Mechanical clot dissolution: new concept

The authors present preliminary data on in vitro mechanical clot dissolution by means of a catheter with a tiny high-speed propeller enclosed in a special housing. Preweighed human blood clots were subjected to the catheter in a test tube with saline at various propeller speeds and durations of application. After filtration of the resultant slurry, the clot residue was weighed and examined histologically. Clot dissolution was found to be related to both the duration and speed of propeller rotation. No fibrin residue was seen after dissolution, although potential embolic material, composed of clumps of cellular debris as large as 208 microns in longest dimension, was found. Mechanical clot dissolution could possibly be used in any natural or synthetic blood vessel in which there is acute or subacute thrombosis, with fewer complications and lower cost than obtained with traditional methods.     

In vitro and clinical feasibility study with an over-the-wire delivery system for pulsed dye laser angioplasty.

The suitability of a pulsed dye laser (504 nm) in experimental and clinical angioplasty was investigated. In an experimental study, the ablation thresholds were 3 J/cm2 +/- 8 (mean +/- standard deviation) for fibrofatty plaque and 25 J/cm2 for calcified tissues under saline. At a radiant exposure of 10 J/cm2 the etch rates were 1.7 microns per pulse +/- 0.3 for media, 2.8 microns/pulse +/- 0.4 for normal intima, and 3.9 microns/pulse +/- 1.1 for fibrofatty plaque (P less than .05). Pressure wave effects with a separation of tissue layers were predominantly localized at the internal elastic lamina. Thermal injury with vacuolations extended 15 microns +/- 6 into adjacent tissue. For clinical study, laser-assisted balloon angioplasty was performed in 10 patients (64 years +/- 14) with occlusions of peripheral arteries using a 9-F multifiber ring catheter. Lesion length ranged from 2 to 12 cm (mean, 7 cm). Laser angioplasty with an 80 mJ/pulse decreased the mean stenosis from 100% to 58% +/- 12% (P less than .005). The ankle-brachial index rose from a median of 0.48 to 0.88 (P less than .001). In 33% of patients, there were subintimal dissections after laser angioplasty. After a mean follow-up of 10.2 months, the overall clinical success was 70% with a primary patency of 78%. The over-the-wire approach with a pulsed dye laser may constitute a safe and feasible tool in laser angioplasty.     

Distribution and size of particles after dynamic angioplasty in cadaveric arteries with the kensey catheter system: A comparison with clinical experience

The distribution and size of atheromatous debris after angioplasty with the Kensey catheter was determined after recanalization of 18 segments of human cadaveric superficial femoral arteries (SFA). The debris produced was studied cytologically and measured semiquantitatively. Nearly 80% of all particles ranged from 5 to 15 μm, approximately the size of red blood cells. More than 20% of all particles exceeded this size and 2% were larger than 100 μm. The use of the Kensey catheter dynamic angioplasty system in the lower extremities contains the risk of embolic complications because more than 20% of all particles are larger than human blood cells. Seven patients with occlusion and 3 with stenoses of the SFA were treated with the Kensey catheter system. Recanalization was successfull in all and in 1 case, small emboli in the anterior tibial artery were observed. There was a 50% restenosis/reocclusion rate between 2 weeks and 10 months.     

Functional properties of the Kensey arterial recanalization catheter. In vitro investigations

The properties of the Kensey catheter (Cordis Corp., Miami Lakes, FL), a new rotational device for recanalization of arterial occlusions, were studied in vitro. There was no effective centering of the catheter tip in the vessel and no measurable dilatation of the vessel lumen during rotation of the catheter tip. Flow studies confirmed recirculation and repeated exposure of particles at the catheter tip. The vortex induced by the rotating cam disappeared in stenotic segments. The maximum size of the pulverized specimen material was 20 microns for the normal arterial wall, 90 microns for the calcified and atheromatous plaque, and 900 microns for the fresh venous thrombus. For plaque material, an additional reduction of large particles to 30 microns was seen with a decrease in force and an increase in rotation speed. The size of thrombus particles decreased with an increase of rotation speed and the duration of treatment.     

In vitro ablation of normal and diseased vascular tissue by a fiber-transmitted holmium laser

An in vitro study was performed to test the ablative potential of a fiber-transmitted pulsed holmium laser (2.1 microns) applied to normal vascular wall, lipomatous plaques, and calcified plaques. Different fluences per pulse of 42, 80, 205, and 315 J/cm2 were used. Ablation of normal tissue and lipomatous plaques was achieved with all power settings. Effective ablation of calcified plaques, however, occurred only after a minimum fluence of 205 J/cm2, and the effect was significantly less pronounced compared to ablation of soft lesions.     

Helical CT angiography with maximum intensity projection in the assessment of aortic coarctation after surgery

OBJECTIVE. The value of CT angiography and three-dimensional (3D) reconstructions was investigated in the postoperative care after surgical repair of aortic coarctation and compared with conventional angiography. SUBJECTS AND METHODS. Twenty-five patients referred because of suspicion of stenosis in the area of former coarctation were prospectively studied with CT angiography and catheter angiography. We determined the morphometric and morphologic findings such as aortic diameter, stenosis, aneurysm, intimal flaps, circumscribed pouch, or arteriosclerotic plaques with 3D reconstructions, using maximum-intensity-projection (MIP) technique and catheter angiography. The results of both techniques were compared. The ratio of the narrowest diameters of the former coarctation and the descending aorta was correlated with the systolic pullback blood pressure gradient in all patients. RESULTS. The former coarctation was normal in 11 patients, (44%), group A; narrowed in 12 children (48%), group B; and dilated in two children (8%), group C. An intimal flap and a circumscribed pouch were delineated in four subjects. MIP reconstructions and catheter angiography revealed identical results regarding the classification into groups A, B, C; intimal flaps; and circumscribed pouches. Statistical analysis revealed good correlation between the narrowest aortic diameters measured on MIP reconstructions and catheter angiography, whereas no correlation between the systolic pullback blood pressure gradient and the diameter ratio of the former coarctation and the descending aorta was found. CONCLUSION. CT angiography and 3D reconstructions using MIP represent a reliable noninvasive technique to replace diagnostic catheter angiography in the postoperative care of patients with coarctation and provide the clinician with valuable information concerning further invasive procedures.     

Laser angioplasty of arterial stenoses

To establish the optimal conditions for recanalization of obstructed arteries without damage to vessel walls, an Nd-YAG laser coupled to a 0.2-mm-diameter optical fiber was used on obstructed human cadaver coronary and peripheral arteries and on poplitieal arteries in amputated limbs. Vaporization of atheromatous plaques was consistently obtained with energy of 360–600 J and a diluted blood perfusate (3 g/100 ml hemoglobin) at a rate of 30 ml/min. The arterial wall was protected from thermal injury by inserting the optical fiber into an inflated balloon catheter and by cooling the system with the perfusate. Since recanalization of occluded arteries was consistently obtained without damage to the arterial wall or debris and thin and flexible optical fibers were easy to guide in the arteries, percutaneous transluminal Nd-YAG laser angioplasty was used in obstructed femoral and popliteal arteries in 12 patients. The first trials in man with Nd-YAG laser showed the method to be feasible, effective, and at low risk, although further studies are required to improve penetration of the obstruction and increase the diameter tunnel.     

New device for percutaneous fragmentation of pulmonary emboli

A new catheter system was designed for percutaneous fragmentation of large pulmonary emboli. The device consists of an impeller rotating at high speed at the center of a self-expandable basket at the tip of a 7-F catheter. The highly flexible catheter was able to reach all tested embolus sites in a glass model of the pulmonary arterial tree. Embolus fragmentation was quick and thorough. Particles in the effluent larger than 10 microns accounted for only about 9% of the treated embolus weight. Wall contact with the rotating impeller was not observed. The impeller-basket catheter promises to be a useful tool for percutaneous treatment of acute pulmonary embolism.     

Preparation of a fine powder of 2-deoxy-2-[18F]fluoro-D-glucose suitable for inhalation to diagnose lung diseases by means of PET

Fine 2-deoxy-2-[18F]fluoro-D-glucose (18FDG) powder was obtained by adding diethyl ether into a methyl alcohol solution of 18FDG and other sugar as seed. When micronized particles of sodium N-acetyl-neuraminate (Neu5Ac-Na) were used as seed crystals, particles containing 18FDG were obtained and 80% of them were smaller than 10 microns in size. More than 60% of these crystals were 4-6 microns in size. In a preclinical study of forced inhalation in a dog, the 18FDG fine powder was mainly distributed in the trachea. The radioactivity in the trachea then increased once and a gradual decrease followed. The radioactivity was transferred into the blood and radioactivity incorporation into the heart was observed. After a normal volunteer inhaled 18FDG dry powder aerosol, the radioactivity was found in the respiratory tract and the peripheral area of the lung by means of PET. Absorption and in vivo dynamics of the 18FDG were also analysed.     

运动影响ApoE~(-/-)小鼠动脉粥样硬化形成的形态学研究

目的:探讨运动对动脉粥样硬化(AS)斑块和主动脉病理形态变化的影响。方法:以30只8周龄的ApoE基因敲除小鼠(ApoE-/-小鼠)建立AS模型,分为ApoE-/-小鼠安静组(n=15)和ApoE-/-小鼠运动组(n=15),15只C57BL/6J小鼠为同源对照安静组。ApoE-/-小鼠饲以"西方膳食"饲料,C57小鼠饲以普通饲料。运动组进行中等强度跑台运动,前6周由10m/min×30min渐增至13m/min×60min,后6周以稳定的运动量(13m/min,60min)进行运动,每周5次。12周实验结束后,采用光学显微镜、体视显微镜及图像分析系统,从形态学角度观察各组小鼠主动脉斑块面积,主动脉大体病理形态、组织学结构及主动脉内膜、中膜厚度。结果:ApoE-/-小鼠安静组主动脉弓、分支口和腹主动脉形成斑块,多为纤维粥样硬化期病变,弹力纤维断裂多见,中膜空泡变性。ApoE-/-小鼠运动组斑块较ApoE-/-小鼠安静组减少,多为早期脂纹脂斑病变,弹力纤维断裂和中膜病变均减轻。经图像分析,ApoE-/-小鼠运动组斑块面积,内膜(I)、中膜(M)厚度及I/M比值较ApoE-/-小鼠安静组减少。结论:运动可减少高脂饮食导致的斑块形成,减轻AS的主动脉壁组织损伤,从而抵御主动脉壁的脂质沉积,延缓AS进程。     

实时图像合成技术在颈部血管动脉粥样硬化中的临床研究

目的评估实时图像合成(SonoCT)技术在颈部血管粥样动脉硬化斑块形成中的临床应用价值。方法用SonoCT技术对12例颈部动脉硬化斑块形成进行检查,并与普通超声进行对比。结果12例动脉硬化,SonoCT与普通超声图像比较斑点的影响明显减少,改进了对比分辨力。同时发现血管图像的伪像被抑制,并增加了实时结构的内容;斑块边界和界面可见度得到改善;血管的内膜及软斑清晰可见;较小的斑块可被SonoCT检出。结论与普通超声比较,SonoCT可减低伪像与干扰,提高图像质量,有增加颈部动脉硬化斑块形成阳性检出率的效果。     

高龄冠心病患者外周动脉硬化与冠状动脉硬化的研究

 目的 观察高龄冠心病患者颈动脉、股动脉、股浅动脉、腘动脉的内-中膜厚度(IMT)与冠状动脉硬化的相关性.方法 选经冠状动脉造影确诊为冠心病的高龄患者86例,选冠状动脉造影证实无冠状动脉狭窄的患者20例为对照组,采用二维超声检测颈、股、股浅、胭动脉的IMT.动脉粥样硬化斑块积分采用Sutton 法,并与冠状动脉病变程度进行对比分析.结果 高龄老年冠心病患者外周动脉的IMT,斑块积分显著高于对照组(P＜0.001).斑块指数与冠状动脉病变程度呈正相关.结论 颈、股、股浅、腘动脉粥样硬化与冠状动脉粥样硬化的病变相平行.     

Reliability of differentiating human coronary plaque morphology using contrast-enhanced multislice spiral computed tomography: a comparison with histology

BACKGROUND: Initial clinical results indicate that multislice spiral computed tomography (MDCT) might be useful for the noninvasive characterization of human coronary plaque morphology by determining tissue density within the lesions. This seems to be of clinical relevance, because coronary artery disease might be detected at an early stage before calcifications occur and noncalcified plaques that may be more likely to rupture could also be visualized noninvasively. The aim of the present study was to evaluate the reliability of contrast-enhanced MDCT in differentiating human atherosclerotic coronary plaque morphology by comparing it with the histopathologic gold standard. METHODS AND RESULTS: Twelve human hearts were scanned postmortem using an MDCT (Somatom Volume Zoom; Siemens, Forchheim, Germany) high-resolution computed tomography scanner to detect atherosclerotic coronary plaques. Density measurements were performed within detected plaque areas. The exact location of each plaque was marked at the surface of the heart to assure accurate histopathologic sectioning of these lesions. The plaques were classified according to a modified Stary classification. Seventeen plaques were identified by MDCT. Six plaques were histopathologically classified as lipid rich (Stary III/IV), 6 plaques as intermediate (Stary V), and 5 plaques as calcific (Stary VII). Lipid-rich plaques had a mean density on MDCT of 42 +/- 22 Hounsfield units (HU), intermediate plaques had a mean density of 70 +/- 21 HU, and calcific plaques had a mean density of 715 +/- 328 HU. ANOVA analysis revealed a significant difference in plaque density between the 3 groups (P < 0.0001). CONCLUSIONS: The comparison with histopathology confirms that tissue density as determined by contrast-enhanced MDCT might be used to differentiate atherosclerotic plaque morphology.     

颈动脉粥样硬化与前循环缺血性脑血管病关系的探讨

 目的 探讨颈动脉粥样硬化与缺血性脑血管病的关系.方法 以216例年龄在40～86岁的前循环缺血性脑血管病患者为研究对象,应用超声诊断仪检测双侧颈动脉颅外段,记录动脉内膜-中层厚度、斑块特征及狭窄率.结果 缺血性脑血管病患者斑块检出率(169/216,78.2%)明显高于对照组(54/171,31.6%);不稳定性斑块在脑梗死组检出率较高(52/168,30.9%),在脑梗死各亚型中有所差异.颈动脉颅外段狭窄率较低(30/216,13.9%),但完全前循环梗死组中重度狭窄率较高(3/8,37.5%).结论 颈动脉粥样硬化与缺血性脑血管病关系密切,常规进行颈动脉颅外段彩色多普勒超声检测,对缺血性脑血管病的预防有不可忽视的指导作用.     

A catheter-based radiation detector for endovascular detection of atheromatous plaques

Purpose Although various radiopharmaceuticals have been developed for the detection of atheromas, external imaging techniques have limitations when it comes to the detection of small plaques. In this study, we developed a charged particle-sensitive detector for the endovascular detection of small plaques.Methods The device consists of a probe, an automatic pullback unit and a controller. The probe, which consists of a plastic scintillator and flexible optical fibres, is 1.0 mm in diameter. The probe was inserted into a catheter placed on ¹⁸F point sources, and then the radioactivity was measured as the probe was pulled out stepwise.Results The sensitivity for ¹⁸F was 9.3 cps/kBq, and there was a close linear correlation between the peak counts and source dose until at least 0.8 MBq. Furthermore, this device showed low background counts (<0.1 cps) and a low detection limit (0.21 kBq). To investigate the effect of background radioactivity on the measurement at the point sources, a ball phantom was prepared and five ¹⁸F point sources were set on the balls surface. Even though 298 MBq of ¹⁸F-fluorodeoxyglucose was injected into the ball, the point sources located every 10 mm on the balls surface were detectable separately.Conclusion The data gathered suggest that a catheter-based radiation detector in combination with charged particle-emitting radiopharmaceuticals is useful for the endovascular detection of small lesions such as coronary plaques.     

Atherosclerotic plaques: classification and characterization with T2-weighted high-spatial-resolution MR imaging-- an in vitro study

PURPOSE: To evaluate if T2-weighted high-spatial-resolution magnetic resonance (MR) imaging (117 microm per pixel) can help accurate classification of atherosclerotic plaques. MATERIALS AND METHODS: Thirty human arteries and 11 carotid endarterectomy specimens from 31 patients underwent T2-weighted MR imaging (2-T magnet; repetition time, 2,000 msec; echo time, 50 msec) at room temperature. After imaging, Bouin fixative was used to fix 26 arteries, and the other 15 arteries were fixed by means of freezing. Specimens were stained with hematoxylin-eosin and safranin or Sudan lipid stain. MR images and histologic slices were classified independently by two radiologists and a pathologist, respectively, on the basis of the American Heart Association classification. RESULTS: Results with MR imaging were the following: type I-II plaques, sensitivity of 67% and specificity of 100%; type IV-Va plaques, sensitivity of 74% and specificity of 85%; type Vb plaques, sensitivity of 90% and specificity of 100%; type Vc plaques, sensitivity of 80% and specificity of 90%. No type III plaque was diagnosed in the study. The overall kappa value was 0.68. CONCLUSION: High-spatial-resolution MR imaging with T2 weighting alone can help accurate classification of fibrocalcic plaques (type Vb), but it is subject to limitations for the classification and analysis of other types of atherosclerotic plaques.     

Dual-lumen catheters: Quality control tests for radiopacity

A protocol utilizing a single-point densitometer was developed for the quality control (Q.C.) of the radiopacity of dual-lumen radiographic catheters where x-rays generated at 80 kVp are typically used. Catheter contrast, defined as the difference between catheter radiopacity and background optical density (O.D.) when an aluminum plate is imaged, forms the basic Q.C. parameter. When a given catheter is repeatedly measured, catheter contrast varies with a standard deviation of 0.013 O.D. units. The effects of minor background O.D. variations on contrast are significant, but empirically correctable. A variation in measured contrast of approx. 0.01 O.D. units is observed per 10 kVp energy variation. Aluminum plate thickness has a significant effect on the results; however, other details of the protocol geometry are less important. Variations due to catheter orientation were examined and imaging of packaged catheters was demonstrated.     

Titanium-nickel intravascular endoprosthesis: a 2-year study in dogs

Twelve 5-mm-internal-diameter intravascular endoprostheses of noncorrosive, shape-memory titanium-nickel (TiNi) alloy were delivered transluminally by catheter and implanted in the iliac (n = 10) and femoral (n = 2) arteries of six normal dogs for either 1 or 2 years in order to evaluate the implantation technique and long-term effects. The patency rates were as follows: at 1 month, 92% (11/12); at 1 year, 100% 11/12 widely patent; 1/12 recanalized); and at 2 years, 100% (3/4 without stenosis; 1/4 with 20% stenosis). No migration, erosion, inflammation, surface thrombus, or stenosis of the side branches was seen; an absence of untoward angiographic and histopathologic effects was detected at 1 and 2 years. The neointima was completely endothelialized, without changes in thickness over time, 229.3 +/- 127.6 microns after 1 year and 223.3 +/- 216.7 microns after 2 years (p = not significant). The neointimal layer became thicker toward its distal aspect (p less than or equal to .05). Satisfactory delivery, long-term patency, and biocompatibility (manifested as a thin, stable neointima) were observed for the TiNi intravascular endoprosthesis at 1 and 2 years.     

Pyonephrosis: imaging and intervention

A series of 70 pyonephrotic kidneys drained by percutaneous nephrostomy tube was examined to evaluate the contribution of radiologic imaging to the diagnosis of pyonephrosis and to assess the diagnostic and therapeutic role of drainage by percutaneous nephrostomy catheter. The diagnosis of pyonephrosis is suspected when the clinical symptoms of fever and flank pain are combined with the radiologic evidence of obstruction to the urinary tract. Sonography gives a prompt diagnosis of hydronephrosis, and needle puncture of the kidney yields pus and establishes the presence of pyonephrosis. A percutaneous nephrostomy catheter is then inserted and serves for initial drainage of infected urine and for evaluation of residual kidney function before definitive surgery. The nephrostomy catheter is used for diagnostic nephrostograms, ureteral perfusions, therapeutic dissolution of stones, and indefinite drainage of the kidney. In 10 azotemic patients, the blood urea nitrogen and serum creatinine values returned to normal levels after antibiotic therapy and nephrostomy drainage of infection. Long-term evaluation of residual renal function by means of an excretory urogram or a renogram was available in another 26 patients and 25 of them showed function of the previously pyonephrotic kidney.     

肝癌重复介入治疗致靶血管损伤原因分析

目的:探讨多次动脉化学性栓塞术(TACE)治疗原发型肝癌过程中,肝动脉及其主要分支狭窄、闭塞的规律及其相关因素。方法:135例原发型肝癌病人行重复肝动脉介入治疗术,观察每次术后肝动脉及其分支新发生狭窄及闭塞的情况。并分析行化疗栓塞时导管末端在血管内的位置与血管闭塞率之间的关系。结果:135例中42例发生严重狭窄或闭塞,闭塞率按治疗频次呈单峰分布,治疗中期(第5-7次),肝动脉主干及大分支发生狭窄、闭塞的比例最高。导管末端与血管内膜接触者,靶血管的早、中期狭窄、闭塞率明显高于无接触组。结论:TACE治疗中导管末端与内膜接触是靶血管早、中期发生狭窄、闭塞常见的重要因素,在操作中应尽量避免。