Image Number 4 for United States Patent #8133253.
A covered vascular filter can be placed in a blood vessel, for the purpose of intercepting thrombus. The filter may be introduced to a desired site for medical treatment through a catheter which defines a lumen or passage and a distal port or opening. The filter tends to resiliently expand from a compressed shape when it is inside the catheter lumen, to an expanded shape when the filter is pushed from the catheter lumen. A cover or sleeve over those portions of the filter that would otherwise contact the vessel wall tends to reduce pressure on the vessel wall. The sleeve also tends to resist growth of the vessel wall among the elements of the filter, called endothelialization. In other words, the sleeve resists incorporation of the filter elements into the vessel wall, enabling the filter to be retrievable for a longer time. The various features of the present invention may be used singly or in any combination, as desired in a particular vascular filter.