Vinograd I. Klin B. Brosh T. Weinberg M. Flomenblit Y. Nevo Z.
Title
A new intratracheal stent made from nitinol, an alloy with "shape memory
effect".
Source
Journal of Thoracic & Cardiovascular Surgery. 107(5):1255-61, 1994 May.
Abstract
Temporary or permanent tracheal splinting in pediatric patients may be
indicated in tracheomalacia or bronchomalacia, repair of congenital
tracheal stenosis, and after tracheal resection. This study presents the
results of the development of a new intraluminal airway stent made from
titanium alloy, a metal with "shape memory effect". At low temperatures
(martensitic state) the titanium alloy stent can be fashioned into a
specific shape; then when heated to a higher temperature (austenitic
state) the stent alters its shape, only to regain its original shape when
recooled to the lower temperature. The stent, connected to a small
electric power supply, was introduced into 20 young rabbits with the use
of a 2.5 cm rigid bronchoscope. After implantation in the martensitic
state the stent was warmed to 40 degrees C, the austenitic state, by an
electric current of 1.5 to 3 ampere for 1 to 2 seconds. After a period of
8 to 10 weeks the stent was removed (in its martensitic state) through the
same-sized bronchoscope after being cooled with 3 to 4 ml of 80% alcohol
solution at 6 degrees C. No signs of airway obstruction developed in any
of the animals after implantation or extraction of the stent. The
biomechanical properties of the trachea, as shown by strain measurements
with the use of incremental forces, showed significant differences between
the stented and unstented segments (p < 0.005). The titanium alloy
intratracheal stent adequately fulfilled the requirements of a temporary
intraluminal airway splint, and because of its unique feature of shape
memory effect the stent could be inserted, fixed, and removed easily, even
in very small airways.