Experimental study of endotracheal expandable metallic stent placement

Various types of Gianturco zig-zag wire stents were implanted into the trachea of three dogs in order to evaluate the suitable conditions of the endotracheal wire stent. The stents were constructed of 0.018, 0.016 and 0.013 inch stainless steel wire respectively. The relaxed diameter of the stents was 3.0 cm and their length were 2 cm, 3 cm, and 4 cm respectively. The stent of 2 cm in length and constructed of 0.013 inch showed minimum pathologic changes to the trachea of the dog compared to the other stents, and also showed the covering of ciliated, columnar epithelium over the stent surface. The experimental data showed that it was possible to use the stent in the tracheobronchial tree of dogs and also showed a potential clinical application.     

Endotracheal expandable metallic stent placement in dogs

Various types of Gianturco zig-zag wire stent were implanted into the tracheas of 4 dogs to define the suitable characteristics of the endotracheal wire stent in these animals. The stents were constructed of 0.45, 0.40, and 0.33 mm stainless steel wire. The diameter of the fully expanded stents was 3 cm and their lengths were 2, 3, and 4 cm. The 2 cm stent constructed of 0.33 mm wire showed minimum pathologic changes of the trachea of the dog compared to the other stents, and at the same time had a complete covering of ciliated columnar epithelium over the stent surface.     

Experimental study of endoesophageal and intestinal expandable metallic stent placement

Gianturco expandable metallic stents were implanted into the esophagus and small intestine of 10 rabbits in order to evaluate the influence of wire stents on the gastrointestinal tract. The stents were constructed of 0.010 inch stainless steel wire. The relaxed diameter of the stents was 12-14 mm and the length was 10 mm. Except for one stent placed in the small intestine, the stents did not migrate and were covered with thickening mucosal epithelium. The mucosal inflammatory changes were slight, but severe intestinal adhesions were noted. The findings in the two groups were not significantly different at three and six weeks. Five rabbits died within three weeks of intestinal disorders caused by severe intestinal adhesions and/or perforations. The experimental data showed that implantation of metallic wire stents into the gastrointestinal tract resulted in severe damage to the esophagus and small intestine of rabbits.     

Clinical experience of expandable metallic stent placement for malignant biliary obstruction]

Expandable metallic stents of modified Gianturco design were used in nine cases of malignant biliary obstruction. Stents were placed through a percutaneous transhepatic approach without any severe complications. Initial patency was obtained seven of nine patients. Of these seven patients, recurrent jaundice was observed in three within four weeks. One patient had recurrent stenosis after four months due to ingrowth of the tumor. Although the expandable metallic stent offers several theoretical advantages over currently available stents, a disadvantage is that tumors may grow through the spaces between the legs of the wire or grow over the stent. We found that multi-modal treatment combined with radiation therapy was indispensable to maintain the patency of the stent in malignant biliary obstruction.     

Fatal complication of an expandable metallic bronchial stent

A case of massive fatal haemoptysis secondary to erosion of a Gianturco expandable wire bronchial stent is described. The stent had been inserted for a benign bronchial stenosis. CT demonstrated erosion of the stent through the oesophagus and a false aneurysm of the descending thoracic aorta. The CT and plain radiographic appearances are presented. The potential for progressive migration and local damage should limit the use of this type of stent in benign bronchial stenoses.     

A study of new retrievable expandable metallic stent

The authors improved retrievable expandable metallic stent (REMS), instead of the nylon suture, the REMS was connected with the stainless steel thread. Under fluoroscopy the stainless steel thread of the shrinking body could be observed and was strong enough to retract the placed stent, then the stent could be removed by the stainless steel hook. We placed the REMS in the I.V.C. of canine, and removed them after one week placement, we could not remove them after two weeks placement. This study suggested that the REMS was considered to be useful and safe for clinical application.     

自膨式国产金属食管覆膜支架治疗食管-气管瘘

目的:探讨自膨式国产金属食管覆膜支架治疗各种食管瘘的方法,常见并发症的预防与处理。方法:采用自膨式国产金属食管覆膜支架,在X线监视下或胃直视下用推送器经口置入食管病变部位,共治疗食管瘘患者57例,其中食管-气管瘘18例,食管-支气管瘘25例,食管-纵隔瘘9例,食管-纵隔-支气管瘘5例。结果:57例患者均顺利完成支架置入,即时堵瘘率为100%,未出现技术问题及严重并发症。所有患者均达到了改善进食、提高生活质量的治疗效果。结论:自膨式国产食管覆膜支架适用于治疗各种食管瘘,操作简便、疗效安全,且价格低廉,是一项值得推广的技术。     

Experimental study of the intraurethral placement of expandable metallic stents

Various types of Gianturco expandable metallic stents were implanted into the urethra of four dogs in order to evaluate the suitable expandability of the stents in urethra and also to determine the effect of the stents on the urethral wall. The stent of 1.5 cm in length and constructed of 0.010 inch round stainless steel wire with twelve zigzag bends showed the suitable expandability on the canine urethra compared to the other stents. The urethra remained patent and the inflammatory changes on the urethral wall were moderately noted. No hematuria or calcifications around the stents were noted in any dogs. The experimental data showed a potential clinical application.     

Hilar malignancy: treatment with an expandable metallic transhepatic biliary stent

An expandable metallic transhepatic biliary endoprosthesis was used to treat 20 patients with hilar malignancy and isolated right and left intrahepatic ducts. In 12 patients, only one intrahepatic ductal system was drained; in eight patients, both systems were drained. In five patients, both systems were drained through a single transhepatic track by arrangement of two stents in a T configuration. The initial technical success rate in placing the stents and achieving internal drainage was 100%. Complications necessitating further intervention occurred in two of the 20 patients. Short-term clinical follow-up was available for 19 of the 20 patients. Two months after stent insertion, two patients complained of persistent jaundice, two patients died without jaundice, and 15 patients were free of symptoms of biliary obstruction. A variety of geometric configurations are possible with this endoprosthesis. The relative merits of these stent arrangements are discussed, and a new technique for placing the stents in a T configuration is described.     

Acute changes in aortic wall mechanical properties after stent placement in rabbits

PURPOSE: To evaluate mechanical property changes after endovascular stent placement in small-diameter arteries. MATERIALS AND METHODS: Self-expanding stents (Wallstent) were placed in the infrarenal aorta of five New Zealand White rabbits via a surgical right femoral approach. Blood pressure changes (deltaP) were monitored in the aorta. Blood flow velocity was measured with a 20-MHz, pulsed Doppler probe (n = 4) to calculate the pulsatility index. Aortic diameter (dA) and diameter changes (delta(d)) were measured with a 20-MHz probe in echo-tracking mode. Diameter compliance (Cd) and distensibility coefficient (DC) were calculated as Cd = 2(delta)d/(delta)P and DC = 2delta(d)/delta(P)/dA. RESULTS: Aortic diameter increased from 3.360 +/- 0.4033 mm to 4.020 +/- 0.3033 mm after stent placement at the stent level only. Compliance decreased from 77.644 +/- 24.306 mm kPa(-1) to 31.150 +/-8.245 x 10(-3) mm kPa(-1) at the stent level, and was then significantly lower than upstream (98.500 +/- 53.196 mm kPa(-1)) and down-stream (59.047 +/- 13.833 mm kPa(-1)). There was no significant change in pulsatility index. CONCLUSIONS: Endovascular stent placement produces a significant decrease in arterial wall compliance of the rabbit abdominal aorta.     

Benign tracheobronchial stenoses: changes in short-term and long-term pulmonary function testing after expandable metallic stent placement

PURPOSE: To determine the short- and long-term improvement in airflow dynamics in patients undergoing tracheobronchial stent placement for benign airway stenoses. METHODS: Twenty-two patients underwent 34 tracheal and/or bronchial stent placement procedures for benign airway stenoses and had the results of pulmonary function tests available. Stent placement indications included bronchomalacia after lung transplantation (n = 11), postintubation stenoses (n = 6), relapsing polychondritis (n = 2), and 1 each of tracheomalacia, tracheal compression, and histoplasmosis. Six patients underwent more than one stent placement procedure (range: 2-7 procedures). The mean forced expiratory volume in one second (FEV(1) ), forced expiratory flow rate in the midportion of the forced vital capacity curve (FEF(25-75) ), forced vital capacity, and peak flow (PF) rate obtained before stent placement were compared with those immediately after stent placement and with those measurements most remote from stent placement using the paired two-tailed test. RESULTS: All patients reported improved respiratory function immediately after stent placement. The mean FEV(1), FEF(25-75), and PF rate improved significantly (p < 0.001, p = 0.002, and p = 0.009, respectively) after stent placement. On long-term follow-up averaging 15 months after stent placement, these parameters declined despite patients' subjective sense of improvement. Segregating the population into transplant and nontransplant airway stenosis etiologies, however, FEF(25-75) and PF rate remained significantly improved (p = 0.045, p = 0.027, respectively), over the long term for the latter. FEV increased after subsequent stent placements for patients receiving multiple stents. CONCLUSION: Stent placement for benign tracheobronchial stenoses provides significant immediate improvement in airflow dynamics. Long-term improvement in airflow obstruction may be expected, and additional stent placements may further improve pulmonary function.     

Fundamental experiment of expansile force of expandable metallic stent

So far expansile force of expandable metallic stent has been estimated by only wall-distending pressure P. We estimated expansile force of stent by not only P but also a force per one unit length of wire F. F corresponds to the degree of digging into the vessel wall. P and F were thought to be useful in selecting the best stent.     

A stent therapy for portal tumor thrombi. Use of Dacron sheet covered self expandable metallic stent]

We developed a method of intraportal placement of a covered stent against portal tumor thrombi. Half around a z-stent was covered with a Dacron mesh sheet. In one case with portal tumor thrombi protruding into the main portal branch, the stent was placed percutaneously-transhepatically, through a coaxial introducer. Immediately after the placement, portal vein was dilated and, which was still patent after six months. No complication has been observed.     

A clinical study of biliary endoprosthesis using an expandable metallic stent--evaluation of early results]

Self-expandable metallic stents were used to relieve biliary obstruction in 58 patients. Fifty-three of 57 patients with malignant obstruction were treated with EMS after radiotherapy. A percutaneous approach was employed in all patients without severe complications. Insertion of EMS was successful in all cases. Within one week of EMS placement, all stents expanded to at least 90% of their original diameter, with the caliber of the bile duct always smaller than that of the EMS due to ischemic edema of the mucosa. In fifty-one of 58 patients, the external biliary drainage catheter could be removed. Cholangioscopy revealed that epithelium covered the EMS from the early phase after placement, enabling the EMS to become a physiological endoprosthesis in the bile duct. Rapid re-obstruction after EMS placement had two mechanisms: reactive obstruction and rebound obstruction, to avoid which adequate therapy to reduce the volume of the tumor is required. Also it is necessary to continue external drainage for at least two weeks after EMS placement. For the management of biliary obstruction, EMBE combined with radiotherapy is a promising treatment modality, with encouraging early results obtained. Further studies will determine the role of EMS in the treatment of patients with non-operable biliary obstructions.     

Covered metallic stent placement in the management of cervical esophageal strictures

PURPOSE: To describe the authors' experience with self-expandable covered metallic stents in 16 patients with malignant and benign cervical esophageal strictures. MATERIALS AND METHODS: Sixteen expandable covered metallic stents were placed with fluoroscopic guidance in 16 patients (14 men, two women; mean age, 60 years; age range, 26-75 years) with malignant and benign strictures of the cervical esophagus. The causes of strictures were ingestion of corrosive agents (n = 3), biopsy-proved squamous cell carcinoma (n = 12), and postsurgical scarring (n = 1). The mean dysphagia scores at presentation were compared with those after stent placement by using the Wilcoxon signed rank test. RESULTS: Stent placement was technically successful in all patients. The reduction in the mean dysphagia score after stent placement was statistically significant (P = .0327). All patients complained of mild to severe foreign body sensation, with four reporting severe pain necessitating immediate stent removal. With the exception of one patient with limited follow-up, complications requiring intervention occurred in all patients, including migration in nine patients and tissue hyperproliferation in two. Of the 12 patients with a malignant stricture of the esophagus, four patients eventually underwent gastrostomy for the placement of a feeding tube and one patient underwent surgery. All four patients with a benign cervical stricture failed to achieve long-lasting improvement with temporary stent placement. CONCLUSIONS: Although the placement of covered metallic stents in the cervical esophagus provides adequate initial palliation, it is associated with poor patient tolerance and a high complication rate.     

金属内支架在治疗恶性胆道梗阻中的应用

目的 :探讨经皮肝穿刺胆道金属内支架置入治疗恶性胆道梗阻临床应用价值。方法 :对 2 7例恶性梗阻性黄疸患者行经皮肝穿胆道金属内支架置入术。男 18例 ,女 9例 ,其中肝癌 6例 ,胆管癌 7例 ,胰腺癌 5例 ,转移癌 9例。梗阻部位在胆总管 12例 ,肝总管肝门区 15例。结果 :经皮肝胆道内支架置入术技术成功率为 10 0 %。 2 7例共置入金属内支架31枚 ,术后 1周复查肝功能血清学指标 ,总胆红素、碱性磷酸酶和谷丙转氨酶较术前明显下降 ,P <0 .0 0 1。随访开通时间平均为 14 1天 ,半年开通率 5 5 .6 % ,并发症发生率为 2 5 .9% ,主要为胆道感染 ,胆道出血等。结论 :金属内支架置入术是治疗胆道梗阻性黄疽的安全、有效的姑息治疗手段