Tracheal stents are often used to maintain the patency of the trachea and bronchia in patients suffering from central airway lesions. Metallic tracheal stents are now widely used in the clinical setting, but these types of stents can cause many intractable material-related complications. Biodegradable tracheal stents are made of biodegradable polymer materials with good mechanical strength for maintaining the patency of the lesion segment during a certain period of time, and then they can be gradually degraded into harmless products in human body. Compared with conventional metallic tracheal stent, biodegradable tracheal stents have a good prospect in clinic. In this article, we review the choice of biodegradable tracheal stent materials, experimental progress in biodegradable tracheal stent as well as the challenges we are facing.
Objective To introduce the experience of treating 85 cases of stanford type B aortic dissection by endovascular implantment of stent-grafts，to provide more clinical evidence for endovascular repairment for stanford B type aortic dissections.Methods Imaging examination by computed tomography angiography （CTA） were done to obtain anatomical detail of dissection. Stent-grafts were implanted under the guide of DSA in all cases. The patients were followed-up for 3 months，6 months，12 months，and then annually by CTA examination to observe the complications and morphological changes of the aneurysm.Results The technical success rate was 95.3%（81/85），and the clinical success rate was 91.8%（78/85）. Eight patients died after operation in hospital，who were all in acute phase，and no patients of chronic phase died，there had statistic differences （P＜0.05）. The perioperative complications’ incidence of endovascular repair which happened in patients of acute phase was higher than that patients of chronic phase （38.2% vs.13.3%，P＜0.05）. Left subclavian artery were covered completely for 13 cases，and partially covered for 22 cases，there was no obvious cerebralvascular insufficiency. There were 41 patients of whom other tears which were not covered during operation exsited at abdominal aortic and one year following-up showed that at those section thromblization of false cavity was not clear. The rest of patients whose abdominal aortic didn’t exist tears hadn’t new tears appeared.Conclusions Regardless in the acute or chronic stage，endovascular therapy is an effective mathod of treating stanford type B dissection. However，implanting stent-grafts have a higher security in chronic period than doing that in acute period. If the right carotid artery，vertebra and Willis ring are smoothly，there is little need to set up a by-pass to left subclavian artery before endovascular repairment. For those patients that other uncovered tears exited，following-up should be a must，and further strategy should be studied and prepared in advance.
Objective To find out the follow-up results of early in-stent restenosis (ISRS) and develop effective way to improve clinical treatment and precaution of restenosis. Methods The data from a registry of 51 consecutive patients who underwent elective carotid artery angioplasty and stenting （CAS） at our institution between Jan. 2003 and Sept. 2005 were retrospectively reviewed. Complete data for 37 of these patients were available. All patients underwent duplex ultrasound scanning in follow-up period, which was used to determine the degree of restenosis. Results CAS was performed in 37 patients， 8.1% (3/37) were women. Mean age was (70.5±5.9) years. Mean time of follow-up was (12.2±7.7) months. Sixteen (43.2%) caces of ISRS （gt;30%） were found by color duplex ultrasound scanning， but only 1 (2.7%) ISRS was found gt;50%; 3 female patients had minor ISRS. Among all factors, female patients had higher incidence of ISRS than male (P=0.038); balloon-expanding after stenting and accompanying with other artherosclerosis of periphery vessel had correlation about ISRS （P=0.037, P=0.016）. Conclusion The severe restenosis rate is acceptable. Female patients were more likely to have ISRS. Balloon-expanding maybe have effect on reducing incidence of ISRS and controlling artherosclerosis was helpful.
Objective To evaluate initial experience with shape memory alloy stent as an alterative to colostomy in patients with intestinal obstruction of rectal cancer. Methods Twenty-one patients with acute and chronic rectal obstructions from malignant causes underwent stent placement. After rectal stent was slenderized in ice water, it was inserted into the strictured rectum by hand or sigmoidoscope. Nitinol mesh stent were deployed in hot water. Results Eighteen patients who had underwent rectal stent placement achieved clinical decompression within 5 hours. Colostomy underwent in 3 patients due to stent failure. Eighteen patients with stent were followed-up, 14 cases died in 56-720 days and 4 other cases were still alive without intestinal obstruction in 2-15 months. Conclusion Nitinol mesh stent may be useful in the management of terminal or high-risk surgical patients for palliative purposes shuning colostomy. Palliation of stent combined with chemotherapy and immunotherapy can be performed to improve survival.
ObjectiveTo investigate the effect of drained versus nondrained pancreaticojejunostomy on prevention of the pancreatic leakage after pancreaticoduodenectomy. MethodsSeventysix patients underwent the standard pancreaticoduodenectomy including resection of the distal stomach,common bile duct, the head of pancreas and the duodenum.Pancreaticenteric reconstruction was accomplished via either pancreaticojejunostomy by endtoside anastomsis or pancreaticojejunostomy by ducttomucosa anastomsis.The stented external drainage of pancreatic duct was used in 45 of 76 patients. ResultsPancreatic leakage was identified in 1 patient in the drained group consisting of 45 patients,in 7 patients in the nondrained group consisting of 31 patients, the incidence of pancreatic leakage in the drained group (2.2%) was significantly less than in the nondrained group (22.6%,P＜0.05).ConclusionComparing the incidences of pancreatic leakage from both groups,the authors believe that the stented external drainage of pancreatic duct can significantly reduce the incidence of pancreatic leakage after pancreaticoduodenectomy.
Objective To identify the short ( lt;30 days) and intermediate ( 30 days to 6 months) benefits and risks of tracheobronchial stents in patients with malignant airway stenosis. Methods 55 cases with malignant airway disease who underwent tracheobronchial stents placement from January 2006 to May 2008 were followed up for 6 months. The efficacy rate, complication rate, reintervention rate, and survival were analyzed. Results There were 61 self-expanding metal stents placed in 55 patients with malignant disease, with no intraoperative mortality. The immediate efficacy rate was 100% , the short-term( lt;30 days) efficacy rate was 94. 5% , and the survival rate in 6 months was 32. 7% . The complications included tumor ingrowth, excessive granulation tissue, stent migration, and restenosis. A total of 14 cases of complicationswere observed, in which two occurred during the short-term period ( lt; 30 days ) and the remaining complications occurred after 30 days. Conclusions Tracheobronchial stents can improve symptoms immediately for the patients with unresectable malignant central airway obstruction with fairly safety. The benefit of airway stents is particularly seen in the short-termperiod and the complications occur mainly after 30 days.
Objective To summarize treatment experience and evaluate clinical outcomes of surgical therapy for Stanford type A aortic dissection （AD）. Methods Clinical data of 48 patients with Stanford type A AD who underwent surgical treatment in General Hospital of Lanzhou Military Region from October 2006 to March 2013 were retrospectively analyzed. There were 41 males and 7 females with their age of 26-72 （47.6±9.2） years. There were 43 patients with acute Stanford type A AD （interval between symptom onset and diagnosis＜14 days） and 5 patients with chronic AD. There were 19 patients with moderate to severe aortic insufficiency and 6 patients with Marfan symdrome but good aortic valve function，who all received Bentall procedure，total arch replacement and stented elephant trunk implantation. There were 8 patients with AD involving the aortic root but good aortic valve function who underwent modified David procedure，total arch replacement and stented elephant trunk implantation. There were 10 patients with AD involving the ascending aorta who received ascending aorta replacement，total arch replacement and stented elephant trunk implantation. There were 5 patients with AD involving partial aortic arch who underwent ascending aorta and hemiarch replacement. Patients were followed up in the 3rd，6th and 12th month after discharge then once every year. Follow-up evaluation included general patient conditions，blood pressure control，chest pain recurrence，mobility and computerized tomography arteriography （CTA）. ResultsCardiopulmonary bypass time was 121-500 （191.4±50.6） minutes，aortic cross-clamp time was 58-212 （112.3±31.7） minutes，and circulatory arrest and selective cerebral perfusion time was 26-56 （34.8±8.7） minutes. Postoperative mechanicalventilation time was 32-250 （76.2±35.6） hours，and ICU stay was 3-20 （7.1±3.4） days. Thoracic drainage within 24 hours postoperatively was 680-1 600 （1 092.5±236.3） ml. Seven patients （14.5%） died perioperatively including 2 patients with multiple organ dysfunction syndrome，2 patients with low cardiac output syndrome，1 patient with renal failure，1patient with delayed refractory hemorrhage，and 1 patient with coma. Twenty patients had other postoperative complicationsand were cured or improved after treatment. A total of 38 patients ［92.7% （38/41）］ were followed up for 3-48 （13.0±8.9） months，and 3 patients were lost during follow-up. During follow-up，there were 36 patients alive and 2 patients who died of other chronic diseases. There was no AD-related death during follow-up. None of the patients required reoperation for AD or false-lumen expansion. CTA at 6th month after discharge showed no anastomotic leakage，graft distortion or obstruction.Conclusion According to aortic intimal tear locations，ascending aorta diameter and AD involving scopes，appropriate surgical strategies，timing and organ protection are the key strategies to achieve optimal surgical results for Stanford type A AD. Combined axillary and femoral artery perfusion and increased lowest intraoperative temperature are good methods for satisfactory surgical outcomes of Stanford type A AD.
Objective To investigate the feasibility and effect of stentedpulmonary autograft replacement and find out the best way to treat mitral valve diseases. Methods From August 2006 to October 2007, 20 male sheep at the age of about 1 year old underwent mitral valves replacement operation in Anzhen Hospital. Weight of these sheep was 50.0±6.0 kg. They were randomly divided into two groups. Ten sheep in the experimental group underwent RossⅡsurgery in which we first sutured pulmonary valve onto a pulmonary valve stent, transferred the valve to the mitral valve annulus and then reestablished the outflow tract of the right ventricle. The other 10 sheep in the control group underwent bioprosthetic valve replacement routinely. Ultrasonic cardiogram (UCG) was employed 6 hour after operation to measure the effective orifice area (EOA) of the mitral valve, mitral peak velocity of early filling, the peak pressure gradient (PPG), the extent of regurgitation, left ventricular enddiastolic dimension (LVEDD) and ejection fraction (EF). Results One sheep in the experimental group died of low cardiac output syndrome; one in the control group died of unmanageable bleeding during operation, and the others all survived. Six hours after operation, UCG of the experimental group showed that the heart valves were well fixed, valve echo was clear, and there was no perivalvular leakage or mitral valve stricture or regurgitation, but moderate pulmonary valve regurgitation occurred in 1 case and mild in 2. There was no significant difference between the two groups in PPG (11.86±1.28 mm Hg vs. 10.98±0.98 mm Hg,t= 1.670,P=0.110) and the mitral peak velocity of early filling (1.72±0.09 m/s vs. 1.65±0.07 m/s, t=1.680,P=0.110). However, EOA of the experimental group was smaller than the control group (2.23±0.09 cm2 vs. 2.39±0.08 cm2, t= 4.240,P= 0.001). Conclusion The experimental result of sheep mitral valves replacement with stentedpulmonary autograft is satisfying. The new mitral valves work well and the surgery method is feasible.
ObjectiveTo investigate the feasibility of lung tissue flap repairing esophagus defect with an inner chitosan tube stentin in order to complete repairing and reconsruction of the esophagus defect.MethodsFifteen Japanese white rabbits were randomly divided into two groups， experiment group(n=10): esophagus defect was repaired with lung tissue flap having inner chitosan tube stent; control group(n=5): esophagus defect was repaired with lung tissue flap without inner chitosan tube stent; and then the gross and histological apearance in both groups were observed at 2, 4,8 weeks after operation, barium sulphate X-ray screen were observed at 10 weeks after operation.ResultsSix rabbits survived for over two weeks in experiment group, lung tissue flap healed with esophageal defect, squamous metaplasia were found on the surface of lung tissue flap in experiment group. At 10 weeks after operation, barium sulphate examination found that barium was fluent through the esophageal and no narrow or reversed peristalsis, the peristalsis was good in experiment group.Four rabbits survived for two weeks and the lung tissue flap healed with esophageal defect, fibrous tissue hyperplasy on the surface of the lung tissue flap in control group. At 10 weeks after operation, barium sulphate examination found that barium was fluent through the esophageal and slight narrow or reversed peristalsis, the peristalsis was not good in control group, otherwise.ConclusionIt is a feasible method to repair the esophageal defect with lung tissue flap with the inner chitosan stent.
Objective To design a novel stentless porcine aortic bioprosthesis and test the feasibility and its function in vitro after the valve was implanted by a modified method. Methods Six stentless porcine aortic bioprosthesis were divided into two groups according to different implantation, single layer suture group: new improvement stentless porcine aortic bioprosthesis sutured with single layer was implanted; double layer suture group: stentless porcine aortic bioprosthesis developmented by our laboratory used double layer suture was implanted. Each group contained three scales: 23 mm ,25 mm and 27 mm. Analogue ex vivo aortic valve replacement was performed , the feasibility of the new implantation was detected. Effective orifice area, transvalvular pressure gradient and regurgitation ratio were recorded at the cardiac output of 2.0 L/min, 3.5 L/min, 5.0 L/min and 7.0 L/min under the guideline of International Organization for tandardization （ISO）5840. Results The average aortic valve implantation time used for single layer suture and tradition double layer suture were 50 min and 70 min respectively. The transvalvular pressure gradient in the single layer suture group were significantly lower than those in double layer suture group under the flow of 5.0 L/min in 23 mm valve and 27 mm valve （13.51±0.51 mm Hg vs. 14.44±0.99 mm Hg, 7.36±0.19 mm Hg vs. 7.53±0.28 mm Hg；P＜0.01）;and the effective orifice area in the single layer suture group were larger than those in double layer suture group in the same case(1.87±0.06 cm2 vs. 1.76±0.08 cm2, 2.26±0.07 cm2 vs. 2.16±0.05 cm2；P＜0.01). There was no statistically difference in other parameters between both groups. Conclusion The novel design of new improvement stentless porcine aortic bioprosthesis used single layer suture has good hemodynamic characteristics as the nature structure . The modified suture method decrease the implantation time.Nemerical data of the evaluation in vitro show that the difference between single layer suture group and double layer suture group in effective orifice area,transvalvular pressure gradient and regurgitation ratio haveno statistical significance. This experiment is the foundation of the animal and clinical experiment in the future.