DIGESTIVE ENDOSCOPY, Issue 4 2010
Eric K. Ganguly
Bile leak after cholecystectomy is well described, with the cystic duct remnant the site of the leak in the majority of cases. Endoscopic retrograde cholangiopancreatography (ERCP) with biliary stent placement has a high success rate in such cases. When ERCP fails, options include surgery, and percutaneous and endoscopic transcatheter occlusion of the site of bile leak. Here, we describe a case of endoscopic transcatheter occlusion of a persistent cystic duct bile leak after cholecystectomy using N -butyl cyanoacrylate glue. A 51-year-old man had persistent pain and bilious drainage following a laparoscopic cholecystectomy. The bile leak persisted after endoscopic placement of a biliary stent for a confirmed cystic duct leak. A repeat ERCP was carried out and the cystic duct was occluded with a combination of angiographic coils and N -butyl cyanoacrylate glue. The patient's pain and bilious drainage resolved. A follow-up cholangiogram confirmed complete resolution of the cystic duct leak and a patent common bile duct. [source]

IMPACT OF BLOOD FLOW OCCLUSION ON LIVER NECROSIS FOLLOWING THERMAL ABLATION

ANZ JOURNAL OF SURGERY, Issue 1-2 2006
Mehrdad Nikfarjam
Background: Laser, radiofrequency and microwave are common techniques for local destruction of liver tumours by thermal ablation. The main limitation of thermal ablation treatment is the volume of necrosis that can be achieved. Blood flow occlusion is commonly advocated as an adjunct to thermal ablation to increase the volume of tissue necrosis based on macroscopic and histological assessment of immediate or direct thermal injury. This study examines the impact of blood flow occlusion on direct and indirect laser induced thermal liver injury in a murine model using histochemical methods to assess tissue vitality. Methods: Thermal ablation produced by neodymium yttrium-aluminium-garnet laser (wavelength 1064 nm) was applied to the liver of inbred male CBA strain mice at 2 W for 50 s (100 J). Treatment was performed with and without temporary portal vein and hepatic artery blood flow occlusion. Animals were killed upon completion of the procedure to assess direct thermal injury or at 24, 48 and 72 h to assess the progression of tissue damage. The maximum diameter of necrosis was assessed by vital staining for nicotinamide adenine dinucleotide (NADH) diaphorase. Microvascular changes were assessed by laser Doppler flowmetry, confocal in vivo microscopy and scanning electron microscopy. Results: The direct thermal injury (mean SE) assessed by NADH diaphorase staining was significantly greater following thermal ablation treatment without blood flow occlusion than with blood flow occlusion (3.3 (0.4) mm vs 2.9 (0.3) mm; P = 0.005). Tissue disruption, cracking and vacuolization was more pronounced adjacent to the fibre insertion site in the group treated with thermal ablation combined with blood flow occlusion. There was an equivalent increase in the extent of injury following therapy in both groups that reached a peak at 48 h. The maximum diameter of necrosis in the thermal ablation alone group at 48 h was significantly greater than the thermal ablation combined with blood flow occlusion group (5.8 (0.4) mm vs 5.3 (0.3) mm; P = 0.011). The patterns of microvascular injury were similar in both groups, varying in extent. Conclusion: Temporary blood flow inflow occlusion appears to decrease the extent of initial injury measured by vital staining techniques and does not alter the time sequence of progressive tissue injury following thermal ablation therapy. [source]

HYPERBARIC OXYGENATION APPLIED IMMEDIATELY AFTER CORONARY OCCLUSION REDUCES MYOCARDIAL NECROSIS AND ACUTE MORTALITY IN RATS

CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 5-6 2009
Leonardo Dos Santos
SUMMARY 1Because in ischaemia there is a critical lack of O2, it has been reasoned that increasing O2 delivery to the ischaemic myocardium could serve as adjunctive therapy for acute myocardial infarction (MI). Accordingly, in the present study, the effect of early hyperbaric oxygenation (HBO) on mortality and MI size after coronary occlusion was examined in rats. 2After coronary occlusion, male Wistar rats were randomly assigned to receive either HBO for 1 h in a hyperbaric chamber (100% O2 at 253 kPa; n = 106) or ambient O2 as the control (n = 111). The extent of myocardial necrosis was assessed (triphenyltetrazolium) immediately after treatment in the HBO (n = 50) and control (n = 47) groups. The remaining rats were evaluated 24 h after occlusion to enable calculation of MI size and mortality. 3Immediately after therapy, the size of the MI was significantly greater in the control group compared with that in the HBO group (40 ± 3 vs 27 ± 2% of the left ventricle (LV), respectively; P < 0.001). The 24 h mortality of control rats was higher than that of HBO rats (34 vs 16%, respectively; P = 0.02). Control rats that survived 24 h had a larger MI than did HBO rats that survived 24 h (40 ± 4 vs 29 ± 3% of the LV, respectively; P = 0.005). Furthermore, large necrotic areas (> 40% of the LV) were more frequent in control than HBO rats (55 vs 27% of infarcted hearts, respectively; P = 0.01). There was less pulmonary congestion observed in HBO rats compared with control rats. 4In conclusion, early therapy with HBO during the onset of an acute ischaemic event decreases the necrotic area and reduces acute mortality. These data support further investigation of HBO as an adjuvant therapy for acute MI. [source]

MODULATION OF SIGNAL TRANSDUCERS AND ACTIVATORS OF TRANSCRIPTION (STAT) FACTOR PATHWAYS DURING FOCAL CEREBRAL ISCHAEMIA: A GENE EXPRESSION ARRAY STUDY IN RAT HIPPOCAMPUS AFTER MIDDLE CEREBRAL ARTERY OCCLUSION

CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 11 2007
Sheng-Li Sun
SUMMARY 1Signal transducers and activators of transcription (STAT) factors are a family of transcription factors that mediate intracellular signalling initiated at cytokine cell surface receptors and transmitted to the nucleus. In the present study, we determined the global changes in STAT gene expression in the hippocampus of rats after focal cerebral ischaemia and reperfusion using microarray analysis. 2The present study used middle cerebral artery occlusion (MCAO) to induce ischaemia and reperfusion in Sprague-Dawley rats. Using superarray Q series Janus tyrosine kinases (Jak)/STAT signalling pathway gene array, a total of 96 genes was screened in adult male rat hippocampus after transient focal cerebral ischaemia. 3The results showed that 23 genes were upregulated at least twofold by ischaemia treatment and that 12 genes were downregulated at least threefold by ischaemia treatment compared with controls. 4After confirmation by quantitative real-time polymerase chain reaction, the data suggest that the gene expression of STAT2, 5a, 5b, 6 and suppressor of cytokine signalling (SOCS) 4 was increased by ischaemia, probably due to a compensatory response of the brain, which may play a protective role in damaged brain tissue. 5The results of the present study provide evidence on global changes in STAT gene expression in the hippocampus of rats after focal cerebral ischaemia and reperfusion, in which STAT2, 5a, 5b, 6 and SOCS4 were confirmed to be significantly modulated during focal cerebral ischaemia. [source]

Lighting and Occlusion in a Wave-Based Framework

COMPUTER GRAPHICS FORUM, Issue 2 2008
Remo Ziegler
Abstract We present novel methods to enhance Computer Generated Holography (CGH) by introducing a complex-valued wave-based occlusion handling method. This offers a very intuitive and efficient interface to introduce optical elements featuring physically-based light interaction exhibiting depth-of-field, diffraction, and glare effects. Fur-thermore, an efficient and flexible evaluation of lit objects on a full-parallax hologram leads to more convincing images. Previous illumination methods for CGH are not able to change the illumination settings of rendered holo-grams. In this paper we propose a novel method for real-time lighting of rendered holograms in order to change the appearance of a previously captured holographic scene. These functionalities are features of a bigger wave-based rendering framework which can be combined with 2D framebuffer graphics. We present an algorithm which uses graphics hardware to accelerate the rendering. [source]

Interactive Volume Rendering with Dynamic Ambient Occlusion and Color Bleeding

COMPUTER GRAPHICS FORUM, Issue 2 2008
Timo Ropinski
Abstract We propose a method for rendering volumetric data sets at interactive frame rates while supporting dynamic ambient occlusion as well as an approximation to color bleeding. In contrast to ambient occlusion approaches for polygonal data, techniques for volumetric data sets have to face additional challenges, since by changing rendering parameters, such as the transfer function or the thresholding, the structure of the data set and thus the light interactions may vary drastically. Therefore, during a preprocessing step which is independent of the rendering parameters we capture light interactions for all combinations of structures extractable from a volumetric data set. In order to compute the light interactions between the different structures, we combine this preprocessed information during rendering based on the rendering parameters defined interactively by the user. Thus our method supports interactive exploration of a volumetric data set but still gives the user control over the most important rendering parameters. For instance, if the user alters the transfer function to extract different structures from a volumetric data set the light interactions between the extracted structures are captured in the rendering while still allowing interactive frame rates. Compared to known local illumination models for volume rendering our method does not introduce any substantial rendering overhead and can be integrated easily into existing volume rendering applications. In this paper we will explain our approach, discuss the implications for interactive volume rendering and present the achieved results. [source]

Scalable Algorithm for Resolving Incorrect Occlusion in Dynamic Augmented Reality Engineering Environments

COMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 1 2010
Amir H. Behzadan
As a result of introducing real-world objects into the visualization, less virtual models have to be deployed to create a realistic visual output that directly translates into less time and effort required to create, render, manipulate, manage, and update three-dimensional (3D) virtual contents (CAD model engineering) of the animated scene. At the same time, using the existing layout of land or plant as the background of visualization significantly alleviates the need to collect data about the surrounding environment prior to creating the final visualization while providing visually convincing representations of the processes being studied. In an AR animation, virtual and real objects must be simultaneously managed and accurately displayed to a user to create a visually convincing illusion of their coexistence and interaction. A critical challenge impeding this objective is the problem of incorrect occlusion that manifests itself when real objects in an AR scene partially or wholly block the view of virtual objects. In the presented research, a new AR occlusion handling system based on depth-sensing algorithms and frame buffer manipulation techniques was designed and implemented. This algorithm is capable of resolving incorrect occlusion occurring in dynamic AR environments in real time using depth-sensing equipment such as laser detection and ranging (LADAR) devices, and can be integrated into any mobile AR platform that allows a user to navigate freely and observe a dynamic AR scene from any vantage position. [source]

Comparison of Endovenous Radiofrequency Versus 810 nm Diode Laser Occlusion of Large Veins in an Animal Model

DERMATOLOGIC SURGERY, Issue 1 2002
Robert A. Weiss MDArticle first published online: 27 FEB 200
background. Endovenous occlusion using radiofrequency (RF) energy has been shown to be effective for the elimination of sapheno-femoral reflux and subsequent elimination of varicose veins. Recently, endovenous laser occlusion has been introduced with initial clinical reports indicating effective treatment for varicose veins. However, in our practice we note increased peri-operative hematoma and tenderness with the laser. Little is known regarding the mechanism of action of this new laser vein therapy. objective. To better understand the mechanism of action of endovenous laser vs. the endovenous RF procedure in the jugular vein of the goat model. methods. A bilateral comparison was performed using 810 nm diode laser transmitted by a bare-tipped optical fiber vs. the RF delivery by engineered electrodes with a temperature feedback loop using a thermocouple (Closure procedure) in three goat jugular veins. Immediate and one-week results were studied radiographically and histologically. Temperature measurements during laser treatment were performed by using an array of up to five thermocouples, spaced 2 mm apart, placed adjacent to a laser fiber tip during goat jugular vein treatment. results. Immediate findings showed that 100% of the laser-treated veins showed perforations by histologic examination and immediate contrast fluoroscopy. The RF-treated side showed immediate constriction with maintenance of contrast material within the vein lumen and no perforations. The difference in acute vein shrinkage was also dramatic as laser treatments resulted in vein shrinkage of 26%, while RF-treated veins showed a 77% acute reduction in diameter. At one week, extravasated blood that leaked into the surrounding tissue of laser treated veins acutely, continued to occupy space and impinge on surrounding structures including nerves. For the laser treatment, the highest average temperature was 729°C (peak temperature 1334°C) observed flush with the laser fiber tip, while the temperature feedback mechanism of the RF method maintains temperatures at the electrodes of 85°C. conclusion. Vein perforations, extremely high intravascular temperatures, failure to cause significant collagen shrinkage, and intact endothelium in an animal model justify a closer look at the human clinical application of the 810 nm endovenous laser technique. Extravasated blood impinging on adjacent structures may theoretically lead to increased peri-operative hematoma and tenderness. Further study and clinical investigation is warranted. [source]

Lesions of the Mitral Valve as a Cause of Central Retinal Artery Occlusion: Presentation and Discussion of Two Cases

ECHOCARDIOGRAPHY, Issue 1 2010
Maryam Ayati M.D.
We present two cases of mitral valve lesions that manifested with unilateral blindness caused by central retinal artery occlusion (CRAO): Case 1. A 68-year-old woman was admitted to our clinic for sudden blindness. Retinal artery angiogram showed CRAO. Transthoracic and transesophageal echocardiography (TEE) documented a mass attached to the ventricular side of the posterior mitral leaflet, which at pathology was identified as a blood cyst. Case 2. A 67-year-old man was admitted for a sudden unilateral painless loss of vision. Retinal angiogram documented CRAO, and TEE showed a highly mobile, spherical, lesion on the atrial side of anterior mitral leaflet. In this case, the pathological finding was a degenerated calcified thrombosis. We report on two cases of very rare abnormalities of the mitral valve presenting with a very rare embolic complication, i.e., CRAO. Like for cryptogenic stroke, transesophageal echocardiography plays a central role in the diagnosis of cardiogenic embolic sources. (Echocardiography 2010;27:E1-E3) [source]

Role of Echocardiography in Percutaneous Occlusion of the Left Atrial Appendage

ECHOCARDIOGRAPHY, Issue 4 2007
Mráz M.D.
Percutaneous occlusion of the left atrial appendage (LAA) is a modern alternative for the treatment of patients with atrial fibrillation (AF) and with a high risk of stroke who are not eligible for long-term anticoagulation therapy. Echocardiography plays a significant role in selecting patients, guiding the procedure, and in the postprocedural follow-up. Objectives and methods: To test the role of transesophagoeal echocardiography (TEE) and intracardiac echocardiography (ICE) in facilitating and shortening the procedure. Results: ICE represents a more convenient approach in patients who are not under generally anesthesia and helps to facilitate transseptal puncture. On the other hand, TEE, having the ability to rotate the image plane, helps to better determine the position of the occluder. Conclusions: Echocardiographic guidance of this procedure is essential. Which approach will be preferred will depend on the development of these two methods. [source]

Infants' Evolving Representations of Object Motion During Occlusion: A Longitudinal Study of 6- to 12-Month-Old Infants

INFANCY, Issue 2 2004
Gustaf Gredebäck
Infants' ability to track temporarily occluded objects that moved on circular trajectories was investigated in 20 infants using a longitudinal design. They were first seen at 6 months and then every 2nd month until the end of their 1st year. Infants were presented with occlusion events covering 20% of the target's trajectory (effective occlusion interval ranged from 500,4,000 msec). Gaze was measured using an ASL 504 infrared eye-tracking system. Results effectively demonstrate that infants from 6 months of age can represent the spatiotemporal dynamics of occluded objects. Infants at all ages tested were able to predict, under certain conditions, when and where the object would reappear after occlusion. They moved gaze accurately to the position where the object was going to reappear and scaled their timing to the current occlusion duration. The average rate of predictive gaze crossings increased with occlusion duration. These results are discussed as a 2-factor process. Successful predictions are dependent on strong representations, themselves dependent on the richness of information available during encoding and graded representations. [source]

The Effects of Graded Occlusion on Manual Search and Visual Attention in 5- to 8-Month-Old Infants

INFANCY, Issue 3 2000
Jeanne L. Shinskey
Young infants may be limited in searching for hidden objects because they lack the means-end motor skill to lift occluders from objects. This account was investigated by presenting 5- to 8-month-old infants with objects hidden behind transparent, semitransparent, and opaque curtains. If a means,end deficit explains search limitations, then infants should search no more for an object behind a transparent curtain than for objects behind semitransparent or opaque curtains. However, level of occlusion had a significant effect on manual search and visual attention. Infants retrieved and contacted the object more, contacted the curtain more, and looked away less with the transparent curtain than with the semi transparent or opaque curtains. Adding a time delay before allowing search and presenting a distraction after occlusion further depressed infants' behavior. The findings fail to support the means,end deficit hypothesis, but are consistent with the account that young infants lack object permanence. [source]

Basis of occlusive therapy in psoriasis: correcting defects in permeability barrier and calcium gradient

INTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 3 2001
Sang Min Hwang MD
Background Although occlusive dressings have great potential in the management of psoriasis vulgaris, the therapeutic mechanism is not completely understood. Occlusion artificially restores and corrects the defective barrier in psoriasis plaques. Additionally, occlusion is know to normalize the epidermal calcium gradients in hyperproliferative murine skin models. Methods To investigate the basis of the therapeutic effect of occlusion on psoriatic plaques, we investigated the ultrastructural morphology of intercorneocyte lipid layers, lamellar bodies, and calcium gradient in chronic plaque-type psoriasis after occlusion with a water vapor-impermeable membrane. The specimens were processed for electron microscopy using: (i) ruthenium tetroxide postfixation; and (ii) ion-capture cytochemistry for calcium localization. Results Occlusion for 7 days resulted in a nearly mature pattern of intercellular multilamellar structures, re-establishment of the near-normal epidermal calcium gradient, and disappearance of calcium precipitates from the stratum corneum interstices. Conclusions The normalization of the permeability barrier and epidermal calcium gradient may play important roles in the therapeutic effects of occlusive dressings in chronic plaque-type psoriasis. [source]

Successful Endovascular Stenting of Total Juxtarenal Aortic Occlusion Performed through Brachial and Femoral Access

JOURNAL OF CARDIAC SURGERY, Issue 3 2009
Mohammad Otahbachi M.D.
No abstract is available for this article. [source]

Emergency Off-Pump Coronary Artery Bypass (OPCAB) for Left Main Coronary Occlusion Using Rapid Aorto-Coronary Perfusion

JOURNAL OF CARDIAC SURGERY, Issue 6 2002
Paul Kerr D.O.
LAD grafted with sapenous vein and immediate aorto-coronary perfusion. Circumflex grafted and patient taken to ICU. Patient discharged on POD #6 after echo shows normal ventricular with no wall motion abnormality. [source]

Temporary Occlusion of the Great Cardiac Vein and Coronary Sinus to Facilitate Radiofrequency Catheter Ablation of the Mitral Isthmus

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 6 2008
ANDRE D'AVILA M.D.
Introduction: Ablation of the mitral isthmus to achieve bidirectional conduction block is technically challenging, and incomplete block slows isthmus conduction and is often proarrhythmic. The presence of the blood pool in the coronary venous system may act as a heat-sink, thereby attenuating transmural RF lesion formation. This porcine study tested the hypothesis that elimination of this heat-sink effect by complete air occlusion of the coronary sinus (CS) would facilitate transmural endocardial ablation at the mitral isthmus. Methods: This study was performed in nine pigs using a 30 mm-long prototype linear CS balloon catheter able to occlude and displace the blood within the CS (the balloon was inflated with ,5 cc of air). Using a 3.5 mm irrigated catheter (35 W, 30 cc/min, 1 minute lesions), two sets of mitral isthmus ablation lines were placed per animal: one with the balloon deflated (CS open) and one inflated (CS Occluded). After ablation, gross pathological analysis of the linear lesions was performed. Results: A total of 17 ablation lines were placed: 7 with CS Occlusion, and 10 without occlusion. Despite similar biophysical characteristics of the individual lesions, lesion transmurality was consistently noted only when using the air-filled CS balloon. Conclusions: Temporary displacement of the venous blood pool using an air-filled CS balloon permits transmurality of mitral isthmus ablation; this may obviate the need for ablation within the CS to achieve bidirectional mitral isthmus conduction. [source]

Asphyxiation by Occlusion of Nose and Mouth by Duct Tape: Two Unusual Suicides

JOURNAL OF FORENSIC SCIENCES, Issue 6 2009
Stephen DeRoux M.D.
Abstract:, The most recent U.S. statistics (2005) determined that 22.2% of suicides are by suffocation. This number likely includes suicidal hanging. Based on previous reports the majority of nonhanging suicidal asphyxiations are accomplished by securing a plastic bag over the head. We report two instances of a far less common method of suicidal asphyxiation, occlusion of the nose and mouth by duct tape. One was a 47-year-old man with a history of paranoid schizophrenia with suicidal ideation and the other was a 52-year-old man who was depressed due to gambling debts. The value of scene investigation, including review of available video surveillance to determine the manner of death is highlighted. [source]

CT Coronary Angiography Predicts the Outcome of Percutaneous Coronary Intervention of Chronic Total Occlusion

JOURNAL OF INTERVENTIONAL CARDIOLOGY, Issue 5 2007
F.R.A.C.P., KEAN H. SOON M.B.B.S.
Background: The success rate of percutaneous coronary intervention (PCI) of chronic total occlusions (CTO) is relatively low. Further evaluation of CTO lesion with CT coronary angiography (CT-CA) may help to better select patients that would benefit from percutaneous revascularization. We aimed to test the possible association between failed PCI and transluminal calcification of CTO as assessed by CT-CA. Methods: Patients with CTO awaiting PCI were scanned with a 16-slice CT. A cardiologist and a radiologist assessed transluminal calcification of CTO lesions on CT images while an interventional cardiologist at a core laboratory assessed conventional variables of invasive fluoroscopic coronary angiography (FCA) associated with failed PCI of CTO. The significance of CT and FCA variables in association with failed PCI were analyzed. Results: In a cohort of 39 patients with 43 CTO lesions, 24 lesions were successfully revascularized. Transluminal calcification ,50% as assessed on CT-CA was strongly associated with failed PCI (odds ratio [OR] of PCI success = 0.10, 95% confidence interval [CI]: 0.02,0.47, P = 0.003). Blunt stump as seen on FCA was also associated with failed PCI (OR of PCI success = 0.24, 95% CI: 0.07,0.86, P = 0.029). There was no significant evidence to support that the duration of CTO, presence of side branch and bridging collaterals, and the absence of microchannels as assessed with FCA were associated with failed PCI. On multivariate analysis, transluminal calcification ,50% on CT-CA was the only significant predictor of failed PCI. Conclusions: Heavy transluminal calcification as assessed with CT-CA is an independent predictor of failed PCI of CTO. CT-CA may have a role in the work-up of CTO patients prior to PCI. [source]

Advances in Transcatheter Patch Occlusion of Heart Defects

JOURNAL OF INTERVENTIONAL CARDIOLOGY, Issue 5 2003
E. B. SIDERIS M.D.
The transcatheter patch device consists of the following components: a sleeve type polyurethane patch, a double balloon support catheter and a retrieval thread. It has been applied in a variety of heart defects, including various types of atrial septal defects, ventricular septal defects and patent ductus arteriosus. New advances include an accelerated release time for many applications and better immobilization. Using accelerated fibrin formation principles, transcatheter path release time has been decreased to less than 24 hours for patent ductus arteriosus and some ventricular septal defects; in contrast 48 hours are required for patch release in large atrial septal defects. The device is also unlikely to move away from the septum using the new immobilization methods. Since the patch is inflatable, only three sizes are required for the occlusion of all defect types and sizes. Conclusion: In conclusion the transcatheter patch is applicable in a variety of heart defects; the procedure is safer and faster, becoming outpatient, for many applications. Furthermore, it is cost effective. (J Interven Cardiol 2003;16:419,424) [source]

A New Biological Matrix for Septal Occlusion

JOURNAL OF INTERVENTIONAL CARDIOLOGY, Issue 2 2003
CHRISTIAN JUX, M.D.
The ideal septal occluder scaffold should promote the healthiest and most complete healing response possible while eventually facilitating the full resorption of the material, leaving "native" tissue behind. An excellent biocompatibility of the scaffold tissue is a prerequisite for quick, complete, and firm ingrowth of the device, optimizing outcomes and minimizing the potential for complications. Intestinal collagen layer (ICL) is a highly purified (acellular) bioengineered type-1 collagen derived from porcine submucosa. It is gradually resorbed by the host organism and subsequently replaced by the host tissue. CardioSEAL® occluders were modified by substituting the conventional polyester fabric for an intestinal collagen layer (ICL). Percutaneous transcatheter closure of interventionally created atrial septal defects was performed in lambs using these modified occluders. A complete pathomorphological investigation including histology was carried out after 2, 4, and 12 weeks follow-up. Standard CardioSEAL implants served as a control group. After 2 weeks in vivo the devices were already covered completely by neo-endothelium. Compared with the conventional synthetic scaffold, ICL devices showed a quicker endothelialization, decreased thrombogenicity, and superior biocompatibility with no significant cellular infiltration observed in the histology of explants with ICL fabrics. After 3 months in vivo the collagen layer remained mechanically intact, but began to show the first histological signs of mild disintegration, gradual resorption, and remodeling. In conclusion, short-term results from preliminary in vivo experiments using a bioengineered collagen matrix as the occluder tissue scaffold showed excellent biocompatibility. This resulted in superior overall results: quicker endothelialization, a decreased thrombogenicity, and decreased immunological host response. (J Interven Cardiol 2003;16:149,152) [source]

Occlusion of an Aberrant Artery to a Pulmonary Sequestration Using a Duct Occluder

JOURNAL OF INTERVENTIONAL CARDIOLOGY, Issue 5 2002
D.C.H., ELLEN CRUSHELL M.D., M.R.C.P.I.
This report describes a female infant with a rare chromosome defect, del. 12 (q22-24.1), who has severe pulmonary valve stenosis, an atrial septal defect, and a small muscular ventricular septal defect. At 4 months of age a balloon pulmonary valvuloplasty was performed in the cardiac catheterization laboratory. During the procedure, a large aberrant artery from the aorta to a sequestration of the right lower lobe of lung was found. The flow-off from the sequestration was into a dilated left atrium. The single artery supplying the sequestration was successfully occluded using an Amplatzer Duct Occluder device. There were no complications and the infant remains well at 1-yearfollow-up. [source]

From Disk Devices to Transcatheter Patches: The Evolution of Wireless Heart Defect Occlusion

JOURNAL OF INTERVENTIONAL CARDIOLOGY, Issue 2 2001
ELEFTHERIOS B. SIDERIS M.D.
Since 1988, we have been using double-disk devices with several device generations and improving results. Our current disk device, "The ButtonSeal Centering on Demand Device", is a multipurpose device made of stainless steel and polyurethane. It has shown high occlusion rates and no significant complications in atrial septal defects (ASDs) up to 30 mm in diameter. It can be used according to the ASD anatomy both in large, single defects (centering) and in multiple fenestrations (noncentering). The ButtonSeal shares the same limitations as other disk devices, namely, the possibility of wire-related problems and the need for significant septal rim. The development of wireless balloon-delivered devices and patches addresses these problems and limitations. Both detachable balloon devices and patches were used experimentally in animals and in feasibility studies in humans. The results showed good occlusion rates and lack of wire-related complications. Both methods required a minimal rim and occluded more defects than the disk devices. The transcatheter patch method was safer and had only one disadvantage, which was the need for 48-hour balloon support. (J Interven Cardiol 2001;14:211,214) [source]

Catheter-Based Angiography in Patients with Cervical Internal Carotid Artery Occlusion: Is it Worth the Cost?

JOURNAL OF NEUROIMAGING, Issue 4 2008
M. Fareed K. Suri MD
No abstract is available for this article. [source]

Association of Pretreatment ASPECTS Scores with tPA-Induced Arterial Recanalization in Acute Middle Cerebral Artery Occlusion

JOURNAL OF NEUROIMAGING, Issue 1 2008
Georgios Tsivgoulis MD
ABSTRACT BACKGROUND AND PURPOSE The Alberta Stroke Program Early CT-Score (ASPECTS) assesses early ischemic changes within the middle cerebral artery (MCA) and predicts poor outcome and increased risk for thrombolysis-related symptomatic ICH. We evaluated the potential relationship between pretreatment ASPECTS and tPA-induced recanalization in patients with MCA occlusions. SUBJECTS & METHODS Consecutive patients with acute ischemic stroke due to MCA occlusion were treated with standard IV-tPA and assessed with transcranial Doppler (TCD) for arterial recanalization. Early recanalization was determined with previously validated Thrombolysis in Brain Ischemia (TIBI) flow-grading system at 120 minutes after tPA-bolus. All pretreatment CT-scans were prospectively scored by trained investigators blinded to TCD findings. Functional outcome at 3 months was evaluated using the modified Rankin Scale (mRS). RESULTS IV-tPA was administered in 192 patients (mean age 68 ± 14 years, median NIHSS-score 17). Patients with complete recanalization (n= 51) had higher median pretreatment ASPECTS (10, interquartile range 2) than patients with incomplete or absent recanalization (n= 141; median ASPECTS 9, interquartile range 3, P= .034 Mann-Whitney U-test). An ASPECTS ,6 was documented in 4% and 17% of patients with present and absent recanalization, respectively (P= .019). Pretreatment ASPECTS was associated with complete recanalization (OR per 1-point increase: 1.54; 95% CI 1.06,2.22, P= .023) after adjustment for baseline characteristics, risk factors, NIHSS-score, pretreatment TIBI grades and site of arterial occlusion on baseline TCD. Complete recanalization (OR: 33.97, 95% CI 5.95,185.99, P < .001) and higher ASPECTS (OR per 1-point increase: 1.91; 95% CI 1.17,3.14, P= .010) were independent predictors of good functional outcome (mRS 0,2). CONCLUSIONS Higher pretreatment ASPECT-scores are associated with a greater chance of complete recanalization and favorable long-term outcome in tPA-treated patients with acute MCA occlusion. [source]

MRI Assessment Followed by Successful Mechanical Recanalization of a Complete Tandem (Internal Carotid/Middle Cerebral Artery) Occlusion and Reversal of a 10-Hour Fixed Deficit

JOURNAL OF NEUROIMAGING, Issue 1 2008
Catalina C. Ionita MD
ABSTRACT BACKGROUND Mechanical clot extraction up to 8 hours after stroke onset is an alternative strategy for opening large vessels, especially for patients ineligible for intravenous thrombolysis. Safety beyond this therapeutic window is untested. METHODS An 81-year-old woman presented 8 hours after she developed left-sided weakness and dysarthria with a National Institutes of Health Stroke Scale (NIHSS) score fluctuating between 6 and 13. Neuroimaging revealed a large perfusion deficit with no diffusion abnormalities. An emergent cerebral angiogram revealed a complete internal carotid artery terminus occlusion. RESULTS Successful mechanical thrombectomy was performed without complication and resulted in almost complete reversal of the patient's deficit to an NIHSS score of 1, 10 hours after stroke onset. CONCLUSION Patients with large hypoperfused areas and minimal diffusion abnormalities on the MRI may benefit from mechanical thrombectomy beyond an 8-hour window. [source]

Intra-Arterial Thrombolysis for Central Retinal Artery Occlusion in United States: Nationwide In-Patient Survey 2001-2003

JOURNAL OF NEUROIMAGING, Issue 4 2007
M. Fareed K. Suri MD
ABSTRACT BACKGROUND Intra-arterial thrombolysis (IAT) has been used as a treatment modality for central retinal artery occlusion (CRAO). However, national estimates of such practice and associated outcomes are not available. We performed this study to determine the frequency and outcomes of thrombolysis among adult patients hospitalized in United States (US) for CRAO. METHODS We determined the rates, hospital outcomes, and hospital charges incurred for patients with CRAO treated with thrombolysis using Nationwide Inpatient Survey (NIS) and compared them with patients treated without thrombolysis. NIS is the largest all-payer inpatient care database in the US approximating a 20-percent stratified sample of US community hospitals. RESULTS There were 1379 admissions for primary diagnosis of CRAO in 2001-2003. IAT was used in 27(1.9%) of the patients with CRAO. There was no in-hospital mortality or intracranial hemorrhage reported among any patient with CRAO treated with thrombolysis. All patients treated with IAT were discharged home. IAT was exclusively used in urbanteaching hospitals. CONCLUSIONS There is potential of benefit from IAT in CRAO, which is only offered in certain centers. Clinical trials are needed to demonstrate this beneficial effect. [source]

The Accuracy of Transcranial Doppler in the Diagnosis of Stenosis or Occlusion of the Terminal Internal Carotid Artery

JOURNAL OF NEUROIMAGING, Issue 4 2004
Jose C. Navarro MD
ABSTRACT Background and Purpose. Transcranial Doppler (TCD) can detect intracranial stenoses and occlusions that can help in the diagnosis and management of ischemic stroke. The accuracy parameters for lesions located in the terminal internal carotid artery (TICA) are less known, unlike other basal cerebral vessels. Patients and Methods. The authors studied consecutive patients referred for TCD who underwent contrast angiography or magnetic resonance angiography. They calculated the sensi tivity, specificity, positive and negative predictive values (PPV and NPV), and likelihood ratios. Results. Forty-three patients had TCD and angiography: mean age was 57 ± 20 years, and 65% were men. Twenty-two patients were diagnosed with TICA stenosis or occlusion on TCD underwent angiography. Four patients had abnormal TCD findings that were not confirmed by angiography. Two of 21 patients with normal TCD showed mod erate (< 50%) stenosis of the TICA and cavernous segment of the internal carotid artery at angiography. Accuracy parameters for TCD were as follows: sensitivity = 90% (confidence interval [CI], 63%-96%), specificity = 83% (CI, 61%-94%), PPV = 82%, NPV = 86%, positive likelihood ratio = 5, and negative likelihood ratio = 0.17. Conclusions. TCD is a sensitive screening tool for the lesions in the TICA. Specificity is likely affected by a wide spectrum of the stenosis severity shown at angiography and time lags between the studies. [source]

A Broad Diagnostic Battery for Bedside Transcranial Doppler to Detect Flow Changes With Internal Carotid Artery Stenosis or Occlusion

JOURNAL OF NEUROIMAGING, Issue 3 2001
Ioannis Christou MD
ABSTRACT Background and Purpose. The authors establish accuracy parameters of a broad diagnostic battery for bedside transcranial Doppler (TCD) to detect flow changes due to internal carotid artery (ICA) stenosis or occlusion. Methods. The authors prospectively studied consecutive patients with stroke or transient ischemic attack referred for TCD. TCD was performed and interpreted at bedside using a standard insonation protocol. A broad diagnostic battery included major criteria: collateral flow signals, abnormal siphon or terminal carotid signals, and delayed systolic flow acceleration in the middle cerebral artery. Minor criteria included a unilateral decrease in pulsatility index (, 0.6 or , 70% of contralateral side), flow diversion signs, and compensatory velocity increase. Angiography or carotid duplex ultrasound (CDU) was used to grade the degree of carotid stenosis using North American criteria. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of TCD findings were determined. Results. Seven hundred and twenty patients underwent TCD, of whom 517 (256 men and 261 women) had angiography and/or CDU within 8.8 ± 0.9 days. Age was 63.1 ± 15.7 years. For a 70% to 99% carotid stenosis or occlusion, TCD had sensitivity of 79.4%, specificity of 86.2%, PPV of 57.0%, NPV of 94.8%, and accuracy of 84.7%. For a 50% to 99% carotid stenosis or occlusion, TCD had sensitivity of 67.5%, specificity of 83.9%, PPV of 54.5%, NPV of 90.0%, and accuracy of 81.6%. TCD detected intracranial carotid lesions with 84.9% accuracy and extracranial carotid lesions with 84.4% accuracy (sensitivity of 88% and 79%, specificity of 85% and 86%, PPV of 24% and 54%, and NPV of 99% and 95%, respectively). The prevalence of the ophthalmic artery flow reversal was 36.4% in patients with , 70% stenosis or occlusion. If present, this finding indicated a proximal ICA lesion location in 97% of these patients. Conclusions. In symptomatic patients, bedside TCD can accurately detect flow changes consistent with hemodynamically significant ICA obstruction; however, TCD should not be a substitute for direct carotid evaluation. Because TCD is sensitive and specific for , 70% carotid stenosis or occlusion in both extracranial and intracranial carotid segments, it can be used as a complementary test to refine other imaging findings and detect tandem lesions. [source]

Occlusion , time to reflect?

JOURNAL OF ORAL REHABILITATION, Issue 6 2005
A personal view
summary, The topic of occlusion presents a conundrum to many practitioners. To some the topic is very complex and yet to others, although important, it illustrates how adaptive the dentition is to change. This commentary presents some arguments as to how the importance of occlusion and its understanding have evolved since the Journal of Oral Rehabilitation was first published. [source]

Skin hydration and possible shunt route penetration in controlled estradiol delivery from ultradeformable and standard liposomes

JOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 10 2001
Gamal M. M. El Maghraby
Human skin delivery of estradiol from ultradeformable and traditional liposomes was explored, comparing occlusive and open application, with the aim of examining the role of skin hydration. Partially hydrated epidermis was used for open hydration, but fully hydrated membranes were used for occluded studies. In addition, we developed a novel technique to investigate the role of shunt route penetration in skin delivery of liposomal estradiol. This compared delivery through epidermis with that through a stratum corneum (SC)/epidermis sandwich from the same skin with the additional SC forming the top layer of the sandwich. This design was based on the fact that orifices of shunts only occupy 0.1% of skin surface area and thus for SC/epidermis sandwiches there will be a negligible chance for shunts to superimpose. The top SC thus blocks most shunts available on the bottom membrane. If shunts play a major role then the delivery through sandwiches should be much reduced compared with that through epidermis, taking into consideration the expected reduction owing to increased membrane thickness. After open application, both ultradeformable and traditional liposomes improved estradiol skin delivery, with the ultradeformable liposomes being superior. Occlusion reduced the delivering efficiency of both vesicle types, supporting the theory that a hydration gradient provides the driving force. Shunt route penetration was found to play only a very minor role in liposomal delivery. In conclusion, full hydration of skin reduces estradiol delivery from liposomes and the shunt route is not the main pathway for this delivery. [source]