This specially designed product is used to encircle a blood vessel. A special material (hygroscopic compressed casein) inside the
donut shaped constrictor imbibes fluid over time. It slowly occludes the blood vessel. A small key is used to lock it in place
after it is slipped over the blood vessel. Sizing - about a 25% reduction in the blood vessel diameter should be achieved upon
initial surgical placement for the best results. For the surgical treatment of porto caval or hepatic shunts.