Miniature bending manipulator for fetoscopic intrauterine laser therapy to treat twin-to-twin transfusion syndrome

作者：Yamashita H^*; Matsumiya K; Masamune K; Liao H; Chiba T; Dohi T

来源：Surgical Endoscopy and Other Interventional Techniques, 2008, 22(2): 430-435.

DOI：10.1007/s00464-007-9444-0

• miniature bending manipulator
• selective laser photocoagulation
• twin-to-twin transfusion syndrome

Background Recent typical therapy for twin-to-twin transfusion syndrome (TTTS) is selective laser photocoagulation of anastomotic communicating vessels on the placenta using the fetoscopic approach. The difficulty of a conventional laser device approach for this procedure depends significantly on the placental location, so a new robotized device is required to bend the direction of laser irradiation flexibly within the narrow uterus.
Methods The authors designed a miniature bending mechanism impelled by a wire-guided linkage driving method that provides a stable procedure for bending laser irradiation from -90 degrees to 90 degrees. Using this bending mechanism, the authors developed a bending manipulator with a diameter of 3.5 mm and a hollow central channel with a diameter of 0.8 mm for passing a glass fiber for neodymium:yttrium-aluminum-garnet (Nd:YAG) laser photocoagulation. The bending mechanism is motorized by an electrical actuator and controlled by a grip-type interface with a small joystick. The robotized tip';s part and the actuator';s part are easily separable for cleaning and sterilization.
Results In performance evaluations of the manipulator, the bending characteristics with a glass fiber were examined. The bending range was -52.6 degrees to 80 degrees, with a very small hysteresis error, and the bending repeatability error was 0.5 degrees +/- 0.2 degrees, which corresponds with the high accuracy of 0.2 +/- 0.1-mm positioning error at the glass fiber';s tip. In the evaluation of Nd:YAG laser photocoagulation, the study confirmed that the manipulator performed effective laser photocoagulation of the placental phantom surface (underwater chicken liver). The large bending range, reaching 80 degrees, enabled a flexible approach from various directions with a high irradiation efficiency of no less than 96.6%.
Conclusions The authors'; original miniature bending manipulator can change the laser irradiating direction with highly repeatable positioning accuracy for speedy, safe, and effective vessel occlusion in clinical practice.

• 出版日期2008-2