Revascularization Strategies in Liver Transplantation

Vascular complications following liver transplantation chan jeopardize the liver graft and recipient survival. Aggressive strategies to diagnose and treat these complications may avoid patient and graft loss. With the evolving knowledge and novel therapies, less invasive strategies are gaining importance in the treatment of post liver transplant vascular complications. Portal, hepatic, and arterial thrombosis may be managed with systemic therapies, endovascular approaches, surgical and lastly with retransplantation. The timing between the diagnosis and the directed treatment is paramount for the success. Revascularization by means of interventional radiology plays an important role in the resolution and long-term patency of arterial and venous complications. This chapter will lead the reader into the most up-to-date treatments of post liver transplant vascular complications

Upward Flame Spread Over Thin Solids in Partial Gravity

The effects of partial-gravity, reduced pressure, and sample width on upward flame spread over a thin cellulose fuel were studied experimentally and the results were compared to a numerical flame spread simulation. Fuel samples 1-cm, 2-cm, and 4-cm wide were burned in air at reduced pressures of 0.2 to 0.4 atmospheres in simulated gravity environments of 0.1-G, 0.16-G (Lunar), and 0.38-G (Martian) onboard the NASA KC-135 aircraft and in normal-gravity tests. Observed steady flame propagation speeds and pyrolysis lengths were approximately proportional to the gravity level. Flames spread more quickly and were longer with the wider samples and the variations with gravity and pressure increased with sample width. A numerical simulation of upward flame spread was developed including three-dimensional Navier-Stokes equations, one-step Arrhenius kinetics for the gas phase flame and for the solid surface decomposition, and a fuel-surface radiative loss. The model provides detailed structure of flame temperatures, the flow field interactions with the flame, and the solid fuel mass disappearance. The simulation agrees with experimental flame spread rates and their dependence on gravity level but predicts a wider flammable region than found by experiment. Some unique three-dimensional flame features are demonstrated in the model results