Balloon Sheaths for Gastrointestinal Guidance and Access: A Preliminary Phantom Study

OBJECTIVE: We wanted to evaluate the feasibility and usefulness of a newly designed balloon sheath for gastrointestinal guidance and access by conducting a phantom study. MATERIALS AND METHODS: The newly designed balloon sheath consisted of an introducer sheath and a supporting balloon. A coil catheter was advanced over a guide wire into two gastroduodenal phantoms (one was with stricture and one was without stricture) ; group I was without a balloon sheath, group ll was with a deflated balloon sheath, and groups III and IV were with an inflated balloon and with the balloon in the fundus and body, respectively. Each test was performed for 2 minutes and it was repeated 10 times in each group by two researchers, and the positions reached by the catheter tip were recorded. RESULTS: Both researchers had better performances with both phantoms in order of group IV, III, II and I. In group IV, both researchers advanced the catheter tip through the fourth duodenal segment in both the phantoms. In group I, however, the catheter tip never reached the third duodenal segment in both the phantoms by both the researchers. The numeric values for the four study groups were significantly different for both the phantoms (p < 0.001). A significant difference was also found between group III and IV for both phantoms (p < 0.001). CONCLUSION: The balloon sheath seems to be feasible for clinical use, and it has good clinical potential for gastrointestinal guidance and access, particularly when the inflated balloon is placed in the gastric body.

Newly Designed Sheaths for Gastroduodenal Intervention: An Experimental Study in a Phantom and Dogs

OBJECTIVE: To evaluate the usefulness of newly designed sheaths for gastroduodenal intervention in a gastric phantom and dogs. MATERIALS AND METHODS: A regular sheath was made using a polytetrafluoroethylene tube (4 mm in diameter, 90 cm long) with a bent tip (4 cm long, 100 degree angle). For the supported type of sheath, a 5 Fr catheter was attached to a regular sheath to act as a side lumen. To evaluate their supportability, we measured the distance of movement of the sheath's tip within a silicone gastric phantom for three types of sheath, the regular type, supported type, and supported type with a supporting guide wire. The experiments were repeated 30 times, and the results were analyzed using ANOVA with the postHoc test. In addition, an animal experiment was performed in six mongrel dogs (total: 12 sessions) to evaluate the torque and supportability of the sheaths in the stomach, while pushing a guide wire or coil catheter under fluoroscopic guidance. RESULTS: In the guide wire application, the distances of movement of the sheath tip in the three types of sheath, the regular type, supported type, and supported type with supporting guide wire, were 8.40+/-0.51 cm, 6.23+/-0.41 cm, and 4.47+/-0.32 cm, respectively (p < 0.001). In the coil catheter application, the corresponding values were 7.22+/-0.70 cm, 5.61+/-0.31 cm and 3.91+/-0.59 cm, respectively (p < 0.001). All three types of sheath rotated smoothly and enabled both the wires and catheters to be guided toward the pylorus of the dog in all cases. CONCLUSION: The newly designed sheaths can be useful for gastroduodenal intervention.

Percutaneous Transcholecystic Approach for an Experiement of Biliary Stent Placement: An Experimental Study in Dogs

PURPOSE: To determine, in an experimental study of biliary stent placement, the usefulness and safety of the percutaneous transcholecystic approach and the patency of a newly designed biliary stent. MATERIALS AND METHODS: A stent made of 0.15-mm-thick nitinol wire, and 10 mm in diameter and 2 cm in length, was loaded in an introducer with an 8-F outer diameter. The gallbladders of seven mongrel dogs were punctured with a 16-G angiocath needle under sonographic guidance, and cholangiography was performed. After anchoring the anterior wall of the gallbladder to the abdominal wall using a T-fastener, the gallbladder body was punctured again under fluoroscopic guidance. The cystic and common bile ducts were selected using a 0.035-inch guide wire and a cobra catheter, and the stent was placed in the common bile duct. Post-stenting cholangiography was undertaken, and an 8.5-F drainage tube was inserted in the gallbladder. Two dogs were followed-up and sacrificed at 2, 4, and 8 weeks after stent placement, respectively, and the other expired 2 days after stent placement. Follow-up cholangiograms were obtained before aninmal was sacrificed, and a pathologic examination was performed. RESULTS: Stent placement was technically successful in all cases. One dog expired 2 days after placement because of bile peritonitis due to migration of the drainage tube into the peritoneal cavity, but the other six remained healthy during the follow-up period. Cholangiography performed before the sacrifice of each dog showed that the stents were patent. Pathologic examination revealed the proliferation of granulation tissue at 2 weeks, and complete endothelialization over the stents by granulation tissue at 8 weeks. CONCLUSION: Percutaneous transcholecystic biliary stent placement appears to be safe, easy and useful. After placement, the stent was patent during the follow-up period.

Development of an Abdominal Aortic Aneurysm Model for Stent-graft Insertion

PURPOSE: To determine the efficacy of an abdominal aortic aneurysm model for stent-graft placement. MATERIALS AND METHODS: The model consists of two parts, the heart and the vascular system. A peristaltic pump and a solenoid valve were used to simulate a pulsatile flow from the heart. A ball-shaped piece of clay was placed inside a square box and liquid silicone was poured. After the silicone was formed, the clay was removed and a silicone tube was used to connect the heart model and the aneurysm model. The silicone tube was also used to simulate the iliac arteries and one end of the artery was clamped and the other one was extended to a water bath. Water at 37 degrees was circulated through the model, and the pressure at the thoracic aorta, aneurysm and iliac artery was measured with the outlet valve opening at 25, 50, and 100% before and after stent-graft placement. RESULTS: The liquid pressure measurements were 253/252, 271/162 and 264/166 mmHg at the thoracic aorta, aneurysm and iliac artery, respectively, when the outlet was 100% open. They were 173/121, 145/99, 145/106 mmHg when the outlet was 50% open, and 35/28, 61/44, 24/22 mmHg when it was 25% open. After placement f the stent-graft, the pressure measurements were 170/132, 174/128, and 167/128 mmHg, respectively. CONCLUSION: Since it was easy to produce, the model was useful for in-vitro stent-graft testing, and a wide range of pressure could be applied.