Design of Novel Endoscopic Suction Grasping and Superelastic Surgical Clips Based on a Novel Model of Thin Collagenous Tissue.

摘要

Current endoscopic manipulation and sealing techniques are ineffective at large puncture repair, fistula closure, and anastomosis in tubular organs.;For manipulation, the working channel of the endoscope is unavoidably small and thus so are the conventional graspers which can be passed through them. Small grasping jaws cannot distribute force widely enough to apply large forces without tearing tissue, thereby limiting the applied pulling force. Additionally, the surface of tubular organs is smooth, concave, and lubricated, making conventional grasping difficult or requiring hooked jaws that further damage the tissue.;Endoscopic tissue sealing is currently accomplished by mechanical clips which protrude into the lumen from the organ wall when deployed and become a possible obstruction when placing several clips to seal larger openings or when performing an anastomosis.;To address these clinical needs, a novel suction grasper and a superelastic, self-closing surgical clip were developed, characterized, and optimized. Additionally, to properly design the grasper and clip, a novel model of the esophageal wall that can be used for puncture and bearing force, in addition to the traditional stress-strain behaviour, was developed and validated. The tissue model was constructed using a bottom-up approach and validated against ex-vivo testing. The bottom-up approach was accomplished by examining the concentrations of each of structural components of tissue (collagen, elastin, muscle) and arranging them according to histological findings.;For the superelastic, self-closing clip, the metallurgy of nitinol was reviewed and used to devise a single-step manufacturing process which would optimize the strain limit and closing force of the material. Next, the optimal diameter of clip and wire were set taking the opening force, material elastic limit, and bearing force on the tissue into account.;Lastly, grasping force from suction was characterized for hole size, number, and distribution and suction force was compared against puncture force. Histology was performed to assess for tissue damage from suction grasping during clip application in vivo.