To address the conflict between the “fitness” and “feasibility” of body-fitted stents, this paper investigates the impact of various smoothing design strategies on the mechanical behaviour and apposition performance of stent. Based on the three-dimensional projection method, the projection region was fitted with the least squares method (fitting orders 1–6 corresponded to models 1–6, respectively) to achieve the effect of smoothing the body-fitted stent. The simulation included the crimping and expansion process of six groups of stents in stenotic vessels with different degrees of plaque calcification. Various metrics were analyzed, including bending stiffness, stent ruggedness, area residual stenosis rate, contact area fraction, and contact volume fraction. The study findings showed that the bending stiffness, stent ruggedness, area residual stenosis rate, contact area fraction and contact volume fraction increased with the fitting order's increase. Model 1 had the smallest contact area fraction and contact volume fraction, 77.63% and 83.49% respectively, in the incompletely calcified plaque environment. In the completely calcified plaque environment, these values were 72.86% and 82.21%, respectively. Additionally, it had the worst “fitness”. Models 5 and 6 had similar values for stent ruggedness, with 32.15% and 32.38%, respectively, which indicated the worst "feasibility" for fabrication and implantation. Models 2, 3, and 4 had similar area residual stenosis rates in both plaque environments. In conclusion, it is more reasonable to obtain the body-fitted stent by using 2nd to 4th order fitting with the least squares method to the projected region. Among them, the body-fitted stent obtained by the 2nd order fitting performs better in the completely calcified environment.
Objective To evaluate the cl inical effect of percutaneous transluminal angioplasty (PTA) and PTA and stenting (PTAS) in treating multilevel arteriosclerosis obl iterans (ASO) of lower extremities. Methods Between January 2007 and October 2009, 29 cases of multilevel ASO of lower extremities were treated with PTA or PTAS. There were 17 males and 12females with an average age of 71 years (range, 56-83 years). The cl inical manifestations were l imbs numb with cold sensation, intermittent claudication (lt; 100 m), and 19 patients had rest pain. According to Fontaine stages classification, there were 7 cases of stage II, 14 cases of stage III, and 8 cases of stage IV. Concomitant diseases included hyperl ipidemia in 13 cases, diabetes in 6 cases, hypertension in 12 cases, chronic heart failure in 5 cases, chronic obstructive pulmonary disease in 3 cases, cerebral infarction in 5 cases, and toe ulcer in 15 cases. The preoperative ankle/brachial index (ABI) was 0.28 ± 0.13. Results In 3 cases of below knee lesions for the guide wire puncturing through the artery wall, 1 case gave up, and 2 cases continued recanal ized other arteries without serious bleeding compl ications. After operation, cerebral infarction occurred in 1 case, pulmonary infection in 2 cases, and groin puncture site hematoma in 2 cases. All patients were followed up 3 to 36 months. Limb skin temperature was significantly improved, and intermittent claudication disappeared or claudication distance lengthened, rest pain disappeared or significantly reduced in 27 patients (30 l imbs). The wound of amputee achieved good heal ing in 2 cases (2 l imbs). In 27 patients undergoing endovascular treatment, the postoperative ABI was 0.72 ± 0.19, showing significant difference when compared with the preoperative one (P lt; 0.05). Conclusion The PTA and PTAS treatment for multilevel ASO of lower extremities is a safe and effective option, and the short-term effect is good. Different treatments should be chosen according to the location and length of vascular occlusion.
Objective
To observe the occurrence condition of endoleak after endovascular aneurysm repair (EVAR) operation for abdominal aortic aneurysm (AAA), and to analyze the factors of the endoleak.
Methods
Between July 2005 and June 2013, 210 cases of AAA were treated with EVAR. Of 210 patients, 175 were male and 35 were female, aging 42-89 years (mean, 65.7 years). The patients were all proved to have infrarenal AAA by computed tomography angiography (CTA). The disease duration ranged from 1 week to 2 years (median, 11.3 weeks). The maximum diameter of the aneurysms was 44-72 mm (mean, 57.3 mm). The proximal landing zone was longer than 1.5 cm. CTA was performed routinely at 2 months after operation to detect the endoleak of contrast agent. If endoleak was found, CTA was performed again at 6 months. If obvious endoleak still existed, digital subtraction angiography (DSA) would be performed to clarify the character and the degree of the endoleak, and EVAR should be done if necessary.
Results
Endoleak occurred in 31 cases (14.8%) during operation, including 11 cases of type I endoleak (8 cases of type IA and 3 cases of type IB), 18 cases of type II endoleak, and 2 cases of type III endoleak (type IIIB). The patients were followed up 2-8 months (mean, 3.1 months). At 2 months after operation, contrast agent endoleak was found in the remnant aneurysm cavity of 12 cases (5.7%). At 6 months after eperation, contrast agent endoleak was found in 10 cases (4.8%) by CTA. In 8 patients receiving DSA, there were 4 cases of type I endoleak (3 cases of type IA and 1 case of type IB), 3 cases of type II endoleak, and 1 case of type III (type IIIB) endoleak. In 5 patients having type I and type III endoleak, collateral movement of stent graft was observed in different degree; after increased stent graft was implanted, the endoleak disappeared after 2-4 months. The patients having type II endoleak were not given special treatment, endoleak still existed at 2 months after reexamination of CTA, but the maximum diameter of AAA had no enlargement.
Conclusion
The collateral movement of stent graft is a very important factor to cause type I and type III endoleak in the patients of AAA after EVAR, and endoleak can be plugged by EVAR again.
ObjectiveTo explore the effectiveness of thoracic endovascular aortic repair (TEVAR) for blunt thoracic aortic injury (BTAI) with hostile stent-graft proximal landing zone.
MethodsA retrospective analysis was made on the clinical data of 13 patients with BTAI with hostile stent-graft proximal landing zone treated by TEVAR between December 2007 and December 2014. There were 10 males and 3 females with the mean age of 44 years (range, 24-64 years). The imaging examination indicated Stanford type B aortic dissection in 7 cases, pseudoaneurysm in 3 cases, aneurysm in 1 case, and penetrating ulcer in 2 cases. According to the partition method of thoracic aortic lesion by Mitchell, 8 cases underwent stent-graft with left subclavian artery (LSA) coverage, 3 underwent chimney stents for LSA, and 2 for left common carotid artery (LCCA). In 2 cases receiving chimney TEVAR involving LCCA, one underwent steel coils at the proximal segment of LSA to avoid type II endoleak and the other underwent in situ fenestration for endovascular reconstruction of LSA.
ResultsAll TEVAR procedures were successfully performed. The mean operation time was 1.8 hours (range, 1-3 hours); the mean intraoperative blood loss was 120 mL (range, 30-200 mL); and the mean hospitalization time was 15 days (range, 7-37 days). No perioperative death and paraplegia occurred. The patients were followed up 3-30 months (mean, 18 months). Type I endoleak occurred in 1 case during operation and spontaneously healed within 6 months. Hematoma at brachial puncture site with median nerve compression symptoms occurred in 1 case at 3 weeks after operation; ultrasound examination showed brachial artery pseudoaneurysm and thrombosis, and satisfactory recovery was obtained after pseudoaneurysmectomy. No obvious chest pain, shortness of breath, left upper limbs weakness, numbness, and dizziness symptoms were observed. Imaging examination revealed that stentgraft and branched stent remained in stable condition. Meanwhile the blood flow was unobstructed. No lesions expanded and ruptured. No new death, bacterial infection, or other serious complications occurred.
ConclusionAccording to Mitchell method, individualized plan may be the key to a promising result. More patients and further follow-up need to be included, studied, and observed.
Objective To summarize the critical point of diagnosis and endovascular repairment (EVR) to thoracic aortic aneurysm (TAA), thoracic pseudoaneurysm (TPA) and aortic dissection (AD), by comparison the computerized tomography angiography (CTA) images before and after EVR to observe effects, so as to explore a unique index of imageology to assess the pathological development and evaluate therapeutically effect in dynamic and systemic reviews in pre, intra, postEVR and followup period. Methods Fortyeight patients involving aneurysm or dissection of thoracic aorta were treated with EVR based on the preoperative CTA imaging. Before and after the introducing of stentgraft, digital substation angiography (DSA) was taken place and sequential enhanced CTA was followed to evaluate the effects of the treatment. All imagings of CTA and DSA were collected and induced into e-FilmTM database to select key sections for analyses and measurement. Results Fortynine EVR were preformed and 54 stent grafts were implanted in 48 cases, with endothelial tears sealed in 42 cases of dissection, aneurismal cavities excluded in 2 cases of aortic aneurysm, and rupture site closed in 4 cases of pseudoaneurysm. Endoleakage happened in 9 cases, which were treated successfully by appropriate measures. One case suffered hemorrhage from introducing artery (iliac) which was controled by surgery, but he died of disseminated intravascular coagulation and then multiple organs failure. Fortyseven cases were followed up in 6-51 months with a satisfied clinical effect. Conclusion EVR is favorable in the effect of repairment to true, false and dissection of thoracic descending aorta. Chest pain and CTA scan is the key of early diagnosis of aortic dissection. Certain sections and leftanterior oblique viewing are the crucial profile for assessment and evaluation before and after operation.
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.
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.
Objective To summarize the progress of endoscopic diagnosis and therapy for pancreatic cancer. Methods Domestic and international publications online involving progress of diagnosis and therapy for pancreatic cancer by using endoscope in recent years were collected and reviewed. Results Recently, early diagnostic rate of pancreatic cancer increased with the development of endoscope and endoscopic technique such as endoscopic ultrasound, endoscopic ultrasound-guided fine needle aspiration, peroral pancreatoscopy, optical coherence tomography, ERCP, and cytology in pancreatic juice. Furthermore, varied therapies such as endoscopic ultrasound guided celiac plexus neurolysis, implantation of iodine 125-particles or pancreatic duct/bile duct stents were performed by endoscope for advanced pancreatic cancer. Conclusion Early diagnostic rate and novel therapeutic alternative of pancreatic cancer are supplied by digestive endoscopy.
Objective To study the diagnostic procedures and management of aortic stent graft infection. Methods Clinical data of 4 patients with aortic stent graft infection from 1998 to 2008 were analyzed retrospectively. Results Primary disease was thoracic endovascular aortic repair in 2 cases and endovascular aneurysm repair in another 2 cases. Constitutional symptoms and abscess information on imaging studies were presented in all patients. Salmonella choleraesuis was revealed in 2 cases. Surgical debridement, drainage and systematic antimicrobial therapies were given to 2 patients. The remaining 2 patients were managed with antimicrobial therapy only. During follow-up, there was no recurrence of infection. Conclusions Infection of aortic stent graft infection is a rare but potentially devastating complication. Radiologic studies can serve as important adjuncts in the diagnosis of endovascular graft infections. Several treatment options are available, some cases may be managed with conservative treatment.
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.
