Development of an implantable artificial anal sphincter using a shape memory alloy.
OBJECTIVE
The authors created a new artificial anal sphincter using a shape memory alloy (AS-SMA) to treat fecal incontinence and evaluated its validity.


METHODS
AS-SMA consists of 2 Ti-Ni plates to sandwich the intestine and generates a pressure of 55 mm Hg at its resting position. With the electric power supply, the 2 metals bend to form an almondlike shape making a maximum gap of 33 mm between each other at the temperature of 55 degrees C. The device was attached to the colostomy in a piglet and was operated several times a day for 1 month. Fecal continence, bowel movements, and general condition of the piglet were recorded. After the experiment, tissue damage around the device was investigated.


RESULTS
Fecal continence was obtained while the device was in the resting position. When it was operated, bowel movements were observed. The bowel movements to operations ratio was 82:105 (78%). During the experiment, the animal had neither abdominal distension nor vomiting. At the autopsy, there was mild inflammation and shallow burns around the device. No compression injury was detected.


CONCLUSIONS
AS-SMA achieved fecal continence of the colostomy. With reduction of the associated side effects, it would be a potential substitute for an impaired anal sphincter.
Nishi
Kotaro
K
Department of Pediatric Surgery, Graduate School of Medicine, Japan.
Kamiyama
Takamichi
T
Wada
Motoshi
M
Amae
Shintaro
S
Ishii
Tomohiro
T
Takagi
Toshiyuki
T
Luo
Yun
Y
Okuyama
Takeshi
T
Yambe
Tomoyuki
T
Hayashi
Yutaka
Y
Ohi
Ryoji
R
D000497:Alloys; D001003:Anal Canal; D000818:Animals; D001187:Artificial Organs; D003125:Colostomy; D004195:Disease Models, Animal; D005242:Fecal Incontinence / Q000628:therapy*; D020007:Implants, Experimental; D011474:Prosthesis Design; D013552:Swine
D000497:Alloys