对大脑中动脉狭窄诊断方法的研究进展

目前对大脑中动脉（middle cerebral artery,MCA）狭窄的诊断方法包括两方面,即影像学技术和多普勒超声检查。影像学技术中数字减影血管造影术（digital subtract angiography,DSA）为诊断MCA狭窄的金标准。经颅多普勒超声（transcranial Doppler sonography,TCD）由于操作便捷、价廉,已成为缺血性脑血管病血管狭窄病因方面的筛查工具。本文总结了国内外应用不同技术对诊断MCA狭窄的研究,着重阐明了TCD在此方面的应用,旨在提出一个合理、经济的检查顺序,优化医疗资源配置。     

CT灌注成像对颈内动脉闭塞与重度狭窄患者血流动力学的评价及临床意义

目的利用CT灌注成像了解症状性颈内动脉闭塞患者的血流动力学类型及其发病机制。方法连续选择2007年1月～2007年12月因缺血性脑血管病收入神经内科、经CT血管成像(CTA)证实为颈内动脉重度狭窄(≥70%)或闭塞的病人30例,其中颈内动脉闭塞14例,重度狭窄16例。脑梗死24例,TIA6例。所有病人入院24小时内完成CT灌注扫描。根据颈内动脉狭窄程度(重度狭窄或闭塞)及临床表现分组对脑血流灌注类型进行分析。结果发现3种灌注类型:Ⅰ型,大脑中动脉和/或大脑前动脉供血区的广泛低灌注(21例);Ⅱ型,仅病灶同侧局部边缘带低灌注(6例);Ⅲ型,灌注正常(3例)。无论颈内动脉有无闭塞,3种灌注类型均存在。脑梗死组患者脑血流灌注主要表现为Ⅰ型,而TIA组主要表现为Ⅱ型或Ⅲ型。结论颈动脉病变脑灌注类型与临床症状有关,而与颈内动脉有无闭塞关系不大。     

Surgical treatment of laryngotracheal stenosis in infants and children

Summary Laryngotracheal stenosis in children is difficult to manage, especially in cases of acquired lesions. Of 317 cases reviewed, 75 surgical cases are reported here: 28 were congenital and 47 acquired, mostly due to endotracheal intubation. A large variety of laryngotracheoplasty techniques have been used in reconstruction, depending on the age and status of the patient, the size of the laryngeal lumen, the exact site of the stenosis and any associated anomalies. The three main techniques used have been described by Evans, Cotton, and Rethi, Stenting relied on Silastic rolls, Montgomery T-tubes and Aboulker Teflon prostheses. The results in 65 patients showed a decannulation rate of 92% in cases of congenital stenosis and 80% in acquired ones. Improvements in therapy still seem necessary in order to reduce the cannulation time following treatment and the sequelae producing dysphonia.Presented at the First European Congress of Oto-Rhino-Laryngology and Cervico-Facial Surgery, Paris 26–29 September 1988     

Use of an introducer sheath for colonic stent placement

We describe a technical modification of Wallstent implantation for the treatment of malignant rectosigmoid and descending colonic obstructions. The modification is the routine placement of an introducer sheath via the rectum before stent implantation in order to straighten the rectosigmoid region. This device facilitates catheter and guide wire manipulations and obtaining specimen biopsies for histopathological studies. The introducer sheath has been used without complications in 21 consecutive patients.     

Flow patterns from metallic vascular endoprostheses: in vitro results

The aim of this study was to determine flow characteristics and pressure gradients of different balloon- and self-expandable stents in an in vitro flow-model. Seven vascular stents (Bridge, Cragg, Memotherm, Palmaz PS 784, Sinus, Symphony, Wallstent), equal in length (60 mm) and diameter (10 mm), were deployed in a closed flow model. The inner diameter of the tube measured 9 mm. Flow at 1.5 and 6 l/min was applied. Flow patterns were visualized by anionic particles illuminated with two helium-neon lasers. Late laminary flow characteristics and pre- /post-stent pressure gradients were determined in either expanded stent, 25 and 50 % tube stenosis. Stent implantation induced a decrease of laminary flow when compared with an unstented tube with and without concentric 25 % stenosis (p < 0.01) at all flow rates and an increase of pressure gradients when compared with an unstented tube for a flow rate of 6 l/min and all stenoses (p < 0.01). At 1.5 l/min most stents revealed no significant change of pressure gradient, the highest gradient measured 4.0 mmHg. Sinus permitted maximum (expanded: 82.1 % and 76.9 % at 25 % stenosis at 1.5 l/min; p < 0.01) and Palmaz minimum of laminary flow at all flow rates and stenoses (70.2 and 52.4 % at 25 % stenosis at 1.5 l/min; p < 0.01). At 6 l/min, when completely expanded, Sinus is equal to Bridge and Memotherm; in 25 % stenosis Sinus is equal to Bridge, Memotherm, and additionally to Cragg and Wall. None of the endoprostheses revealed laminary flow at 50 % stenosis. Inadequate stent deployment bears the risk of creating less laminary flow and pressure gradients. Since flow disturbances and pressure gradients may influence neointimal hyperplasia, stent design and completeness of stent expansion are important factors regarding the appearance of thrombus formation and postinterventional restenosis. Received: 27 April 2000 Revised: 20 July 2000 Accepted: 26 July 2000     

Effect of an experimental stenosis in the porcine descending thoracic aorta

OBJECTIVE: To investigate the alterations of mechanical properties in pre- (A) and post- (B) stenotic aortic regions after an experimentally induced stenosis in the descending thoracic aorta. METHODS: Eight healthy, normalipemic and normotensive Landrace pigs were subjected to thoracotomy under sterile conditions. In the upper segment of the descending thoracic aorta a circumferential symmetric constriction 5 mm in length was imposed and stabilized; thus, a 15-20 mm Hg pressure gradient was established. The pressure gradient was verified via catheterization of the vessel with pressure tip catheters. Pre- and poststenotic hemodynamic disturbances were recorded by the use of a bidirectional Doppler flowmeter. Pressure and flow measurements were carried out before, 10 min after, and 90 days after the creation of the stenosis. Euthanasia was performed after 90 days, and the descending thoracic aorta removed. In the A and B regions serial sections of aorta (5 mm in length) create appropriate aortic "rings," to test in a uniaxial tension device, in order to determine the mechanical properties of the vessel. Histological analysis was performed, so as to estimate the content (%) of collagen and elastin fibers within the aortic wall. Eight sham-operated pigs were used as controls. RESULTS: Reverse blood flow was recorded at both the A and B sites, and was maintained until euthanasia. Reverse flow in the poststenotic region B was greater than that in the prestenotic region. Mechanical analysis showed that the aortic wall in A and B regions became stiffer particularly at high strains (P < 0.05). Histological analysis indicated that the percentage of elastin fibers remained almost the same in both regions while the percentage of collagen fibers increased considerably, especially in the B region (P < 0.05). CONCLUSIONS: A nonhemodynamically significant experimental stenosis located at the level of the descending thoracic aorta induced reverse blood flow before and after the stenosis. The higher the reverse flow, the more collagen fibers were produced and the stiffer the aortic wall. Since hypercholesterolemia can be ruled out as a hardening factor in the present study, disturbed flow seems to be an independent factor which activates fibroblasts to overproduce collagen and to eventually reduce the aorta's compliance.     

Percutaneous treatment of superior vena cava syndrome using metallic stents

The purpose of this study was to evaluate the results of treatment of superior vena cava syndrome (SVCS) in patients with benign and malignant disease using expandable metallic stent. From January 1995 to April 2000, 87 expandable stents were implanted in 82 patients (59 men, 23 women; mean age 57.8 years, age range 39–79 years) for the treatment of SVCS. The SVCS was defined as symptomatic bilateral obstruction of venous drainage from head, neck and upper extremities. In 68 patients SVCS was due to malignant neoplasia, and in 14 cases it was due to benign aetiology. All patients were treated with expandable stent. We implanted 81 Wallstent prostheses and 6 Palmaz stents. Adjuvant thrombolysis was applied in 12 patients who required fibrinolysis. After recanalization, the stent was implanted in all cases in SVC (infra- or supra-azygos vein). All patients were treated with heparin of low molecular weight (HBPM) during 6 months. Patency was analyzed according to clinical symptoms and Doppler US or venograms exploration. Technical success was observed in all cases. Clinical success was reached in 78 of 82 patients (95.1%) (absence of symptoms in 2 or 3 days). Four patients suffered immediate thrombosis which required fibrinolitic treatment with a new prosthesis placement in 1 case. The follow-up for the malignant process was of 7.1 months (range 1–39 months) and in benign cases was 31.2 months (range 11–61 months). Sixty-two (91.1%) patients with malignancy died without SVCS symptomatology. All the patients with benign pathology are alive. Clinical primary patency in malignant cases was 87% with assisted patency of 96.2%. Endovascular therapy using metallic stent and thrombolysis is a successful method to treat SVCS due to benign or malignant aetiology. Electronic Publication