retrograde reperfusion.

Spontaneous motility of passive emulsion droplets in polar active gels.

We study by computer simulations the dynamics of a droplet of passive, isotropic fluid, embedded in a polar active gel. The latter represents a fluid of active force dipoles, which exert either contractile or extensile stresses on their surroundings, modelling for instance a suspension of cytoskeletal filaments and molecular motors. When the polarisation of the active gel is anchored normal to the droplet at its surface, the nematic elasticity of the active gel drives the formation of a hedgehog defect; this defect then drives an active flow which propels the droplet forward. In an extensile gel, motility can occur even with tangential anchoring, which is compatible with a defect-free polarisation pattern. In this case, upon increasing activity the droplet first rotates uniformly, and then undergoes a discontinuous nonequilibrium transition into a translationally motile state, powered by bending deformations in the surrounding active medium.