| abstract |
A cannula having a proximal end, a distal end, and a lumen extending between the proximal and distal ends is provided. The diameter of the lumen of the cannula can be varied to take into account differences in the diameter of access and target vessels during cannulation. The cannula is further characterized by at least one mechanism that, upon actuation, serves to alter the conformation of the cannula between a normal profile conformation and a low profile conformation. The normal profile conformation is characterized by the cannula having a lumen diameter at the point of insertion which is smaller than the lumen diameter both proximal and distal to the point of insertion, with the lumen diameter distal to the point of insertion also expandable to the diameter of the cannulized vessel of the patient. The low profile conformation is characterized by the cannula having a lumen diameter at the point of insertion that is greater than the lumen diameter distal to the point of insertion. |