ABSTRACT
When the shunt cannot be completely occluded, partial ligation is performed while monitoring portal blood pressure using a monometer and evaluating the splanchnic viscera for signs of congestion. Recently a new tool, an ameroid constrictor ring, has become available to gradually occlude the shunting vessel . ii. Ameroid constrictor ring. This is a circular metal band with a casein lining and a key mechanism that allows it to be placed around the shunting vessel. The lining of the ring slowly expands, gradually occluding the shunting vessel between 28-35 days after placement. With gradual occlusion portal flow through the liver slowly increases avoiding development of severe portal hypertension. The ameroid constrictor also eliminates a second surgery to occlude completely the shunting vessel as is often done following partial ligation. iii. Disadvantages to using an ameroid constrictor include increased expense ($40-$60), until familiarity is gained, the ring can be somewhat cumbersome and awkward to place, and depending on the extent of vessel manipulation during placement venous thrombosis may occur. The ameroid ring is in the early stages of clinical application and long-term evaluation of its efficacy is not available.
