Page 60 - Advances in Biomechanics and Tissue Regeneration

54 3. DESIGN, SIMULATION, AND EXPERIMENTATION OF COLONIC STENTS

FIG. 3.24 Stent manufacturing: (A) slotted tube [54]; (B) stent after expansion process; (C) final free expanded shape of the stent, with a maximum
diameter of 35mm.

3.5.4 Animal Experimentation

Sooner or later the process of validating a new design will go through in vivo experimentation. Normally, it is car-
ried out in animals of porcine species, between 40 and 60kg, due to anatomical similarities of the descending colon
with humans.
In this case, the in vivo test is described for validation of a stent geometry corresponding to the prototype proposed
by the same authors in [53, 54]. It is a self-expanding stent with diamond cell type and bell-shaped profile with lon-
gitudinal variable radial strength.
The in vivo testing procedure includes:
1. Surgical creation of a model of acute colon stenosis.
2. Implantation of the stent after the appearance of the first symptoms.
3. Radiological and endoscopic follow-up for 10days (minimum).
4. Control of physical conditions, nutritional tolerance, depositional habit, and weight gain.

I. BIOMECHANICS