The CQL features a higher “crack” pressure than most valves, which helps to create a higher level of hypobaric suspension.
Designed to work with liners with a seal band, the Hands Free Valve offers auto expulsion and a manual twist option that increases airflow for donning and doffing.
A variety of techniques have been used clinically, and improved venous hemodynamics and valve competency have been demonstrated. Glutaraldehyde-preserved venous valve transplantation in the dog.
However, the majority of these valve studies await confirmation by other investigators over extended periods.
Many have failed in early experimental evaluation, with some advancing to the clinical arena, but few remain in research and development.
Valves constructed from autogenous cells, or from autogenous venous tissue, not originally “de novo” valve tissue, have proven more promising.
The standard dictionary definition of “artificial” is “not arising from natural growth.” Therefore, and for this review, an artificial venous valve is not considered as a “de novo” venous valve. Implantation of cryopreserved allograft pulmonary monocusp patch to treat nonthrombotic femoral vein incompetence.
In general, two categories of artificial venous valves have been studied: valves devoid of autogenous components; and valves constructed, at least partially, from autogenous components.
Fresh allograft vein segments containing a valve were transplanted into the femoral vein of 14 dogs with only 7% patent at four weeks.7 A human umbilical vein fitted over an aluminum mandrel, sculptured into a bicuspid valve and then glutaraldehydefixed, was implanted as a xenograft. A multicenter, phase I evaluation of cryopreserved venous valve allografts for the treatment of chronic deep venous insufficiency.
All ten canine transplants failed in three days.8 A liquid pellethane bicuspid valve was poured and fashioned using the same aluminum mandrel as that used for the umbilical vein experiment.