Missing data represent a general problem in many scientific fields, especially in medical survival analysis. Dealing with censored data, interpolation method is one of important methods. However, most of the interpolation methods replace the censored data with the exact data, which will distort the real distribution of the censored data and reduce the probability of the real data falling into the interpolation data. In order to solve this problem, we in this paper propose a nonparametric method of estimating the survival function of right-censored and interval-censored data and compare its performance to SC (self-consistent) algorithm. Comparing to the average interpolation and the nearest neighbor interpolation method, the proposed method in this paper replaces the right-censored data with the interval-censored data, and greatly improves the probability of the real data falling into imputation interval. Then it bases on the empirical distribution theory to estimate the survival function of right-censored and interval-censored data. The results of numerical examples and a real breast cancer data set demonstrated that the proposed method had higher accuracy and better robustness for the different proportion of the censored data. This paper provides a good method to compare the clinical treatments performance with estimation of the survival data of the patients. This provides some help to the medical survival data analysis.
Objective To observe the effects of vitrectomy for persistent fetal vasculature (PFV).Methods The clinical data of 11 patients (14 eyes) with PFV, including posterior PFV (one eye) and combined PFV (13 eyes), were retrospectively analyzed. Vitrectomy was performed for all patients, lensectomy was performed for seven eyes, retinotomy was performed for five eyes, retinotomy and scleral buckling was performed for one eye. Intraoperative and postoperative complications were observed. The followup period ranged from eight to 74 months, with the mean of 44 months. The visual acuity （VA） and intraocular pressure before and after surgery were comparatively analyzed.Results There were no intraoperative complications in all the patients. The surgery was performed successfully in 12 eyes （86.0%） and failed in two eyes （14.0%）. The postoperative VA of five eyes (35.7%) increased, four eyes （28.6%） didnprime;t change and five eyes （35.7%） decreased. The postoperative intraocular pressure of two eyes （14.3%） increased,11 eyes （78.6%） didnprime;t change and one eye （7.1%） decreased. There was one eye with persistent hypotension and one eye with recurrent retinal detachment after surgery.Conclusion Vitrectomy can prevent complications and improve visual acuity in some PFV patients.
New biodegradable intravascular stent can reduce risk of foreign bodies retained, thus, it is widely concerned and some of the products have been introduced into the clinic. However, the characteristic of biodegradable may lead to more safety concerns associated with thrombosis. To ensure the safety, the thrombus formation experiment in vivo needs to be carefully designed and evaluated based on GB/T 16886.4 standard, but current standard do not provide explicit testing and evaluating methods. Establishing animal model with experimental pigs, the study compares biodegradable coronary stents and metal stents by simulating clinical implantation in vivo on the thrombus formation in the implanting process, and after the short-term and long-term implantation. The evaluation methods include gross observation, digital subtraction angiography intraoperative analysis, optical coherence tomography analysis, scanning electron microscopy and so on. The results show that combining these methods could comprehensively evaluate the whole process of the thrombus formation from the beginning of implantation to the end of preclinical animal experiments, so that, it may better predict the clinical thrombosis risk, and the selection of the control was very important. The study tries to use the comparison examples of thrombosis on the new medical instrument to provide the clue for thrombosis evaluation in vivo on similar instruments and show the methodology on the preclinical evaluation.
Objective To evaluate the feasibility of X-ray guided access to the extrahepatic segment of the main portal vein (PV) to create a transjugular extrahepatic portacaval shunt (TEPS). Methods 5F pigtail catheter was inserted into the main PV as target catheter by percutaneous transhepatic path under ultrasound guidance. The RUPS-100 puncture system was inserted into the inferior vena cava (IVC) by transjugular path under ultrasound guidance. Fluency covered stent was deployed to create the extrahepatic portacaval shunt after puncturing the target catheter from the IVC under the X-ray guidance, then shunt venography was performed. Enhanced CT of the abdomen helped identify and quantify the patency of the shunt and the presence of hemoperitoneum. Results The extrahepatic portacaval shunts were created successfully by only 1 puncture in 6 pigs. No extravasation was observed in shunt venography. One pig died of anesthesia on the day of operation. The extrahepatic portacaval shunts were failed in 2 pigs 3 days after the operation (one was occluded and the other one was narrowed by 80%). The extrahepatic portacaval shunts were occluded 2 weeks after the operation in the remaining 3 pigs. The shunts were out of the liver and no hemoperitoneum was identified at necropsy in the 6 pigs. Conclusion TEPS is technically safe and feasible under the X-ray guidance.
Coronary atherosclerotic heart disease is a serious threat to human life and health. In recent years, the main treatment for it is to implant the intravascular stent into the lesion to support blood vessels and reconstruct blood supply. However, a large number of experimental results showed that mechanical injury and anti-proliferative drugs caused great damage after stent implantation, and increased in-stent restenosis and late thrombosis risk. Thus, maintaining the integrity and normal function of the endothelium can significantly reduce the rate of thrombosis and restenosis. Stem cell mobilization, homing, differentiation and proliferation are the main mechanisms of endothelial repair after vascular stent implantation. Vascular factor and mechanical microenvironmental changes in implanted sites have a certain effect on re-endothelialization. In this paper, the process of injury caused by stent implantation, the repair mechanism after injury and its influencing factors are expounded in detail. And repairing strategies are analyzed and summarized. This review provides a reference for overcoming the in-stent restenosis, endothelialization delay and late thrombosis during the interventional treatment, as well as for designing drug-eluting and biodegradation stents.
ObjectiveTo explore the current research status of endovascular treatment for isolated superior mesenteric artery dissection (ISMAD) so as to provide a reference for vascular surgeons and patients in selecting treatment methods. MethodThe recent domestic and international literature on the endovascular treatment for ISMAD was collected and summarized. ResultsThe current endovascular treatment methods for ISMAD mainly included catheter-directed thrombolysis and stent placement. For the ISMAD patients with true intraluminal thrombus formation, true luminal occlusion, and partial embolization of branch vessels, the catheter-directed thrombolysis was performed by continuously pumping urokinase locally to dissolve thrombus and improve distal blood supply. The stent placement mainly included two main types: bare stent placement and covered stent placement, both aiming to promote true lumen recanalization, false lumen thrombosis, and vascular remodeling through mechanical support and blood flow redirection. The bare stents had unique advantages such as being well-developed, offering a wide range of options, and having stable performance. However, covered stents were superior to bare stents in terms of mid-term patency rate and in-stent restenosis. ConclusionsWith the development of technology, endovascular treatment has become an indispensable method for ISMAD patients. Extensive multicenter cases reports from both domestic and international studies have supported the safety and efficacy of endovascular treatment. Catheter-directed thrombolysis and stent placement (bare stent and covered stent) offer targeted solutions for various types of ISMAD patients, providing more minimally invasive and effective treatment.
Objective To explore a method of loading exosomes onto absorbable stents. MethodsBy building a stent-(3-aminopropyl) triethoxysilane-1, 2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy (polyethylene glycol) 5000]-exosomes connection, the exosomes were loaded onto absorbable stents to obtained the exosome-eluting absorbable stents. The surface conditions of the stents and absorption of exosomes were observed by scanning electron microscope and identified through the time-of-flight mass spectrometry; the roughness of the stents’ surfaces was observed by atomic force microscope; the appearances and sizes of the stents were observed by stereomicroscope; and the radial force was tested by tensile test machine. The absorbable stents were used as control. Results The scanning electron microscope observation showed that the exosome-eluting absorbable stents had some small irregular cracks on the surface where many exosomes could be seen. The atomic force microscopy observation showed that within the range of 5 μm2, the surface roughness of the absorbable stents was ±20 nm, while the surface roughness of the exosome-eluting absorbable stents was ±70 nm. In the results of time-of-flight mass spectrometry, both the exosome-eluting absorbable stents and exosomes had a peak at the mass charge ratio of 81 (m/z 81), while the absorbable stents did not have this peak. The peak of exosome-eluting absorbable stents at m/z 73 showed a significant decrease compared to the absorbable stents. The stereomicroscope observation showed that the sizes of exosome-eluting absorbable stents met standards and the surfaces had no cracks, burrs, or depressions. The radial force results of the exosome-eluting absorbable stents met the strength standards of the original absorbable stent. Conclusion By applying the chemical connection method, the exosomes successfully loaded onto the absorbable stents. And the sizes and radial forces of this exosome-eluting absorbable stents meet the standards of the original absorbable stents.
Objective-To apply self-pulmonary tissue flap to reconstruct esophagus directly or with alloy stent in this research. Methods Twenty-four dogs were divided into two groups, middle bronchus was ligated to prepare pulmonaryflap and incised, a 4 to 6 cm long and 1/2 to 2/3 perimeter defect was made in esophageal wall. Esophagus defect was repaired only with pulmonary flap (experimental group) and with pulmonary flap having self-expanded stent inside (control group). The gross appearance, histological apearance and barium X-ray films were observed at 2,4,6,8,10 and 12 weeks after operation. Results Two dogs died of anatomotic leak in experimental group, three dogs died of anatomotic leak and two dogs died of perforation of ulcer in control group. The growth of esophagus epithelium was observed from periphery area to central area after 8 to 10 weeks of operation. In pulmonary flap mass fibrous tissue proliferated and fibroblasts were active, but no necrosis occurred. Barium X-ray ofregenerated esophagus showed that mild stenosis and weakened peristalisis were observed in the middle of resophagus replacement, and that no obstruction, leakage, and dilation above anastomotic stoma occurred. Conclusion Pulmonary tissue flap can well support the mucosa crawl in the defect of esophagus. It is necessary to find a more suitable and satisfied stent for repairing segmental defect.
Objective To systematically evaluate the efficacy and safety of sirolimus-eluting stents (SES) versus bare-metal stents (BMS) in treating patients with ST-segment elevation myocardial infarction. Methods The databases such as PubMed (1960 to Mar. 2011), EMbase (1980 to Mar. 2011), the Cochrane Central Register of Controlled Trials (1989 to Mar. 2011), CBM (1979 to Mar. 2011), VIP (1989 to Mar. 2011) and CNKI (1979 to Mar. 2011) were searched to collect all the randomized controlled trials (RCTs) on SES versus BMS in patients with ST-segment elevation myocardial infarction. After the data extraction and methodological quality evaluation, meta-analysis was conducted with RevMan 4.2 software. Results A total of 7 RCTs were included. Among 2 555 patients involved, 1 282 were in the SES group, while the other 1273 were in the BMS group. The results of meta-analyses showed that SES was superior to BMS in the target-lesion revascularization (OR=0.27, 95%CI 0.16 to 0.45, Plt;0.000 01) and target-vessel revascularization (OR=0.33, 95%CI 0.24 to 0.46, Plt;0.000 01). In contrast, there were no differences between SES and BMS in death, stent thrombosis and recurrence of myocardial infarction. Conclusion With the one-year clinical outcomes, SES is more effective than BMS in reducing the rate of target-vessel revascularization and target-lesion revascularization.
ObjectiveThis study was aimed to evaluate the clinical efficacy of mechanical thrombectomy using the AngioJet System for the treatment of lower extremity acute arterial embolism and thrombosis.MethodsThe clinical data of 20 patients with acute lower extremity arterial embolism and thrombosis admitted to the Department of Vascular Surgery in the People’s Hospital in Gansu Province where the author worked from September 2016 to March 2017, were retrospectively analyzed. All patients were treated with the AngioJet mechanical thrombectomy system. Clinical data of the patients were retrospectively collected. The clinical efficacy of AngioJet mechanical thrombectomy wasanalyzed.ResultsEighteen (90.0%) of the 20 patients successfully completed the mechanical thrombectomy by using the AngioJet System. The mean time for hospital stay and operation was (4.2±1.4) d and (1.3±0.4) h, respectively. The average doses of urokinase and heparin during operation were (35.80±12.30) ×104 U and (45.10±8.30) mg, respectively. Two patients received a complementary treatment of incision for removing the thrombus. Two patients received catheter-directed thrombolysis after the mechanical thrombectomy, 5 patients received bare-metal stent implantation after balloon expansion. Clinical success was in 16 cases. According to the Cooley standard, 10 patients were in excellent condition,6 in good condition, 2 in fair condition, and 2 in poor condition. There were 2 cases of distal arterial embolization,2 cases of antecardial discomfort of bradycardia, and 4 cases of bleeding at the puncture point, but no serious bleeding complications such as gastrointestinal and intracranial hemorrhage occurred. A total of 16 patients presented myoglobinuria during and after operation. All patients were followed up for 6–12 months. The results of ultrasound examination showed that the artery was patency in 15 cases. One patient died of myocardial infarction in 9 months after surgery,2 patients developed lower extremity ischemia symptoms again after surgery, and 2 patients had lower extremity ulcer caused by lower extremity ischemia symptoms. During the follow-up period, no lower limb necrosis, amputation, and death occurred in the remaining patients.ConclusionsThe AngioJet mechanical thrombectomy system is safe and effective. Combined with the use of catheter-directed thrombolysis and stent implantation, the AngioJet mechanical thrombectomy could lead to quick recovery of the perfusion of the lower extremity and improve the limb salvage rates, exhibiting excellent clinical value.