Science.gov

Sample records for intra-hepatic porto-systemic shunt

  1. Transjugular intrahepatic porto-systemic shunt in the elderly: Palliation for complications of portal hypertension

    PubMed Central

    Syed, Mubin I; Karsan, Hetal; Ferral, Hector; Shaikh, Azim; Waheed, Uzma; Akhter, Talal; Gabbard, Alan; Morar, Kamal; Tyrrell, Robert

    2012-01-01

    AIM: To present a dedicated series of transjugular intrahepatic porto-systemic shunts (TIPS) in the elderly since data is sparse on this population group. METHODS: A retrospective review was performed of patients at least 65 years of age who underwent TIPS at our institutions between 1997 and 2010. Twenty-five patients were referred for TIPS. We deemed that 2 patients were not considered appropriate candidates due to their markedly advanced liver disease. Of the 23 patients suitable for TIPS, the indications for TIPS placement was portal hypertension complicated by refractory ascites alone (n = 9), hepatic hydrothorax alone (n = 2), refractory ascites and hydrothorax (n = 1), gastrointestinal bleeding alone (n = 8), gastrointestinal bleeding and ascites (n = 3). RESULTS: Of these 23 attempted TIPS procedure patients, 21 patients had technically successful TIPS procedures. A total of 29 out of 32 TIPS procedures including revisions were successful in 21 patients with a mean age of 72.1 years (range 65-82 years). Three of the procedures were unsuccessful attempts at TIPS and 8 procedures were successful revisions of our existing TIPS. Sixteen of 21 patients who underwent successful TIPS (excluding 5 patients lost to follow-up) were followed for a mean of 14.7 mo. Ascites and/or hydrothorax was controlled following technically successful procedures in 12 of 13 patients. Bleeding was controlled following technically successful procedures in 10 out of 11 patients. CONCLUSION: We have demonstrated that TIPS is an effective procedure to control refractory complications of portal hypertension in elderly patients. PMID:22400084

  2. Transjugular Intrahepatic Porto-Systemic Shunt Placement in a Patient with Left-Lateral Split-Liver Transplant and Mesenterico-Left Portal Vein by Pass Placement

    SciTech Connect

    Miraglia, Roberto Maruzzelli, Luigi; Luca, Angelo

    2011-12-15

    This is a report of a successful placement of a transjugular intrahepatic porto-systemic shunt in a young patient with previous left-lateral, split-liver transplant and mesenterico-left portal vein by pass placement after posttransplant extrahepatic portal vein thrombosis.

  3. Technical concepts for vascular electromagnetic navigated interventions: aortic in situ fenestration and transjugular intrahepatic porto-systemic shunts.

    PubMed

    Penzkofer, Tobias; Isfort, Peter; Na, Hong-Sik; Wilkmann, Christoph; Osterhues, Sabine; Besting, Andreas; Hänisch, Christoph; Bisplinghoff, Stefan; Jansing, Johannes; von Werder, Sylvie; Gooding, Jorge; de la Fuente, Mathias; Mahnken, Andreas H; Disselhorst-Klug, Catherine; Schmitz-Rode, Thomas; Kuhl, Christiane K; Bruners, Philipp

    2014-04-01

    This work presents concepts for complex endovascular procedures using electromagnetic navigation technology (EMT). Navigation software interfacing a standard commercially available navigation system was developed, featuring registration, electromagnetic field distortion correction, breathing motion detection and gating, and state-of-the-art 3D imaging post processing. Protocols for endovascularly placed, in-situ fenestrated abdominal aortic stent grafts and an EMT guided transjugular intrahepatic portosystemic shunt (TIPSS) creation have been designed. A dedicated set of interventional devices was developed for each of the procedures: For aortic in-situ fenestration a combination of high-porosity stentgrafts, steerable catheters and electromagnetically navigated guidewires was used, for TIPSS a dual-navigated (sheath and stylet) TIPSS-device was designed and manufactured. The developed devices underwent phantom testing, in preparation for animal experiments to prove the feasibility of the approach. Once established, these systems could aid in performing these challenging interventional radiology procedures, exploiting the unique characteristics of electromagnetic navigation and solving multiple of the problems associated with these interventions being performed under X-ray fluoroscopy, such as lacking real-time 3D information or extensive exposure to ionizing radiation. PMID:24176959

  4. A retrospective analysis of the impact of diastolic dysfunction on one-year mortality after transjugular intrahepatic porto-systemic shunt, liver transplantation and non-transplant abdominal surgery in patients with cirrhosis

    PubMed Central

    Shounak, Majumder; Vimal, Rabdiya; Colin, Swales; David I, Silverman

    2015-01-01

    Background The incidence of diastolic dysfunction (DD) approaches 40% in patients with cirrhosis. However, the clinical impact of DD remains a subject of considerable debate. Surgery in patients with cirrhosis is innately hazardous. Diastolic heart failure has been linked to increased mortality after transjugular intrahepatic porto-systemic shunt surgery (TIPSS). To date, none of the commonly accepted preoperative risk assessment models applied to patients with liver disease incorporates DD. We aimed to examine the relationship between DD and postoperative outcomes in patients with cirrhosis undergoing abdominal surgery. Methods Patients with cirrhosis who underwent abdominal surgery between January 2000 and December 2011 were included if they had preoperative echocardiography done within 3 months of surgery. The echocardiographic images were reviewed using flow and tissue Doppler techniques to identify the presence of DD. Outcomes analyzed included one-year mortality and postoperative complications. Results A total of 140 patients were included in the study of which 63 patients (45%) met pre-established criteria for DD. Those with DD were older (P < 0.005) and less likely to have an isolated viral etiology of cirrhosis (P<0.05). The one-year mortality rate was 22.2% (14/63) in patients with DD and 20.8% (16/77) in those without DD (P=0.42). Postoperative complications were not statistically different in the two groups. Conclusion DD is common in patients with cirrhosis. In patients with cirrhosis undergoing TIPS and/or abdominal surgery, the presence of DD does not increase post-procedure complications or one-year mortality. PMID:26129720

  5. Colectomy for Porto-Systemic Encephalopathy: Is it Still Topical?

    PubMed

    Ennaifer, Rym; Hayfa, Romdhane; Hefaiedh, Rania; Marsaoui, Lobna; Hadj, Najet Bel; Khalfallah, Tahar

    2013-01-25

    Hepatic encephalopathy (HE) is a common long term complication of porto-systemic shunt. We report herein the case of a 59-year-old man with Child-Pugh A cirrhosis treated successfully 9 years earlier with distal splenorenal shunt for uncontrolled variceal bleeding. In the last year, he developed a severe and persistent hepatic encephalopathy secondary to the shunt, which was resistant to medical therapy. As liver transplantation was not available and obliteration of the shunt was hazardous, we performed subtotal colectomy in order to reduce ammonia production. This therapeutic option proved successful, as the grade of encephalopathy decreased and the patient improved. Our experience indicates that colonic exclusion should be considered as an option in the management of HE refractory to medical treatment in highly selected patients when liver transplantation is not available or even as a bridge given the long waiting time on lists. PMID:24765497

  6. Iron Deficiency Impairs Intra-Hepatic Lymphocyte Mediated Immune Response.

    PubMed

    Bonaccorsi-Riani, Eliano; Danger, Richard; Lozano, Juan José; Martinez-Picola, Marta; Kodela, Elisavet; Mas-Malavila, Roser; Bruguera, Miquel; Collins, Helen L; Hider, Robert C; Martinez-Llordella, Marc; Sanchez-Fueyo, Alberto

    2015-01-01

    Hepatic expression of iron homeostasis genes and serum iron parameters predict the success of immunosuppression withdrawal following clinical liver transplantation, a phenomenon known as spontaneous operational tolerance. In experimental animal models, spontaneous liver allograft tolerance is established through a process that requires intra-hepatic lymphocyte activation and deletion. Our aim was to determine if changes in systemic iron status regulate intra-hepatic lymphocyte responses. We used a murine model of lymphocyte-mediated acute liver inflammation induced by Concanavalin A (ConA) injection employing mice fed with an iron-deficient (IrDef) or an iron-balanced diet (IrRepl). While the mild iron deficiency induced by the IrDef diet did not significantly modify the steady state immune cell repertoire and systemic cytokine levels, it significantly dampened inflammatory liver damage after ConA challenge. These findings were associated with a marked decrease in T cell and NKT cell activation following ConA injection in IrDef mice. The decreased liver injury observed in IrDef mice was independent from changes in the gut microflora, and was replicated employing an iron specific chelator that did not modify intra-hepatic hepcidin secretion. Furthermore, low-dose iron chelation markedly impaired the activation of isolated T cells in vitro. All together, these results suggest that small changes in iron homeostasis can have a major effect in the regulation of intra-hepatic lymphocyte mediated responses. PMID:26287688

  7. Rapid Intra-Hepatic Dissemination of Hepatocellular Carcinoma with Pulmonary Metastases Following Combined Loco-Regional Therapy

    PubMed Central

    2013-01-01

    This manuscript describes an unusual case of rapid intra-hepatic dissemination of hepatocellular carcinoma with pulmonary metastases occurring 1 month after combined chemoembolization and radiofrequency ablation. Inferior vena cava and portal vein invasion tumor thrombus was also detected, possibly accounting for the mechanism of disease dissemination route of disease. PMID:23901322

  8. Symptomatic hepatic hydrothorax successfully treated with transjugular intrahepatic portosystemic shunt (TIPS)–role of titration of portosystemic gradient reduction to avoid post-TIPS encephalopathy

    PubMed Central

    Krishnamoorthy, T L; Taneja, M; Chang, P E

    2014-01-01

    Key Clinical Message We describe a challenging case of hepatic hydrothorax secondary to nonalcoholic steatohepatitis cirrhosis. Our management involved successfully treating the hydrothorax with a transjugular intrahepatic porto-systemic shunt but having to manage the subsequent complication of hepatic encephalopathy. We conclude with a review of the available literature. PMID:25356258

  9. Transjugular Intrahepatic Portosystemic Shunt Dysfunction: Concordance of Clinical Findings, Doppler Ultrasound Examination, and Shunt Venography

    PubMed Central

    Owen, Joshua M; Gaba, Ron Charles

    2016-01-01

    Objectives: The objective of this study was to evaluate the concordance between clinical symptoms, Doppler ultrasound (US), and shunt venography for the detection of stent-graft transjugular intrahepatic portosystemic shunt (TIPS) dysfunction. Materials and Methods: Forty-one patients (M:F 30:11, median age 55 years) who underwent contemporaneous clinical exam, Doppler US, and TIPS venography between 2003 and 2014 were retrospectively studied. Clinical symptoms (recurrent ascites or variceal bleeding) were dichotomously classified as present/absent, and US and TIPS venograms were categorized in a binary fashion as normal/abnormal. US abnormalities included high/low (>190 or <90 cm/s) TIPS velocity, significant velocity rise/fall (>50 cm/s), absent flow, and return of antegrade intra-hepatic portal flow. Venographic abnormalities included shunt stenosis/occlusion and/or pressure gradient elevation. Clinical and imaging concordance rates were calculated. Results: Fifty-two corresponding US examinations and venograms were assessed. The median time between studies was 3 days. Forty of 52 (77%) patients were symptomatic, 33/52 (64%) US examinations were abnormal, and 20/52 (38%) TIPS venograms were abnormal. Concordance between clinical symptoms and TIPS venography was 48% (25/52), while the agreement between US and shunt venography was 65% (34/52). Clinical symptoms and the US concurred in 60% (31/52) of the patients. The sensitivity of clinical symptoms and US for the detection of venographically abnormal shunts was 80% (16/20) and 85% (17/20), respectively. Both clinical symptoms and the US had low specificity (25%, 8/32 and 50%, 16/32) for venographically abnormal shunts. Conclusion: Clinical findings and the US had low concordance rates with TIPS venography, with acceptable sensitivity but poor specificity. These findings suggest the need for improved noninvasive imaging methods for stent-graft TIPS surveillance. PMID:27563495

  10. Distal splenorenal shunt

    MedlinePlus

    ... shunt procedure; Renal - splenic venous shunt; Warren shunt; Cirrhosis - distal splenorenal; Liver failure - distal splenorenal ... hepatitis Blood clots Certain congenital disorders Primary biliary cirrhosis When blood cannot flow normally through the portal ...

  11. Ventriculomammary shunt: an unusual ventriculoperitoneal shunt complication.

    PubMed

    Chaudhry, Nauman S; Johnson, Jeremiah N; Morcos, Jacques J

    2015-02-01

    Ventriculoperitoneal (VP) shunt malfunctions are common and can result in significant consequences for patients. Despite the prevalence of breast augmentation surgery and breast surgery for other pathologies, few breast related VP shunt complications have been reported. A 54-year-old woman with hydrocephalus post-subarachnoid hemorrhage returned 1 month after VP shunt placement complaining of painful unilateral breast enlargement. After investigation, it was determined that the distal VP shunt catheter had migrated from the peritoneal cavity into the breast and wrapped around her breast implant. The breast enlargement was the result of cerebrospinal fluid retention. We detail this unusual case and review all breast related VP shunt complications reported in the literature. To avoid breast related complications related to VP shunt procedures, it is important to illicit pre-procedural history regarding breast implants, evade indwelling implants during catheter tunneling and carefully securing the abdominal catheter to prevent retrograde catheter migration to the breast. PMID:25127261

  12. Complications of denver shunt.

    PubMed

    Perera, Eranga; Bhatt, Shweta; Dogra, Vikram S

    2011-01-01

    Hepatic hydrothorax secondary to transdiaphragmatic spread of peritoneal fluid can cause respiratory discomfort to the patient. Draining of hydrothorax helps relieve these symptoms. Pleurovenous shunt (Denver shunt) is a relatively non-invasive method of shunting the pleural fluid to the central venous system. Reported complications of pleurovenous shunts are shunt failure, pulmonary edema, post shunt coagulopathy, deep vein thrombosis, and infection. We report a rare case of a leak at the venous end of the catheter that was placed within the right internal jugular vein, resulting in a large collection in the neck. PMID:21915387

  13. A Novel Approach to Ultrasound-Mediated Tissue Decellularization and Intra-Hepatic Cell Delivery in Rats.

    PubMed

    Pahk, Ki Joo; Mohammad, Goran Hamid; Malago, Massimo; Saffari, Nader; Dhar, Dipok Kumar

    2016-08-01

    Liver transplantation is the mainstay of treatment for end stage liver diseases, including metabolic and congenital liver diseases. The number of suitable donor organs is, however, limited, and a whole-liver transplant requires complex surgery. Cell therapy, such as intra-portal hepatocytes transplantation, has been considered as a bridging therapy to liver transplantation but has shown a mixed clinical outcome with limited success, including low level of engraftment of transplanted hepatocytes. Here, we report a novel cell delivery technique in a rat model by creating a cavity inside the liver parenchyma by non-invasive high intensity focused ultrasound histotripsy. Our in vivo experimental results together with histologic observations show that direct injection of cells inside the cavity can facilitate successful uptake, proliferation and integration of the transplanted hepatocytes in the recipient liver. We were able to restore the plasma albumin level to 50% of the normal level in Nagase analbuminemic rats (serum albumin level of the Nagase rats was initially nil) by cell therapy after high intensity focused ultrasound-mediated histotripsy. We believe that this novel technique would enable the delivery of a large number of cells into the liver to restore liver function, particularly as a treatment for metabolic liver diseases. This novel method of intra-hepatic hepatocyte transplantation might be an invaluable tool for cell therapy in the future. PMID:27184248

  14. Direct measurement of porto-systemic gradient in a failing Fontan circulation.

    PubMed

    Velpula, Madhavi; Sheron, Nick; Guha, Neill; Salmon, Tony; Hacking, Nigel; Veldtman, Gruschen R

    2011-01-01

    We describe the case history of a 42-year-old man with cardiac cirrhosis, portal hypertension, and life-threatening variceal bleeding after Fontan revision surgery. Direct pressure measurements in the portal vein, though high, demonstrated only a modest portosystemic gradient (PSG), 9 mm Hg. A transjugular intrahepatic portosystemic shunt procedure was performed. This reduced the PSG (3 mm Hg). His bleeding was controlled. The patient's histopathological findings were identical to that previously documented in Fontan patients, raising the question of whether these subdiaphragmatic hemodynamics are representative of the broader failing Fontan population. PMID:21356034

  15. Ventriculoperitoneal shunt - discharge

    MedlinePlus

    ... page: //medlineplus.gov/ency/patientinstructions/000149.htm Ventriculoperitoneal shunt - discharge To use the sharing features on this ... JavaScript. Your child has hydrocephalus and needed a shunt placed to drain excess fluid and relieve pressure ...

  16. [Shunt and short circuit].

    PubMed

    Rangel-Abundis, Alberto

    2006-01-01

    Shunt and short circuit are antonyms. In French, the term shunt has been adopted to denote the alternative pathway of blood flow. However, in French, as well as in Spanish, the word short circuit (court-circuit and cortocircuito) is synonymous with shunt, giving rise to a linguistic and scientific inconsistency. Scientific because shunt and short circuit made reference to a phenomenon that occurs in the field of the physics. Because shunt and short circuit are antonyms, it is necessary to clarify that shunt is an alternative pathway of flow from a net of high resistance to a net of low resistance, maintaining the stream. Short circuit is the interruption of the flow, because a high resistance impeaches the flood. This concept is applied to electrical and cardiovascular physiology, as well as to the metabolic pathways. PMID:17257492

  17. Short-term fasting induces intra-hepatic lipid accumulation and decreases intestinal mass without reduced brush-border enzyme activity in mink (Mustela vison) small intestine.

    PubMed

    Bjornvad, C R; Elnif, J; Sangild, P T

    2004-11-01

    For many mammalian species short-term fasting is associated with intestinal atrophy and decreased digestive capacity. Under natural conditions, strictly carnivorous animals often experience prey scarcity during winter, and they may therefore be particularly well adapted to short-term food deprivation. To examine how the carnivorous gastrointestinal tract is affected by fasting, small-intestinal structure, brush-border enzyme activities and hepatic structure and function were examined in fed mink (controls) and mink that had been fasted for 1-10 days. During the first 1-2 days of fasting, intestinal mass decreased more rapidly than total body mass and villus heights were reduced 25-40%. In contrast, tissue-specific activity of the brush-border enzymes sucrase, maltase, lactase, aminopeptidase A and dipeptidylpeptidase IV increased 0.5- to 1.5-fold at this time, but returned to prefasting levels after 6 days of fasting. After 6-10 days of fasting there was a marked increase in the activity of hepatic enzymes and accumulation of intra-hepatic lipid vacuoles. Thus, mink may be a useful model for studying fasting-induced intestinal atrophy and adaptation as well as mechanisms involved in accumulation of intra-hepatic lipids following food deprivation in strictly carnivorous domestic mammals, such as cats and ferrets. PMID:15503054

  18. Distal splenorenal shunt

    MedlinePlus

    ... transjugular intrahepatic portal systematic shunt for variceal bleeding: a randomized trial. Gastroenterology. 2006;130(6):1643-51. Sicklick JK, D'Angelica M, Fong Y. The liver. In: Townsend CM Jr, Beauchamp RD, Evers BM, Mattox KL, ...

  19. Hydrocephalus and Shunts

    MedlinePlus

    ... or anesthesia. When ventricles start to get too big, it is a strong sign that the shunt is not working right. It is important to know that some people (between 5 and 15 percent) with Spina Bilda may have ...

  20. Shunt tube calcification as a late complication of ventriculoperitoneal shunting.

    PubMed

    Salim, Abubakr Darrag; Elzain, Mohammed Awad; Mohamed, Haddab Ahmed; Ibrahim Zayan, Baha Eldin Mohamed

    2015-01-01

    Shunt calcification is a rare complication of ventriculoperitoneal shunting that occurs years later after the initial operation this condition is rarely reported in literature. Two patients with shunt calcifications were described. The first patient was 17-year-old lady who had congenital hydrocephalus and shunted in the early infancy, she was presented recently complaining of itching of the skin along the shunt track and limitation of neck movement. The patient was then operated with removal of the old peritoneal catheter and replacing it with a new one. The second patient was 17-year-old boy originally was a case of posterior fossa pilocytic astrocytoma associated with obstructive hydrocephalus, he was operated with both shunting for the hydrocephalus and tumor removal, 6 years later he presented with shunt exposure. Calcification of the shunt tube was discovered intraoperatively upon shunt removal. Shunt calcification has been observed mainly in barium-impregnated catheters. Introducing plain silicone-coated shunt tubing may reduce the rate of this condition. The usual complaints of the patients suffering from this condition are pain in the neck and chest wall along the shunt pathway and limitation of the neck movement due to shunt tube tethering, but features of shunt dysfunction and skin irritation above the shunt may be present. In this review, plain X-ray and operative findings showed that the most extensive calcification is present in the neck, where the catheters were subject to heavy mechanical stress. Disturbed calcium and phosphate metabolisms may be involved in this condition. Shunt calcification is a rare condition that occurs due to material aging presenting with features of shunt tethering, dysfunction or overlying skin irritation. Plain X-ray is needed to detect calcification while shunt removal, replacement or endoscopic third ventriculostomy may carry solution for this condition. PMID:26396620

  1. Aqueous shunts for glaucoma

    PubMed Central

    Minckler, Don; Vedula, Satyanarayana S; Li, Tianjing; Mathew, Milan; Ayyala, Ramesh; Francis, Brian

    2014-01-01

    Background Aqueous shunts are employed for intraocular pressure (IOP) control in primary and secondary glaucomas that fail medical, laser, and other surgical therapies. Objectives This review compares aqueous shunts for IOP control and safety. Search strategy We searched CENTRAL, MEDLINE, PubMed, EMBASE, NRR in January 2006, LILACS to February 2004 and reference lists of included trials. Selection criteria We included all randomized and quasi-randomized trials in which one arm of the study involved shunts. Data collection and analysis Two authors independently extracted data for included studies and a third adjudicated discrepancies. We contacted investigators for missing information. We used fixed-effect models and summarized continuous outcomes using mean differences. Main results We included fifteen trials with a total of 1153 participants with mixed diagnoses. Five studies reported details sufficient to verify the method of randomization but only two had adequate allocation concealment. Data collection and follow-up times were variable. Meta-analysis of two trials comparing Ahmed implant with trabeculectomy found trabeculectomy resulted in lower mean IOPs 11 to 13 months later (mean difference 3.81 mm Hg, 95% CI 1.94 to 5.69 mm Hg). Meta-analysis of two trials comparing double-plate Molteno implant with the Schocket shunt was not done due to substantial heterogeneity. One study comparing ridged with standard double-plate Molteno implants found no clinically significant differences in outcome. Two trials investigating the effectiveness of adjunctive mitomycin (MMC) with the Molteno and Ahmed implants found no evidence of benefit with MMC. Two trials that investigated surgical technique variations with the Ahmed found no benefit with partial tube ligation or excision of Tenon's capsule. One study concluded there were outcome advantages with a double versus a single-plate Molteno implant and one trial comparing the 350 mm2 and 500 mm2 Baerveldt shunts found no

  2. Transjugular intrahepatic portosystemic shunt (TIPS)

    MedlinePlus

    ... gov/ency/article/007210.htm Transjugular intrahepatic portosystemic shunt (TIPS) To use the sharing features on this page, please enable JavaScript. Transjugular intrahepatic portosystemic shunt (TIPS) is a procedure to create new connections ...

  3. Transjugular intrahepatic portosystemic shunt.

    PubMed

    Patidar, Kavish R; Sydnor, Malcolm; Sanyal, Arun J

    2014-11-01

    Transjugular intrahepatic portosystemic shunt (TIPS) is an established procedure for the complications of portal hypertension. The largest body of evidence for its use has been supported for recurrent or refractory variceal bleeding and refractory ascites. Its use has also been advocated for acute variceal bleed, hepatic hydrothorax, and hepatorenal syndrome. With the replacement of bare metal stents with polytetrafluoroethylene-covered stents, shunt patency has improved dramatically, thus, improving outcomes. Therefore, reassessment of its utility, management of its complications, and understanding of various TIPS techniques is important. PMID:25438287

  4. Transjugular intrahepatic portosystemic shunt.

    PubMed

    Ochs, Andreas

    2005-01-01

    The transjugular intrahepatic portosystemic shunt (TIPS) is an interventional treatment resulting in decompression of the portal system by creation of a side-to-side portosystemic anastomosis. Since its introduction 16 years ago, more than 1,000 publications have appeared demonstrating broad acceptance and increasing clinical use. This review summarizes our present knowledge about technical aspects and complications, follow-up of patients and indications. A technical success rate near 100% and a low occurrence of complications clearly depend on the skills of the operator. The follow-up of the TIPS patient has to assess shunt patency, liver function, hepatic encephalopathy and the possible development of hepatocellular carcinoma. Shunt patency can best be monitored by duplex sonography and can avoid routine radiological revision. Short-term patency may be improved by anticoagulation, while such a treatment does not influence long-term patency. Stent grafts covered with expanded polytetrafluoroethylene show promising long-term patency comparable with that of surgical shunts. With respect to the indications of TIPS, much is known about treatment of variceal bleeding and refractory ascites. The thirteen randomized studies that are available to date show that survival is comparable in patients receiving TIPS or endoscopic treatment for acute or recurrent variceal bleeding. Another group comprises patients with refractory ascites and related complications, such as hepatorenal syndrome and hepatic hydrothorax. It has been demonstrated that TIPS improves these complications. Five randomized studies comparing TIPS with paracentesis and one study comparing TIPS with the peritoneo-venous shunt showed good response of ascites but controversial results on survival. In addition, TIPS has been successfully applied to patients with Budd-Chiari syndrome, portal vein thrombosis, before liver transplantation, and for the treatment of ectopic variceal bleeding. PMID:15920326

  5. 30 CFR 56.6401 - Shunting.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Shunting. 56.6401 Section 56.6401 Mineral....6401 Shunting. Except during testing— (a) Electric detonators shall be kept shunted until connected to the blasting line or wired into a blasting round; (b) Wired rounds shall be kept shunted...

  6. Outcome analysis of shunt surgery in hydrocephalus

    PubMed Central

    Ahmed, Ashraf; Sandlas, Gursev; Kothari, Paras; Sarda, Dinesh; Gupta, Abhaya; Karkera, Parag; Joshi, Prashant

    2009-01-01

    Aim: To study the clinical outcome of shunt surgeries in children suffering from hydrocephalus. Methods: A prospective study of 50 children with hydrocephalus who underwent a ventriculo-peritoneal shunt insertion over a period of two years. These patients were then followed up for shunt related complications, shunt revisions and outcome. Results: Twenty six of the 50 patients (52%) suffered from complications. The most common complications were shunt blockage (n=7) and shunt infection (n=6). These complications necessitated repeated shunt revisions. Conclusions: Infective complications of hydrocephalus are more likely to leave behind an adverse neurological outcome in the form of delayed milestones and mental retardation. PMID:20376249

  7. To shunt or not to shunt: hydrocephalus and dysraphism.

    PubMed

    Rekate, H L

    1985-01-01

    Objective criteria are available for decision making in children with ventriculomegaly and spina bifida cystica. Figure 29.7 is the evaluation algorithm used in the Hydrocephalus/Myelodysplasia Clinic at Rainbow Babies and Children's Hospital. In children without serious neurosurgical complications such as the Chiari crisis or problems with wound healing, we rely on three reasonably objective measurements for decision making. Head circumference: Measured daily while in hospital and at each visit. If the pattern of head growth crosses multiple percentile lines indicating that the child will be severely megalencephalic, a shunt will be performed. Ultrasonography: Ultrasound determinations are made in the first few days of life, prior to discharge, at 6 weeks of age, and each 6 weeks of age until 6 months. Some measurements of ventricular size (usually CT scan because of a small anterior fontanelle) should be made at age 1 year. Denver Developmental Testing (DDST): These are performed at age 6 weeks and each 6 weeks thereafter. If the child shows significant ventriculomegaly, a shunt is performed. When the results are questionable the decision is delayed and the test repeated in 6 weeks. Whether a shunt is or is not placed in an infant with ventriculomegaly and myelodysplasia, follow-up must remain compulsive. Following shunting, not only should the head circumference stabilize, but the cortical mantle should increase. Often children shunted in this situation fail to show signs of increased intracranial pressure with shunt malfunction and must be followed with serial head circumference measurements as well as ultrasounds and CT scans. If the decision is made not to shunt the child the work of Hall et al. (10) would suggest the possibility that later in life shunts may be needed to prevent scoliosis secondary to hydromyelia. More information is needed as the aggressively treated population become adults. PMID:2415285

  8. Percutaneous Placement and Management of Peritoneovenous Shunts

    PubMed Central

    Martin, Louis G.

    2012-01-01

    Peritoneovenous shunts are used in the treatment of recurrent ascites or recurrent pleural effusions. Generally speaking, the shunts allow passage of ascites or pleural effusions (by either passive or active means) back into the central venous system. The most recent development in peritoneovenous shunts, known as the Denver Shunt, is a modification of a shunt developed for the treatment of hydrocephalus. In recent years, the Denver shunt has been placed by interventional radiologists. It is used to treat both cirrhotic and malignant effusions in the peritoneal and pleural cavities. Reported complications of the shunt are shunt occlusion, infection, post-shunt coagulopathy, deep vein thrombosis, catheter breakage, and leaks. This article discusses the technical aspects related to the percutaneous placement and maintenance of the Denver Shunt. PMID:23729983

  9. Orthopaedic complications of lumboperitoneal shunts.

    PubMed

    McIvor, J; Krajbich, J I; Hoffman, H

    1988-01-01

    Lumboperitoneal (LP) shunts performed for communicating hydrocephalus have been reported to lead to neurologic deficits in the lower limbs and spinal deformities as a result of arachnoiditis. A chart review of 375 children who underwent LP shunts between 1960 and 1981 at The Hospital For Sick Children in Toronto was undertaken. Of the 375 charts reviewed, evidence of shunt-induced neurologic deficits was seen in 63 patients. Thirty-four patients had back pain with or without sciatica, 45 patients had hamstring tightness, and 40 patients had foot deformities. Forty-nine patients had lumbar hyperlordosis, lordoscoliosis, and scoliosis. These deformities are postulated to be the result of arachnoiditis involving the conus medullaris and lower lumbar roots. PMID:3192696

  10. 49 CFR 236.838 - Wire, shunt.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Wire, shunt. 236.838 Section 236.838 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Wire, shunt. A wire forming part of a shunt circuit....

  11. 30 CFR 57.6401 - Shunting.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Shunting. 57.6401 Section 57.6401 Mineral...-Surface and Underground § 57.6401 Shunting. Except during testing— (a) Electric detonators shall be kept shunted until connected to the blasting line or wired into a blasting round; (b) Wired rounds shall...

  12. Students with Shunts: Program Considerations.

    ERIC Educational Resources Information Center

    French, Ron; And Others

    1997-01-01

    Examines how the medical condition of hydrocephalus can affect physical education students and physical education programs, and stresses the need to provide physical educators with information on students' medical conditions. Describes hydrocephalus and its treatment with ventricular peritoneal shunts, and offers suggestions on modifying…

  13. Shunt regulation electric power system

    NASA Technical Reports Server (NTRS)

    Wright, W. H.; Bless, J. J. (Inventor)

    1971-01-01

    A regulated electric power system having load and return bus lines is described. A plurality of solar cells interconnected in a power supplying relationship and having a power shunt tap point electrically spaced from the bus lines is provided. A power dissipator is connected to the shunt tap point and provides for a controllable dissipation of excess energy supplied by the solar cells. A dissipation driver is coupled to the power dissipator and controls its conductance and dissipation and is also connected to the solar cells in a power taping relationship to derive operating power therefrom. An error signal generator is coupled to the load bus and to a reference signal generator to provide an error output signal which is representative of the difference between the electric parameters existing at the load bus and the reference signal generator. An error amplifier is coupled to the error signal generator and the dissipation driver to provide the driver with controlling signals.

  14. Arterioportal shunts on dynamic computed tomography

    SciTech Connect

    Nakayama, T.; Hiyama, Y.; Ohnishi, K.; Tsuchiya, S.; Kohno, K.; Nakajima, Y.; Okuda, K.

    1983-05-01

    Thirty-two patients, 20 with hepatocelluar carcinoma and 12 with liver cirrhosis, were examined by dynamic computed tomography (CT) using intravenous bolus injection of contrast medium and by celiac angiography. Dynamic CT disclosed arterioportal shunting in four cases of hepatocellular carcinoma and in one of cirrhosis. In three of the former, the arterioportal shunt was adjacent to a mass lesion on CT, suggesting tumor invasion into the portal branch. In one with hepatocellular carcinoma, the shunt was remote from the mass. In the case with cirrhosis, there was no mass. In these last two cases, the shunt might have been caused by prior percutaneous needle puncture. In another case of hepatocellular carcinoma, celiac angiography but not CT demonstrated an arterioportal shunt. Thus, dynamic CT was diagnostic in five of six cases of arteriographically demonstrated arterioportal shunts.

  15. 21 CFR 886.3920 - Aqueous shunt.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Aqueous shunt. 886.3920 Section 886.3920 Food and... OPHTHALMIC DEVICES Prosthetic Devices § 886.3920 Aqueous shunt. (a) Identification. An aqueous shunt is an... Review Guidance of 2/12/90 (K90-1),” and (3) “Aqueous Shunts—510(k) Submissions.”...

  16. Radiological Insertion and Management of Peritoneovenous Shunt

    SciTech Connect

    Bratby, M. J.; Hussain, F. F. Lopez, A. J.

    2007-06-15

    The purpose of the study was to report our experience of the management of complications following the insertion of a peritoneovenous shunt for intractable malignant ascites. From June 1999 to January 2006, 26 patients underwent insertion of a peritoneovenous shunt for ascites by interventional radiologists. We have used ultrasound and shuntography to assist in the diagnosis of the cause of shunt blockage. Successful techniques for the restoration of the shunt function include port- pumping, stripping of any fibrin sheath, and revision of either the venous or peritoneal catheter. The procedure was initially successful in all patients with continued patency until death in 17. A further four patients are still alive with a functioning shunt. There was one rapid postprocedure death resulting from pulmonary edema. Two patients developed pneumothorax, managed successfully with either a chest drain or aspiration. Shunt dysfunction occurred eight times in seven patients. There were five successful revisions in four patients. Overall, shunt patency has been maintained in 80.1% of patients. Shunt dysfunction is seen in a significant number of patients, but successful revision of the shunt can be achieved in the majority.

  17. Headaches in patients with shunts.

    PubMed

    Rekate, Harold L; Kranz, Dory

    2009-03-01

    Headache is one of the most common afflictions suffered by humans. Headache in patients with a shunt triggers a series of events that includes utilization of expensive technologies and often potentially dangerous surgical intervention. The purpose of this study was to determine the incidence of headaches in patients with shunts and, hopefully, the relationship of those headache disorders to the treatment of hydrocephalus. The Hydrocephalus Association maintains a self-reporting database recorded from individuals treated for hydrocephalus and their families. This database was mined to determine the incidence of severe headaches requiring treatment and interfering with normal life in patients who have been treated for hydrocephalus. There were 1,242 responders between the ages of 19 months and 45 years of age. Of these, 1,233 answered the question, "Do you or your family member suffer from (does your child complain of) frequent or chronic headaches?" This subset forms the basis of this study. Three groups were defined by age: children (19 months-12 years), adolescents (13 years-19 years), and young adults (20 years-45 years). Most respondents were initially treated during infancy (before 18 months of age); 84% of children and 69% of both adolescents and young adults were treated very early in life. Severe headaches became a more frequent problem as the age of the population treated for hydrocephalus increased. In terms of frequency and severity of headaches, direct comparisons with epidemiologic studies of normal populations are difficult because of the limitations of data available in the database. However, it is likely that this population has a higher incidence of severe headaches than normal populations. The cost of management of headaches in this population is very high, and the patients are at risk throughout life. Early treatment decisions have a significant effect on later quality of life. Strategies that lead to normalization of cerebrospinal fluid dynamics

  18. [Temporary distance shunting of the anastomosis with a probe shunt].

    PubMed

    Abdulzhalilov, M K; Gaĭbatov, S P

    2003-01-01

    The authors present results of using temporary shunting of intestinal anastomosis in combination with selective lavage of the suture line with a curative antiseptic mixture in experiment in 12 dogs and in clinic in 36 patients with a probe of the authors' original construction. The probe consists of a polychlorvenyl tube with the inner diameter 0.8-1.0 cm, having two inflatable rubber cuffs mounted on the distal end at a distance of 15 cm from each other. After inflation of the cuffs a closed isolated cavity is formed in the zone of intestinal sutures, into which the distal end of the tube is opened for the decompression and selective intraluminal lavage of the anastomosis. The using of the temporary shunting of intestinal anastomosis in combination with selective intraluminal lavage with a mixture of broad-spectrum antibiotics and antioxidant 1.5% Reamberin accelerates the process of the intestinal suture healing, results in favorable course of the postoperative period, prevents complications. PMID:14768105

  19. 21 CFR 874.3820 - Endolymphatic shunt.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Endolymphatic shunt. 874.3820 Section 874.3820 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES EAR, NOSE, AND THROAT DEVICES Prosthetic Devices § 874.3820 Endolymphatic shunt....

  20. 21 CFR 874.3820 - Endolymphatic shunt.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Endolymphatic shunt. 874.3820 Section 874.3820 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES EAR, NOSE, AND THROAT DEVICES Prosthetic Devices § 874.3820 Endolymphatic shunt....

  1. 21 CFR 874.3820 - Endolymphatic shunt.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Endolymphatic shunt. 874.3820 Section 874.3820 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES EAR, NOSE, AND THROAT DEVICES Prosthetic Devices § 874.3820 Endolymphatic shunt....

  2. 21 CFR 874.3820 - Endolymphatic shunt.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Endolymphatic shunt. 874.3820 Section 874.3820 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES EAR, NOSE, AND THROAT DEVICES Prosthetic Devices § 874.3820 Endolymphatic shunt....

  3. 21 CFR 874.3820 - Endolymphatic shunt.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Endolymphatic shunt. 874.3820 Section 874.3820 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES EAR, NOSE, AND THROAT DEVICES Prosthetic Devices § 874.3820 Endolymphatic shunt....

  4. Does the Warren Shunt Correct Hypersplenism?

    PubMed Central

    Mavor, Andrew I. D.; Giles, Geoffrey R.

    1990-01-01

    It has been suggested that patients with bleeding varices and hypersplenism will show significant improvements in leucocyte and platelet counts following distal splenorenal (Warren) shunt surgery. Whilst this may be true in the short term, this report shows that in the long term hypersplenism is not relieved, whereas the lienorenal shunt is associated with a return of normal haematological values. PMID:2282329

  5. 49 CFR 236.802 - Shunt.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Shunt. 236.802 Section 236.802 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF... OF SIGNAL AND TRAIN CONTROL SYSTEMS, DEVICES, AND APPLIANCES Definitions § 236.802 Shunt. A...

  6. 49 CFR 234.229 - Shunting sensitivity.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Shunting sensitivity. 234.229 Section 234.229 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION..., Inspection, and Testing Maintenance Standards § 234.229 Shunting sensitivity. Each highway-rail...

  7. 49 CFR 236.56 - Shunting sensitivity.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Shunting sensitivity. 236.56 Section 236.56 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION...: All Systems Track Circuits § 236.56 Shunting sensitivity. Each track circuit controlling home...

  8. 49 CFR 236.56 - Shunting sensitivity.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Shunting sensitivity. 236.56 Section 236.56 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION...: All Systems Track Circuits § 236.56 Shunting sensitivity. Each track circuit controlling home...

  9. 49 CFR 236.56 - Shunting sensitivity.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Shunting sensitivity. 236.56 Section 236.56 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION...: All Systems Track Circuits § 236.56 Shunting sensitivity. Each track circuit controlling home...

  10. 49 CFR 234.229 - Shunting sensitivity.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Shunting sensitivity. 234.229 Section 234.229 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION..., Inspection, and Testing Maintenance Standards § 234.229 Shunting sensitivity. Each highway-rail...

  11. 49 CFR 236.56 - Shunting sensitivity.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Shunting sensitivity. 236.56 Section 236.56 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION...: All Systems Track Circuits § 236.56 Shunting sensitivity. Each track circuit controlling home...

  12. 49 CFR 236.56 - Shunting sensitivity.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Shunting sensitivity. 236.56 Section 236.56 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION...: All Systems Track Circuits § 236.56 Shunting sensitivity. Each track circuit controlling home...

  13. Congenital Portosystemic Shunt: Our Experience

    PubMed Central

    Timpanaro, Tiziana; Passanisi, Stefano; Sauna, Alessandra; Trombatore, Claudia; Pennisi, Monica; Petrillo, Giuseppe; Smilari, Pierluigi; Greco, Filippo

    2015-01-01

    Introduction. Congenital portosystemic venous malformations are rare abnormalities in which the portal blood drains into a systemic vein and which are characterized by extreme clinical variability. Case Presentations. The authors present two case reports of a congenital extrahepatic portosystemic shunt (Type II). In the first patient, apparently nonspecific symptoms, such as headache and fatigue, proved to be secondary to hypoglycemic episodes related to the presence of a portosystemic shunt, later confirmed on imaging. During portal vein angiography, endovascular embolization of the portocaval fistula achieved occlusion of the anomalous venous tract. In the second patient, affected by Down's syndrome, the diagnosis of a portosystemic malformation was made by routine ultrasonography, performed to rule out concurrent congenital anomalies. Because of the absence of symptoms, we chose to observe this patient. Conclusions. These two case reports demonstrate the clinical heterogeneity of this malformation and the need for a multidisciplinary approach. As part of a proper workup, clinical evaluation must always be followed by radiographic diagnosis. PMID:25709849

  14. [Systemic-pulmonary artery shunt using Golaski graft: trial for measurement of the shunt flow].

    PubMed

    Togo, T; Ito, T; Hata, M; Murata, S; Osaka, K; Komatsu, T; Tabayashi, K; Haneda, K; Mohri, T

    1995-03-01

    For the systemic-pulmonary artery shunt operation, the modified Blalock-Taussig shunt was the first choice for procedure in our institution. Since 1990, Golaski knitted Dacron graft (4 or 5 mm in diameter) was used for the prosthesis. Ex-vivo flow calibration of the electromagnetic flow meter (Nihon Koden, MFV-3100) to Golaski graft showed good correlation between the real flow and value measured by the electromagnetic flow meter. Shunt flow was measured in the consecutive clinical fifteen cases. The shunt flow per body surface area of the patient who required additional shunt operation was 721 ml/min/m2 and one patient in whom the congestive heart failure developed after the shunt operation, had the shunt flow of 3,022 ml/min/m2. The adequate shunt flow in these cases was ranged from 745 to 2,820 ml/min/m2 (mean +/- 1 SD, 1,490 +/- 587.8). Therefore we performed the systemic-pulmonary artery shunt operation using Golaski graft to get the shunt flow of 1,000 ml/min/m2 (approximately a third of cardiac index) for the guide of good results. PMID:7897896

  15. The Preventable Shunt Revision Rate: a potential quality metric for pediatric shunt surgery.

    PubMed

    Venable, Garrett T; Rossi, Nicholas B; Morgan Jones, G; Khan, Nickalus R; Smalley, Zachary S; Roberts, Mallory L; Klimo, Paul

    2016-07-01

    OBJECTIVE Shunt surgery consumes a large amount of pediatric neurosurgical health care resources. Although many studies have sought to identify risk factors for shunt failure, there is no consensus within the literature on variables that are predictive or protective. In this era of "quality outcome measures," some authors have proposed various metrics to assess quality outcomes for shunt surgery. In this paper, the Preventable Shunt Revision Rate (PSRR) is proposed as a novel quality metric. METHODS An institutional shunt database was queried to identify all shunt surgeries performed from January 1, 2010, to December 31, 2014, at Le Bonheur Children's Hospital. Patients' records were reviewed for 90 days following each "index" shunt surgery to identify those patients who required a return to the operating room. Clinical, demographic, and radiological factors were reviewed for each index operation, and each failure was analyzed for potentially preventable causes. RESULTS During the study period, there were 927 de novo or revision shunt operations in 525 patients. A return to the operating room occurred 202 times within 90 days of shunt surgery in 927 index surgeries (21.8%). In 67 cases (33% of failures), the revision surgery was due to potentially preventable causes, defined as inaccurate proximal or distal catheter placement, infection, or inadequately secured or assembled shunt apparatus. Comparing cases in which failure was due to preventable causes and those in which it was due to nonpreventable causes showed that in cases in which failure was due to preventable causes, the patients were significantly younger (median 3.1 vs 6.7 years, p = 0.01) and the failure was more likely to occur within 30 days of the index surgery (80.6% vs 64.4% of cases, p = 0.02). The most common causes of preventable shunt failure were inaccurate proximal catheter placement (33 [49.3%] of 67 cases) and infection (28 [41.8%] of 67 cases). No variables were found to be predictive of

  16. 21 CFR 882.4545 - Shunt system implantation instrument.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... implantation instrument. (a) Identification. A shunt system implantation instrument is an instrument used in the implantation of cerebrospinal fluid shunts, and includes tunneling instruments for passing shunt... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Shunt system implantation instrument....

  17. Pneumocephalus following ventriculoperitoneal shunt. Case report.

    PubMed

    Pitts, L H; Wilson, C B; Dedo, H H; Weyand, R

    1975-11-01

    The authors describe a case of massive pneumocephalus following ventriculoperitoneal shunting for hydrocephalus. After multiple diagnostic and surgical procedures, congenital defects in the tegmen tympani of both temporal bones were identified as the sources for entry of air. A functioning shunt intermittently established negative intracranial pressure and allowed ingress of air through these abnormalities; when the shunt was occluded, air did not enter the skull, and there was no cerebrospinal fluid leakage. Repair of these middle ear defects prevented further recurrence of pneumocephalus. PMID:1181396

  18. Current concepts in congenital portosystemic shunts.

    PubMed

    Mankin, Kelley M Thieman

    2015-05-01

    Congenital portosystemic shunts (CPSS) are vascular abnormalities that allow portal blood to bypass the liver and join systemic circulation. Laboratory and imaging studies are performed preoperatively to diagnose CPSS and hopefully identify an anatomic location of the shunt. CPSS can be found in different locations in both small and large breed dogs. Most CPSS are best managed surgically. The goal of surgical management of CPSS is to slowly redirect blood from the shunting vessel through the portal vasculature while avoiding portal hypertension. Many surgical management methods are available, including open and less invasive procedures, such as laparoscopy and embolization. PMID:25737000

  19. Canine congenital portosystemic shunts: Disconnections dissected.

    PubMed

    Van den Bossche, L; van Steenbeek, F G

    2016-05-01

    Canine congenital portosystemic shunts (CPSS) are vascular anomalies that connect the portal vein with the systemic circulation, therefore bypassing the hepatic parenchyma. Portosystemic shunts exist in two different subtypes: extrahepatic and intrahepatic. This congenital disorder is also described in mice, cat, sheep and man. Research has been focused on pathophysiology, diagnostics and treatment of CPSS and this has resulted in increased knowledge, although the aetiology of the disease remains unclear. This review focuses on the aetiology and genetic basis of both intra- and extrahepatic shunts. PMID:27061656

  20. Ventriculoperitoneal Shunt Peritoneal Catheter Knot Formation

    PubMed Central

    Ul-Haq, Anwar; Al-Otaibi, Faisal; Alshanafey, Saud; Sabbagh, Mohamed Diya; Al Shail, Essam

    2013-01-01

    The ventriculoperitoneal (VP) shunt is a common procedure in pediatric neurosurgery that carries a risk of complications at cranial and abdominal sites. We report on the case of a child with shunt infection and malfunction. The peritoneal catheter was tethered within the abdominal cavity, precluding its removal. Subsequently, laparoscopic exploration identified a knot at the distal end of the peritoneal catheter around the omentum. A new VP shunt was inserted after the infection was healed. This type of complication occurs rarely, so there are a limited number of case reports in the literature. This report is complemented by a literature review. PMID:24109528

  1. Reversible occlusion shunt for intraventricular chemotherapy in shunt-dependent brain tumor patients.

    PubMed

    Czech, T; Reinprecht, A; Dietrich, W; Hainfellner, J A; Slavc, I

    1997-01-01

    Intraventricular chemotherapy is increasingly used in the treatment of pediatric brain tumors with leptomeningeal seeding. However, some patients are shunt dependent after surgery, probably due to adhesions in the area of surgery. To avoid drug diversion in these patients we connected the reservoir to a reversible occlusion device. Over a 2-year period a shunt value with an on-off device was inserted into the shunt assembly of eight children with various brain tumors with a poor prognosis undergoing intraventricular chemotherapy. All eight patients had tumor cells in the ventricular cerebrospinal fluid (CSF) and/or metastases by magnetic resonance imaging. The number of intraventricular drug applications ranged from 10 to 51. No shunt malfunctions or shunt-related infections occurred. The temporary closure of the shunt after drug delivery was well tolerated. In all six children with tumor cells in the ventricular CSF a negative cytology was achieved over a 3- to 8-week period. PMID:9211542

  2. Scintisplenoportography in assessing patency of distal splenorenal shunts

    SciTech Connect

    Teres, J.; Herranz, R.; Visa, J.; Lomena, F.; Pera, C.; Rodes, J.

    1983-06-01

    Scintisplenoportography was performed on 33 occasions in 28 cirrhotic patients who had bled from esophagogastric varices. In 17 cases scintisplenoportography was carried out after a retroperitoneal distal splenorenal shunt procedure and in the remaining 16 instances in patients without any surgical shunt. In four patients scintisplenoportography was performed before and after a surgical shunt procedure, and in one case, before and after the shunt thrombosed. Gammagraphic patterns and spleen-heart times helped determine which patients did not have a surgical shunt, which had a patent shunt, and which patients had a thrombosed shunt. A patent shunt pattern and a thrombosed shunt pattern have been defined. It is concluded that scintisplenoportography is a useful, reproducible, and safe method to assess the patency of distal splenorenal shunts.

  3. Arne Torkildsen and the ventriculocisternal shunt: the first clinically successful shunt for hydrocephalus.

    PubMed

    Eide, Per Kristian; Lundar, Tryggve

    2016-05-01

    Arne Torkildsen was a pioneering Norwegian neurosurgeon who introduced the ventriculocisternal shunt, the first clinically successful shunt for CSF diversion in hydrocephalus. The procedure, usually referred to as ventriculocisternostomy (VCS), Torkildsen's operation, orTorkildsen's shunt, became internationally recognized as an efficient operation for the treatment of noncommunicating hydrocephalus. The operation gained widespread use in the 1940s and 1950s before the introduction of extracranial shunts. In this paper, the authors look more closely at Torkildsen's development of the VCS and examine how this surgical approach differed from other procedures for treating hydrocephalus before World War II. Long-term results of the VCS are presented. PMID:26339852

  4. Severe respiratory failure following ventriculopleural shunt

    PubMed Central

    Alam, Shahzad; Manjunath, Nagaraju M.

    2015-01-01

    Cerebrospinal fluid (CSF) diversion procedure has been used for long to treat hydrocephalus in children. The principle of shunting is to establish a communication between the CSF and a drainage cavity (peritoneum, right atrium, and pleura). Ventriculoperitoneal shunt is used most commonly, followed secondly by ventriculopleural shunt (VPLS). Hydrothorax due to excessive CSF accumulation is a rare complication following both the type of shunts and is more frequently seen with VPLS. We report a case of a 6-year-old female child presenting with massive CSF hydrothorax with respiratory failure following VPLS. The aim of the article is to highlight early recognition of this rare and life-threatening condition, which could easily be missed if proper history is not available. PMID:26730125

  5. Severe respiratory failure following ventriculopleural shunt.

    PubMed

    Alam, Shahzad; Manjunath, Nagaraju M

    2015-11-01

    Cerebrospinal fluid (CSF) diversion procedure has been used for long to treat hydrocephalus in children. The principle of shunting is to establish a communication between the CSF and a drainage cavity (peritoneum, right atrium, and pleura). Ventriculoperitoneal shunt is used most commonly, followed secondly by ventriculopleural shunt (VPLS). Hydrothorax due to excessive CSF accumulation is a rare complication following both the type of shunts and is more frequently seen with VPLS. We report a case of a 6-year-old female child presenting with massive CSF hydrothorax with respiratory failure following VPLS. The aim of the article is to highlight early recognition of this rare and life-threatening condition, which could easily be missed if proper history is not available. PMID:26730125

  6. Syringosubarachnoid shunting using a myringotomy tube

    PubMed Central

    Leschke, Jack M.; Mumert, Michael L.; Kurpad, Shekar N.

    2016-01-01

    Background: Syringomyelia results from obstruction of cerebrospinal fluid (CSF) flow due to a multitude of causes. Often symptoms of pain, weakness, and sensory disturbance are progressive and require surgical treatment. We present here a rare technique for syringosubarachnoid shunting. Case Description: We present the case of a 38-year-old male who suffered a traumatic cervical spinal cord injury due to a motor vehicle accident. With progressive pain and motor decline, a magnetic resonance imaging was obtained and showed a new syrinx extending cervical multiple segments. A unique surgical procedure using a myringotomy tube to shunt CSF into the subarachnoid space was employed in this case. The patient's examination stabilized postoperatively, and at 2 months and 6 months follow-up visits, his strength and sensation continued to improve. Conclusion: We used a myringotomy tube for syringosubarachnoid shunting for the surgical management of a posttraumatic syrinx with good results. This technique minimizes suturing and may minimize shunt-related complications. PMID:26862456

  7. Cell shunt resistance and photovoltaic module performance

    SciTech Connect

    McMahon, T.J.; Basso, T.S.; Rummel, S.R.

    1996-05-01

    Shunt resistance of cells in photovoltaic modules can affect module power output and could indicate flawed manufacturing processes and reliability problems. The authors describe a two-terminal diagnostic method to directly measure the shunt resistance of individual cells in a series-connected module non-intrusively, without deencapsulation. Peak power efficiency vs. light intensity was measured on a 12-cell, series-connected, single crystalline module having relatively high cell shunt resistances. The module was remeasured with 0.5-, 1-, and 2-ohm resistors attached across each cell to simulate shunt resistances of several emerging technologies. Peak power efficiencies decreased dramatically at lower light levels. Using the PSpice circuit simulator, the authors verified that cell shunt and series resistances can indeed be responsible for the observed peak power efficiency vs. intensity behavior. The authors discuss the effect of basic cell diode parameters, i.e., shunt resistance, series resistance, and recombination losses, on PV module performance as a function of light intensity.

  8. Transjugular Intrahepatic Portosystemic Shunt Versus Surgical Shunting in the Management of Portal Hypertension

    PubMed Central

    Huang, Long; Yu, Qing-Sheng; Zhang, Qi; Liu, Ju-Da; Wang, Zhen

    2015-01-01

    Background: The purpose of this article was to clarify the optimal management concerning transjugular intrahepatic portosystemic shunts (TIPSs) and surgical shunting in treating portal hypertension. Methods: All databases, including CBM, CNKI, WFPD, Medline, EMBASE, PubMed and Cochrane up to February 2014, were searched for randomized controlled trials (RCTs) comparing TIPS with surgical shunting. Four RCTs, which were extracted by two independent investigators and were evaluated in postoperative complications, mortality, 2- and 5-year survival, hospital stay, operating time and hospitalization charges. Results: The morbidity in variceal rehemorrhage was significantly higher in TIPS than in surgical shunts (odds ratio [OR] = 7.45, 95% confidence interval[CI]: (3.93–14.15), P < 0.00001), the same outcomes were seen in shunt stenosis (OR = 20.01, 95% CI: (6.67–59.99), P < 0.000001) and in hepatic encephalopathy (OR = 2.50, 95% CI: (1.63–3.84), P < 0.0001). Significantly better 2-year survival (OR = 0.66; 95% CI: (0.44–0.98), P = 0.04) and 5-year survival (OR = 0.44; 95% CI: (0.30–0.66), P < 0.00001) were seen in patients undergoing surgical shunting compared with TIPS. Conclusions: Compared with TIPS, postoperative complications and survival after surgical shunting were superior for patients with portal hypertension. Application of surgical shunting was recommended for patients rather than TIPS. PMID:25758281

  9. Vasopressin and splanchnic shunting. A quantitative comparison.

    PubMed Central

    Chandler, J G

    1982-01-01

    To analyze the relationship between the splanchnic and systemic effects of vasopressin and to measure its efficacy in lowering portal pressure relative to what can be accomplished by zero gradient shunting, intraoperative measurements of cardiac output and relevant pressures were made in 30 patients undergoing selective or total shunts. Vasopressin caused a significant increase in systemic vascular resistance and pulmonary capillary wedge pressure, but an insignificant overall reduction in cardiac index (CI). However, in ten patients the decrease in CI exceeded 20%, suggesting a subpopulation of especially susceptible individuals. High initial CI, age, pre-existent heart disease, and severity of cirrhosis did not predict greater vulnerability. Adding an infusion of nitroprusside regularly reverted CI to control levels, regardless of the extent of cardiac output depression. Vasopressin was 38% as effective as a subsequent shunt in reducing splanchnic venous pressure. The portal hypotensive action bore no relationship to CI, but the pressure decrease caused by vasopressin was predictive of the reduction that could be achieved by shunting. The effects of the two types of shunts on systemic hemodynamics were minor and remarkably similar. PMID:7073352

  10. Pleuroperitoneal shunt for recurrent malignant pleural effusions.

    PubMed Central

    Tsang, V; Fernando, H C; Goldstraw, P

    1990-01-01

    The therapeutic options available for the management of malignant pleural effusions associated with a restricting malignant cortex remain unsatisfactory. The efficacy of pleuroperitoneal shunts was evaluated in 16 patients with recurrent malignant effusions. There were no operative deaths; one patient died on the third postoperative day as a result of lymphangitis carcinomatosa. The median hospital stay was five (range 3-21) days. Palliation was obtained in all but one of the other 15 patients. There was no appreciable reaccumulation of pleural fluid as judged by radiography. Two patients developed occlusion of the shunt. In one case this was due to blood clots in the pleural catheter and necessitated insertion of a new shunt. The other shunt was removed because of obstructing infected fibrin debris, and a rib resection was performed. There were eight deaths related to the underlying malignancy after a mean interval of 7.3 (range 1.5-23) months. The other six patients are still alive, with a mean survival of 11.0 (range 5-20) months, and have achieved good symptomatic relief. The insertion of a pleuroperitoneal shunt can offer effective palliation for patients with recurrent malignant pleural effusions. Images PMID:1696401

  11. Radionuclide demonstration of intrapulmonary shunting in cirrhosis

    SciTech Connect

    Bank, E.R.; Thrall, J.H.; Dantzker, D.R.

    1983-05-01

    The association of hepatic cirrhosis and severe arterial hypoxemia has been well described. Although alterations in ventilatory function may partially account for the hypoxemia, the principal mechanism is thought to be a microangiopathic change in the pulmonary vasculature resulting in intrapulmonary arteriovenous shunting with resultant systemic desaturation. Whole-body radionuclide scans with technetium-99m macroaggregated albumin labeling have been diagnostic of right-to-left shunting by their demonstration of tracer accumulation within the extrapulmonary circulation. A case of severe pulmonary arteriovenous shunting in an alcoholic patient in whom hepatic disease had not been of apparent clinical significance before radionuclide scanning is reported. He did not have cuntaeous angiomata as have all other patients with alcoholic cirrhosis and hypoxemia.

  12. Radionuclide demonstration of intrapulmonary shunting in cirrhosis

    SciTech Connect

    Bank, E.R.; Thrall, J.H.; Dantzker, D.R.

    1983-05-01

    The association of hepatic cirrhosis and severe arterial hypoxemia has been well described. Although alterations in ventilatory function may partially account for the hypoxemia, the principal mechanism is thought to be a microangiopathic change in the pulmonary arteriovenous shunting with resultant systemic desaturation. Whole-body radionuclide scans with technetium-99m macroaggrregated albumin (/sup 99m/Tc MAA) labeling have been diagnostic of right-to-left shunting by their demonstration of tracer accumulation within the extrapulmonary circulation. A case of severe pulmonary arteriovenous shunting in an alcoholic patient in whom hepatic disease had not been of apparent clinical significance before radionuclide scanning is reported. He did not have cutaneous angiomata as have all other patients with alcoholic cirrhosis and hypoxemia.

  13. A canine model of multiple portosystemic shunting.

    PubMed

    Howe, L M; Boothe, H W; Miller, M W; Boothe, D M

    2000-01-01

    The objective of this study was to develop and describe an experimental canine model of multiple acquired portosystemic shunts (PSS) similar in nature to spontaneously occurring PSS. Sixteen dogs were used and were divided into a control (n = 6) and a diseased group (n = 10). Dogs of the diseased group were administered dimethylnitrosamine (2 mg/kg of body weight, po) twice weekly, and clinicopathologic, ultrasonographic, and hepatic scintigraphic findings were recorded during the development of hepatic disease and PSS. Surgery was then performed to permit visual verification of multiple shunts, catheter placement for portography examination, and biopsy of the liver. All diseased dogs developed severe hepatic disease and multiple PSS as documented visually at surgery and on portography. Based on this study, dimethylnitrosamine-induced portosystemic shunting appears to be an appropriate model for spontaneously occurring multiple PSS secondary to portal hypertension. PMID:10741951

  14. Ventricular shunt infections: Immunopathogenesis and clinical management

    PubMed Central

    Gutierrez-Murgas, Yenis; Snowden, Jessica N.

    2014-01-01

    Ventricular shunts are the most common neurosurgical procedure performed in the United States. This hydrocephalus treatment is often complicated by infection of the device with biofilm-forming bacteria. In this review, we discuss the pathogenesis of shunt infection, as well as the implications of the biofilm formation on treatment and prevention of these infections. Many questions remain, including the contribution of glia and the impact of inflammation on developmental outcomes following infection. Immune responses within the CNS must be carefully regulated to contain infection while minimizing bystander damage; further study is needed to design optimal treatment strategies for these patients. PMID:25156073

  15. Collagen plug occlusion of Molteno tube shunts.

    PubMed

    Stewart, W; Feldman, R M; Gross, R L

    1993-01-01

    We report five patients in whom collagen lacrimal plugs were used to temporarily occlude the lumen of Molteno shunts to prevent early postoperative hypotony. Only one eye, with a double plate, developed hypotony and a flat anterior chamber that required reformation. However, in three patients, the collagen plugs did not dissolve and had to be removed surgically to lower the intraocular pressure. Although the semipermeability of collagen is desirable, its unpredictable degradation renders it unsuitable for temporary occlusion of tube shunts. Other biodegradable materials may be more appropriate for this purpose. PMID:8446334

  16. 49 CFR 236.57 - Shunt and fouling wires.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Shunt and fouling wires. 236.57 Section 236.57...: All Systems Track Circuits § 236.57 Shunt and fouling wires. (a) Except as provided in paragraph (b) of this section, shunt wires and fouling wires hereafter installed or replaced shall consist of...

  17. 21 CFR 882.4545 - Shunt system implantation instrument.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Shunt system implantation instrument. 882.4545... (CONTINUED) MEDICAL DEVICES NEUROLOGICAL DEVICES Neurological Surgical Devices § 882.4545 Shunt system implantation instrument. (a) Identification. A shunt system implantation instrument is an instrument used...

  18. 21 CFR 876.5955 - Peritoneo-venous shunt.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Peritoneo-venous shunt. 876.5955 Section 876.5955...) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Therapeutic Devices § 876.5955 Peritoneo-venous shunt. (a) Identification. A peritoneo-venous shunt is an implanted device that consists of a catheter and a...

  19. 49 CFR 236.104 - Shunt fouling circuit.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Shunt fouling circuit. 236.104 Section 236.104 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION...: All Systems Inspections and Tests; All Systems § 236.104 Shunt fouling circuit. Shunt fouling...

  20. 49 CFR 236.725 - Circuit, switch shunting.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Circuit, switch shunting. 236.725 Section 236.725 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Circuit, switch shunting. A shunting circuit which is closed through contacts of a switch...

  1. 49 CFR 234.229 - Shunting sensitivity.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Shunting sensitivity. 234.229 Section 234.229 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... sensitivity. Each highway-rail grade crossing train detection circuit shall detect the application of a...

  2. 49 CFR 234.229 - Shunting sensitivity.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Shunting sensitivity. 234.229 Section 234.229 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... sensitivity. Each highway-rail grade crossing train detection circuit shall detect the application of a...

  3. 49 CFR 234.229 - Shunting sensitivity.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Shunting sensitivity. 234.229 Section 234.229 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... sensitivity. Each highway-rail grade crossing train detection circuit shall detect the application of a...

  4. Muzzle shunt augmentation of conventional railguns

    SciTech Connect

    Parker, J.V.

    1990-01-01

    Augmentation is a well-known technique for reducing the armature current and hence the armature power dissipation in a plasma armature railgun. In spite of the advantages, no large augmented railguns have been built, primarily due to the mechanical and electrical complexity introduce by the extra conductors required. It is possible to achieve some of the benefits of augmentation in conventional railgun by diverting a fraction {phi} of the input current through a shunt path at the muzzle of the railgun. In particular, the relation between force and armature current is the same as that obtained in an n-turn, series connected augmented railgun with n = 1/(1-{phi}). The price of this simplification is a reduction in electrical efficiency and some additional complexity in the external electrical system. Additions to the electrical system are required to establish the shunt current and to control its magnitude during projectile acceleration. The relationship between muzzle shunt augmentation and conventional series augmentation is developed and various techniques is developed and various techniques for establishing and controlling the shunt current are illustrated with a practical example. 5 refs., 8 figs., 2 tabs.

  5. Fabrication of capacitively-shunted superconducting qubits

    NASA Astrophysics Data System (ADS)

    Yoder, Jonilyn L.; Gudmundsen, Theodore J.; Bolkhovsky, Vladimir; Welander, Paul B.; Gustavsson, Simon; Hover, David; Kerman, Andrew J.; Sears, Adam P.; Oliver, William D.

    2014-03-01

    Improvements in superconducting qubit coherence times and reproducibility have been demonstrated using capacitive shunting. In this study, we present methods for the preparation of both capacitively-shunted charge qubits (transmons) and capacitively-shunted flux qubits. Hybrid fabrication techniques were employed to combine high-quality-factor aluminum capacitive shunts with shadow-evaporated Josephson junctions, and the Josephson junctions were prepared using suspended-bridge germanium masks. We also will describe process testing results that were acquired to assess wafer-to-wafer reproducibility of our fabrication protocols. This research was funded in part by the Office of the Director of National Intelligence (ODNI), Intelligence Advanced Research Projects Activity (IARPA); and by the Assistant Secretary of Defense for Research and Engineering under Air Force Contract number FA8721-05-C-0002. All statements of fact, opinion or conclusions contained herein are those of the authors and should not be construed as representing the official views or policies of IARPA, the ODNI, or the U.S. Government.

  6. Platypnea-Orthodeoxia Syndrome: To Shunt or Not to Shunt, That is the Question

    PubMed Central

    Kiefer, Todd L.; Velazquez, Eric J.

    2016-01-01

    Platypnea-orthodeoxia syndrome is a rare disease defined by dyspnea and deoxygenation, induced by an upright position, and relieved by recumbency. Causes include shunting through a patent foramen ovale and pulmonary arteriovenous malformations. A 79-year-old woman experienced 2 syncopal episodes at rest and presented at another hospital. In the emergency department, she was hypoxic, needing 6 L/min of oxygen. Her chest radiograph showed nothing unusual. Transthoracic echocardiograms with saline microcavitation evaluation were mildly positive early after agitated-saline administration, suggesting intracardiac shunting. She was then transferred to our center. Right-sided heart catheterization revealed no oximetric evidence of intracardiac shunting while the patient was supine and had a low right atrial pressure. However, her oxygen saturation dropped to 78% when she sat up. Repeat transthoracic echocardiography while sitting revealed a dramatically positive early saline microcavitation-uptake into the left side of the heart. Transesophageal echocardiograms showed a patent foramen ovale, with right-to-left shunting highly dependent upon body position. The patient underwent successful percutaneous patent foramen ovale closure, and her oxygen supplementation was suspended. In patients with unexplained or transient hypoxemia in which a cardiac cause is suspected, it is important to evaluate shunting in both the recumbent and upright positions. In this syndrome, elevated right atrial pressure is not necessary for significant right-to-left shunting. Percutaneous closure, if feasible, is first-line therapy in these patients. PMID:27303248

  7. Platypnea-Orthodeoxia Syndrome: To Shunt or Not to Shunt, That is the Question.

    PubMed

    Klein, Michael R; Kiefer, Todd L; Velazquez, Eric J

    2016-06-01

    Platypnea-orthodeoxia syndrome is a rare disease defined by dyspnea and deoxygenation, induced by an upright position, and relieved by recumbency. Causes include shunting through a patent foramen ovale and pulmonary arteriovenous malformations. A 79-year-old woman experienced 2 syncopal episodes at rest and presented at another hospital. In the emergency department, she was hypoxic, needing 6 L/min of oxygen. Her chest radiograph showed nothing unusual. Transthoracic echocardiograms with saline microcavitation evaluation were mildly positive early after agitated-saline administration, suggesting intracardiac shunting. She was then transferred to our center. Right-sided heart catheterization revealed no oximetric evidence of intracardiac shunting while the patient was supine and had a low right atrial pressure. However, her oxygen saturation dropped to 78% when she sat up. Repeat transthoracic echocardiography while sitting revealed a dramatically positive early saline microcavitation-uptake into the left side of the heart. Transesophageal echocardiograms showed a patent foramen ovale, with right-to-left shunting highly dependent upon body position. The patient underwent successful percutaneous patent foramen ovale closure, and her oxygen supplementation was suspended. In patients with unexplained or transient hypoxemia in which a cardiac cause is suspected, it is important to evaluate shunting in both the recumbent and upright positions. In this syndrome, elevated right atrial pressure is not necessary for significant right-to-left shunting. Percutaneous closure, if feasible, is first-line therapy in these patients. PMID:27303248

  8. Episodic ventriculomegaly due to hypernatremia mimicking shunt malfunction: case report.

    PubMed

    Jernigan, Sarah C; Stone, Scellig S D; Aronson, Joshua P; Putman, Melissa; Proctor, Mark R

    2015-10-01

    Patients with shunted hydrocephalus presenting with altered mental status and ventriculomegaly are generally considered to be in shunt failure requiring surgical treatment. The authors describe a case of shunted hydrocephalus secondary to a disseminated neuroectodermal tumor in a pediatric patient in whom rapid fluctuations in sodium levels due to diabetes insipidus repeatedly led to significant changes in ventricle size, with invasively confirmed normal shunt function and low intracranial pressure. This clinical picture exactly mimics shunt malfunction, requires urgent nonsurgical therapy, and underscores the importance of considering serum osmolar abnormalities in the differential diagnosis for ventriculomegaly. PMID:26186358

  9. Passively Shunted Piezoelectric Damping of Centrifugally-Loaded Plates

    NASA Technical Reports Server (NTRS)

    Duffy, Kirsten P.; Provenza, Andrew J.; Trudell, Jeffrey J.; Min, James B.

    2009-01-01

    Researchers at NASA Glenn Research Center have been investigating shunted piezoelectric circuits as potential damping treatments for turbomachinery rotor blades. This effort seeks to determine the effects of centrifugal loading on passively-shunted piezoelectric - damped plates. Passive shunt circuit parameters are optimized for the plate's third bending mode. Tests are performed both non-spinning and in the Dynamic Spin Facility to verify the analysis, and to determine the effectiveness of the damping under centrifugal loading. Results show that a resistive shunt circuit will reduce resonant vibration for this configuration. However, a tuned shunt circuit will be required to achieve the desired damping level. The analysis and testing address several issues with passive shunt circuit implementation in a rotating system, including piezoelectric material integrity under centrifugal loading, shunt circuit implementation, and tip mode damping.

  10. Late calcification and rupture: a rare complication of ventriculoperitoneal shunting.

    PubMed

    Kural, Cahit; Kirik, Alparslan; Pusat, Serhat; Senturk, Tolga; Izci, Yusuf

    2012-01-01

    A 10-year old boy who had undergone a ventriculoperitoneal (V/P) shunt because of hydrocephalus at 10 days of age was doing well until 20 days ago, when he began to experience headache and seizures. CT scan revealed dilated lateral ventricles and calcification at the shunt site. X-rays showed an unusual calcification pattern around the shunt tube and rupture of the tube between the mastoid bone and clavicle. The patient underwent surgery and the shunt was changed completely. The ventricles became small in the follow-up. Even though V/P shunts may induce fibrous tissue formation and calcification around the tube, there are a few cases of shunt rupture and calcification of shunts in the literature. Possible mechanisms of the rupture and calcification are discussed in this paper. PMID:23208915

  11. A large spontaneous intrahepatic portosystemic shunt in a cirrhotic patient

    PubMed Central

    Qi, Xingshun; Ye, Chun; Hou, Yue; Guo, Xiaozhong

    2016-01-01

    Summary A spontaneous portosystemic shunt is a rare malformation of the vessels supplying the liver. This condition often leads to the development of hepatic encephalopathy due to excessive shunting of blood from the portal vein to the inferior vena cava. Some studies have suggested that the presence of spontaneous portosystemic shunts is inversely associated with the appearance of large esophageal varices. Spontaneous intrahepatic portosystemic shunts (SIPSS) are far less frequently observed than extrahepatic portosystemic shunts, which include spleno-gastric-renal shunts, mesenteric-caval shunts, and a large patent umbilical vein. Reported here is a case of decompensated liver cirrhosis with a large SIPSS without any incidence of overt hepatic encephalopathy. PMID:26989653

  12. Resistively shunted piezocomposites for passive damping

    NASA Astrophysics Data System (ADS)

    Yarlagadda, Shridhar

    The goal of this work was to theoretically model, fabricate and characterize 3-3 coupled piezocomposite structures, using shunted piezoelectric fibers with integrated resistive shunting. Advantages and disadvantages of the different shunted piezocomposite configurations were examined from both modeling and fabrication points of view. Two configurations of practical interest were chosen for detailed study: (1) piezoelectric whiskers in a resistive matrix, and (2) piezoelectric whiskers in a layer of epoxy and shunted with a thin film resistive coating. Two different models were developed: a "smeared" dynamic model and a finite element model. Composite beam theory was modified to include shunted piezoelectric behavior and governing equations and boundary conditions were formulated. For the finite element model, a shunted piezoelectric element was formulated and the discretized governing equations were converted to state-space form. Modeling results demonstrated the possibility of modal loss factors as high as 10% in a single mode, for an effective piezoelectric volume fraction of 25%, as well the ability to tailor achievable levels of damping. Non-linear potential variation and local effects were successfully modeled. The critical parameters affecting modal damping were piezoelectric whisker volume fraction, shunt resistance, structural geometry and the location of whiskers. Experimental efforts involved fabrication of shunted piezocomposites for both configurations. Using chopped continuous poled PZT-5H fibers; a whisker/resistive matrix composite was successfully fabricated. For the resistive matrix case, matrix conductivity was a function of filler volume fraction and showed the percolation effect. However, the dielectric constant of the matrix also increased significantly (factor of 1000) at the design filler volume fraction, which drastically altered the electrical behavior of the piezocomposite from the designed case. The change in dielectric constant appeared

  13. Jugular Foramen Arteriovenous Shunt with Subarachnoid Hemorrhage

    PubMed Central

    Rodesch, G.; Comoy, J.; Hurth, M.; Lasjaunias, P.

    1991-01-01

    The authors report the case of a 37-year-old man with an extracerebral arteriovenous fistula at the skull base, revealed by subarachnoid and intraventricular hemorrhage. The malformation was fed by the neuromeningeal trunk of the ascending pharyngeal artery and drained into left laterobulbar veins. Embolization with bucrylate was performed and occluded totally the shunting zone. A 1-year follow-up angiogram confirmed the good stability of the result, the patient being asymptomatic. This case emphasizes the quality of results that can be obtained with bucrylate in arterioverious fistulas presenting with hemorrhage. It confirms that the external carotid artery must be studied when dealing with intracranial hemorrhage. On the other hand, magnetic resonance imaging and angiography may depict vascular abnormalities but do not always indicate the shunting area, thus the pathologic type of the malformation. ImagesFigure 1Figure 2Figure 3Figure 4Figure 5Figure 5p136-b PMID:17170835

  14. Active shunt capacitance cancelling oscillator circuit

    DOEpatents

    Wessendorf, Kurt O.

    2003-09-23

    An oscillator circuit is disclosed which can be used to produce oscillation using a piezoelectric crystal, with a frequency of oscillation being largely independent of any shunt capacitance associated with the crystal (i.e. due to electrodes on the surfaces of the crystal and due to packaging and wiring for the crystal). The oscillator circuit is based on a tuned gain stage which operates the crystal at a frequency, f, near a series resonance frequency, f.sub.S. The oscillator circuit further includes a compensation circuit that supplies all the ac current flow through the shunt resistance associated with the crystal so that this ac current need not be supplied by the tuned gain stage. The compensation circuit uses a current mirror to provide the ac current flow based on the current flow through a reference capacitor that is equivalent to the shunt capacitance associated with the crystal. The oscillator circuit has applications for driving piezoelectric crystals for sensing of viscous, fluid or solid media by detecting a change in the frequency of oscillation of the crystal and a resonator loss which occur from contact of an exposed surface of the crystal by the viscous, fluid or solid media.

  15. Bobble-head doll syndrome associated with subduroperitoneal shunt malfunction.

    PubMed

    Ahn, Y; Cho, B K; Wang, K C

    1997-04-01

    Bobble-head doll syndrome is known to be associated with aqueductal stenosis or cystic lesions of the III ventricle. The direction of movement is usually vertical. In the literature, only five cases of purely horizontal movement have been reported. Bobble-head doll syndrome manifested as a sign of shunt malfunction has been described in one case with a ventriculoperitoneal shunt. The authors report on a 10-year-old boy who showed subduroperitoneal shunt malfunction associated with horizontal bobble-head doll syndrome. The head bobbing disappeared immediately after shunt revision. Unlike the previously reported cases, in the present case the lesion was asymmetric, though the significance of this for the lateral movement is not clear. This case also showed more marked ventricular dilatation on subduroperitoneal shunt malfunction than in the pre-shunt state. The underlying mechanism of the ventricular dilatation is unknown. PMID:9202861

  16. Alternative uses for the subgaleal shunt in pediatric neurosurgery.

    PubMed

    Tubbs, R Shane; Smyth, Matthew D; Wellons, John C; Blount, Jeffrey P; Grabb, Paul A; Oakes, W Jerry

    2003-07-01

    The subgaleal shunt has been used for the temporary bypass of the normal cerebrospinal fluid (CSF) pathways. We retrospectively reviewed all subgaleal shunts placed at the Children's Hospital, Birmingham, Ala., USA, from 1997 to the present and examined all uses (e.g. indication, length of follow-up) of the subgaleal shunt outside its use for temporary CSF diversion in premature infants with intraventricular hemorrhage and subsequent hydrocephalus. The average length of survival of the primary subgaleal shunt in this population was 32.2 days. We have had good success with subgaleal shunts in children with malignant brain tumors, intraventricular abscesses, chronic truncal wounds, chronic subdural hygromas and meningitis. However, the greatest utility has been in those scenarios in which the peritoneal cavities were not currently, but with time would be, candidates for distal shunt implantation. Examples of these instances are patients with hydrocephalus and necrotizing enterocolitis or hydrocephalus and preoperative abdominal wall pathology such as omphalocele. PMID:12784073

  17. Urinary bladder calculi complicating ventriculo-vesical shunt.

    PubMed

    Shahul Hameed, A S; Yousaf, I; Choudhari, K A

    2005-10-01

    A rare case of vesical calculi complicating the procedure of ventriculo-vesical shunt is presented. In addition to highlighting technical difficulties in placing shunt catheters into the urinary system, the potential complications are discussed. We consider this route of cerebrospinal fluid(CSF) diversion less physiological compared with the peritoneal, pleural or the venous sites, and discourage use of the urinary bladder as the drainage site for the shunting of CSF. PMID:16455572

  18. Controlling hysteresis in superconducting constrictions with a resistive shunt

    NASA Astrophysics Data System (ADS)

    Kumar, Nikhil; Winkelmann, C. B.; Biswas, Sourav; Courtois, H.; Gupta, Anjan K.

    2015-07-01

    We demonstrate control of the thermal hysteresis in superconducting constrictions by adding a resistive shunt. In order to prevent thermal relaxation oscillations, the shunt resistor is placed in close proximity to the constriction, making the inductive current-switching time smaller than the thermal equilibration time. We investigate the current-voltage characteristics of the same constriction with and without the shunt-resistor. The widening of the hysteresis-free temperature range is explained on the basis of a simple model.

  19. Semi-shunt field emission in electronic devices

    NASA Astrophysics Data System (ADS)

    Karpov, V. G.; Shvydka, Diana

    2014-08-01

    We introduce a concept of semi-shunts representing needle shaped metallic protrusions shorter than the distance between a device electrodes. Due to the lightening rod type of field enhancement, they induce strong electron emission. We consider the corresponding signature effects in photovoltaic applications; they are: low open circuit voltages and exponentially strong random device leakiness. Comparing the proposed theory with our data for CdTe based solar cells, we conclude that stress can stimulate semi-shunts' growth making them shunting failure precursors. In the meantime, controllable semi-shunts can play a positive role mitigating the back field effects in photovoltaics.

  20. A compact, coaxial shunt current diagnostic for X pinches

    NASA Astrophysics Data System (ADS)

    Wang, Liangping; Zhang, Jinhai; Li, Mo; Zhang, Xinjun; Zhao, Chen; Zhang, Shaoguo

    2015-08-01

    A compact coaxial shunt was applied in X-pinches experiments on Qiangguang pulsed power generator. The coaxial shunt was designed to have a compact construction for smaller inductance and more, for conveniently assembling upon the X pinch load structure. The coaxial shunt is also a cheap current probe and was easily built by research groups. The shunt can monitor a 100 kA high current with a 100 ns rise time. The calibration results showed that the probe used in the experiments has a resistance of 3.2 mΩ with an uncertainty of 3%, and its response time to the step signal is less than 7 ns.

  1. Superconducting fault current-limiter with variable shunt impedance

    DOEpatents

    Llambes, Juan Carlos H; Xiong, Xuming

    2013-11-19

    A superconducting fault current-limiter is provided, including a superconducting element configured to resistively or inductively limit a fault current, and one or more variable-impedance shunts electrically coupled in parallel with the superconducting element. The variable-impedance shunt(s) is configured to present a first impedance during a superconducting state of the superconducting element and a second impedance during a normal resistive state of the superconducting element. The superconducting element transitions from the superconducting state to the normal resistive state responsive to the fault current, and responsive thereto, the variable-impedance shunt(s) transitions from the first to the second impedance. The second impedance of the variable-impedance shunt(s) is a lower impedance than the first impedance, which facilitates current flow through the variable-impedance shunt(s) during a recovery transition of the superconducting element from the normal resistive state to the superconducting state, and thus, facilitates recovery of the superconducting element under load.

  2. Results of portal systemic shunts in Budd-Chiari syndrome.

    PubMed Central

    Vons, C; Smadja, C; Bourstyn, E; Szekely, A M; Bonnet, P; Franco, D

    1986-01-01

    Nine patients with Budd-Chiari syndrome (BCS) were treated by a portal systemic shunt. One had thrombosis of the superior mesenteric vein (SMV) and another had complete obstruction of the retrohepatic inferior vena cava (IVC). All other patients had a marked stenosis of the retrohepatic IVC with caval pressure ranging from 12 to 24 mmHg (mean: 17 mmHg). Seven patients had an interposition mesocaval shunt using an autologous jugular vein. The patient with a thrombosed SMV had a portoatrial shunt. The patient with an obstructed IVC had a cavoatrial shunt after an erroneous portacaval shunt had failed to relieve ascites. There were no operative deaths and no major postoperative complications. One patient died 19 months after operation of acute leukemia complicating polycythemia rubra vera. All other patients were alive and well 8 months to 6 years after operation. None of them had encephalopathy. These results suggest several comments: Portal systemic shunts are a good treatment for BCS and have a low operative risk. The mesocaval shunt is an efficient procedure, even when there is stenosis of the IVC with high caval pressure; shunts to the right atrium should be performed only in the case of complete obstruction or inaccessibility of the IVC. The long-term prognosis is excellent, except in patients with potential malignancies. Therefore, portal systemic shunts should be indicated early in patients with symptomatic BCS. PMID:3963896

  3. Ventriculoperitoneal shunt malfunction caused by proximal catheter fat obstruction.

    PubMed

    Mizrahi, Cezar José; Spektor, Sergey; Margolin, Emil; Shoshan, Yigal; Ben-David, Eliel; Cohen, José E; Moscovici, Samuel

    2016-08-01

    Ventriculoperitoneal (VP) shunt placement is the mainstay of treatment for hydrocephalus, yet shunts remain vulnerable to a variety of complications. Although fat droplet migration into the subarachnoid space and cerebrospinal fluid pathways following craniotomy has been observed, a VP shunt obstruction with fat droplets has never been reported to our knowledge. We present the first reported case of VP shunt catheter obstruction by migratory fat droplets in a 55-year-old woman who underwent suboccipital craniotomy for removal of a metastatic tumor of the left medullocerebellar region, without fat harvesting. A VP shunt was inserted 1month later due to communicating hydrocephalus. The patient presented with gait disturbance, intermittent confusion, and pseudomeningocele 21days after shunt insertion. MRI revealed retrograde fat deposition in the ventricular system and VP shunt catheter, apparently following migration of fat droplets from the fatty soft tissue of the craniotomy site. Spinal tap revealed signs of aseptic meningitis. Steroid treatment for aseptic "lipoid" meningitis provided symptom relief. MRI 2months later revealed partial fat resorption and resolution of the pseudomeningocele. VP shunt malfunction caused by fat obstruction of the ventricular catheter should be acknowledged as a possible complication in VP shunts after craniotomy, even in the absence of fat harvesting. PMID:27010421

  4. Impedance Changes Indicate Proximal Ventriculoperitoneal Shunt Obstruction In Vitro.

    PubMed

    Basati, Sukhraaj; Tangen, Kevin; Hsu, Ying; Lin, Hanna; Frim, David; Linninger, Andreas

    2015-12-01

    Extracranial cerebrospinal fluid (CSF) shunt obstruction is one of the most important problems in hydrocephalus patient management. Despite ongoing research into better shunt design, robust and reliable detection of shunt malfunction remains elusive. The authors present a novel method of correlating degree of tissue ingrowth into ventricular CSF drainage catheters with internal electrical impedance. The impedance based sensor is able to continuously monitor shunt patency using intraluminal electrodes. Prototype obstruction sensors were fabricated for in-vitro analysis of cellular ingrowth into a shunt under static and dynamic flow conditions. Primary astrocyte cell lines and C6 glioma cells were allowed to proliferate up to 7 days within a shunt catheter and the impedance waveform was observed. During cell ingrowth a significant change in the peak-to-peak voltage signal as well as the root-mean-square voltage level was observed, allowing the impedance sensor to potentially anticipate shunt malfunction long before it affects fluid drainage. Finite element modeling was employed to demonstrate that the electrical signal used to monitor tissue ingrowth is contained inside the catheter lumen and does not endanger tissue surrounding the shunt. These results may herald the development of "next generation" shunt technology that allows prediction of malfunction before it affects patient outcome. PMID:25014951

  5. Over-drainage and persistent shunt-dependency in patients with idiopathic intracranial hypertension treated with shunts and bariatric surgery

    PubMed Central

    Roth, Jonathan; Constantini, Shlomi; Kesler, Anat

    2015-01-01

    Background: Idiopathic intracranial hypertension (IIH) may lead to visual impairment. Shunt surgery is indicated for refractory IIH-related symptoms that persist despite medical treatment, or those presenting with significant visual decline. Obesity is a risk factor for IIH; a reduction in weight has been shown to improve papilledema. Bariatric surgery (BS) has been suggested for treating IIH associated with morbid obesity. In this study, we describe a high rate of over-drainage (OD) seen in patients following shunts and BS. Methods: The study cohort includes 13 patients with IIH that underwent shunt surgery for treatment of the IIH-related symptoms. Six patients underwent BS in addition to the shunt surgery (but not concomitantly). Seven patients had only shunt surgeries with no BS. Data were collected retrospectively. Results: BS effectively led to weight reduction (body mass index decreasing from 43 ± 4 to 28 ± 5). Patients undergoing BS had 1–6 (2.5 ± 1.9) shunt revisions for OD following BS, as opposed to 0–3 (1.4 ± 1.1) revisions prior to BS over similar time spans (statistically insignificant difference), and 0–6 (1.6 ± 2.5) revisions among the non-BS patients over a longer time span (statistically insignificant difference). Two patients in the BS group underwent shunt externalization and closure; however, they proved to be shunt-dependent. Conclusions: Patients with IIH that undergo shunt surgery and BS (not concomitantly) may suffer from OD symptoms, necessitating multiple shunt revisions, and valve upgrades. Despite BS being a valid primary treatment for some patients with IIH, among shunted patients, BS may not lead to resolution of IIH-related symptoms and patients may remain shunt-dependent. PMID:26713173

  6. Shunting branch of portal vein and stent position predict survival after transjugular intrahepatic portosystemic shunt

    PubMed Central

    Bai, Ming; He, Chuang-Ye; Qi, Xing-Shun; Yin, Zhan-Xin; Wang, Jian-Hong; Guo, Wen-Gang; Niu, Jing; Xia, Jie-Lai; Zhang, Zhuo-Li; Larson, Andrew C; Wu, Kai-Chun; Fan, Dai-Ming; Han, Guo-Hong

    2014-01-01

    AIM: To evaluate the effect of the shunting branch of the portal vein (PV) (left or right) and the initial stent position (optimal or suboptimal) of a transjugular intrahepatic portosystemic shunt (TIPS). METHODS: We retrospectively reviewed 307 consecutive cirrhotic patients who underwent TIPS placement for variceal bleeding from March 2001 to July 2010 at our center. The left PV was used in 221 patients and the right PV in the remaining 86 patients. And, 224 and 83 patients have optimal stent position and sub-optimal stent positions, respectively. The patients were followed until October 2011 or their death. Hepatic encephalopathy, shunt dysfunction, and survival were evaluated as outcomes. The difference between the groups was compared by Kaplan-Meier analysis. A Cox regression model was employed to evaluate the predictors. RESULTS: Among the patients who underwent TIPS to the left PV, the risk of hepatic encephalopathy (P = 0.002) and mortality were lower (P < 0.001) compared to those to the right PV. Patients who underwent TIPS with optimal initial stent position had a higher primary patency (P < 0.001) and better survival (P = 0.006) than those with suboptimal initial stent position. The shunting branch of the portal vein and the initial stent position were independent predictors of hepatic encephalopathy and shunt dysfunction after TIPS, respectively. And, both were independent predictors of survival. CONCLUSION: TIPS placed to the left portal vein with optimal stent position may reduce the risk of hepatic encephalopathy and improve the primary patency rates, thereby prolonging survival. PMID:24574750

  7. 49 CFR 236.60 - Switch shunting circuit; use restricted.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Switch shunting circuit; use restricted. 236.60 Section 236.60 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD... Instructions: All Systems Track Circuits § 236.60 Switch shunting circuit; use restricted. Switch...

  8. 49 CFR 236.724 - Circuit, shunt fouling.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Circuit, shunt fouling. 236.724 Section 236.724 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Circuit, shunt fouling. The track circuit in the fouling section of a turnout, connected in multiple...

  9. 21 CFR 882.4545 - Shunt system implantation instrument.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Shunt system implantation instrument. 882.4545 Section 882.4545 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES NEUROLOGICAL DEVICES Neurological Surgical Devices § 882.4545 Shunt system implantation instrument. (a) Identification....

  10. Internal carotid artery rupture caused by carotid shunt insertion

    PubMed Central

    Illuminati, Giulio; Caliò, Francesco G.; Pizzardi, Giulia; Vietri, Francesco

    2015-01-01

    Introduction Shunting is a well-accepted method of maintaining cerebral perfusion during carotid endarterectomy (CEA). Nonetheless, shunt insertion may lead to complications including arterial dissection, embolization, and thrombosis. We present a complication of shunt insertion consisting of arterial wall rupture, not reported previously. Presentation of case A 78-year-old woman underwent CEA combined with coronary artery bypass grafting (CABG). At the time of shunt insertion an arterial rupture at the distal tip of the shunt was detected and was repaired via a small saphenous vein patch. Eversion CEA and subsequent CABG completed the procedure whose postoperative course was uneventful. Discussion Shunting during combined CEA-CABG may be advisable to assure cerebral protection from possible hypoperfusion due to potential hemodynamic instability of patients with severe coronary artery disease. Awareness and prompt management of possible shunt-related complications, including the newly reported one, may contribute to limiting their harmful effect. Conclusion Arterial wall rupture is a possible, previously not reported, shunt-related complication to be aware of when performing CEA. PMID:26255001

  11. [Temporary vascular shunt technique for resource scarce environments].

    PubMed

    Ouattara, N; Mlynski, A; Pierret, C

    2011-10-01

    The purpose of this report is to describe a simple and reproducible technique for temporary vascular shunting. This technique is appropriate only for exceptional situations involving scant resource availability. It is not intended to replace conventional vascular shunting techniques. PMID:22235609

  12. Biosynthetic route towards saxitoxin and shunt pathway

    PubMed Central

    Tsuchiya, Shigeki; Cho, Yuko; Konoki, Keiichi; Nagasawa, Kazuo; Oshima, Yasukatsu; Yotsu-Yamashita, Mari

    2016-01-01

    Saxitoxin, the most potent voltage-gated sodium channel blocker, is one of the paralytic shellfish toxins (PSTs) produced by cyanobacteria and dinoflagellates. Recently, putative biosynthetic genes of PSTs were reported in these microorganisms. We previously synthesized genetically predicted biosynthetic intermediates, Int-A’ and Int-C’2, and also Cyclic-C’ which was not predicted based on gene, and identified them all in the toxin-producing cyanobacterium Anabaena circinalis (TA04) and the dinoflagellate Alexandrium tamarense (Axat-2). This study examined the incorporation of 15N-labeled intermediates into PSTs (C1 and C2) in A. circinalis (TA04). Conversions from Int-A’ to Int-C’2, from Int-C’2 to Cyclic-C’, and from Int-A’ and Int-C’2 to C1 and C2 were indicated using high resolution-LC/MS. However, Cyclic-C’ was not converted to C1 and C2 and was detected primarily in the extracellular medium. These results suggest that Int-A’ and Int-C’2 are genuine precursors of PSTs, but Int-C’2 converts partially to Cyclic-C’ which is a shunt product excreted to outside the cells. This paper provides the first direct demonstration of the biosynthetic route towards saxitoxin and a shunt pathway. PMID:26842222

  13. Flexural waves focusing through shunted piezoelectric patches

    NASA Astrophysics Data System (ADS)

    Yi, K.; Collet, M.; Ichchou, M.; Li, L.

    2016-07-01

    In this paper, we designed and analyzed a piezo-lens to focus flexural waves in thin plates. The piezo-lens is comprised of a host plate and piezoelectric arrays bonded on the surfaces of the plate. The piezoelectric patches are shunted with negative capacitance circuits. The effective refractive indexes inside the piezo-lens are designed to fit a hyperbolic secant distribution by tuning the negative capacitance values. A homogenized model of a piezo-mechanical system is adopted in the designing process of the piezo-lens. The wave focusing effect is studied by the finite element method. Numerical results show that the piezo-lens can focus flexural waves by bending their trajectories, and is effective in a large frequency band. The piezo-lens has the ability to focus flexural waves at different locations by tuning the shunting negative capacitance values. The piezo-lens is shown to be effective for flexural waves generated by different types of sources.

  14. Shunt attachment and method for interfacing current collection systems

    DOEpatents

    Denney, Paul E.; Iyer, Natraj C.; Hannan, III, William F.

    1992-01-01

    A composite brush to shunt attachment wherein a volatile component of a composite but mostly metallic brush, used for current collection purposes, does not upon welding or brazing, adversely affect the formation of the interfacial bond with a conductive shunt which carries the current from the zone of the brush. The brush to shunt attachment for a brush material of copper-graphite composite and a shunt of copper, or substituting silver for copper as an alternative, is made through a hot isostatic pressing (HIP). The HIP process includes applying high pressure and temperature simultaneously at the brush to shunt interface, after it has been isolated or canned in a metal casing in which the air adjacent to the interface has been evacuated and the interfacial area has been sealed before the application of pressure and temperature.

  15. Shunt attachment and method for interfacing current collection systems

    DOEpatents

    Denney, P.E.; Iyer, N.C.; Hannan, W.F. III.

    1992-12-08

    A composite brush to shunt attachment wherein a volatile component of a composite but mostly metallic brush, used for current collection purposes, does not upon welding or brazing, adversely affect the formation of the interfacial bond with a conductive shunt which carries the current from the zone of the brush. The brush to shunt attachment for a brush material of copper-graphite composite and a shunt of copper, or substituting silver for copper as an alternative, is made through a hot isostatic pressing (HIP). The HIP process includes applying high pressure and temperature simultaneously at the brush to shunt interface, after it has been isolated or canned in a metal casing in which the air adjacent to the interface has been evacuated and the interfacial area has been sealed before the application of pressure and temperature. 6 figs.

  16. Portasystemic shunt fraction quantification with colonic iodine-123 iodoamphetamine

    SciTech Connect

    Yen, C.K.; Pollycove, M.; Crass, R.; Lin, T.H.; Baldwin, R.; Lamb, J.

    1986-08-01

    Portasystemic shunting was quantified in dogs with (/sup 123/I)iodoamphetamine (IMP) administered transrectally into the colon and monitored externally with a gamma camera. IMP was absorbed rapidly and unchanged from the colon. After direct injection into the portal vein, IMP was almost completely extracted by the liver on the first pass, and the washout half-life was approximately 60 min. Based on these kinetic data, computer simulation of this biologic system was carried out. Errors associated with simplified models are calculated. The simplest model with insignificant error, which assumed that the tracer behaved like microspheres, was used to quantitate portasystemic shunt fraction in animals with surgically created shunts. Results were compared with the standard of /sup 99m/Tc-labeled macroaggregated albumin infused into a branch of inferior mesenteric vein. For shunt fractions ranging from 0 to 100%, an excellent correlation was seen, indicating that this approach is potentially a simple, noninvasive method of portasystemic shunt fraction quantification.

  17. Management of Ventriculo-Peritoneal Shunts in the Paediatric Population

    PubMed Central

    Low, David; Drake, James M; Seow, Wan Tew; Ng, Wai Hoe

    2010-01-01

    The treatment of hydrocephalus is a challenging one. The development of shunt devices have greatly improved the survival and quality of life of paediatric patients with hydrocephalus; however, shunt dysfunction is a common problem which represents a significant scope of work for paediatric neurosurgeons with shunt failures occuring in up to 40 to 50% of patients during the first two years after shunt surgery. Numerous pathologies ranging from congenital to acquired conditions can result in the development of hydrocephalus in the paediatric population. Obstruction of proximal or distal catheter ends, misplacement, infections and over drainage are some of the common problems accounting for shunt failures. We discussed some of the pertinent problems and nuances involved in treatment of paediatric hydrocephalus with VPS as well as to review the role of endoscopic procedures as an alternative to VPS. PMID:22028738

  18. Parylene MEMS patency sensor for assessment of hydrocephalus shunt obstruction.

    PubMed

    Kim, Brian J; Jin, Willa; Baldwin, Alexander; Yu, Lawrence; Christian, Eisha; Krieger, Mark D; McComb, J Gordon; Meng, Ellis

    2016-10-01

    Neurosurgical ventricular shunts inserted to treat hydrocephalus experience a cumulative failure rate of 80 % over 12 years; obstruction is responsible for most failures with a majority occurring at the proximal catheter. Current diagnosis of shunt malfunction is imprecise and involves neuroimaging studies and shunt tapping, an invasive measurement of intracranial pressure and shunt patency. These patients often present emergently and a delay in care has dire consequences. A microelectromechanical systems (MEMS) patency sensor was developed to enable direct and quantitative tracking of shunt patency in order to detect proximal shunt occlusion prior to the development of clinical symptoms thereby avoiding delays in treatment. The sensor was fabricated on a flexible polymer substrate to eventually allow integration into a shunt. In this study, the sensor was packaged for use with external ventricular drainage systems for clinical validation. Insights into the transduction mechanism of the sensor were obtained. The impact of electrode size, clinically relevant temperatures and flows, and hydrogen peroxide (H2O2) plasma sterilization on sensor function were evaluated. Sensor performance in the presence of static and dynamic obstruction was demonstrated using 3 different models of obstruction. Electrode size was found to have a minimal effect on sensor performance and increased temperature and flow resulted in a slight decrease in the baseline impedance due to an increase in ionic mobility. However, sensor response did not vary within clinically relevant temperature and flow ranges. H2O2 plasma sterilization also had no effect on sensor performance. This low power and simple format sensor was developed with the intention of future integration into shunts for wireless monitoring of shunt state and more importantly, a more accurate and timely diagnosis of shunt failure. PMID:27589973

  19. Portosystemic Shunt Surgery in Patients with Idiopathic Noncirrhotic Portal Hypertension.

    PubMed

    Karagul, Servet; Yagci, Mehmet Ali; Tardu, Ali; Ertugrul, Ismail; Kirmizi, Serdar; Sumer, Fatih; Isik, Burak; Kayaalp, Cuneyt; Yilmaz, Sezai

    2016-01-01

    BACKGROUND Idiopathic noncirrhotic portal hypertension (INCPH) is a rare disease characterized by increased portal venous pressure in the absence of cirrhosis and other causes of liver diseases. The aim of the present study was to present our results in using portosystemic shunt surgery in patients with INCPH. MATERIAL AND METHODS Patients who had been referred to our Liver Transplantation Institute for liver transplantation and who had undergone surgery from January 2010 to December 2015 were retrospectively analyzed. Patients with INCPH who had undergone portosystemic shunt procedure were included in the study. Age, sex, symptoms and findings, type of portosystemic shunt, and postoperative complications were assessed. RESULTS A total of 1307 patients underwent liver transplantation from January 2010 to December 2015. Eleven patients with INCPH who did not require liver transplantation were successfully operated on with a portosystemic shunt procedure. The mean follow-up was 30.1±19 months (range 7-69 months). There was no mortality in the perioperative period or during the follow-up. Two patients underwent surgery again due to intra-abdominal hemorrhage; one had bleeding from the surgical site except the portacaval anastomosis and the other had bleeding from the h-graft anastomosis. No patient developed encephalopathy and no patient presented with esophageal variceal bleeding after portosystemic shunt surgery. Shunt thrombosis occurred in 1 patient (9.9%). Only 1 patient developed ascites, which was controlled medically. CONCLUSIONS Portosystemic shunt surgery is a safe and effective procedure for the treatment of patients with INCPH. PMID:27194018

  20. Current status of transjugular intrahepatic portosystemic shunts.

    PubMed Central

    Patel, N. H.; Chalasani, N.; Jindal, R. M.

    1998-01-01

    The use of the transjugular intrahepatic portosystemic shunt (TIPS) has emerged as an important nonoperative modality for variceal bleeding, intractable ascites, and for selected cases of hepatic venous obstruction. We believe that TIPS should be viewed as a 'bridge' to liver transplantation and should be carried out only in experienced centres. The adverse haemodynamic changes on the cardiopulmonary system after TIPS should be borne in mind. Prospective trials to evaluate the role of TIPS versus sclerotherapy in variceal bleeding will be watched with interest. There is, however, an urgent need to improve long-term results of TIPS as stent thrombosis and stenosis occur frequently. We advocate routine surveillance to detect these problems at an early stage. PMID:10320885

  1. Muzzle shunt augmentation of conventional railguns

    SciTech Connect

    Parker, J.V. . Physics Div.)

    1991-01-01

    This paper reports on augmentation which is a technique for reducing the armature current and hence the armature power dissipation in a plasma armature railgun. In spite of the advantages, no large augmented railguns have been built, primarily due to the mechanical and electrical complexity introduced by the extra conductors required. it is possible to achieve some of the benefits of augmentation in a conventional railgun by diverting a fraction {phi} of the input current through a shunt path at the muzzle of the railgun. In particular, the relation between force and armature current is the same as that obtained in an n-turn, series-connected augmented railgun with n = 1/(1 {minus} {phi}). The price of this simplification is a reduction in electrical efficiency and some additional complexity in the external electrical system.

  2. Ultrasound-Guided Retrieval and Position Replacement of a Dislodged Fetal Pleuro-Amniotic Shunt: A Novel Approach for a Known Complication of Feto-Amniotic Shunting.

    PubMed

    Adams, Tracy M; Kunzier, Nadia B; Chavez, Martin R; Vintzileos, Anthony M

    2016-01-01

    Untreated fetal pleural effusion can cause significant perinatal morbidity and mortality. Treatment of pleural effusions with pleuro-amniotic shunting has been shown to improve outcomes. Pleuro-amniotic shunting is associated with complications including ruptured membranes, preterm labor and shunt dislodgement into either the amniotic cavity or the fetal thorax. Shunt dislodgement into the thoracic cavity can cause prenatal complications from the shunt itself or may necessitate neonatal surgery for removal. We present a case where a novel ultrasound-guided technique was used to replace the dislodged pleural shunt in utero, thereby effectively draining the effusion while simultaneously obviating the need for neonatal surgery and decreasing possible perinatal complications. PMID:25660293

  3. 49 CFR 236.309 - Loss of shunt protection; where required.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Loss of shunt protection; where required. 236.309... Standards § 236.309 Loss of shunt protection; where required. (a) A loss of shunt of 5 seconds or less shall not permit an established route to be changed at an automatic interlocking. (b) A loss of shunt of...

  4. Nuclear Medicine to Evaluate Complications of Cerebral Shunts: Two Cases and Review of Literature

    PubMed Central

    Vettiyil, Beth; Bessette, Sabrina; McQuiston, Samuel; Greiner, Francis

    2015-01-01

    We present two cases of cerebral shunts - a ventriculopleural shunt and a ventriculoperitoneal shunt, with their associated complications. We also hope to provide a comprehensive literature review on various imaging modalities, including nuclear medicine studies in evaluating cerebral shunt complications. PMID:26420995

  5. Ion beam sputter-etched ventricular catheter for hydrocephalus shunt

    NASA Technical Reports Server (NTRS)

    Banks, B. A. (Inventor)

    1983-01-01

    A cerebrospinal fluid shunt in the form of a ventricular catheter for controlling the condition of hydrocephalus by relieving the excessive cerebrospinal fluid pressure is described. A method for fabrication of the catheter and shunting the cerebral fluid from the cerebral ventricles to other areas of the body is also considered. Shunt flow failure occurs if the ventricle collapse due to improper valve function causing overdrainage. The ventricular catheter comprises a multiplicity of inlet microtubules. Each microtubule has both a large openings at its inlet end and a multiplicity of microscopic openings along its lateral surfaces.

  6. Pollutants removal in subsurface infiltration systems by shunt distributing wastewater with/without intermittent aeration under different shunt ratios.

    PubMed

    Pan, Jing; Yuan, Fang; Zhang, Yang; Huang, Linli; Yu, Long; Zheng, Fanping; Cheng, Fan; Zhang, Jiadi

    2016-10-01

    Matrix dissolved oxygen (DO), removal of COD, TP and nitrogen in subsurface infiltration systems (SISs), named SIS A (without intermittent aeration and shunt distributing wastewater), SIS B (with shunt distributing wastewater) and SIS C (with intermittent aeration and shunt distributing wastewater) were investigated. Aerobic conditions were developed in 50cm depth and anoxic or anaerobic conditions were not changed in 80 and 110cm depth by intermittent aeration. Under appropriate shunt ratios, shunt distributing wastewater improved denitrification and had little influence on COD, TP and NH3-N removal. Under the optimal shunt ratio of 1:2 for SIS C, high average removal rates of COD (90.06%), TP (93.17%), NH3-N (88.20%) and TN (85.79%) were obtained, which were higher than those in SIS A (COD: 82.56%, TP: 92.76%, NH3-N: 71.08%, TN: 49.24%) and SIS B (COD: 81.12%, TP: 92.58%, NH3-N: 69.14%, TN: 58.73%) under the optimal shunt ratio of 1:3. PMID:27347804

  7. Postpriapism erectile dysfunction and shunt-related urethral stricture: long-term morbidity after proximal shunt for ischaemic priapism

    PubMed Central

    Bello, Jibril Oyekunle

    2014-01-01

    Recent guidelines have advocated for step-wise treatment of increasing invasiveness in the management of ischaemic priapism though with low-level evidences. In the past, proximal shunts were favoured as first-line treatment. We present an African man who had proximal shunt (cavernoso-spongiosal) three decades ago for ischaemic priapism and subsequently had long-term morbidity over the three decades with adverse effect on his quality of life. Recent guidelines appear to be sound despite their limitations and more invasive cavernoso-spongiosal shunts may be associated with significant long-term morbidities and poor quality of life. PMID:25709730

  8. Use of cine phase-contrast MRI in the assessment of distal splenorenal shunt function.

    PubMed

    Cabassa, Paolo; Ravanelli, Marco; Alberti, Daniele; Maroldi, Roberto

    2012-06-01

    Magnetic resonance imaging (MRI) features of a surgical splenorenal shunt in a 28-year-old girl are described. The woman underwent color doppler ultrasonography during follow up for the shunt, which was inconclusive. MR was used to investigate the function of the shunt. Velocity and flow direction in splanchnic vessels and in the shunt were evaluated using cine fast phase-contrast sequences. MR findings could be of help in the evaluation of patients undergoing surgical shunts during follow up. PMID:22405982

  9. A case of breast cancer involving a ventriculoperitoneal shunt.

    PubMed

    Kamei, Mirei; Kikuchi, Nobuyuki; Ichimura, Homare; Chujo, Masao; Takahashi, Yoshiaki; Sugio, Kenji

    2016-12-01

    An 84-year-old woman was examined for an enlargement of an induration in the left breast. A ventriculoperitoneal shunt had been placed for postoperative normal pressure hydrocephalus of a cerebral hemorrhage, and it had penetrated the mass according to the computed tomography findings. Breast cancer was diagnosed after a close examination; however, close observation was selected because her family rejected treatment. She developed somnolence 7 months after the initial examination, and ventricular dilatation and expansion of the low-density region around the ventricle were noted on computed tomography, suggesting that the enlarged tumor had excluded the shunt and caused obstruction. The growth of breast carcinoma involving a shunt tube can be the cause of obstruction of a ventriculoperitoneal shunt. Our findings suggest that a breast lesion should be evaluated at both pre- and postoperation. PMID:26943684

  10. 21 CFR 874.3850 - Endolymphatic shunt tube with valve.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... (CONTINUED) MEDICAL DEVICES EAR, NOSE, AND THROAT DEVICES Prosthetic Devices § 874.3850 Endolymphatic shunt... of a pressure-limiting valve associated with a tube intended to be implanted in the inner ear...

  11. 21 CFR 874.3850 - Endolymphatic shunt tube with valve.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... (CONTINUED) MEDICAL DEVICES EAR, NOSE, AND THROAT DEVICES Prosthetic Devices § 874.3850 Endolymphatic shunt... of a pressure-limiting valve associated with a tube intended to be implanted in the inner ear...

  12. 21 CFR 874.3850 - Endolymphatic shunt tube with valve.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... (CONTINUED) MEDICAL DEVICES EAR, NOSE, AND THROAT DEVICES Prosthetic Devices § 874.3850 Endolymphatic shunt... of a pressure-limiting valve associated with a tube intended to be implanted in the inner ear...

  13. 21 CFR 874.3850 - Endolymphatic shunt tube with valve.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... (CONTINUED) MEDICAL DEVICES EAR, NOSE, AND THROAT DEVICES Prosthetic Devices § 874.3850 Endolymphatic shunt... of a pressure-limiting valve associated with a tube intended to be implanted in the inner ear...

  14. 21 CFR 874.3850 - Endolymphatic shunt tube with valve.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... (CONTINUED) MEDICAL DEVICES EAR, NOSE, AND THROAT DEVICES Prosthetic Devices § 874.3850 Endolymphatic shunt... of a pressure-limiting valve associated with a tube intended to be implanted in the inner ear...

  15. 8. VIEW OF SHUNT LOCOMOTIVE NO. 9072 POSITIONING ELECTRIC DIESEL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. VIEW OF SHUNT LOCOMOTIVE NO. 9072 POSITIONING ELECTRIC DIESEL LOCOMOTIVE NO. 6734 ON TURNTABLE, adjacent to Erecting Shop and Machine Shop - Juniata Shops, Turntable, South of Sixth Street at Third Avemue, Altoona, Blair County, PA

  16. 5. VIEW OF SHUNT LOCOMOTIVE NO. 9072 POSITIONING ELECTRIC DIESEL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. VIEW OF SHUNT LOCOMOTIVE NO. 9072 POSITIONING ELECTRIC DIESEL LOCOMOTIVE NO. 6734 ON TURNTABLE, adjacent to Erecting Shop and Machine Shop - Juniata Shops, Turntable, South of Sixth Street at Third Avemue, Altoona, Blair County, PA

  17. 6. VIEW OF SHUNT LOCOMOTIVE NO. 9072 POSITIONING ELECTRIC DIESEL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. VIEW OF SHUNT LOCOMOTIVE NO. 9072 POSITIONING ELECTRIC DIESEL LOCOMOTIVE NO. 6734 ON TURNTABLE, adjacent to Erecting Shop and Machine Shop - Juniata Shops, Turntable, South of Sixth Street at Third Avemue, Altoona, Blair County, PA

  18. 4. VIEW OF SHUNT LOCOMOTIVE NO. 9072 POSITIONING ELECTRIC DIESEL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. VIEW OF SHUNT LOCOMOTIVE NO. 9072 POSITIONING ELECTRIC DIESEL LOCOMOTIVE NO. 6734 ON TURNTABLE, adjacent to Erecting Shop and Machine Shop - Juniata Shops, Turntable, South of Sixth Street at Third Avemue, Altoona, Blair County, PA

  19. 7. VIEW OF SHUNT LOCOMOTIVE NO. 9072 POSITIONING ELECTRIC DIESEL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. VIEW OF SHUNT LOCOMOTIVE NO. 9072 POSITIONING ELECTRIC DIESEL LOCOMOTIVE NO. 6734 ON TURNTABLE, adjacent to Erecting Shop and Machine Shop - Juniata Shops, Turntable, South of Sixth Street at Third Avemue, Altoona, Blair County, PA

  20. 9. VIEW OF SHUNT LOCOMOTIVE NO. 9072 POSITIONING ELECTRIC DIESEL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. VIEW OF SHUNT LOCOMOTIVE NO. 9072 POSITIONING ELECTRIC DIESEL LOCOMOTIVE NO. 6734 ON TURNTABLE, adjacent to Erecting Shop and Machine Shop - Juniata Shops, Turntable, South of Sixth Street at Third Avemue, Altoona, Blair County, PA

  1. 21 CFR 876.5955 - Peritoneo-venous shunt.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...) Identification. A peritoneo-venous shunt is an implanted device that consists of a catheter and a pressure activated one-way valve. The catheter is implanted with one end in the peritoneal cavity and the other in...

  2. 21 CFR 876.5955 - Peritoneo-venous shunt.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...) Identification. A peritoneo-venous shunt is an implanted device that consists of a catheter and a pressure activated one-way valve. The catheter is implanted with one end in the peritoneal cavity and the other in...

  3. 21 CFR 876.5955 - Peritoneo-venous shunt.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...) Identification. A peritoneo-venous shunt is an implanted device that consists of a catheter and a pressure activated one-way valve. The catheter is implanted with one end in the peritoneal cavity and the other in...

  4. 21 CFR 876.5955 - Peritoneo-venous shunt.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...) Identification. A peritoneo-venous shunt is an implanted device that consists of a catheter and a pressure activated one-way valve. The catheter is implanted with one end in the peritoneal cavity and the other in...

  5. Percutaneous ultrasound-guided insertion of ventriculo-atrial shunts.

    PubMed

    McCracken, James Albert; Bahl, Anuj; McMullan, John

    2016-08-01

    Ventriculo-atrial (VA) shunts have been in use for >60 years but less frequently so of late. This is due to a combination of the risk of cardiac complications, lack of expertise and a lengthy operation. We present our consecutive prospective series of 10 VA shunts inserted using a percutaneous method employing the Sonowand Invite™ neuronavigation system for both the distal and proximal catheters, over a 13-month period. We had two complications of cases needing revision, but our series highlights a safe and reproducible method of inserting a VA shunt. About 30% of the procedures were carried out by a trainee as the primary surgeon. This technique does not necessarily require the expertise of a complex hydrocephalus surgeon and is thus able to be in the armoury of any neurosurgeon needing to do a VA shunt procedure. The indications, operative data and outcomes of our patients are discussed. PMID:27025913

  6. Essentially nonlinear piezoelectric shunt circuits applied to mistuned bladed disks

    NASA Astrophysics Data System (ADS)

    Zhou, B.; Thouverez, F.; Lenoir, D.

    2014-04-01

    An essentially nonlinear piezoelectric shunt circuit is proposed for the practical realization of nonlinear energy sink, and then applied to a mistuned bladed disk for blade vibration reduction. First, the global dynamics of a single degree-of-freedom linear mechanical oscillator, coupled to an essentially nonlinear shunted piezoelectric attachment, is studied. Under certain conditions, the nonlinear targeted energy transfer, i.e. a fast, passive energy transfer from the mechanical oscillator to the nonlinear attachment is observed. A numerical method, referred to as the variable-coefficient harmonic balance method, is developed to calculate quasi-periodic responses arising in the electromechanical system under harmonic forcing. Characterized by the nonexistence of a resonance frequency, the essentially nonlinear shunt circuit is able to work robustly over a broad frequency band with a smaller inductance requirement compared with the linear resonant shunt circuit.

  7. [Sapheno-peritoneal shunt for the treatment of ascites].

    PubMed

    Nagy, Z; Gyurkovics, E; Kaliszky, P; Kupcsulik, P

    2001-08-01

    For the surgical treatment of drug resistant ascites caused by hepatic cirrhosis usually different types of valvular plastic tubes are used, implanted as peritoneo-venous shunts. These shunts drain the ascites into the jugular vein. In the 1st Surgical Department of the Semmelweis University Budapest we have performed 267 peritoneo-venous shunt operations. We introduced a new method using an autolog venous graft with a peritoneo-venous anastomosis, that drains the ascites into the saphenous, then femoral vein. So far we performed 5 such interventions. The early results suggest that sapheno-peritoneal shunt can be successfully used for treatment of ascites. With this operation complications of plastic grafts are avoidable. PMID:11550492

  8. [A simple peritoneovenous shunt in the treatment of chronic ascites].

    PubMed

    Pafko, P; Hladík, P

    2001-02-01

    The authors describe their own initial experience with a peritoneo-venous shunt in otherwise incurable ascites. It is a simple procedure which is more satisfactory than the formerly used technique of implantation of Le Veen's system. PMID:12881921

  9. In vitro flow measurements in ion sputtered hydrocephalus shunts

    NASA Technical Reports Server (NTRS)

    Cho, Y. I.; Back, L. H.

    1989-01-01

    This paper describes an experimental procedure for accurate measurements of the pressure-drop/flow rate relationship in hydrocephalus shunts. Using a fish-hook arrangement, small flow rates in a perforated ion-sputtered Teflon microtubule were measured in vitro in a pressured system and were correlated with pressure in the system. Results indicate that appropriate drainage rates could be obtained in the physiological range for hydrocephalus shunts.

  10. Paediatric ventriculoperitoneal shunt infection caused by Actinomyces neuii

    PubMed Central

    Anderson, Ian A; Jarral, Fazain; Sethi, Kavita; Chumas, Paul D

    2014-01-01

    We present the first reported case of ventriculoperitoneal shunt infection secondary to Actinomyces neuii in a paediatric patient. Our patient was managed with temporary shunt removal, intrathecal antibiotics and a prolonged course of intravenous and then oral antibiotics. She went on to make a complete recovery. Subsequent cerebrospinal fluid analysis at 5 months post-treatment demonstrated no evidence of residual infection. PMID:24859562

  11. Hearing Loss in Patients with Shunt-Treated Hydrocephalus.

    PubMed

    Panova, Margarita V; Geneva, Ina E; Madjarova, Kalina I; Bosheva, Miroslava N

    2015-01-01

    Hearing loss is a common manifestation of the long-term complications in patients with shunt treated hydrocephalus along with motor development disturbance, cognitive and visual impairment, epilepsy and endocrine disorders. The aim of the present study was to investigate the alterations of hearing in patients with shunt treated hydrocephalus of non-tumor etiology and at least one year after implantation of ventriculo-peritoneal shunt, as well as their impact on the quality of life of patients. The study included 70 patients (age range 1.25 years - 21.25 years) with shunted non-tumor hydrocephalus and at least one year after placement of the shunt system. Hearing alterations were proved by measuring the brainstem auditory evoked potentials (BAEP) for children up to 5 years of age and children with mental retardation; audiograms was used for children older than 5 years with normal neuro-psychological development (NPD). Of the 70 studied patients 17 (24%) had hearing loss (10 bilateral and 7-unilateral) and all of them had sensorineural hearing loss, which is associated with low weight at birth, posthemorrhagic hydrocephalus and brainstem symptoms at the time of diagnosis of hydrocephalus. Hearing pathology was found more often in shunt-treated patients with NPD retardation, poor functional status and low quality of life. Children with shunt-treated hydrocephalus have hearing loss of sensorineural type. Children with brain stem symptomatology at diagnosing hydrocephalus and children with post-hemorrhagic hydrocephalus show higher risk of hearing loss. Children with shunted hydrocephalus and hearing loss show lower NPD, lower quality of life and lower functional status. PMID:27180348

  12. [Angiological and neurological problems after shunt surgery in haemodialysis patients].

    PubMed

    Brittinger, W D

    2005-06-01

    Vascular access induced complications contribute to the morbidity of patients on regular dialysis treatment. Impaired peripheral perfusion, cardiac stress and nerve lesions are the most common of these complications. In the first part of this paper, angiological problems caused by creating arterio-venous shunts are described. Shunt volumes, blood circulation in the shunt arm and shunt-induced alterations of the circulatory blood volume are discussed as well as the conditions under which these parameters gain pathogenic importance. After describing the different shunt-specific circulatory disturbances in detail, the whole spectrum of preventive interventions are discussed. Based on the author's experience during more than four decades in this field, it is strongly recommended to treat even slight but clinically relevant circulatory disorders caused by arterio-venous shunts. The second part of this paper deals with neurological complications in access surgery for dialysis. The pathogenesis of these complications and the measures necessary to avoid them are discussed. Depending on the skin incision, 5 to 20 % of the patients with fistulas between the radial artery and the cephalic vein at the wrist show lesions of the superficial branch of the radial nerve or of the lateral forearm nerve branches. Fistulas with the ulnar artery at the dorsal aspect of the lower forearm frequently cause irritations of the ulnar nerve's superficial palmar branch. Fistulas with the basilic vein in the upper arm often are associated with lesions of the medial cutaneous nerve of the forearm, especially when the vein is "subcuticularized". Aside from these rather benign lesions, sometimes severe sensomotoric functional losses of the median, radial, and ulnar nerves occur, predominantly after implantation of vascular graft shunts in the upper arm. Similar nerve damage can also be observed in association with severe impairment of the peripheral perfusion caused by this type of shunt. Nerve

  13. Proximal ventricular shunt malfunctions in children: Factors associated with failure.

    PubMed

    Buster, Bryan E; Bonney, Phillip A; Cheema, Ahmed A; Glenn, Chad A; Conner, Andrew K; Safavi-Abbasi, Sam; Andrews, Mason B; Gross, Naina L; Mapstone, Timothy B

    2016-02-01

    Ventricular shunt failures and subsequent revisions are a significant source of patient morbidity. We conducted a review of pediatric patients undergoing placement or revision of ventricular shunts at our institution between January 2007 and December 2008. Patients were followed through to July 2014. Data collected included patient demographics, shunt history and indication for procedure, approach taken for shunt placement, and location of shunt tip in relation to the foramen of Monro. Univariate and multivariate analyses were conducted to identify factors associated with proximal failure. A total of 87 procedures were identified in 40 patients, consisting of 23 initial placements and 64 revisions. Thirty-nine proximal catheter malfunctions were identified. Indications for shunt placement included Chiari II malformation (33%) and intraventricular hemorrhage (33%). Mean follow-up period was 5.5 years. Median time to shunt failure was 1.57 years. In the multivariate model, younger age at placement was associated with decreased time to proximal failure (hazard ratio [HR]=0.80 per increasing year of age, 95% confidence interval [CI] 0.64-0.98). Both anterior approach (HR=0.39, 95% CI 0.23-0.67) and farther distance to foramen of Monro (HR=0.02 per increasing 10mm, 95% CI 0.00-0.22) were associated with increased time to proximal failure when the catheter tip was located within the contralateral lateral ventricle. Optimizing outcomes in patients with shunt-dependent hydrocephalus continues to be a challenge. Despite unsatisfactory outcomes, particularly in the pediatric population, few conclusions can be drawn from studies assessing operative variables. PMID:26601815

  14. First Report of Ventriculoperitoneal Shunt Infection due to Cyberlindnera fabianii

    PubMed Central

    Baghdadi, Jonathan; Hemarajata, Peera; Humphries, Romney; Kelesidis, Theodoros

    2015-01-01

    Fungal infections in the central nervous system (CNS) are associated with significant morbidity and death. Transient fungemia in immunocompetent patients without any other risk factors for fungemia has been suggested as a possible mechanism that may lead to serious fungal ventriculoperitoneal (VP) shunt infections, but evidence is lacking. The clinical spectrum, diagnosis, and optimal therapy of Cyberlindnera fabianii infections remain to be determined. We describe the first case of CNS infection due to C. fabianii that occurred in an immunocompetent adult with a VP shunt. Spontaneous translocation with yeast that is not part of the normal gastrointestinal flora in the setting of ingestion of multiple servings of a fermentation product was the likely source from which Cyberlindnera fabianii gained entrance into the VP shunt system, causing meningitis in this patient. The authors conclude that, in view of the high morbidity associated with yeast infection of the CNS, long-term antifungal therapy should be strongly considered in cases where the VP shunt cannot be completely removed. Transient fungemia may lead to invasive disease in an immunocompetent host with VP shunt, even in the absence of any other risk factors for fungemia and even after remote placement of the VP shunt. PMID:26618013

  15. Temporary arterial shunts to maintain limb perfusion after arterial injury: an animal study

    NASA Technical Reports Server (NTRS)

    Dawson, D. L.; Putnam, A. T.; Light, J. T.; Ihnat, D. M.; Kissinger, D. P.; Rasmussen, T. E.; Bradley, D. V. Jr

    1999-01-01

    BACKGROUND: Temporary shunt placement can quickly restore perfusion after extremity arterial injury. This study examined the adequacy of limb blood flow with shunt use, non-heparin-bonded shunt patency over prolonged periods, and the safety of this technique. METHODS: Common iliac arteries were divided and 4.0-mm Silastic Sundt shunts placed in 16 anesthetized pigs. Eight (group I) had shunts placed immediately; eight others (group II) were shunted after an hour of limb ischemia and hemorrhagic shock. Physiologic parameters and femoral artery blood flow in both hindlimbs were continuously monitored. Limb lactic acid generation, oxygen utilization, and hematologic and metabolic effects were serially evaluated for 24 hours. RESULTS: Shunts remained patent in 13 of 16 pigs. Shunts thrombosed in two group I animals because of technical errors, but functioned well after thrombectomy and repositioning. Patency could not be maintained in one animal that died from shock. Flow in group I shunted limbs was 57 (+/-11 SD) % of control. For group II animals in shock, shunted limb flow initially averaged 46 +/- 15% of control, but 4 hours after shunt placement, the mean limb blood flow was the same as in group I. Increased oxygen extraction compensated for the lower flow. Lactic acid production was not increased in comparison to control limbs. CONCLUSION: Shunts provided adequate flow in this model of extremity trauma. Correctly placed shunts stayed patent for 24 hours, without anticoagulation, if shunt placement followed resuscitation.

  16. Laparoscopy for ventriculoperitoneal shunt implantation and revision surgery

    PubMed Central

    Pinto, Fernando Campos Gomes; de Oliveira, Matheus Fernandes

    2014-01-01

    Ventriculoperitoneal shunting (VPS) is a widely accepted technique for the treatment of hydrocephalus. The probability of shunt dysfunction is pretty high throughout life. Laparoscopy has become a valuable tool to perform VPS and treat abdominal complications. An electronic literature search was performed to reveal the published data relating laparoscopy and ventriculoperitoneal shunt in Medline, Embase, Scielo and Lilacs databases. The keywords employed were “laparoscopy” OR “laparoscopic surgery” AND “ventriculoperitoneal shunt” OR “shunt” AND “surgery” OR “implantation” OR “revision” OR “complication”. No high quality trials were developed comparing conventional laparotomic incision vs laparoscopic approach. Both approaches have evolved and currently there are less invasive options for laparotomy, like periumbilical small incisions; and for laparoscopy, like smaller and less incisions. Operating room time, blood loss and hospital stay may be potentially smaller in laparoscopic surgery and complications are probably the same as laparotomy. In revision surgery for abdominal complications after VPS, visualization of whole abdominal cavity is fundamental to address properly the problem and laparoscopic approach is valuable once it is safe, fast and much less invasive than laparotomy. Ventriculoperitoneal shunting is a widely accepted technique for the treatment of hydrocephalus. Laparoscopy assisted shunt surgery in selected cases might be a less invasive and more effective option for intrabdominal manipulation. The laparoscopic approach allows a better catheter positioning, lysis of fibrotic bundles and peritoneal inspection as well, without any additional complication. PMID:25228943

  17. A simplified technique of performing splenorenal shunt (Omar's technique).

    PubMed

    Shah, Omar Javed; Robbani, Irfan

    2005-01-01

    The splenorenal shunt procedure introduced by Robert Linton in 1947 is still used today in those regions of the world where portal hypertension is a common problem. However, because most surgeons find Linton's shunt procedure technically difficult, we felt that a simpler technique was needed. We present the surgical details and results of 20 splenorenal anastomosis procedures performed within a period of 30 months. Half of the patients (Group I) underwent Linton's conventional technique of splenorenal shunt; the other half (Group II) underwent a newly devised, simplified shunt technique. This new technique involves dissection of the fusion fascia of Toldt. The outcome of the 2 techniques was identical with respect to the reduction of preshunt portal pressure. However, our simplified technique was advantageous in that it significantly reduced the duration of surgery (P <0.001) and the amount of intraoperative blood loss (P <0.003). No patient died after either operation. Although Linton's splenorenal shunt is difficult and technically demanding, it is still routinely performed. The new technique described here, in addition to being simpler, helps achieve good vascular control, permits easier dissection of the splenic vein, enables an ideal anastomosis, decreases intraoperative blood loss, and reduces the duration of surgery. Therefore, we recommend the routine use of this simplified technique (Omar's technique) for the surgical treatment of portal hypertension. PMID:16429901

  18. Shunt site chronic calcified extradural hematoma: An avoidable complication

    PubMed Central

    Mishra, Sudhansu Sekhar; Satapathy, Mani Charan; Senapati, Satya Bhusan

    2014-01-01

    Extradural hematoma (EDH) after ventriculoperitoneal (VP) shunt procedure is a rare, dangerous but easily avoidable and manageable complication. It is more common in children and young adults presumably due to relatively lax adhesion of dura to calvarium. We report a case of an 18-year-old male with acqueductal stenosis who underwent VP shunt procedure. Three months later, a computed tomography (CT) scan was done for the complaints of intractable headache and altered sensorium which showed chronic calcified EDH near shunt site. The ventricular catheter was in position and the ventricles were decompressed. After surgical decompression of EDH his symptoms improved. We discuss the factors leading to formation of EDH, with stress on proper technique to prevent or minimize such an avoidable complication. PMID:25250078

  19. Material-induced shunts in multicrystalline silicon solar cells

    SciTech Connect

    Breitenstein, O. Bauer, J.; Rakotoniaina, J. P.

    2007-04-15

    By applying lock-in thermography imaging, light-beam-induced current imaging, electron-beam-induced current imaging at different stages of sample preparation, and infrared light microscopy in transmission mode, the physical nature of the dominant material-induced shunts in multicrystalline solar cells made from p-type silicon material has been investigated. It turns out that these shunts are due to silicon carbide (SiC) filaments, which grow preferentially in grain boundaries and cross the whole cell. These filaments are highly n-type doped, like the emitter layer on the surface of the cells. They are electrically connected both with the emitter and with the back contact, thereby producing internal shunts in the solar cell.

  20. Bidirectional Glenn shunt: a step in the right direction.

    PubMed

    Narayan, R; Balakrishnan, K G; Pillai, V R; Tharakan, J A; Titus, T; Kumar, R S

    1996-01-01

    Bidirectional Glenn (BDG) shunt was carried out in 14 patients (age range 1.5-22 years; mean 9.3 years) for a variety of congenital cyanotic heart diseases with decreased pulmonary blood flow. Postoperative cardiac catheterisation was carried out in 10 patients including successful balloon angioplasty of the shunt and LPA in one patient. There was a significant improvement in oxygen saturation and a drop in haematocrit level at follow-up. Doppler echocardiography studies in 13 patients revealed functioning shunts in all cases with low velocity continuous flow. Thus BDG is a useful palliative procedure and could be undertaken as the first stage of total cavopulmonary connection in high-risk Fontan groups where biventricular repair is not feasible. PMID:8908825

  1. Shunted Piezoelectric Vibration Damping Analysis Including Centrifugal Loading Effects

    NASA Technical Reports Server (NTRS)

    Min, James B.; Duffy, Kirsten P.; Provenza, Andrew J.

    2011-01-01

    Excessive vibration of turbomachinery blades causes high cycle fatigue problems which require damping treatments to mitigate vibration levels. One method is the use of piezoelectric materials as passive or active dampers. Based on the technical challenges and requirements learned from previous turbomachinery rotor blades research, an effort has been made to investigate the effectiveness of a shunted piezoelectric for the turbomachinery rotor blades vibration control, specifically for a condition with centrifugal rotation. While ample research has been performed on the use of a piezoelectric material with electric circuits to attempt to control the structural vibration damping, very little study has been done regarding rotational effects. The present study attempts to fill this void. Specifically, the objectives of this study are: (a) to create and analyze finite element models for harmonic forced response vibration analysis coupled with shunted piezoelectric circuits for engine blade operational conditions, (b) to validate the experimental test approaches with numerical results and vice versa, and (c) to establish a numerical modeling capability for vibration control using shunted piezoelectric circuits under rotation. Study has focused on a resonant damping control using shunted piezoelectric patches on plate specimens. Tests and analyses were performed for both non-spinning and spinning conditions. The finite element (FE) shunted piezoelectric circuit damping simulations were performed using the ANSYS Multiphysics code for the resistive and inductive circuit piezoelectric simulations of both conditions. The FE results showed a good correlation with experimental test results. Tests and analyses of shunted piezoelectric damping control, demonstrating with plate specimens, show a great potential to reduce blade vibrations under centrifugal loading.

  2. Pleuro-peritoneal shunting. Alternative therapy for pleural effusions.

    PubMed Central

    Little, A G; Kadowaki, M H; Ferguson, M K; Staszek, V M; Skinner, D B

    1988-01-01

    Pleural effusions are resistant to standard therapy, which causes discomfort and can require prolonged hospitalization. As an alternative, pleuroperitoneal shunting for pleural effusions of various etiologies was evaluated. We implanted 36 shunts in 29 patients. Two patients had bilateral shunts and five had shunt revisions. The effusion was related to a malignancy in 22 patients, postoperative chylothorax in two patients, and other causes in five patients. Therapeutic thoracentesis had been attempted in 28 patients, and eight had had chest tube placement previously with attempted sclerosis. Seven patients had a trapped lung syndrome. There was no operative mortality. All patients were deemed ready for discharge from the hospital if they had recovered from the operation within 48 hours. Five patients had poor results, either because of a moribund status or their refusal or inability to pump the shunt. Of the remaining 24 patients, four had good results with temporary improvement, and excellent results were achieved in 20 patients (83.3%), who experienced symptomatic relief and stabilization or regression of pleural effusion until the time of their death. Patients with chylothorax experienced complete resolution. The 14 patients with malignant effusions had a median survival of 4 months, and there were no instances of peritoneal tumor seeding. In conclusion, pleuroperitoneal shunting is an alternative therapy for pleural effusions that requires a limited hospitalization only, is associated with minimal and short-term discomfort, achieves excellent results in properly selected patients, and is the only viable therapy when lung expansion cannot be achieved. Images Fig. 1. Figs. 3A-C. Figs. 3A-C. Figs. 4A and B. Figs. 5A-C. Figs. 5A-C. Figs. 6A-C. Figs. 6A-C. PMID:3178332

  3. Utility of Operative Glaucoma Tube Shunt Viscoelastic Bolus Flush

    PubMed Central

    Groth, Sylvia L; Greider, Kelsi L

    2015-01-01

    ABSTRACT Objective: To assess the utility of viscoelastic injection to induce bleb expansion and decrease intraocular pressure (IOP) in eyes with encapsulated glaucoma tube shunt blebs. Design: Case series. Subjects and participants: Forty-three glaucomatous eyes, including 13 eyes with congenital, 13 uveitic, 5 neovascular, 5 open angle, 4 narrow angle and 3 traumatic glaucomas. Methods, interventions or testing: All patients underwent viscoelastic flush procedure. A pre-bent 27 or 30-gauge cannula was passed through a 25-gauge paracentesis, advanced over the iris across the anterior chamber, and insinuated into the tube shunt lumen. Once the cannula was firmly lodged in position, 0.45 to 0.85 ml of viscoelastic was injected to hyperinflate the bleb. Main outcome measures: Paired t-tests were performed comparing preoperative IOP and number of medications used preoperatively vs levels measured at 1, 6, 12, 18 and 24 months. Results: Intraocular pressure was reduced from a mean preoperative level of 26.0 ± 1.2 (sem) mm Hg to 15.8 ± 1.0 at 1 month, remaining stable thereafter at each 6-month interval with 15.1 ± 1.1 mm Hg at 24 months (p < 0.0001). Medication use did not vary significantly from baseline. Pressure remained < 21 mm Hg after 2 years in 85% of eyes cannulated within 1 year of primary tube shunt implantation (n = 23), and in 62% of eyes cannulated more than 1 year after tube shunt placement (n = 20). Conclusion: Tube shunt expansion with bolus viscoelastic flush successfully restored encapsulated bleb function, providing a substantial (~10 mm Hg) IOP decrease into the mid-normal pressure range. This persisted in the majority of treated eyes for the entire study period. How to cite this article: Groth SL, Greider KL, Sponsel WE. Utility of Operative Glaucoma Tube Shunt Viscoelastic Bolus Flush. J Curr Glaucoma Pract 2015;9(3):73-76. PMID:26997840

  4. Rare sequelae following ventriculoatrial shunt: Case report and review of literature

    PubMed Central

    Gopal, Vinu Venu; Peethambaran, Anil Kumar

    2016-01-01

    Ventriculoatrial shunt (VA) is one of the oldest solutions for hydrocephalus. However over subsequent years various complication of VA shunt such as obstructions, malposition, shunt infections, cardiac complications such as endocarditis, traumatic perforation, heart failure, tricuspid regurgitation, intraatrial thrombus, and pulmonary hypertension are reported. Hence, VA shunt procedure has fallen into disrepute. Still VA shunt may be a good option in selected patients with hostile peritoneum. Newer placement strategies and monitoring methods have been put forward to reduce complication following VA shunt. In this case report, we share a rare case of endocarditis with tricuspid regurgitation following a migrated retained calcified shunt tube in the right ventricle of heart 30 years after of VA shunt that was successfully managed. PMID:27057231

  5. Rare sequelae following ventriculoatrial shunt: Case report and review of literature.

    PubMed

    Gopal, Vinu Venu; Peethambaran, Anil Kumar

    2016-01-01

    Ventriculoatrial shunt (VA) is one of the oldest solutions for hydrocephalus. However over subsequent years various complication of VA shunt such as obstructions, malposition, shunt infections, cardiac complications such as endocarditis, traumatic perforation, heart failure, tricuspid regurgitation, intraatrial thrombus, and pulmonary hypertension are reported. Hence, VA shunt procedure has fallen into disrepute. Still VA shunt may be a good option in selected patients with hostile peritoneum. Newer placement strategies and monitoring methods have been put forward to reduce complication following VA shunt. In this case report, we share a rare case of endocarditis with tricuspid regurgitation following a migrated retained calcified shunt tube in the right ventricle of heart 30 years after of VA shunt that was successfully managed. PMID:27057231

  6. Predictors of mortality after transjugular portosystemic shunt

    PubMed Central

    Ascha, Mona; Abuqayyas, Sami; Hanouneh, Ibrahim; Alkukhun, Laith; Sands, Mark; Dweik, Raed A; Tonelli, Adriano R

    2016-01-01

    AIM: To investigate if echocardiographic and hemodynamic determinations obtained at the time of transjugular intrahepatic portosystemic shunt (TIPS) can provide prognostic information that will enhance risk stratification of patients. METHODS: We reviewed medical records of 467 patients who underwent TIPS between July 2003 and December 2011 at our institution. We recorded information regarding patient demographics, underlying liver disease, indication for TIPS, baseline laboratory values, hemodynamic determinations at the time of TIPS, and echocardiographic measurements both before and after TIPS. We recorded patient comorbidities that may affect hemodynamic and echocardiographic determinations. We also calculated Model for End-stage Liver Disease (MELD) score and Child Turcotte Pugh (CTP) class. The following pre- and post-TIPS echocardiographic determinations were recorded: Left ventricular ejection fraction, right ventricular (RV) systolic pressure, subjective RV dilation, and subjective RV function. We recorded the following hemodynamic measurements: Right atrial (RA) pressure before and after TIPS, inferior vena cava pressure before and after TIPS, free hepatic vein pressure, portal vein pressure before and after TIPS, and hepatic venous pressure gradient (HVPG). RESULTS: We reviewed 418 patients with portal hypertension undergoing TIPS. RA pressure increased by a mean ± SD of 4.8 ± 3.9 mmHg (P < 0.001), HVPG decreased by 6.8 ± 3.5 mmHg (P < 0.001). In multivariate linear regression analysis, a higher MELD score, lower platelet count, splenectomy and a higher portal vein pressure were independent predictors of higher RA pressure (R = 0.55). Three variables predicted 3-mo mortality after TIPS in a multivariate analysis: Age, MELD score, and CTP grade C. Change in the RA pressure after TIPS predicted long-term mortality (per 1 mmHg change, HR = 1.03, 95%CI: 1.01-1.06, P < 0.012). CONCLUSION: RA pressure increased immediately after TIPS particularly in

  7. Endophthalmitis associated with Glaucoma Shunt Intraluminal Stent Exposure

    PubMed Central

    Kerr, Nathan M; Ruddle, Jonathan B; Ang, Ghee Soon

    2016-01-01

    ABSTRACT Endophthalmitis post glaucoma drainage implant (GDI) surgery is rare, often associated with tube or plate exposure. We report a case of endophthalmitis following glaucoma shunt intraluminal stent exposure in a patient who underwent Baerveldt glaucoma implant surgery. Endophthalmitis following manipulation of intraluminal stents is a rare complication of GDIs but potentially vision threatening condition that needs to be carefully screened for and treated immediately. How to cite this article: Kwon HJ, Kerr NM, Ruddle JB, Ang GS. Endophthalmitis associated with Glaucoma Shunt Intraluminal Stent Exposure. J Curr Glaucoma Pract 2016;10(1):36-37. PMID:27231417

  8. Modeling, analysis and verification of a partial shunt system

    SciTech Connect

    Lee, J.R.

    1996-12-31

    Spacecraft power system modeling, analysis and verification techniques using the electronic circuit simulation programs such as SPICE and SABER are presented. Partial shunt control system dynamics including the loop gain and bus impedance are derived. A typical partial shunt system is modeled and the loop gain of the system is simulated using an electronic circuit simulator. To confirm the circuit model simulation results prior to expensive hardware testing, they should be compared with the results simulated from a transfer function model derived from circuit equations. The spacecraft test results finally verify the modeling and analysis.

  9. Computed tomographic morphology and clinical features of extrahepatic portosystemic shunts in 172 dogs in Japan.

    PubMed

    Fukushima, K; Kanemoto, H; Ohno, K; Takahashi, M; Fujiwara, R; Nishimura, R; Tsujimoto, H

    2014-03-01

    Canine extrahepatic congenital portosystemic shunts (EH-cPSS) are classified into several anatomical types, depending on the origin and termination of the shunt vessel. The aim of this retrospective study was to determine the proportion and clinical features of each anatomical shunt type in a population of dogs presented to a veterinary teaching hospital in Japan. Dogs diagnosed with EH-cPSS using computed tomographic (CT) portography were included (n=172) and shunts were classified based on previous reports. Clinical data were collected from case records and analysed statistically. The most common anatomical type was the spleno-phrenic shunt (n=64), followed by the spleno-azygos (n=38), right gastric-caval (n=29), spleno-caval (n=21), right gastric-caval with caudal loop (n=9), right gastric-phrenic (n=6), colono-caval (n=3), spleno-phrenic and azygos (n=1), and porto-caval (n=1) shunts. Spleno-phrenic and spleno-azygos shunts were diagnosed more frequently in older dogs than right gastric-caval and spleno-caval shunts (P<0.05). The portal vein/aortic (PV/Ao) ratio was significantly larger in dogs with spleno-phrenic shunts than in dogs with spleno-azygos, right gastric-caval or spleno-caval shunts (P<0.05). The PV/Ao ratio was significantly larger in dogs with spleno-azygos shunts than in dogs with right gastric-caval shunts. Dogs with spleno-phrenic shunts had significantly lower serum alkaline phosphatase activities than those with right gastric-caval or spleno-caval shunts. Dogs with spleno-phrenic shunts had significantly lower fasting ammonia concentrations than those with spleno-caval shunts. PMID:24512983

  10. Treatment of Portosystemic Shunt Myelopathy with a Stent Graft Deployed through a Transjugular Intrahepatic Route

    SciTech Connect

    Jain, Deepak Arora, Ankur; Deka, Pranjal; Mukund, Amar Bhatnagar, Shorav; Jindal, Deepti Kumar, Niteen Pamecha, Viniyendra

    2013-08-01

    A case of surgically created splenorenal shunt complicated with shunt myelopathy was successfully managed by placement of a stent graft within the splenic vein to close the portosystemic shunt and alleviate myelopathy. To our knowledge, this is the first report of a case of shunt myelopathy in a patient with noncirrhotic portal fibrosis without cirrhosis treated by a novel technique wherein a transjugular intrahepatic route was adopted to deploy the stent graft.

  11. Percutaneous rheolytic mechanical thrombectomy in thrombosed direct intrahepatic portosystemic shunt: Report of two cases

    PubMed Central

    Tsetis, Dimitrios; Kehagias, Elias; Samonakis, Dimitrios; Kouroumalis, Elias; Hatzidakis, Adam

    2015-01-01

    We report two patients with Budd–Chiari syndrome, who underwent direct intrahepatic portosystemic shunt complicated by shunt thrombosis. Percutaneous AngioJet mechanical thrombectomy in combination with manual catheter aspiration and balloon disruption of the residual clot was successful, restoring patency of the thrombosed shunt. PMID:26767124

  12. Early onset tension pneumocephalus following ventriculoperitoneal shunt insertion for normal pressure hydrocephalus: a case report.

    PubMed

    Barada, Wissam; Najjar, Marwan; Beydoun, Ahmad

    2009-04-01

    The occurrence of tension pneumocephalus following ventriculoperitoneal (v.p.) shunt insertion is extremely rare, and is usually of delayed onset. We report a patient who developed an acute subdural tension pneumocephalus within 1 day following placement of a v.p. shunt for normal pressure hydrocephalus as a complication from shunt surgery. PMID:19185417

  13. Successful Embolization of a Spontaneous Mesocaval Shunt Using the Amplatzer Vascular Plug II

    SciTech Connect

    Boixadera, Helena; Tomasello, Alejandro; Quiroga, Sergi; Cordoba, Joan; Perez, Mercedes; Segarra, Antoni

    2010-10-15

    A 48-year-old man with alcoholic liver cirrhosis and hepatic encephalopathy was found to have a large, spontaneous mesocaval shunt. The shunt was successfully occluded with the use of an Amplatzer Vascular Plug. To our knowledge, this is the first report of the use of this device to embolize a mesocaval shunt involving the superior mesenteric vein.

  14. High-Flow Arterio-Hepatic Venous Shunt in Hepatocellular Carcinoma: Use of Multi-Electrode Radiofrequency for Shunt Obliteration

    SciTech Connect

    Pua, Uei

    2015-10-15

    Intra-tumoral arterio-hepatic venous shunting (AHVS) poses an impediment to transarterial chemoembolization of liver tumors. Not only does it present a potential hazard for systemic shunting and embolization, but also the altered flow dynamics may also result in poor delivery of drug/embolics to the target tumor bed. Current available techniques to overcome AVHS include arterial embolization (particles, coils, glue, etc.) or temporary venous occlusion using balloons. We hereby illustrate the use of radiofrequency ablation to obliterate a complex AHVS consisting of a varix-like venous aneurysm.

  15. Transjugular Intrahepatic Portosystemic Shunt Complications: Prevention and Management

    PubMed Central

    Suhocki, Paul V.; Lungren, Matthew P.; Kapoor, Baljendra; Kim, Charles Y.

    2015-01-01

    Transjugular intrahepatic portosystemic shunt (TIPS) insertion has been well established as an effective treatment in the management of sequelae of portal hypertension. There are a wide variety of complications that can be encountered, such as hemorrhage, encephalopathy, TIPS dysfunction, and liver failure. This review article summarizes various approaches to preventing and managing these complications. PMID:26038620

  16. The Evolution of Transjugular Intrahepatic Portosystemic Shunt: Tips

    PubMed Central

    Fanelli, Fabrizio

    2014-01-01

    Since Richter's description in the literature in 1989 of the first procedure on human patients, transjugular intrahepatic portosystemic shunt (TIPS) has been worldwide considered as a noninvasive technique to manage portal hypertension complications. TIPS succeeds in lowering the hepatic sinusoidal pressure and in increasing the circulatory flow, thus reducing sodium retention, ascites recurrence, and variceal bleeding. Required several revisions of the shunt TIPS can be performed in case of different conditions such as hepatorenal syndrome, hepatichydrothorax, portal vein thrombosis, and Budd-Chiari syndrome. Most of the previous studies on TIPS procedure were based on the use of bare stents and most patients chose TIPS 2-3 years after traditional treatment, thus making TIPS appear to be not superior to endoscopy in survival rates. Bare stents were associated with higher incidence of shunt failure and consequently patients required several revisions during the follow-up. With the introduction of a dedicated e-PTFE covered stent-graft, these problems were completely solved, No more reinterventions are required with a tremendous improvement of patient's quality of life. One of the main drawbacks of the use of e-PTFE covered stent-graft is higher incidence of hepatic encephalopathy. In those cases refractory to the conventional medical therapy, a shunt reduction must be performed. PMID:27335841

  17. Comparison of passive inductor designs for piezoelectric shunt damping

    NASA Astrophysics Data System (ADS)

    Lossouarn, Boris; Thierry, Olivier; Aucejo, Mathieu; Deü, Jean-François

    2016-04-01

    Considering piezoelectric damping, a resonant shunt can lead to a significant vibration reduction when tuned to the mechanical mode to control. However, limits appear when looking at practical applications in a low frequency range: the required inductance is often too high to be satisfied with standard passive components. Moreover, even if the inductor is eventually available, the internal resistance of the component generally exceeds the value which is required for a shunt optimization. Suitable inductors can be designed for applications requiring high inductance and low resistance values. Indeed, the permeance of a magnetic circuit can be significantly increased by the use of closed cores made of high permeability materials. In this paper, three designs are described and compared: an inductor from standard series and two handmade inductors involving a ferrite core and a nanocrystalline toroid. The components are successively integrated into a piezoelectric shunt dedicated to the vibration control of a cantilever beam. Depending on the frequency of the target mechanical mode to control, the benefits and the limits of the different inductors are observed. It is shown that custom designs can definitely extend to lower frequency the application of the passive resonant shunt strategy.

  18. Embolization of nonvariceal portosystemic collaterals in transjugular intrahepatic portosystemic shunts

    SciTech Connect

    Bilbao, Jose Ignacio; Arias, Mercedes; Longo, Jesus Maria; Alejandre, Pedro Luis; Betes, Maria Teresa; Elizalde, Arlette Maria

    1997-03-15

    Percutaneous embolization of large portosystemic collaterals was performed in three patients following placement of a transjugular intrahepatic portosystemic shunt in order to improve hepatopetal portal flow. Improved hepatic portal perfusion was achieved in these cases, thereby theoretically reducing the risk of chronic hepatic encephalopathy.

  19. Synchrony with shunting inhibition in a feedforward inhibitory network

    PubMed Central

    Hwang, Dong-Uk; Carney, Paul R.; Ditto, William L.

    2010-01-01

    Recent experiments have shown that GABAA receptor mediated inhibition in adult hippocampus is shunting rather than hyperpolarizing. Simulation studies of realistic interneuron networks with strong shunting inhibition have been demonstrated to exhibit robust gamma band (20–80 Hz) synchrony in the presence of heterogeneity in the intrinsic firing rates of individual neurons in the network. In order to begin to understand how shunting can contribute to network synchrony in the presence of heterogeneity, we develop a general theoretical framework using spike time response curves (STRC's) to study patterns of synchrony in a simple network of two unidirectionally coupled interneurons (UCI network) interacting through a shunting synapse in the presence of heterogeneity. We derive an approximate discrete map to analyze the dynamics of synchronous states in the UCI network by taking into account the nonlinear contributions of the higher order STRC terms. We show how the approximate discrete map can be used to successfully predict the domain of synchronous 1:1 phase locked state in the UCI network. The discrete map also allows us to determine the conditions under which the two interneurons can exhibit in-phase synchrony. We conclude by demonstrating how the information from the study of the discrete map for the dynamics of the UCI network can give us valuable insight into the degree of synchrony in a larger feedforward network of heterogeneous interneurons. PMID:20135213

  20. Peritoneo-vulvar catheter extrusion after shunt operation.

    PubMed

    Nagulic, M; Djordjevic, M; Samardzic, M

    1996-04-01

    We report an unusual case of catheter extrusion through the external genitalia. between the labium majus and the labium minus, in a 6-month-old hydrocephalic baby. The event occurred 5 months after placement of a ventriculoperitoneal shunt. PMID:8739410

  1. Bilhemia: A Rare Complication of Transjugular Intraheptic Portosytemic Shunt

    PubMed Central

    Zhang, Michael

    2015-01-01

    A 56-year-old woman with cirrhosis due to chronic hepatitis C underwent emergent transjugular intrahepatic portosystemic shunt (TIPS) due to a ruptured esophageal varix during esophagogastroduodenoscopy. Following TIPS, the patient experienced a rapid rise in serum bilirubin with no evidence of biliary obstruction or hepatic injury. She was determined to have bilhemia, a rare but serious complication of TIPS. PMID:26504882

  2. The Evolution of Transjugular Intrahepatic Portosystemic Shunt: Tips.

    PubMed

    Fanelli, Fabrizio

    2014-01-01

    Since Richter's description in the literature in 1989 of the first procedure on human patients, transjugular intrahepatic portosystemic shunt (TIPS) has been worldwide considered as a noninvasive technique to manage portal hypertension complications. TIPS succeeds in lowering the hepatic sinusoidal pressure and in increasing the circulatory flow, thus reducing sodium retention, ascites recurrence, and variceal bleeding. Required several revisions of the shunt TIPS can be performed in case of different conditions such as hepatorenal syndrome, hepatichydrothorax, portal vein thrombosis, and Budd-Chiari syndrome. Most of the previous studies on TIPS procedure were based on the use of bare stents and most patients chose TIPS 2-3 years after traditional treatment, thus making TIPS appear to be not superior to endoscopy in survival rates. Bare stents were associated with higher incidence of shunt failure and consequently patients required several revisions during the follow-up. With the introduction of a dedicated e-PTFE covered stent-graft, these problems were completely solved, No more reinterventions are required with a tremendous improvement of patient's quality of life. One of the main drawbacks of the use of e-PTFE covered stent-graft is higher incidence of hepatic encephalopathy. In those cases refractory to the conventional medical therapy, a shunt reduction must be performed. PMID:27335841

  3. CONTEXT VIEW ALONG EXISTING PERIMETER TRACKS LOOKING TOWARDS SHUNTS IN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    CONTEXT VIEW ALONG EXISTING PERIMETER TRACKS LOOKING TOWARDS SHUNTS IN THEIR PRESENT-DAY POSITIONS, STORAGE SHED, AND MACHINE SHOP. LOOKING NORTHEAST. - Pennsylvania Railway Ore Dock, Lake Erie at Whiskey Island, approximately 1.5 miles west of Public Square, Cleveland, Cuyahoga County, OH

  4. Risk factors for shunt malfunction in pediatric hydrocephalus: a multicenter prospective cohort study.

    PubMed

    Riva-Cambrin, Jay; Kestle, John R W; Holubkov, Richard; Butler, Jerry; Kulkarni, Abhaya V; Drake, James; Whitehead, William E; Wellons, John C; Shannon, Chevis N; Tamber, Mandeep S; Limbrick, David D; Rozzelle, Curtis; Browd, Samuel R; Simon, Tamara D

    2016-04-01

    OBJECT The rate of CSF shunt failure remains unacceptably high. The Hydrocephalus Clinical Research Network (HCRN) conducted a comprehensive prospective observational study of hydrocephalus management, the aim of which was to isolate specific risk factors for shunt failure. METHODS The study followed all first-time shunt insertions in children younger than 19 years at 6 HCRN centers. The HCRN Investigator Committee selected, a priori, 21 variables to be examined, including clinical, radiographic, and shunt design variables. Shunt failure was defined as shunt revision, subsequent endoscopic third ventriculostomy, or shunt infection. Important a priori-defined risk factors as well as those significant in univariate analyses were then tested for independence using multivariate Cox proportional hazard modeling. RESULTS A total of 1036 children underwent initial CSF shunt placement between April 2008 and December 2011. Of these, 344 patients experienced shunt failure, including 265 malfunctions and 79 infections. The mean and median length of follow-up for the entire cohort was 400 days and 264 days, respectively. The Cox model found that age younger than 6 months at first shunt placement (HR 1.6 [95% CI 1.1-2.1]), a cardiac comorbidity (HR 1.4 [95% CI 1.0-2.1]), and endoscopic placement (HR 1.9 [95% CI 1.2-2.9]) were independently associated with reduced shunt survival. The following had no independent associations with shunt survival: etiology, payer, center, valve design, valve programmability, the use of ultrasound or stereotactic guidance, and surgeon experience and volume. CONCLUSIONS This is the largest prospective study reported on children with CSF shunts for hydrocephalus. It confirms that a young age and the use of the endoscope are risk factors for first shunt failure and that valve type has no impact. A new risk factor-an existing cardiac comorbidity-was also associated with shunt failure. PMID:26636251

  5. TIPS Versus Peritoneovenous Shunt in the Treatment of Medically Intractable Ascites

    PubMed Central

    Rosemurgy, Alexander S.; Zervos, Emmanuel E.; Clark, Whalen C.; Thometz, Donald P.; Black, Thomas J.; Zwiebel, Bruce R.; Kudryk, Bruce T.; Grundy, L Shane; Carey, Larry C.

    2004-01-01

    Objective: We undertook a prospective randomized clinical trial comparing TIPS to peritoneovenous (PV) shunts in the treatment of medically intractable ascites to establish relative efficacy and morbidity, and thereby superiority, between these shunts. Methods: Thirty-two patients were prospectively randomized to undergo TIPS or peritoneovenous (Denver) shunts. All patients had failed medical therapy. Results: After TIPS versus peritoneovenous shunts, median (mean ± SD) duration of shunt patency was similar: 4.4 months (6 ± 6.6 months) versus 4.0 months (5 ± 4.6 months). Assisted shunt patency was longer after TIPS: 31.1 months (41 ± 25.9 months) versus 13.1 months (19 ± 17.3 months) (P < 0.01, Wilcoxon test). Ultimately, after TIPS 19% of patients had irreversible shunt occlusion versus 38% of patients after peritoneovenous shunts. Survival after TIPS was 28.7 months (41 ± 28.7 months) versus 16.1 months (28 ± 29.7 months) after peritoneovenous shunts. Control of ascites was achieved sooner after peritoneovenous shunts than after TIPS (73% vs. 46% after 1 month), but longer-term efficacy favored TIPS (eg, 85% vs. 40% at 3 years). Conclusion: TIPS and peritoneovenous shunts treat medically intractable ascites. Absence of ascites after either is uncommon. PV shunts control ascites sooner, although TIPS provides better long-term efficacy. After either shunt, numerous interventions are required to assist patency. Assisted shunt patency is better after TIPS. Treating medically refractory ascites with TIPS risks early shunt-related mortality for prospects of longer survival with ascites control. This study promotes the application of TIPS for medically intractable ascites if patients undergoing TIPS have prospects beyond short-term survival. PMID:15166968

  6. Effect of peritoneo-venous shunt on portal pressure.

    PubMed Central

    Samanta, A K; Leevy, C M

    1989-01-01

    The cause of variceal bleed after a peritoneo-venous shunt is not known. Portal haemodynamic consequences of a peritoneo-venous shunt are poorly understood. The most critical period after a peritoneo-venous shunt is the early postoperative period when rapid mobilisation of peritoneal fluid occurs. Serial changes in the portal pressure during the early postoperative period have not been recorded. In the present study preoperative wedge hepatic vein (WHV), right atrial (RA) and pulmonary capillary wedged (PCW) pressures, cardiac index (CI), and plasma volume (PV) were measured in five alcoholic cirrhotic patients with tense ascites for up to 20 hours postoperatively. The longterm effect was assessed by repeating the intrahepatic and/or wedged hepatic vein pressures in three of the surviving patients after 10 to 20 months. A significant increase in the circulatory dynamics and portal pressure was seen within two hours after shunt placement. Wedged hepatic vein pressure increased from 27.6 (8.2) mmHg to 37.2 (9.2) mmHg (p less than 0.01), RA pressure increased from 6.8 (1.5) mmHg to 14.0 (4.3) mmHg (p less than 0.05), PCW increased from 7.2 (3.5) mmHg to 19.3 (5.7) mmHg (p less than 0.01), CI increased from 3.4 (0.27) lit/m2/min to 4.3 (0.85) lit/m2/min (p less than 0.05). This was accompanied by a 34% increase in the plasma volume from 1838.5 (142.1) to 2471.4 (210) ml/m2. These derangements were maintained up to 20 hours postoperatively. After 10 to 20 months, repeat measurements revealed a return to preoperative measurements. It is concluded that there is an acute increase portal pressure after a peritoneo-venous shunt attributed to increased circulation plasma volume, resulting from rapid mobilisation of ascitic fluid after the shunt. A sudden increase in portal pressure might be an important provoking factor for variceal bleeding after peritoneo-venus shunt. PMID:2920931

  7. Pulmonary Arterial Hypertension Associated with Congenital Portosystemic Shunts Treated with Transcatheter Embolization and Pulmonary Vasodilators.

    PubMed

    Sato, Haruka; Miura, Masanobu; Yaoita, Nobuhiro; Yamamoto, Saori; Tatebe, Shunsuke; Aoki, Tatsuo; Satoh, Kimio; Ota, Hideki; Takase, Kei; Sugimura, Koichiro; Shimokawa, Hiroaki

    2016-01-01

    Cardiopulmonary abnormalities are often present in patients with liver diseases. We herein report a case of congenital portosystemic shunts complicated by hepatopulmonary syndrome (HPS) and portopulmonary hypertension (PoPH). A 57-year-old woman complained of dyspnea and was subsequently diagnosed with HPS and PoPH caused by congenital portosystemic shunts. Although shunt closure by transcatheter embolization was successfully performed, her dyspnea worsened and pulmonary artery pressure and pulmonary vascular resistance elevated. Conventional vasodilator therapy was started, resulting in an improvement of pulmonary hypertension (PH). In some patients with congenital portosystemic shunts, shunt closure could exacerbate PH, and vasodilator therapy may be effective. PMID:27580545

  8. Control of an electromechanical hydrocephalus shunt--a new approach.

    PubMed

    Elixmann, Inga M; Kwiecien, Monika; Goffin, Christine; Walter, Marian; Misgeld, Berno; Kiefer, Michael; Steudel, Wolf-Ingo; Radermacher, Klaus; Leonhardt, Steffen

    2014-09-01

    Hydrocephalus is characterized by an excessive accumulation of cerebrospinal fluid (CSF). Therapeutically, an artificial pressure relief valve (so-called shunt) is implanted which opens in case of increased intracranial pressure (ICP) and drains CSF into another body compartment. Today, available shunts are of a mechanical nature and drainage depends on the pressure drop across the shunt. According to the latest data, craniospinal compliance is considered to be even more important than mean ICP alone. In addition, ICP is not constant but varies due to several influences. In fact, heartbeat-related ICP waveform patterns depend on volume changes in the cranial vessels during a heartbeat and changes its shape as a function of craniospinal compliance. In this paper, we present an electromechanical shunt approach, which changes the CSF drainage as a function of the current ICP waveform. A series of 12 infusion tests in patients were analyzed and revealed a trend between the compliance and specific features of the ICP waveform. For waveform analysis of patient data, an existing signal processing algorithm was improved (using a Moore machine) and was implemented on a low-power microcontroller within the electromechanical shunt. In a test rig, the ICP waveforms were replicated and the decisions of the ICP analysis algorithm were verified. The proposed control algorithm consists of a cascaded integral controller which determines the target ICP from the measured waveform, and a faster inner-loop integral controller that keeps ICP close to the target pressure. Feedforward control using measurement data of the patient's position was implemented to compensate for changes in hydrostatic pressure during change in position. A model-based design procedure was used to lay out controller parameters in a simple model of the cerebrospinal system. Successful simulation results have been obtained with this new approach by keeping ICP within the target range for a healthy waveform. PMID

  9. Fuzzy Inference System Approach for Locating Series, Shunt, and Simultaneous Series-Shunt Faults in Double Circuit Transmission Lines

    PubMed Central

    Swetapadma, Aleena; Yadav, Anamika

    2015-01-01

    Many schemes are reported for shunt fault location estimation, but fault location estimation of series or open conductor faults has not been dealt with so far. The existing numerical relays only detect the open conductor (series) fault and give the indication of the faulty phase(s), but they are unable to locate the series fault. The repair crew needs to patrol the complete line to find the location of series fault. In this paper fuzzy based fault detection/classification and location schemes in time domain are proposed for both series faults, shunt faults, and simultaneous series and shunt faults. The fault simulation studies and fault location algorithm have been developed using Matlab/Simulink. Synchronized phasors of voltage and current signals of both the ends of the line have been used as input to the proposed fuzzy based fault location scheme. Percentage of error in location of series fault is within 1% and shunt fault is 5% for all the tested fault cases. Validation of percentage of error in location estimation is done using Chi square test with both 1% and 5% level of significance. PMID:26413088

  10. New and improved ways to treat hydrocephalus: Pursuit of a smart shunt

    PubMed Central

    Lutz, Barry R.; Venkataraman, Pranav; Browd, Samuel R.

    2013-01-01

    The most common treatment for hydrocephalus is placement of a cerebrospinal fluid shunt to supplement or replace lost drainage capacity. Shunts are life-saving devices but are notorious for high failure rates, difficulty of diagnosing failure, and limited control options. Shunt designs have changed little since their introduction in 1950s, and the few changes introduced have had little to no impact on these long-standing problems. For decades, the community has envisioned a “smart shunt” that could provide advanced control, diagnostics, and communication based on implanted sensors, feedback control, and telemetry. The most emphasized contribution of smart shunts is the potential for advanced control algorithms, such as weaning from shunt dependency and personalized control. With sensor-based control comes the opportunity to provide data to the physician on patient condition and shunt function, perhaps even by a smart phone. An often ignored but highly valuable contribution would be designs that correct the high failure rates of existing shunts. Despite the long history and increasing development activity in the past decade, patients are yet to see a commercialized smart shunt. Most smart shunt development focuses on concepts or on isolated technical features, but successful smart shunt designs will be a balance between technical feasibility, economic viability, and acceptable regulatory risk. Here, we present the status of this effort and a framework for understanding the challenges and opportunities that will guide introduction of smart shunts into patient care. PMID:23653889

  11. Lumboatrial shunt in a patient with Crouzon syndrome complicated by pseudotumor cerebri.

    PubMed

    Sankey, Eric W; Khattab, Mohamed H; Elder, Benjamin D; Goodwin, C Rory; Rekate, Harold L; Rigamonti, Daniele

    2015-09-01

    A 25-year-old man with Crouzon syndrome complicated by pseudotumor cerebri and multiple shunt failures presented with progressive back and neck pain, intermittent headaches, and associated vomiting secondary to shunt infection. Due to his previous history of repeated failure of both ventriculoperitoneal and lumboperitoneal (LP) shunting procedures, the decision was made to place a lumboatrial (LA) shunt via an approach through the internal jugular vein. The procedure was uncomplicated and the man's symptoms were relieved. Despite significant improvement, the LA shunt limited his exercise tolerance, and as an avid runner and weight lifter, he requested reconversion back to an LP shunt. At a follow-up of 20months, he continued to do well both clinically and radiographically. This case report summarizes the successful placement and use of an LA shunt for the treatment of intracranial hypertension in the setting of Crouzon syndrome. PMID:26021731

  12. Cerebral venous thrombosis after ventriculoperitoneal shunting: a case report.

    PubMed

    Matsubara, Teppei; Ayuzawa, Satoshi; Aoki, Tsukasa; Ikeda, Go; Shiigai, Masanari; Matsumura, Akira

    2014-01-01

    Ventriculoperitoneal shunting (VPS) is a simple procedure, but there are several potential complications. We describe the first reported case of cerebral venous thrombosis (CVT) after VPS. A 69-year-old man suffering from normal pressure hydrocephalus underwent left VPS. Two months later he developed CVT and cerebral venous hemorrhage in the left frontal lobe. Computed tomography (CT) and magnetic resonance imaging (MRI) revealed the thrombus formation just adjacent to the shunt tube. One possible cause is compression of the cortical vein after brain shift and/or tension of the cortical vein due to intracranial hypotension. A protein C deficiency was also detected. Surgeons should be aware that cerebral venous thrombosis can occur after VPS. PMID:24257484

  13. Maintenance of silastic–teflon shunts for intermittent haemodialysis

    PubMed Central

    McIntosh, C. S.; Petrie, J. C.; Macleod, M.

    1969-01-01

    The occurrence of infection in the tissues surrounding external arteriovenous shunts was studied and die important relationship of pyogenic infection to clotting was confirmed. The local application of fusidic add tulle and lanolin greatly reduced the occurrence of both infection and clotting and the need for cannula replacement. Urokinase used for declotting shunts when standard procedures had failed, restored blood flow whether dotting was related to infection or to local vascular factors. This treatment is not advised when clotting is associated with a local abscess, as it may make cannula replacement necessary. Severe local vascular factors, such as metastatic calcification, Raynaud's phenomenon, and venous stenosis, may lead to poor blood flow, so that despite clot lysis elective cannula replacement or the creation of a subcutaneous arteriovenous fistula is required. Imagesp718-a PMID:5354876

  14. Cerebral Venous Thrombosis after Ventriculoperitoneal Shunting: A Case Report

    PubMed Central

    MATSUBARA, Teppei; AYUZAWA, Satoshi; AOKI, Tsukasa; IKEDA, Go; SHIIGAI, Masanari; MATSUMURA, Akira

    2014-01-01

    Ventriculoperitoneal shunting (VPS) is a simple procedure, but there are several potential complications. We describe the first reported case of cerebral venous thrombosis (CVT) after VPS. A 69-year-old man suffering from normal pressure hydrocephalus underwent left VPS. Two months later he developed CVT and cerebral venous hemorrhage in the left frontal lobe. Computed tomography (CT) and magnetic resonance imaging (MRI) revealed the thrombus formation just adjacent to the shunt tube. One possible cause is compression of the cortical vein after brain shift and/or tension of the cortical vein due to intracranial hypotension (IH). A protein C deficiency was also detected. Surgeons should be aware that cerebral venous thrombosis can occur after VPS. PMID:24257484

  15. [Surgical treatment of refractory ascites with peritoneovenous shunt].

    PubMed

    Massari, R; Fulgente, R; Marinelli, S; Romessis, M

    1995-01-01

    Leveen and associates described a peritoneo-venous shunt which proved to be useful in patients with intractable ascites. Medical therapy, paracentesis and peritoneovenous shunt have been compared, but there is uncertainty about their relative merits. Therefore, the leveen device has be placed in last years in an increasing number of patients: it has not been shown by prospective trials to prolong survival significantly, although it may shorten hospitalization and improve the quality of life. A number of early and late complications were described but they do not influence the general results: origin and features of such complications are discussed as well as their prevention and treatment and personal cases are presented. Selection of patients and careful surgical procedure seems to be mandatory for better results. PMID:8706187

  16. Congenital intrahepatic portosystemic shunts: Imaging findings and endovascular management.

    PubMed

    Chandrasekharan, Rajsekar; Pullara, Sreekumar K; Thomas, Tixon; Kader, Nazar Puthukudiyil; Moorthy, Srikanth

    2016-01-01

    We present two cases of congenital intrahepatic portosystemic shunts in which the right portal vein directly communicated with the inferior venacava (IVC) in one patient and with the hepatic vein in the other. Multiple hepatic nodules consistent with focal nodular hyperplasia (FNH) were seen in the first patient. The second patient presented with recurrent history of hepatic encephalopathy. Percutaneous transhepatic embolization was performed using coils and Amplatz device following which she completely recovered. PMID:27081230

  17. Congenital intrahepatic portosystemic shunts: Imaging findings and endovascular management

    PubMed Central

    Chandrasekharan, Rajsekar; Pullara, Sreekumar K; Thomas, Tixon; Kader, Nazar Puthukudiyil; Moorthy, Srikanth

    2016-01-01

    We present two cases of congenital intrahepatic portosystemic shunts in which the right portal vein directly communicated with the inferior venacava (IVC) in one patient and with the hepatic vein in the other. Multiple hepatic nodules consistent with focal nodular hyperplasia (FNH) were seen in the first patient. The second patient presented with recurrent history of hepatic encephalopathy. Percutaneous transhepatic embolization was performed using coils and Amplatz device following which she completely recovered. PMID:27081230

  18. Transient response of a static VAR shunt compensator

    SciTech Connect

    Best, R.A.; Zelaya-De La Parra, H.

    1996-05-01

    A typical static VAR shunt compensator has been analyzed so that the step response and steady-state errors can be identified. The results show that the steady-state error is dependent upon the error in the measurement of the currents` phase alone. They also show that an unstable condition can occur, though it should rarely arise in practice. All the theory was verified on a low power (240 V, 3 A) system.

  19. Transjugular Intrahepatic Portosystemic Shunt before and after Liver Transplantation.

    PubMed

    Saad, Wael E

    2014-09-01

    The transjugular intrahepatic portosystemic shunt (TIPS) has long been referred to as a procedure performed as "a bridge to transplantation" since, like many other portosystemic shunts, it decompresses the portal circulation and stabilizes patients but does not definitively treat portal hypertension. One of the major advantages of TIPS over surgically placed portosystemic shunts in the transplant era is that the TIPS is intrahepatic and is removed in situ with the native liver, and usually does not need additional surgery (unlike takedown/ligation of surgical shunts). There are several studies that evaluate TIPS before transplantation-not as a bridge/temporizing measure, but as a prelude to the transplant to decompress the portal circulation and reduce portosystemic engorgement and collaterals and thus, in theory, reduce intraoperative bleeding during liver transplantation. However, these studies, mostly in the transplant literature, have been equivocal from an intraoperative and posttransplant clinical outcome standpoint. TIPS creation in liver transplant recipients is another interesting aspect of TIPS. There has been a debate about whether or not liver transplantation adds additional technical difficulty to the TIPS procedure. Initially, many theories were proposed as to the technical difficulty of TIPS in a transplanted liver. However, recent opinions and published studies demonstrate that whole-graft liver transplantation does not pose a significant technical difficulty to TIPS. Moreover, there are several recent studies evaluating the outcomes of TIPS in liver transplant recipients, showing that outcomes are less favorable when compared with TIPS in nontransplanted patients. This article discusses the results of TIPS as a preoperative prelude to liver transplantation. In addition, it discusses the technical and clinical outcomes of TIPS in liver transplant recipients. PMID:25177084

  20. Could there be light at the end of the tunnel? Mesocaval shunting for refractory esophageal varices in patients with contraindications to transjugular intrahepatic portosystemic shunt

    PubMed Central

    Davis, Jessica; Chun, Albert K; Borum, Marie L

    2016-01-01

    Cirrhotic patients with recurrent variceal bleeds who have failed prior medical and endoscopic therapies and are not transjugular intrahepatic portosystemic shunt candidates face a grim prognosis with limited options. We propose that mesocaval shunting be offered to this group of patients as it has the potential to decrease portal pressures and thus decrease the risk of recurrent variceal bleeding. Mesocaval shunts are stent grafts placed by interventional radiologists between the mesenteric system, most often the superior mesenteric vein, and the inferior vena cava. This allows flow to bypass the congested hepatic system, reducing portal pressures. This technique avoids the general anesthesia and morbidity associated with surgical shunt placement and has been successful in several case reports. In this paper we review the technique, candidate selection, potential pitfalls and benefits of mesocaval shunt placement. PMID:27429715

  1. Feasibility of externalized peritoneovenous shunt (EPVS) for malignant ascites

    PubMed Central

    2011-01-01

    Purpose To evaluate a new modified peritoneovenous shunt therapy, the externalized peritoneovenous shunt (EPVS) system placement, used to treat patients with malignant ascites. Methods We retrospectively reviewed 10 patients, who were not suited for conventional peritoneovenous shunts (PVS), with malignant ascites, which was refractory to medical therapies. Patient characteristics, technical success, efficacy, duration of EPVS placement, adverse events, and outcome were evaluated. Clinical efficacy of the EPVS was evaluated by the change in subjective symptoms. Results The primary reasons for applying EPVS were severe anasarca in 4 patients, potential PVS dysfunction in 3 patients, poor performance status in 2 patients, and a history of PVS occlusion in 1 patient. EPVS was successfully placed in all patients, and it provided clinical efficacy in 8 patients (80%). Early death occurred within 7 days after EPVS placement in 2 patients because of renal failure. The median duration of EPVS placement was 10.4 days (range, 2-28 days). In 6 patients (60%), the EPVS was exchanged to conventional PVS sequentially, since the initial EPVS placement resulted in an improvement of the subjective symptoms of the patients, without serious complications. Conclusion EPVS placement may be an option for patients with malignant ascites who may not be appropriate for conventional PVS placement. PMID:21777451

  2. Modified Blalock-Taussig Shunt with an Umbilical Vein Graft

    PubMed Central

    Leão, Luiz Eduardo V.; Andrade, José Carlos S.; Succi, José Ernesto; Cueva, Clotario C.; Ribeiro, Expedito E.; Carvalho, Antonio Carlos C.; Buffolo, Enio

    1985-01-01

    We describe a modification of the Blalock Taussig anastomosis, with the interposition of a glutaraldehyde-tanned umbilical vein graft between the subclavian and pulmonary arteries. This operation was performed in 64 children: 11 were less than 1 month of age (17.2%), and 23 were between 1 and 6 months of age (34.9%). Hospital deaths occurred in six patients—all less than 6 months of age (9.4%). There was no instance of shunt occlusion noted. The clinical course was uneventful among survivors, except for one patient who died of endocarditis in the late postoperative follow-up. The shunt procedure may be performed very rapidly, with minimal dissection, allowing the use of a graft larger than the diameter of the subclavian artery. This modification of the Blalock Taussig operation compares favorably with our previous experience with other shunt procedures and may be considered a valuable alternative in the palliative surgical treatment of several malformations with severe pulmonary oligemia. Images PMID:15227043

  3. Myomucosal shunt following total laryngectomy: a report of 31 cases.

    PubMed

    Brasnu, D; Strome, M; Ménard, M; Pfauwadel, M C; Martinez, P; Janot, F; Laccourreye, H

    1989-01-01

    An original technique of voice rehabilitation following total laryngectomy based on the concept of a myomuscosal unit was originally described by Strome. Thirty-one cases of myomucosal shunts (MMS) are analyzed in the present report. The 14 initial cases failed because of a lack clinical and surgical experience and insufficient selection of the patients. Among the last 17 cases, 1 was lost to follow-up, 1 had an insufficient follow-up, and 2 patients refused to speak with the MMS instead of a patent shunt; 5 of the remaining patients had voices evaluated as excellent, 7 had voices interpreted as good and only 1 patient had a voice evaluated as poor. Aspiration was not a problem. Eleven patients were found to stenose their shunt, but fistula were recalibrated successfully. The MMs can be used safely in oncological surgery and only 1 of 31 deaths in our total experience was due to a local recurrence. These findings show that the MMS is a reliable procedure for voice restoration following total laryngectomy; a prosthesis is not required and there are currently no oncological limits to the procedure. However, a very close follow-up of the patients is required after surgery. PMID:2686602

  4. Transjugular intrahepatic portosystemic shunt combined with esophagogastric variceal embolization in the treatment of a large gastrorenal shunt

    PubMed Central

    Jiang, Qin; Wang, Ming-Quan; Zhang, Guo-Bing; Wu, Qiong; Xu, Jian-Ming; Kong, De-Run

    2016-01-01

    AIM: To evaluate the efficacy and safety of transjugular intrahepatic portosystemic shunt (TIPS) combined with stomach and esophageal variceal embolization (SEVE) in cirrhotic patients with a large gastrorenal vessel shunt (GRVS). METHODS: Eighty-one cirrhotic patients with gastric variceal bleeding (GVB) associated with a GRVS were enrolled in the study and accepted TIPS combined with SEVE (TIPS + SEVE), by which portosystemic pressure gradient (PPG), biochemical, TIPS-related complications, shunt dysfunction, rebleeding, and death were evaluated. RESULTS: The PPGs before TIPS were greater than 12 mmHg in 81 patients. TIPS + SEVE treatment caused a significant decrease in PPG (from 37.97 ± 6.36 mmHg to 28.15 ± 6.52 mmHg, t = 19.22, P < 0.001). The percentage of reduction in PPG was greater than 20% from baseline. There were no significant differences in albumin, alanine aminotransferase, aspartate aminotransferase, bilirubin, prothrombin time, or Child-Pugh score before and after operation. In all patients, rebleeding rates were 3%, 6%, 12%, 18%, and 18% at 1, 3, 6, 12, and 18 mo, respectively. Five patients (6.2%) were diagnosed as having hepatic encephalopathy. The rates of shunt dysfunction were 0%, 4%, 9%, 26%, and 26%, at 1, 3, 6, 12, and 18 mo, respectively. The cumulative survival rates in 1, 3, 6, 12, and 18 mo were 100%, 100%, 95%, 90%, and 90%, respectively. CONCLUSION: Our preliminary results indicated that the efficacy and safety of TIPS + SEVE were satisfactory in cirrhotic patients with GVB associated with a GRVS (GVB + GRVS). PMID:27458505

  5. Depiction of ventriculoperitoneal shunt obstruction with single-photon emission computed tomography/computed tomography

    PubMed Central

    Aksoy, Sabire Yılmaz; Vatankulu, Betül; Uslu, Lebriz; Halac, Metin

    2016-01-01

    An 83-year-old male patient with ventriculoperitoneal shunt underwent radionuclide shunt study using single-photon emission computed tomography/computed tomography (SPECT/CT) to evaluate the shunt patency. The planar images showed activity at the cranial region and spinal canal but no significant activity at the peritoneal cavity. However, SPECT/CT images clearly demonstrated accumulation of activity at the superior part of bifurcation level with no activity at the distal end of shunt as well as no spilling of radiotracer into the peritoneal cavity indicating shunt obstruction. SPECT/CT makes the interpretation of radionuclide shunt study more accurate and easier as compared with traditional planar images. PMID:27385906

  6. Development of chronic hepatocerebral degeneration eight years after a distal splenorenal (Warren) shunt.

    PubMed Central

    Bleasel, A F; Waugh, R C; McCaughan, G W

    1989-01-01

    It is well known that chronic encephalopathy may be a major complication after the establishment of a surgical portal caval shunt for an episode of variceal haemorrhage. In an effort to minimise this problem Warren and colleagues developed the distal splenorenal shunt where the portal and mesenteric blood flow to the liver was left intact. It is now recognised, however, that the longterm incidence of encephalopathy may be no different with this type of shunt compared with conventional surgical portal systemic shunts. Acquired chronic hepatocerebral degeneration has not been reported after such a selective shunt. A patient with primary biliary cirrhosis is reported who developed the clinical features of this syndrome eight years after a successful distal splenorenal shunt. Images Fig. 1 Fig. 2 PMID:2583570

  7. Ventriculoatrial shunt catheter displacement in a child with partial anomalous pulmonary venous return: case report.

    PubMed

    Elhammady, Mohamed Samy A; Benglis, David M; Bhatia, Sanjiv; Sandberg, David I; Ragheb, John

    2008-07-01

    Ventriculoatrial (VA) shunts remain the most used alternative to ventriculoperitoneal shunts in infants with hydrocephalus. The authors report a case of an acute VA shunt malfunction as a result of distal catheter displacement in an 18-month-old girl with partial anomalous pulmonary venous return. The child presented with respiratory compromise, and a chest radiograph revealed a lung infiltrate and normal position of the distal shunt catheter tip. Computed tomography demonstrated stable ventricle size in comparison with previous studies. As the patient's respiratory distress progressed, she required intubation, mechanical ventilation with high airway pressures and inspired oxygen concentrations, muscle relaxants, and sedation. A routine morning chest radiograph several days after admission revealed displacement of the distal catheter into the left innominate vein. Later that day the child's pupils were noted to be large and unreactive and a distal shunt malfunction was diagnosed. Complications of VA shunts and the presumed mechanism by which the catheter became displaced are discussed. PMID:18590399

  8. A multi-stack simulation of shunt currents in vanadium redox flow batteries

    NASA Astrophysics Data System (ADS)

    Wandschneider, F. T.; Röhm, S.; Fischer, P.; Pinkwart, K.; Tübke, J.; Nirschl, H.

    2014-09-01

    A model for the shunt currents in an all-vanadium redox flow battery consisting of 3 stacks which are electrically connected in series. It is based on an equivalent circuit which treats the shunt current pathways as Ohmic resistors. The conductivity of the vanadium electrolyte has been measured for different state-of-charges in order to implement a dependency of the resistances on the state-of-charge of the system. Published results are used to validate the simulation data of a single stack. Three setups of pipe networks are evaluated using the model. The pipe connections between the stacks give rise to external shunt currents, which also increase the amount of shunt currents within the stacks. These connections also lead to a nonuniform distribution of the shunt currents. The effects of the shunt currents on the Coulombic efficiency and the energy efficiency of the system are studied by the means of the model.

  9. Thoracic complications of ventriculoperitoneal shunts: case report and review of the literature.

    PubMed

    Taub, E; Lavyne, M H

    1994-01-01

    Thoracic complications of ventriculoperitoneal shunts are rare, but potentially serious. The authors report a case of a drainage of cerebrospinal fluid into the tracheobronchial tree through a peritoneal shunt catheter that migrated into the chest. After injection of contrast material into the shunt, a plain radiograph of the chest revealed a bronchogram. The symptoms resolved after a revision of the shunt. Published case reports of this and other thoracic complications of ventriculoperitoneal shunts are comprehensively reviewed. A classification of such complications into three types is proposed as follows: intrathoracic trauma during placement of a shunt, migration of the peritoneal catheter into the chest (by either a supradiaphragmatic or a transdiaphragmatic route), and pleural effusion accompanying cerebrospinal fluid ascites. The possible mechanisms and contributing factors are discussed. PMID:8121558

  10. Chemoembolic Hepatopulmonary Shunt Reduction to Allow Safe Yttrium-90 Radioembolization Lobectomy of Hepatocellular Carcinoma

    SciTech Connect

    Gaba, Ron C.; VanMiddlesworth, Kyle A.

    2012-12-15

    Yttrium-90 ({sup 90}Y) radioembolization represents an emerging transcatheter treatment option for the management of hepatocellular carcinoma (HCC). Elevation of the hepatopulmonary shunt fraction risks nontarget radiation to the lungs and may limit the use of {sup 90}Y therapy in patients with locally advanced disease with vascular invasion, who often demonstrate increased shunting. We present two cases in which patients with HCC and portal vein invasion resulting in elevated hepatopulmonary shunt fractions underwent chemoembolic shunt closure to allow safe {sup 90}Y radioembolization. Both patients demonstrated excellent tumor response and patient survival. On this basis, we propose a role for chemoembolic reduction of the lung shunt fraction before {sup 90}Y radioembolization in patients with extensive tumor-related hepatopulmonary shunting.

  11. Tension pneumocephalus complicating ventriculoperitoneal shunt for cerebrospinal fluid rhinorrhoea: case report.

    PubMed

    Ikeda, K; Nakano, M; Tani, E

    1978-04-01

    A case of spontaneous nontraumatic cerebrospinal fluid rhinorrhoea secondary to aqueductal stenosis is reported. The patient required direct repair of the fistula after the insertion of a ventriculoperitoneal shunt for aqueductal stenosis. We emphasise an unusual complication of tension pneumocephalus in a case where the shunt patency had been substantiated. Intracranial pressure fall due to the siphon effect in the ventriculoperitoneal shunt tubing in the erect position might be responsible for ingress of an excessive amount of air. PMID:650239

  12. Management for traumatic chronic subdural hematoma patients with well-controlled shunt system for hydrocephalus

    PubMed Central

    Yamada, Shoko Mitrrt; Tomia, Yusuke; Murakami, Hideki; Nakane, Makoto

    2015-01-01

    Key Clinical Message Traumatic CSDH enlarged in two cases with VP or LP shunt system although the shunt valve pressure was increased to 200 mmH2O. In surgery, the hematoma cavity pressure was found to be 130 and 140 mmH2O, suggesting that to raise the shunt valve pressure is not effective for decreasing CSDH volume. PMID:26273439

  13. Reversibility of intrapulmonary arteriovenous shunts in liver cirrhosis documented by serial radionuclide perfusion lung scans

    SciTech Connect

    Chen, N.S.; Barnett, C.A.; Farrer, P.A.

    1984-05-01

    Using serial perfusion lung scans, the opening up and closure of right-to-left intrapulmonary arteriovenous shunts has been documented over a period of several weeks in a patient with chronic alcoholic liver disease. The presence of the shunts correlates well with the severity of hypoxemia and the presence of nodular mottling on chest radiographs. The time course of these changes with clinical status suggests lability and the functional nature of these shunts.

  14. Distribution of extrahepatic congenital portosystemic shunt morphology in predisposed dog breeds

    PubMed Central

    2012-01-01

    Background An inherited basis for congenital extrahepatic portosystemic shunts (EHPSS) has been demonstrated in several small dog breeds. If in general both portocaval and porto-azygous shunts occur in breeds predisposed to portosystemic shunts then this could indicate a common genetic background. This study was performed to determine the distribution of extrahepatic portocaval and porto-azygous shunts in purebred dog populations. Results Data of 135 client owned dogs diagnosed with EHPSS at the Faculty of Veterinary Medicine of Utrecht University from 2001 – 2010 were retrospectively analyzed. The correlation between shunt localization, sex, age, dog size and breed were studied. The study group consisted of 54 males and 81 females from 24 breeds. Twenty-five percent of dogs had porto-azygous shunts and 75% had portocaval shunts. Of the dogs with porto-azygous shunts only 27% was male (P = 0.006). No significant sex difference was detected in dogs with a portocaval shunt. Both phenotypes were present in almost all breeds represented with more than six cases. Small dogs are mostly diagnosed with portocaval shunts (79%) whereas both types are detected. The age at diagnosis in dogs with porto-azygous shunts was significantly higher than that of dogs with portocaval shunts (P < 0.001). Conclusion The remarkable similarity of phenotypic variation in many dog breeds may indicate common underlying genes responsible for EHPSS across breeds. The subtype of EHPSS could be determined by a minor genetic component or modulating factors during embryonic development. PMID:22784395

  15. Breast Capsular Cerebrospinal Fluid Collection from Migration of a Ventriculoperitoneal Shunt Catheter

    PubMed Central

    Knaus, William J.; Kamali, Parisa; Chun, Yoon

    2016-01-01

    Summary: In this case report we have described an unusual complication of ventriculoperitoneal shunt migration into a breast implant capsule. The patient was appropriately diagnosed with computed tomographic imaging and successfully managed with shunt revision and cerebrospinal fluid aspiration. Given the high complication profile of ventriculoperitoneal shunt catheters, this case suggests an opportunity for improved perioperative communication between plastic surgeons and neurosurgeons in patients with breast implants. Coordination regarding the subcutaneous catheter tunneling may hopefully minimize the risk of this complication. PMID:27257570

  16. Embolization of portal-systemic shunts in cirrhotic patients with chronic recurrent hepatic encephalopathy

    SciTech Connect

    Sakurabayashi, Shin; Sezai, Shuichi; Yamamoto, Yoshihiro; Hirano, Masanori; Oka, Hiroshi

    1997-03-15

    Purpose. To evaluate the efficacy of embolization of portal-systemic shunts in cirrhotic patients with chronic recurrent hepatic encephalopathy (CRHE). Methods. Seven cirrhotic patients with CRHE refractory to medical treatment (3 men and 4 women, mean age 66 years) were studied. Five patients had splenorenal shunts, 1 had a gastrorenal shunt, and 1 had an intrahepatic portal vein-hepatic vein shunt. Shunt embolization was performed using stainless steel coils, with a percutaneous transhepatic portal vein approach in 4 patients and a transrenal vein approach in 3 patients. Results. After embolization, the shunt disappeared in 4 patients on either ultrasound pulsed Doppler monitoring or portography. Complications observed in the 7 patients were fever, transient pleural effusion, ascites, and mild esophageal varices. For 3-6 months after embolization, the 4 patients whose shunts disappeared showed minimal or no reappearance of a shunt, and had no recurrence of encephalopathy. The serum ammonia levels decreased and electroencephalograms also improved. One of the 4 patients, who developed mild esophageal varices, required no treatment. Treatment was effective in 3 of the 4 patients (75%) who underwent embolization via a transhepatic portal vein. Conclusion. Transvascular embolization of shunts improved the outcome in 4 of 7 patients. The most effective embolization was achieved via the percutaneous transhepatic portal vein approach.

  17. Optimization of shunt placement for the Norwood surgery using multi-domain modeling.

    PubMed

    Moghadam, Mahdi Esmaily; Migliavacca, Francesco; Vignon-Clementel, Irene E; Hsia, Tain-Yen; Marsden, Alison L

    2012-05-01

    An idealized systemic-to-pulmonary shunt anatomy is parameterized and coupled to a closed loop, lumped parameter network (LPN) in a multidomain model of the Norwood surgical anatomy. The LPN approach is essential for obtaining information on global changes in cardiac output and oxygen delivery resulting from changes in local geometry and physiology. The LPN is fully coupled to a custom 3D finite element solver using a semi-implicit approach to model the heart and downstream circulation. This closed loop multidomain model is then integrated with a fully automated derivative-free optimization algorithm to obtain optimal shunt geometries with variable parameters of shunt diameter, anastomosis location, and angles. Three objective functions: (1) systemic; (2) coronary; and (3) combined systemic and coronary oxygen deliveries are maximized. Results show that a smaller shunt diameter with a distal shunt-brachiocephalic anastomosis is optimal for systemic oxygen delivery, whereas a more proximal anastomosis is optimal for coronary oxygen delivery and a shunt between these two anatomies is optimal for both systemic and coronary oxygen deliveries. Results are used to quantify the origin of blood flow going through the shunt and its relationship with shunt geometry. Results show that coronary artery flow is directly related to shunt position. PMID:22757490

  18. The role of persistent foramen ovale and other shunts in decompression illness.

    PubMed

    Wilmshurst, Peter T

    2015-06-01

    A persistent foramen ovale (PFO) and other types of right-to-left shunts are associated with neurological, cutaneous and cardiovascular decompression illness (DCI). A right-to-left shunt is particularly likely to be implicated in causation when these types of DCI occur after dives that are not provocative. It is believed that venous nitrogen bubbles that form after decompression pass through the shunt to circumvent the lung filter and invade systemic tissues supersaturated with nitrogen (or other inert gas) and as a result there is peripheral amplification of bubble emboli in those tissues. Approximately a quarter of the population have a PFO, but only a small proportion of the population with the largest right-to-left shunts are at high risk of shunt-mediated DCI. The increased risk of DCI in people with migraine with aura is because migraine with aura is also associated with right-to-left shunts and this increased risk of DCI appears to be confi ned to those with a large PFO or other large shunt. Various ultrasound techniques can be used to detect and assess the size of right-to-left shunts by imaging the appearance of bubble contrast in the systemic circulation after intravenous injection. In divers with a history of shunt-mediated DCI, methods to reduce the risk of recurrence include cessation of diving, modification of future dives to prevent venous bubble liberation and transcatheter closure of a PFO. PMID:26165532

  19. Combined phacoemulsification with ExPRESS shunt in angle closure glaucoma

    PubMed Central

    Rao, Aparna

    2015-01-01

    Summary A 60-year-old woman diagnosed with primary angle closure glaucoma with extensive peripheral anterior synechiae (PAS) and advanced glaucomatous optic neuropathy unresponsive to maximal medical treatment, underwent clear corneal phacoemulsification and ExPRESS (Alcon Inc, Fort Worth, TX) shunt surgery in the right eye with intraoperative placement tailored to avoid areas of PAS. Postoperatively her visual acuity in the right eye was 20/20 and intraocular pressure was 13 mm Hg with the shunt in place and functioning bleb at final follow-up. The ExPRESS shunt can be used in angle closure eyes with good outcomes after proper placement of the shunt.

  20. Gold shunt for refractory advanced low-tension glaucoma with spared central acuity

    PubMed Central

    Le, Ryan; Gupta, Neeru

    2016-01-01

    The aim of this study is to report a case of gold shunt surgery for uncontrolled, low-tension glaucoma with good central vision, after having a previously failed trabeculectomy and tube shunt surgeries. The patient was receiving maximum medical glaucoma therapy of four different types with intraocular pressure of 17 mm Hg prior to gold shunt surgery. Five years later, intraocular pressure is well controlled in the low teens without the need for ocular medications, and glaucoma is stable following gold shunt surgery. PMID:27051320

  1. Interatrial shunt flow profiles in newborn infants: a colour flow and pulsed Doppler echocardiographic study.

    PubMed Central

    Hiraishi, S; Agata, Y; Saito, K; Oguchi, K; Misawa, H; Fujino, N; Horiguchi, Y; Yashiro, K

    1991-01-01

    Interatrial shunt flow profiles in 36 normal term infants were examined serially by colour flow and pulsed Doppler echocardiographic techniques from within an hour of birth to four or five days after birth. Shunt flow across the foramen ovale was detected in 33 normal infants (92%) within an hour of birth (mean 40 minutes). The occurrence of interatrial shunting decreased with age, but a shunt signal was still detected in 17 infants (47%) on the fourth or fifth day of life, by then the ductus arteriosus had already closed in all the normal infants. The direction of interatrial shunt flow was predominantly left-to-right, but in 64% there was a coexistent small right-to-left shunt in diastole within an hour of birth; by four to five days it was found in 19%. In the six patients with persistent fetal circulation the direction of the interatrial shunt flow was predominantly right-to-left with biphasic peaks in diastole and systole at the early stage of the disease, and the period of right-to-left shunt flow during each cardiac cycle was significantly longer than that in normal infants examined within 1 hour of birth. In all patients the ductus closed before the foramen ovale. At the time of ductal closure in all patients with persistent fetal circulation right-to-left shunt flow was seen during diastole and its period was still prolonged. These findings suggest that interatrial shunting, predominantly left-to-right, is common in normal newborn infants. Evaluation of the characteristics of the interatrial shunt by Doppler echocardiography may be useful for predicting the progress of or improvement in neonates with persistent fetal circulation. Images PMID:1993129

  2. Shunting arc plasma source for pure carbon ion beam.

    PubMed

    Koguchi, H; Sakakita, H; Kiyama, S; Shimada, T; Sato, Y; Hirano, Y

    2012-02-01

    A plasma source is developed using a coaxial shunting arc plasma gun to extract a pure carbon ion beam. The pure carbon ion beam is a new type of deposition system for diamond and other carbon materials. Our plasma device generates pure carbon plasma from solid-state carbon material without using a hydrocarbon gas such as methane gas, and the plasma does not contain any hydrogen. The ion saturation current of the discharge measured by a double probe is about 0.2 mA∕mm(2) at the peak of the pulse. PMID:22380206

  3. A theoretical and experimental study of coplanar waveguide shunt stubs

    NASA Technical Reports Server (NTRS)

    Dib, Nihad I.; Ponchak, George E.; Katehi, Linda P. B.

    1993-01-01

    A comprehensive theoretical and experimental study of straight and bent coplanar waveguide (CPW) shunt stubs is presented. In the theoretical analysis, the CPW is assumed to be inside a cavity while, the experiments are performed on open structures. For the analysis of CPW discontinuities with air-bridges, a hybrid technique was developed which was validated through extensive theoretical and experimental comparisons. The effect of the cavity resonances on the behavior of the stubs with and without air-bridges is investigated. In addition, the encountered radiation loss due to the discontinuities is evaluated experimentally.

  4. Shunting arc plasma source for pure carbon ion beama)

    NASA Astrophysics Data System (ADS)

    Koguchi, H.; Sakakita, H.; Kiyama, S.; Shimada, T.; Sato, Y.; Hirano, Y.

    2012-02-01

    A plasma source is developed using a coaxial shunting arc plasma gun to extract a pure carbon ion beam. The pure carbon ion beam is a new type of deposition system for diamond and other carbon materials. Our plasma device generates pure carbon plasma from solid-state carbon material without using a hydrocarbon gas such as methane gas, and the plasma does not contain any hydrogen. The ion saturation current of the discharge measured by a double probe is about 0.2 mA/mm2 at the peak of the pulse.

  5. Perturbation theory for a resistivity shunted Josephson element

    NASA Technical Reports Server (NTRS)

    Thompson, E. D.

    1973-01-01

    We present a systematic perturbation theory, extendable in principle to all orders of magnitude, for the solution of the equations of motion of an ideal Josephson element shunted by a resistance and driven by a dc current source and a small time-dependent source. We present second-order results for the case in which the time dependence is that of a single sinusoid, and these results are compared with other numerical and analytical calculations. Near, but not on, the first constant voltage step where the perturbation theory appears divergent, the current-voltage characteristic is calculated by means of a nonperturbative adiabatic procedure. The impedance and responsivity agree with earlier results.

  6. [PERITONEAL VENOUS SHUNT IN THE TREATMENT OF MALIGNANTASCITIS: PRELIMINARY REPORT

    PubMed

    Brazzini, Augusto; Cantella, Raúl

    1998-01-01

    The present study, mentions the use of a valve for the drainage os ascitic fluid, better known as the peritoneo venous shunt, as a paliation treatment in terminal oncologic patients. It was performed in four patients with diseminated carcinomas, of diferent primary ethiology. These patients had a bad life quality, because when admitted in our Radiology suite, the clinical examination showed shortness of breathearly saciety, lethargy, and were found handiccapped to perform their habitual skills. This is a short and preliminar series, but it is an encouraging report, because, the quality of life, our goal, is improved. PMID:12209221

  7. Piezoelectric vibration damping using resonant shunt circuits: an exact solution

    NASA Astrophysics Data System (ADS)

    Soltani, P.; Kerschen, G.; Tondreau, G.; Deraemaeker, A.

    2014-12-01

    The objective of this paper is to propose an exact closed-form solution to the {{H}∞ } optimization of piezoelectric materials shunted with inductive-resistive passive electrical circuits. Realizing that Den Hartog's method which imposes fixed points of equal height in the receptance transfer function is approximate, the parameters of the piezoelectric tuned vibration absorber are calculated through the direct minimization of the maxima of the receptance. The method is applied to a one-degree-of-freedom primary oscillator considering various values of the electromechanical coupling coefficients.

  8. The Transjugular Intrahepatic Portosystemic Shunt: Technique and Instruments.

    PubMed

    Keller, Frederick S; Farsad, Khashayar; Rösch, Josef

    2016-03-01

    Although transjugular intrahepatic portosystemic shunt (TIPS) was first described in 1971, it took 15 more years for technology, in the form of expandable metallic stents, to be developed to make TIPS a viable, widespread clinical procedure. Currently, expanded polytetrafluoroethylene-covered stent grafts that exhibit significantly greater long-term patency are used for TIPS creation by most interventionalists. TIPS creation requires specific interventional skills, tools, and devices for success. In the hands of skillful, experienced interventional radiologists, TIPS creation is performed safely and successfully in greater than 95% of cases. PMID:26997084

  9. Transcatheter closure of modified Blalock-Taussig shunt with Gianturco-Grifka Vascular Occlusion Device.

    PubMed

    Hoyer, M H; Leon, R A; Fricker, F J

    1999-12-01

    A 15-year-old girl with previous repair of a complex cyanotic congenital heart defect had persistence of a modified left Blalock-Taussig shunt that could not be ligated at surgery. Six years later, antegrade delivery of a Gianturco-Grifka Vascular Occlusion Device resulted in complete closure of the shunt. Cathet. Cardiovasc. Intervent. 48:365-367, 1999. PMID:10559814

  10. Visual disturbance following shunt malfunction in a patient with congenital hydrocephalus.

    PubMed

    Oyama, Hirofumi; Hattori, Kenichi; Kito, Akira; Maki, Hideki; Noda, Tomoyuki; Wada, Kentaro

    2012-01-01

    A 25-year-old woman presented with complaints of nausea and headache. She had been treated with a ventriculoperitoneal shunt for hydrocephalus when she was 7 months old. Her bilateral optic discs showed moderate atrophy. Right visual acuity allowed only perception of hand movement and left visual acuity was 0.02 (1.2). Computed tomography (CT) showed mild ventricular dilation but no periventricular lucency. Intracranial pressure (ICP) was not high when the shunt valve was punctured. Her visual acuity deteriorated 5 days after the consultation. She was referred again 8 days after the first consultation. The bilateral optic discs were completely pale. Both pupils were dilated on admission, and the bilateral direct light reflexes were absent. The patient could slightly detect only green light stimulus. CT showed moderate enlargement of the ventricle. ICP was 47 cmH(2)O when the shunt valve was punctured. Shuntgraphy showed obstruction of the shunt at the distal end of peritoneal catheter. Emergent total shunt revision was performed. She could detect dark stimulus and the still-dilated left pupil had recovered direct light reflex on the next day. The visual acuity was 0.01 (0.7) on the left 6 months after the operation, although she was blind in the right eye and the bilateral optic discs were completely pale. Visual loss associated with shunt failure remains a major morbidity in shunted congenital hydrocephalus. Early diagnosis and shunt revision may allow visual recovery. PMID:23183081

  11. Role of the distal splenorenal shunt in management of variceal bleeding in Latin America.

    PubMed

    Orozco, H; Mercado, M A; Takahashi, T; García-Tsao, G; Guevara, L; Hernández Ortíz, J; Hernández-Cendejas, A; Tielve, M

    1990-07-01

    In the early 1970s, we began to perform selective shunts on a regular basis for the treatment of portal hypertension. In a 15-year period, 177 patients (155 with liver cirrhosis) were treated with 3 kinds of selective shunts: the Warren shunt (128 patients) the end-to-end splenorenal shunt (29 patients), and the splenocaval shunt (20 patients). One hundred sixty-seven of the procedures were elective. Operative mortality was 14%, and survival for the Child's class A group was 75% at 1 year, 69% at 5 years, and 65% at 15 years. Incapacitating encephalopathy was observed in 7% of the patients, rebleeding in 6%, and shunt thrombosis in 6%. Postoperative portal vein alterations included reduced venous diameter (13%) and thrombosis (21%). Experience with the Warren shunt in schistosomiasis, a disease in which normal liver function is the rule in Latin American countries, is discussed. We believe that, when feasible, the selective shunts are the treatment of choice for portal hypertension in Latin American countries. PMID:2368881

  12. Normal-pressure hydrocephalus: current understanding of diagnostic tests and shunting

    SciTech Connect

    Black, P.M.

    1982-02-01

    Normal-pressure hydrocephalus is no longer difficult to diagnose or treat-cranial computed tomographic scanning has made the diagnosis of ventricular enlargement straightforward, and shunt placement often helps the patient whose condition can be traced to a specific cause. Predicting accurately whether a patient will benefit from a shunt, however, is still problematic.

  13. Shunt Devices for the Treatment of Adult Hydrocephalus: Recent Progress and Characteristics

    PubMed Central

    MIYAKE, Hiroji

    2016-01-01

    Various types of shunt valves have been developed during the past 50 years, most of which can be classified into the following categories: (1) fixed differential pressure valves; (2) fixed differential pressure (DP) valves with an antisiphon mechanism; (3) programmable DP valves; (4) programmable DP valves with an antisiphon mechanism; and (5) programmable antisiphon valves. When considering the myriad of possible postoperative condition changes, such as the onset of accidental non-related diseases or trauma in adults, and changes in normal physiological development or anticipation of future shunt removal in children, it has become standard to use the programmable valve as a first choice for cerebrospinal fluid shunting. However, it is still unclear what type of shunt valve is suitable for each individual case. Based on the results of SINPHONI and more recently SINPHONI 2 trials, the programmable DP valve is recommended as the first line shunt valve. The programmable DP valve with an antisiphon mechanism is thought to be beneficial for tall, slender patients, who have a tendency for easily developing complications of overdrainage, however, this type of valve must be used cautiously in obese patients because of the increased risk of underdrainage. Although the current evidence is still insufficient, the programmable antisiphon valve, which costs the same as the programmable DP valve, is also thought to be the first line shunt valve. The quick reference table is applicable for most shunt valves, and for patients with either the ventriculoperitoneal or the lumboperitoneal shunt. PMID:27041631

  14. How shunting inhibition affects the discharge of lumbar motoneurones: a dynamic clamp study in anaesthetized cats

    PubMed Central

    Brizzi, L; Meunier, C; Zytnicki, D; Donnet, M; Hansel, D; d'Incamps, B Lamotte; van Vreeswijk, C

    2004-01-01

    In the present work, dynamic clamp was used to inject a current that mimicked tonic synaptic activity in the soma of cat lumbar motoneurones with a microelectrode. The reversal potential of this current could be set at the resting potential so as to prevent membrane depolarization or hyperpolarization. The only effect of the dynamic clamp was then to elicit a constant and calibrated increase of the motoneurone input conductance. The effect of the resulting shunt was investigated on repetitive discharges elicited by current pulses. Shunting inhibition reduced very substantially the firing frequency in the primary range without changing the slope of the current–frequency curves. The shift of the I–f curve was proportional to the conductance increase imposed by the dynamic clamp and depended on an intrinsic property of the motoneurone that we called the shunt potential. The shunt potential ranged between 11 and 37 mV above the resting potential, indicating that the sensitivity of motoneurones to shunting inhibition was quite variable. The shunt potential was always near or above the action potential voltage threshold. A theoretical model allowed us to interpret these experimental results. The shunt potential was shown to be a weighted time average of membrane voltage. The weighting factor is the phase response function of the neurone that peaks at the end of the interspike interval. The shunt potential indicates whether mixed synaptic inputs have an excitatory or inhibitory effect on the ongoing discharge of the motoneurone. PMID:15169842

  15. Scintigraphic evaluation of hepatic blood flow after intrahepatic portosystemic shunt (TIPS).

    PubMed

    Menzel, J; Schober, O; Reimer, P; Domschke, W

    1997-06-01

    In patients with liver cirrhosis a transjugularly placed intrahepatic portocaval shunt (TIPS) is a non-surgical portosystemic device which aims to reduce portal venous pressure. In comparison with Doppler sonography, we evaluated in 28 patients the diagnostic impact of liver perfusion scintigraphy (with technetium-99m diethylene triamine penta-acetic acid) in the assessment of changes in the hepatic blood flow after TIPS shunting. The arterial and portal contributions to hepatic flow were calculated from the areas under the biphasic time-activity curve. In the course of TIPS shunting, patency is threatened by reocclusion. Angiography is the gold standard for TIPS shunt reassessment. However, there is a need for a less invasive diagnostic procedure, such as scintigraphy or Doppler sonography, for the early detection of shunt insufficiency. Scintigraphy demonstrated that prior to TIPS shunting the portal venous contribution to hepatic perfusion was reduced to 29.2%, this reduction being due to portal hypertension. After TIPS placement a significant increase in portal venous perfusion was observed (38.2%; P<0.02). TIPS shunt occlusion was identified in patients by a significant reduction in the scintigraphically measured portal venous contribution to hepatic blood flow. Hepatic perfusion scintigraphy appears to be a valuable method to determine the immediate effect of TIPS on hepatic blood flow. Post-TIPS follow-up studies of hepatic haemodynamics by liver perfusion scintigraphy appear able to contribute to the detection of TIPS shunt occlusion before the clinical consequences of this complication have become apparent. PMID:9169570

  16. Reasons, procedures, and outcomes in ventriculoatrial shunts: A single-center experience

    PubMed Central

    Yavuz, Celal; Demırtas, Sinan; Calıskan, Ahmet; Kamasak, Kaan; Karahan, Oguz; Guclu, Orkut; Yazıcı, Suleyman; Mavıtas, Binali

    2013-01-01

    Background: Ventricular shunts are used to drain cerebrospinal fluid into extra-cranial spaces. Ventriculoatrial (VA) shunts are provided to transfer cerebrospinal fluid from the cerebral ventricle into the right atrium of the heart. A single center experience of indications, procedure, and clinical outcomes in VA shunt was presented in current study. Methods: VA shunts were applied in 10 patients who had repeated previous shunt dysfunction or infection. The reasons, clinical findings, replacement methods, and postoperative clinical follow-ups and outcomes were recorded retrospectively. Results: There were seven female (70%) and three (30%) male patients; their ages ranged from 5 to 13 years (mean ± SD; 8.5 ± 2.6 years). Shunt re-placement reasons were as follows: Shunt occlusion in five patients, intraperitoneal infection in four patients and a distal catheter was kinked and knotted in one patient. Postoperative early complications were seen in one patient as early catheter thrombosis and catheter revision were applied. Late complications were seen in two patients as follows: Catheter infection and infective endocarditis occurred in one patient and pulmonary thrombus occurred in one other patient. There was not any catheter-related mortality observed at the one year follow-up period. Conclusion: VA shunts may be an option for cerebrospinal fluid drainage at necessary conditions. However, sterilization and general training on asepsy and antisepsy are the most important determinants affecting the clinical outcome due to the cardio systemic relationship. PMID:23493480

  17. Shunt Devices for the Treatment of Adult Hydrocephalus: Recent Progress and Characteristics.

    PubMed

    Miyake, Hiroji

    2016-05-15

    Various types of shunt valves have been developed during the past 50 years, most of which can be classified into the following categories: (1) fixed differential pressure valves; (2) fixed differential pressure (DP) valves with an antisiphon mechanism; (3) programmable DP valves; (4) programmable DP valves with an antisiphon mechanism; and (5) programmable antisiphon valves. When considering the myriad of possible postoperative condition changes, such as the onset of accidental non-related diseases or trauma in adults, and changes in normal physiological development or anticipation of future shunt removal in children, it has become standard to use the programmable valve as a first choice for cerebrospinal fluid shunting. However, it is still unclear what type of shunt valve is suitable for each individual case. Based on the results of SINPHONI and more recently SINPHONI 2 trials, the programmable DP valve is recommended as the first line shunt valve. The programmable DP valve with an antisiphon mechanism is thought to be beneficial for tall, slender patients, who have a tendency for easily developing complications of overdrainage, however, this type of valve must be used cautiously in obese patients because of the increased risk of underdrainage. Although the current evidence is still insufficient, the programmable antisiphon valve, which costs the same as the programmable DP valve, is also thought to be the first line shunt valve. The quick reference table is applicable for most shunt valves, and for patients with either the ventriculoperitoneal or the lumboperitoneal shunt. PMID:27041631

  18. Evaluation of LeVeen-shunt patency using Tc-99m labelled macroaggregated albumin.

    PubMed

    Adil, Allah Rakha; Waqar, Amin

    2005-12-01

    A LeVeen peritoneo-venous shunt is placed for intractable ascites. Determination of obstruction site in the shunt tube is a difficult problem. We describe a simple nuclear medicine method using 111MBq (3mCi) of Technetium-99m labeled macro-aggregated albumin injected intraperitoneally. PMID:16398982

  19. Ventriculoperitoneal shunt for treatment of hydrocephalus in a French bulldog puppy

    PubMed Central

    Giacinti, Jolene A.

    2016-01-01

    A 6.5-week-old bulldog was presented with lethargy, anorexia, and stunted growth. A domed skull, ventrolateral strabismus, hypermetria, and delayed hopping were observed. Congenital hydrocephalus was diagnosed and a ventriculoperitoneal shunt was placed. After surgery, a shunt obstruction occurred but resolved with treatment. The puppy responded well and neurological deficits continued to improve after surgery. PMID:26933271

  20. Shunt currents in vanadium flow batteries: Measurement, modelling and implications for efficiency

    NASA Astrophysics Data System (ADS)

    Fink, H.; Remy, M.

    2015-06-01

    Shunt currents are an important factor which must be considered when designing a stack for flow batteries. They lead to a reduction of the coulombic efficiency and can cause furthermore a critical warming of the electrolyte. Shunt currents inevitably appear at bypass connections of the hydraulic system between the single cells of a stack. In this work the shunt currents of a five-celled mini stack of a vanadium flow battery with external hydraulic system and their effects are investigated directly. The external hydraulic system allows the implementation of current sensors for direct measurement of the shunt currents; moreover, the single bypass channels can be interrupted by clamping the tube couplings and with it the shunt currents between the cells when the pumps are off. Thus the shares of losses by cross contamination and by shunt currents are quantified separately by charge conservation measurements. The experimentally gained data are compared to a shunt current model based on a equivalent circuit diagram and the linear equation system derived from it. Experiments and model data are in good agreement. The effects of shunt currents for different flow frame geometries and number of cells in a stack are simulated and presented in this work.

  1. Electroacoustic absorbers: bridging the gap between shunt loudspeakers and active sound absorption.

    PubMed

    Lissek, Hervé; Boulandet, Romain; Fleury, Romain

    2011-05-01

    The acoustic impedance at the diaphragm of an electroacoustic transducer can be varied using a range of basic electrical control strategies, amongst which are electrical shunt circuits. These passive shunt techniques are compared to active acoustic feedback techniques for controlling the acoustic impedance of an electroacoustic transducer. The formulation of feedback-based acoustic impedance control reveals formal analogies with shunt strategies, and highlights an original method for synthesizing electric networks ("shunts") with positive or negative components, bridging the gap between passive and active acoustic impedance control. This paper describes the theory unifying all these passive and active acoustic impedance control strategies, introducing the concept of electroacoustic absorbers. The equivalence between shunts and active control is first formalized through the introduction of a one-degree-of-freedom acoustic resonator accounting for both electric shunts and acoustic feedbacks. Conversely, electric networks mimicking the performances of active feedback techniques are introduced, identifying shunts with active impedance control. Simulated acoustic performances are presented, with an emphasis on formal analogies between the different control techniques. Examples of electric shunts are proposed for active sound absorption. Experimental assessments are then presented, and the paper concludes with a general discussion on the concept and potential improvements. PMID:21568400

  2. 21 CFR 882.5550 - Central nervous system fluid shunt and components.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Central nervous system fluid shunt and components. 882.5550 Section 882.5550 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... shunt is a device or combination of devices used to divert fluid from the brain or other part of...

  3. 21 CFR 882.5550 - Central nervous system fluid shunt and components.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Central nervous system fluid shunt and components. 882.5550 Section 882.5550 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... shunt is a device or combination of devices used to divert fluid from the brain or other part of...

  4. 21 CFR 882.5550 - Central nervous system fluid shunt and components.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Central nervous system fluid shunt and components. 882.5550 Section 882.5550 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... shunt is a device or combination of devices used to divert fluid from the brain or other part of...

  5. 21 CFR 882.5550 - Central nervous system fluid shunt and components.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Central nervous system fluid shunt and components. 882.5550 Section 882.5550 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... shunt is a device or combination of devices used to divert fluid from the brain or other part of...

  6. 21 CFR 882.5550 - Central nervous system fluid shunt and components.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Central nervous system fluid shunt and components. 882.5550 Section 882.5550 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... shunt is a device or combination of devices used to divert fluid from the brain or other part of...

  7. Transjugular Intrahepatic Portosystemic Shunts in Children with Biliary Atresia

    SciTech Connect

    Huppert, Peter E.; Goffette, Pierre; Sokal, Emil M.; Schweizer, Paul; Claussen, Claus D.

    2002-12-15

    Purpose: We retrospectively evaluated the technical and long-term clinical results of transjugularintrahepatic portosystemic shunts (TIPS) in children with portal hypertension and biliary atresia (BA). Methods: Nine children with BA and recurrent bleeding from esophagogastric and/or intestinal varices were treated by TIPS at the age of 34-156 months and followed-up in two centers. Different types of stents were used. Results: Shunt insertion succeeded in all patients, but in two a second procedure was necessary. Seven procedures lasted more than 3 hr, mainly due to difficult portal vein puncture.Variceal bleeding ceased in all patients; however, 16 reinterventions were performed in eight patients for clinical reasons (n =11) and sonographically suspected restenosis (n =5). Four patients underwent successful liver transplantation 4-51 months after TIPS and five are in good clinical conditions 64-75 months after TIPS. Conclusions: TIPS in children with BA is technically difficult, mainly due to periportal fibrosis and small portal veins. Frequency of reinterventions seems to be higher compared with adults.

  8. Transjugular Intrahepatic Portosystemic Shunt (TIPS): Current Status and Future Possibilities

    SciTech Connect

    Bilbao, Jose Ignacio; Quiroga, Jorge; Herrero, Jose Ignacio; Benito, Alberto

    2002-08-15

    Since the insertion of the first TIPS in 1989 much has been learned about this therapeutic procedure. It has an established role for the treatment of some complications of portal hypertension: prevention of recurrent variceal bleeding and rescue of patients with acute uncontrollable variceal bleeding. In addition TIPS is useful for Budd-Chiari syndrome, refractory ascites and hepatorenal syndrome, although its specific role in these indications remains to be definitively established. However, the decrease in sinusoidal blood flow induced by TIPS can lead to the patient developing hepatic encephalopathy and liver failure in some cases. Therefore, TIPS should be used with caution in patients with very poor liver function. From a technical point of view, successful placement of TIPS is achieved in more than 98% of cases by experienced groups. At present, evaluation of TIPS dysfunction based on morphology probably leads to an overdiagnosis of this complication since most of these cases are not associated with clinical manifestations (recurrent bleeding or refractory ascites). The major disadvantage of TIPS remains its poor long-term patency requiring a mandatory surveillance program. The indicator for shunt function/malfunction should be the portosystemic pressure gradient, which is best assessed by intravascular measurements. Shunt obstructions may be prevented or reduced by the use of stent-grafts in the future.

  9. Shunt volume dynamics in stroke patients with patent foramen ovale.

    PubMed

    Reichenberger, F; Kaps, M; Seeger, W; Tanislav, C

    2013-09-01

    A variation in right atrial and pulmonary arterial pressure might result in a shunt dynamic across a patent foramen ovale (PFO). In the present study we tested if peak exercise facilitates a restoration of right to left shunt (RLS) in stroke patients who demonstrated a functional PFO closure (no evidence of RLS across an initially demonstrated PFO). In stroke patients with PFO demonstrating a functional closure, the RLS was reassessed on peak exercise using contrast-enhanced transcranial Doppler sonography. The exercise procedure consisted of a cardiopulmonary exercise test with supplementary stress echocardiography for assessment of pulmonary circulation. Four stroke patients with initially PFO curtain pattern and a subsequent functional PFO closure (no evidence for RLS) underwent the procedure. In all four patients a RLS could be resurrected during peak physical exercise after a Valsalva strain. While in two patients peak exercise led to an RLS in a countable range of microembolic signals, in two patients a curtain pattern was obtained. One patient showed evidence for reoccurrence of RLS on peak exercise without a Valsalva strain. The patients with curtain pattern had a better peak exercise performance. Although the systolic pulmonary arterial pressure increased during exercise in all patients, there was no direct correlation with the detected RLS. After a functional PFO closure peak exercise combined with a Valsalva strain facilitates the reoccurrence of RLS in stroke patients. PMID:23743402

  10. Fabrication and characterization of shunted μ-SQUID

    SciTech Connect

    Kumar, Nikhil; Fournier, T.; Courtois, H.; Gupta, Anjan K.

    2014-04-24

    In order to eliminate hysteresis, we have fabricated and characterized niobium based shunted micron size superconducting quantum interference devices (μ-SQUIDs). We find a wide temperature range where these μ-SQUIDs are non-hysteretic in nature and show a very good I{sub c} vs. B oscillations in hysteretic regime and V vs. B oscillations in non-hysteretic regime. Here we report the characteristics of a shunted- μ-SQUID (Wf38LS72D5). In this device we have achieved a large voltage modulation, in non-hysteretic regime, at various temperatures including such as 1.1 mV at 6.62 K with a transfer function V{sub Φ} = 7.2mV/Φ{sub 0}. The figures within the original article PDF file, as supplied to AIP Publishing, were affected by a PDF-processing error. Consequently, the article re-flowed and pagination increased from 3 to 4 pages. This article was updated on 14 May 2014 to correct the PDF-processing error, with the scientific content remaining unchanged. Readers are advised that the replacement article PDF file contains an additional blank page to preserve the original pagination.

  11. Design and measurement of improved capacitively-shunted flux qubits

    NASA Astrophysics Data System (ADS)

    Sears, Adam; Birenbaum, Jeffrey; Hover, David; Gudmundsen, Theodore; Kerman, Andrew; Welander, Paul; Yoder, Jonilyn L.; Gustavsson, Simon; Jin, Xiaoyue; Kamal, Archana; Clarke, John; Oliver, William

    2014-03-01

    The addition of a capacitive or inductive shunt across one of the junctions can alter the coherence properties of a classic flux or RF-SQUID qubit. We have studied the performance of capacitively shunted flux qubits fabricated with MBE aluminum, starting from a 2D coplanar waveguide geometry used in similar high-performance transmon qubits, and measured dispersively. We will detail the importance of design parameters that preserve the flux qubit's anharmonicity and discuss conclusions about materials quality based on calculations of the participation of junction, dielectric, and superconductor components. This research was funded in part by the Office of the Director of National Intelligence (ODNI), Intelligence Advanced Research Projects Activity (IARPA); and by the Assistant Secretary of Defense for Research & Engineering under Air Force Contract number FA8721-05-C-0002. All statements of fact, opinion or conclusions contained herein are those of the authors and should not be construed as representing the official views or policies of IARPA, the ODNI, or the U.S. Government Present address: SLAC National Accelerator Laboratory, Menlo Park, CA.

  12. Hepatic focal nodular hyperplasia with congenital portosystemic shunt.

    PubMed

    Cho, Yuki; Shimono, Taro; Morikawa, Hiroyasu; Shintaku, Haruo; Tokuhara, Daisuke

    2014-12-01

    Hepatic focal nodular hyperplasia (FNH) is a rare benign tumor in children. Vascular anomalies have been identified as pathological features of FNH, but the etiology remains unclear. We describe a rare case including the time course of formation of hepatic FNH in response to congenital portosystemic shunt (PSS). A 4-month-old girl was identified on newborn mass screening to have hypergalactosemia, but no inherited deficiencies in galactose-metabolizing enzymes were found. Ultrasonography and per-rectal portal scintigraphy showed intrahepatic PSS of the right lobe as a cause of the hypergalactosemia. At age 12 months, the patient had elevated hepatic enzymes and small hypoechoic hepatic lesions around the shunt. On abdominal contrast-enhanced ultrasonography spoke-wheel sign and central stellate scar were seen, which are typical features of hepatic FNH without biopsy. Congenital intrahepatic PSS should be evaluated on abdominal contrast-enhanced ultrasonography and observed over time because of its potential to develop into hepatic FNH. PMID:25521987

  13. Fabrication and characterization of shunted μ-SQUID

    NASA Astrophysics Data System (ADS)

    Kumar, Nikhil; Fournier, T.; Courtois, H.; Gupta, Anjan K.

    2014-04-01

    In order to eliminate hysteresis, we have fabricated and characterized niobium based shunted micron size superconducting quantum interference devices (μ-SQUIDs). We find a wide temperature range where these μ-SQUIDs are non-hysteretic in nature and show a very good Ic vs. B oscillations in hysteretic regime and V vs. B oscillations in non-hysteretic regime. Here we report the characteristics of a shunted- μ-SQUID (Wf38LS72D5). In this device we have achieved a large voltage modulation, in non-hysteretic regime, at various temperatures including such as 1.1 mV at 6.62 K with a transfer function VΦ = 7.2mV/Φ0. The figures within the original article PDF file, as supplied to AIP Publishing, were affected by a PDF-processing error. Consequently, the article re-flowed and pagination increased from 3 to 4 pages. This article was updated on 14 May 2014 to correct the PDF-processing error, with the scientific content remaining unchanged. Readers are advised that the replacement article PDF file contains an additional blank page to preserve the original pagination.

  14. Relationship between migraine and cardiac and pulmonary right-to-left shunts.

    PubMed

    Wilmshurst, P; Nightingale, S

    2001-02-01

    A relationship between migraine with aura and the presence of right-to-left shunts has been reported in two studies. Right-to-left shunts are also associated with some forms of decompression illness. While conducting research in divers with decompression illness, it was our impression that divers with a large shunt often had a history of migraine with aura in everyday life and after dives. Therefore we routinely asked all divers about migraine symptoms. The medical records of the last 200 individuals referred for investigation of decompression illness were reviewed to determine the association between right-to-left shunts and migraine aura after diving, and migraine in daily life unconnected with diving. Migraine with aura in daily life unconnected with diving occurred significantly more frequently in individuals who had a large shunt which was present at rest (38 of 80; 47.5%) compared with those who had a shunt which was smaller or only seen after a Valsalva manoeuvre (four of 40; 10%) or those with no shunt (11 of 80; 13.8%) (P<0.001). Hemiplegic migraine occurred in 10 divers, each of whom had a shunt that was present at rest; in eight of these cases the shunt was large. The prevalence of migraine without aura was similar in all groups. Post-dive migraine aura was significantly more frequent in individuals who had a large shunt present at rest (21 of 80; 26.3%) compared with those who had a shunt that was smaller or only seen after a Valsalva manoeuvre (five of 40; 12.5%) or no shunt (one of 80; 1.3%) (P<0.001). Thus individuals with a large right-to-left shunt have an increased prevalence of migraine with aura in daily life unconnected with diving, and they also have an increased incidence of migraine aura after dives, but only when the dives liberate venous bubbles. These data suggest the possibility that, in some individuals, right-to-left shunts have a role in the aetiology of migraine with aura. The observations suggest that paradoxical gas embolism may

  15. Pulmonary shunt: a comparison between oxygen and inert gas infusion methods.

    PubMed

    Hlastala, M P; Colley, P S; Cheney, F W

    1975-12-01

    Pulmonary shunt measurement was compared using the standard oxygen (Berggren) technique and a new multiple inert gas infusion (Wagner et al.) technique in 11 mongrel dogs with either regional atelectasis or diffuse pulmonary edema. Relative retentions of sulfur hexafluoride, ethane, cyclopropane, halothane, diethyl ether, and acetone were used to calculate intrapulmonary shunt. Relative dilution of oxygen (Berggren method) was used to calculate total right to left shunt. The two methods gave similar results in the range of 20-80%. At low shunts the oxygen method measured higher values. This is because of the greater relative importance of fixed extrapulmonary shunts at this level and, as well, error in the measurement of PO2. Both techniques are suitable for normal clinical use. PMID:175043

  16. Sound absorption of a finite micro-perforated panel backed by a shunted loudspeaker.

    PubMed

    Tao, Jiancheng; Jing, Ruixiang; Qiu, Xiaojun

    2014-01-01

    Deep back cavities are usually required for micro-perforated panel (MPP) constructions to achieve good low frequency absorption. To overcome the problem, a close-box loudspeaker with a shunted circuit is proposed to substitute the back wall of the cavity of the MPP constructions to constitute a composite absorber. Based on the equivalent circuit model, the acoustic impedance of the shunted loudspeaker is formulated first, then a prediction model of the sound absorption of the MPP backed by shunted loudspeaker is developed by employing the mode solution of a finite size MPP coupled by an air cavity with an impendence back wall. The MPP absorbs mid to high frequency sound, and with properly adjusted electrical parameters of its shunted circuit, the shunted loudspeaker absorbs low frequency sound, so the composite absorber provides a compact solution to broadband sound control. Numerical simulations and experiments are carried out to validate the model. PMID:24437763

  17. Ventricular enlargement due to acute hypernatremia in a patient with a ventriculoperitoneal shunt.

    PubMed

    Andres, Robert H; Pendharkar, Arjun V; Kuhlen, Dominique; Mariani, Luigi

    2010-07-01

    Patients requiring CSF shunts frequently have comorbidities that can influence water and electrolyte balances. The authors report on a case involving a ventriculoperitoneal shunt in a patient who underwent intravenous hyperhydration and withdrawal of vasopressin substitution prior to scheduled high-dose chemotherapy regimen for a metastatic suprasellar germinoma. After acute neurological deterioration, the patient underwent CT scanning that demonstrated ventriculomegaly. A shunt tap revealed no flow and negative opening pressure. Due to suspicion of proximal shunt malfunction, the comatose patient underwent immediate surgical exploration of the ventricle catheter, which was found to be patent. However, acute severe hypernatremia was diagnosed during the procedure. After correction of the electrolyte disturbances, the patient regained consciousness and made a good recovery. Although rare, the effects of acute severe hypernatremia on brain volume and ventricular size should be considered in the differential diagnosis of ventriculoperitoneal shunt failure. PMID:19911884

  18. Indigenous cost-effective peritoneo-venous shunt for refractory ascites.

    PubMed

    Marimuthu, K; Kumar, A Suresh; Sabanathan, S; Gowrishankar, A; Kumar, P Sasi; Rajkumar, J S

    2004-01-01

    About 5% of patients with chronic liver disease develop massive refractory ascites. These patients cease to respond to diuretic therapy and may develop prerenal azotemia. There is a small but definite role for the peritoneo-venous shunt in these patients. In our study of 36 patients, managed with locally made, single-valved peritoneo-venous shunts (GSAIMS shunts), shunt failure and complication rates were assessed postoperatively. There is a definite improvement in quality of life with this cost-effective locally made shunt if patients are selected carefully. Long-term follow-up of these patients is not possible because most of these patients succumb to advanced liver disease. PMID:15285240

  19. An Unusual Complication of Ventriculoperitoneal Shunt: Urinary Bladder Stone Case Report and Literature Review

    PubMed Central

    Xu, Songtao; Sheng, Weixin; Qiu, Yufa; Wang, Jianguo

    2016-01-01

    Introduction: Ventriculoperitoneal (V-P) shunt surgery is the most common technique used for the treatment of hydrocephalus. The migration of ventriculoperitoneal shunt to the bladder is rare. Only two cases have been previously reported in the literature. Case Presentation: We report on a 38-year-old male who had hydrocephalus and V-P shunt for 12 years. Two years ago, he found himself with recurrent urinary tract infections, haematuria and urges incontinence, and then he was diagnosed with bladder perforation and merge stones. The patient had an abdominal operation to cut off and take out the shunt catheter, as well as a transurethral holmium laser lithotripsy. Conclusions: Bladder perforation and stones are rare examples of complications in V-P surgical procedures. Controlling the effective length of the terminal V-P shunt and modifying it appropriately can effectively reduce these complications. PMID:26889393

  20. Laparoscopic Cholecystectomy for Acute Calcular Cholecystitis in a Patient with Ventriculoperitoneal Shunt: A Case Report and Literature Review

    PubMed Central

    Albarrak, Abdullah A.; Khairy, Sami; Ahmed, Alzahrani Mohammed

    2015-01-01

    Management of patients who have ventriculoperitoneal shunt presenting with acute calcular cholecystitis has remained a clinical challenge. In this paper, the hospital course and the follow-up of a patient presenting with acute calcular cholecystitis and ventriculoperitoneal shunt managed with laparoscopic cholecystectomy are presented followed by literature review on the management of acute calcular cholecystitis in patients who have ventriculoperitoneal shunts. PMID:26798543

  1. Relationship between right-to-left shunts and cutaneous decompression illness.

    PubMed

    Wilmshurst, P T; Pearson, M J; Walsh, K P; Morrison, W L; Bryson, P

    2001-05-01

    The presence of a large right-to-left shunt is associated with neurological decompression illness after non-provocative dives, as a result of paradoxical gas embolism. A small number of observations suggest that cutaneous decompression illness is also associated with a right-to-left shunt, although an embolic aetiology of a diffuse rash is more difficult to explain. We performed a retrospective case--control comparison of the prevalence and sizes of right-to-left shunts determined by contrast echocardiography performed blind to history in 60 divers and one caisson worker with a history of cutaneous decompression illness, and 123 historical control divers. We found that 47 (77.0%) of the 61 cases with cutaneous decompression illness had a shunt, compared with 34 (27.6%) of 123 control divers (P<0.001). The size of the shunts in the divers with cutaneous decompression illness was significantly greater than in the controls. Thus 30 (49.2%) of the 61 cases with cutaneous decompression illness had a large shunt at rest, compared with six (4.9%) of the 123 controls (P<0.001). During closure procedures in 17 divers who had cutaneous decompression illness, the mean diameter of the foramen ovale was 10.9 mm. Cutaneous decompression illness occurred after dives that were provocative or deep in subjects without shunts, but after shallower and non-provocative dives in those with shunts. The latter individuals are at increased risk of neurological decompression illness. We conclude that cutaneous decompression illness has two pathophysiological mechanisms. It is usually associated with a large right-to-left shunt, when the mechanism is likely to be paradoxical gas embolism with peripheral amplification when bubble emboli invade tissues supersaturated with nitrogen. Cutaneous decompression illness can also occur in individuals without a shunt. In these subjects, the mechanism might be bubble emboli passing through an 'overloaded' lung filter or autochthonous bubble formation

  2. Choice of valve type and poor ventricular catheter placement: Modifiable factors associated with ventriculoperitoneal shunt failure.

    PubMed

    Jeremiah, Kealeboga Josephine; Cherry, Catherine Louise; Wan, Kai Rui; Toy, Jennifer Ah; Wolfe, Rory; Danks, Robert Andrew

    2016-05-01

    Ventriculoperitoneal (VP) shunt insertion is a common neurosurgical procedure, essentially unchanged in recent years, with high revision rates. We aimed to identify potentially modifiable associations with shunt failure. One hundred and forty patients who underwent insertion of a VP shunt from 2005-2009 were followed for 5-9years. Age at shunt insertion ranged from 0 to 91years (median 44, 26% <18years). The main causes of hydrocephalus were congenital (26%), tumour-related (25%), post-haemorrhagic (24%) or normal pressure hydrocephalus (19%). Fifty-eight (42%) patients required ⩾1 shunt revision. Of these, 50 (88%) were for proximal catheter blockage. The median time to first revision was 108days. Early post-operative CT scans were available in 105 patients. Using a formal grading system, catheter placement was considered excellent in 49 (47%) but poor (extraventricular) in 13 (12%). On univariate analysis, younger age, poor ventricular catheter placement and use of a non-programmable valve were associated with shunt failure. On logistic regression modelling, the independent associations with VP shunt failure were poor catheter placement (odds ratio [OR] 4.9, 95% confidence interval [CI] 1.3-18.9, p=0.02) and use of a non-programmable valve (OR 0.4, 95% CI 0.2-1.0, p=0.04). In conclusion, poor catheter placement (revision rate 77%) was found to be the strongest predictor of shunt failure, with no difference in revisions between excellent (43%) and moderate (43%) catheter placement. Avoiding poor placement in those with mild or moderate ventriculomegaly may best reduce VP shunt failures. There may also be an influence of valve choice on VP shunt survival. PMID:26758704

  3. Comparison of outcomes between patients with idiopathic normal pressure hydrocephalus who received a primary versus a salvage shunt.

    PubMed

    Moran, Dane; Hung, Alice; Vakili, Sharif; Fialho, Hugo; Jeon, Lee; Sankey, Eric W; Jusué-Torres, Ignacio; Lu, Jennifer; Goodwin, C Rory; Elder, Benjamin D; Rigamonti, Daniele

    2016-07-01

    Placement of a ventriculoperitoneal (VP) shunt is the treatment of choice for communicating hydrocephalus; however, the extent to which VP shunting is able to relieve symptoms in patients who had previously been treated with cerebrospinal fluid diverting therapy at an outside institution remains unclear. A retrospective review of patients with idiopathic normal pressure hydrocephalus treated with VP shunts at a single institution between 1993 and 2013 was conducted. Patients were classified as having received a primary VP shunt if they had not been previously treated with a VP shunt, ventriculoatrial shunt, lumboperitoneal shunt, or endoscopic third ventriculostomy. Patients were classified as having received a salvage VP shunt if they had been previously treated by one of these four modalities at an outside institution prior to their presentation to our institution. There were 357 patients who received a primary shunt and 33 patients who received a salvage shunt. Patients who had a salvage shunt placed had significantly higher odds of requiring a future revision (54% versus 41%; odds ratio=2.85; 95% confidence interval [CI]: 1.24-6.57; p=0.014). Patients who received a salvage shunt had statistically significantly lower rates of gait improvement at 6months in comparison to patients who received a primary shunt (relative risk=0.35; 95% CI: 0.14-0.87; p=0.025). Despite these findings, there was no significant difference at last follow-up in improvement in gait, continence, and cognition, indicating that outcomes for patients requiring a salvage shunt were comparable to patients receiving a primary shunt. PMID:26898583

  4. Splenopancreatic disconnection. Improved selectivity of distal splenorenal shunt.

    PubMed Central

    Warren, W D; Millikan, W J; Henderson, J M; Abu-Elmagd, K M; Galloway, J R; Shires, G T; Richards, W O; Salam, A A; Kutner, M H

    1986-01-01

    Distal splenorenal shunt (DSRS) improves survival from variceal bleeding in nonalcoholic cirrhotics but not in alcoholic subjects. The metabolic response after DSRS is also different in alcoholic and nonalcoholic cirrhotics. Portal perfusion, quality of blood perfusing the liver, cardiac output, and liver blood flow do not change in nonalcoholics. In alcoholics, portal perfusion is frequently lost (60%), quality of blood perfusing the liver decreases, and cardiac output and liver blood flow increase. It is proposed that portal flow is lost in alcoholics via pancreatic and colonic collaterals after surgery. Elimination of this sump by adding complete dissection of the splenic vein and division of the splenocolic ligament to DSRS (splenopancreatic disconnection, SPD) could preserve portal perfusion, decrease shunt loss of hepatotrophic factor, and improve survival in alcoholic cirrhotics. This report compares data 1 year after surgery in two groups of cirrhotics: group I (8 nonalcoholic; 16 alcoholic) had DSRS without SPD; group II (17 nonalcoholic; 11 alcoholic) received DSRS + SPD. Methods: Portal perfusion grade, cardiac output (CO), liver blood flow (f), hepatic function (GEC), and hepatic volume (vol) were measured before and 1 year after surgery. Shunt loss of hepatotrophic factor was estimated by insulin response (change in plasma concentration over 10 minutes: AUC) after arginine stimulation. Results: Groups I and II were similar before surgery. Metabolically, nonalcoholics remained stable after both DSRS and DSRS + SPD. After standard DSRS, alcoholics lost portal perfusion (75%, p less than 0.05), CO, and f increased (p less than 0.05), and quality of blood perfusing the liver was decreased (GEC/f: p less than 0.05). DSRS + SPD preserved portal perfusion better (p less than 0.05) in alcoholic cirrhotics than did DSRS alone. After DSRS + SPD, the metabolic response in alcoholics resembled that of nonalcoholics. CO, f, and GEC/f remained stable. These data

  5. Ventriculosternal Shunting for the Management of Hydrocephalus: Case Report of A Novel Technique

    PubMed Central

    Hung Pang, Peter Ka; Chan, Kwong Yau; Ching Kwok, John Kwong

    2015-01-01

    BACKGROUND: Conventional cerebrospinal fluid diversion such as ventriculoperitoneal or ventriculoatrial shunting for the management of hydrocephalus is one of the commonest neurosurgical procedures. However, in selected patients, surgical options are limited when relative contraindications for these operations exist. A patient who underwent ventriculosternal shunting, a novel procedure, is presented with durable and successful outcomes. OBJECTIVE: To demonstrate the feasibility, durability, and safety of ventriculosternal shunting for the management of hydrocephalus. METHODS: A patient with end-stage renal failure and heart failure with recurrent pleural effusion suffered from post–subarachnoid hemorrhage communicating hydrocephalus. Because of the need for continuous ambulatory peritoneal dialysis and the risk of introducing excessive cardiac preloading, conventional shunting was relatively contraindicated. Ventriculosternal shunting was performed by adopting the cancellous matrix of the sternum as the anatomic receptacle for intraosseous cerebrospinal fluid absorption. After placement of the ventricular catheter in the usual manner, the distal end was inserted into the sternum. RESULTS: There was demonstrable clinical and radiological improvement in hydrocephalus by ventriculosternal shunting. Cerebrospinal fluid intraosseous absorption by this novel procedure translated into both physical and cognitive recovery. The procedure was tolerable, effective, and durable, with the patient suffering no complications 3 years after the procedure. CONCLUSION: Ventriculosternal shunting for the management of hydrocephalus is a feasible, safe, and durable surgical treatment option for selected patients when conventional procedures are contraindicated. ABBREVIATION: VS, ventriculosternal PMID:26114598

  6. Pediatric hydrocephalus: Does the shunt device pressure selection affect the outcome?

    PubMed Central

    Sinha, Arvind; Sharma, Anuj; Gupta, Charitesh

    2012-01-01

    Aim: To compare the efficacy of low- versus medium-pressure shunts in pediatric hydrocephalus in a randomized controlled trial. Materials and Methods: Forty patients of pediatric hydrocephalus were randomized into two groups. The Chhabra differential pressure VP shunt (low or medium) was inserted in every patient. Postoperative follow-up was performed for symptomatic improvement and radiological evaluation (by sonography or computed tomography scan) for ventricle hemispheric ratio (VHR). Comparative analysis of pre- and postoperative VHR and need of redo surgery for shunt malformation were carried out to establish outcomes. Results: Nineteen patients had a low-pressure and 21 patients had a medium-pressure shunt inserted. The age of the patients ranged from 1 day to 10 years. The average preoperative VHR in group A was 55.37%, which reduced to 40% postoperatively (P = 0.00005); likewise, the pre- and postoperative VHR in group B were 61.57% and 42%, respectively, which was statistically significant (P = 0.0006). The complications of shunts and incidence of redo shunt surgery in both groups were not found to be statistically significant (P = 0.5614). Conclusions: The study found no significant difference in the outcome of patients with low- or medium-pressure shunt placement in pediatric hydrocephalus. PMID:22529548

  7. Portasystemic shunting versus liver transplantation for the Budd-Chiari syndrome.

    PubMed Central

    Bismuth, H; Sherlock, D J

    1991-01-01

    Over 12 years, 22 patients with the Budd-Chiari syndrome were treated surgically. Eighteen underwent a mesenterico-caval shunt (MCS); two, a side-to-side portacaval shunt; one, a mesenterico-atrial shunt (MAS); and one, a liver transplantation (OLT). One patient died after operation from the precipitating condition, and two MCS grafts that thrombosed were restored. All 21 surviving patients remain well, free from ascites, and all shunts are patent after a mean follow-up of 5.6 +/- 1 years, five patients with more than 10 years' follow-up. This long-term survival achieved by portasystemic shunts suggests that they have a major role in the treatment of the Budd-Chiari syndrome. The authors prefer the mesenterico-caval shunt using a jugular graft. This ensures a total portasystemic shunt, avoids subhepatic surgery, and reduces the long-term risk of prosthetic graft thrombosis. The MAS was reserved for cases with complete caval thrombosis. Patients with significant degrees of caval compression were satisfactorily decompressed by MCS. In patients not promptly treated, the disease progresses to cirrhosis, and such patients must be evaluated for transplantation similarly to those with other hepatopathies. Images Fig. 1. Fig. 3. Fig. 4. Fig. 5A and B. PMID:1953111

  8. Shunt diode analysis using light emission for gallium arsenide solar cell predictability

    NASA Astrophysics Data System (ADS)

    Kilmer, Louis C.; Honsberg, Christiana; Phillips, James E.; Barnett, Allen M.

    The use of light emission as a defect analysis technique has been expanded to better differentiate the types of shunt defects and analyze their effects on GaAs solar cells. Light emission from full-size 2-cm x 2-cm space solar cells was detected, recorded, digitized, and enhanced in order to analyze the low-level light emission and the shunt diode's effects. Shunt diodes are of particular importance because they have been found to be the type of defect which is most likely to degrade and cause failure in GaAs solar cells. To analyze how the shunt diodes affect the quality of the solar cell, the pattern of light emission must be studied. In studying the low-level light emission, it was found that the pattern of light emission is different than that of the high-level light emission. The different light patterns show the changing effects of the shunt diodes. It is concluded that the shunt diode dominates over the junction diode at low values of current and that the junction diode dominates over the shunt diode at high values of current.

  9. Shunt Testing In Vivo: Observational Study of Problems with Ventricular Catheter.

    PubMed

    Czosnyka, Zofia H; Sinha, Rohitiwa; Morgan, James A D; Wawrzynski, James R; Price, Steven J; Garnett, Matthew; Pickard, John D; Czosnyka, M

    2016-01-01

    Most shunt obstructions happen at the inlet of the ventricular catheter. Three hundred six infusion studies from 2007 to 2011 were classified as having a typical pattern of either proximal occlusion or patency. We describe different patterns of shunt ventricular obstruction.Solid block: Cerebrospinal fluid (CSF) aspiration was impossible. Baseline pressure was without pulse waveform (respiratory waveform may be visible). A quick increase of pressure to a level compatible with the shunt's setting was recorded in response to infusion. Distal occlusion of the shunt via transcutaneous compression resulted in a rapid increase in pressure to levels above 50 mmHg. This pattern was attributed to a solid ventricular block.Slit ventricles: At baseline, a pattern similar to that of the solid block was observed. After compression, the pressure increases, the pulse waveform appears, and the intracranial pressure is often stabilized at 25-40 mmHg. It is probable that previously slit ventricles were opened during the test.Partial block: In a partial block of the ventricular catheter by an in-growing choroid plexus, the pulse waveform at baseline was observed and CSF aspiration was possible. During infusion, the pressure increased, but the pulse amplitude disappeared. During the increase in the pressure in the shunt prechamber, the connection with the ventricles is disturbed by repositioning of the plexus.Infusion study via the shunt prechamber is able to visualize ventricular obstruction of the hydrocephalus shunt. PMID:27165935

  10. Controversies: Optic nerve sheath fenestration versus shunt placement for the treatment of idiopathic intracranial hypertension

    PubMed Central

    Spitze, Arielle; Lam, Peter; Al-Zubidi, Nagham; Yalamanchili, Sushma; Lee, Andrew G

    2014-01-01

    Background: Idiopathic intracranial hypertension (IIH) has been increasing in prevalence in the past decade, following the obesity epidemic. When medical treatment fails, surgical treatment options must be considered. However, controversy remains as to which surgical procedure is the preferred surgical option – optic nerve sheath fenestration (ONSF) or cerebrospinal fluid (CSF) shunting – for the long-term treatment of this syndrome. Purpose: To provide a clinical update of the pros and cons of ONSF versus shunt placement for the treatment of IIH. Design: This was a retrospective review of the current literature in the English language indexed in PubMed. Methods: The authors conducted a PubMed search using the following terms: Idiopathic IIH, pseudotumor cerebri, ONSF, CSF shunts, vetriculo-peritoneal shunting, and lumbo-peritoneal shunting. The authors included pertinent and significant original articles, review articles, and case reports, which revealed the new aspects and updates in these topics. Results: The treatment of IIH remains controversial and lacks randomized controlled clinical trial data. Treatment of IIH rests with the determination of the severity of IIH-related visual loss and headache. Conclusion: The decision for ONSF versus shunting is somewhat institution and surgeon dependent. ONSF is preferred for patients with visual symptoms whereas shunting is reserved for patients with headache. There are positive and negative aspects of both procedures, and a prospective, randomized, controlled trial is needed (currently underway). This article will hopefully be helpful in allowing the reader to make a more informed decision until that time. PMID:25449938

  11. [The efficacy of transcatheter embolization of severe arterioportal shunts in hepatocellular carcinoma].

    PubMed

    Hiyoshi, Yukiharu; Beppu, Toru; Okabe, Kazutoshi; Hayashi, Hiromitsu; Masuda, Toshiro; Okabe, Hirohisa; Mizumoto, Takao; Komori, Hiroyuki; Tanaka, Hiroshi; Horino, Kei; Ishiko, Takatoshi; Takamori, Hiroshi; Hirota, Masahiko; Baba, Hideo

    2007-11-01

    Transcatheter arterial embolizations of severe arterioportal shunt (A-P shunt) were performed with steel coils in 3 patients with hepatocellurlar carcinoma (HCC) as shown below. Case 1: A 56-year-old man with HCC associated with portal hypertension (esophageal varices and ascites abnominal pain), portal vein tumor thrombus and severe A-P shunt was performed in critical conditions. Case 2: A 51-year-old man with HCC, lung and adrenal gland metastases was accompanied with severe portal hypertention caused by A-P shunt and was in a harmful condition similar to case 1. Case 3: A 68-year-old woman with HCC associated with autoimmune hepatitis was performed a hepatic resection. Then multiple intrahepatic recurrences appeared 6 months later. A-P shunt made impossible to detect the feeding artery of tumor. After embolization of A-P shunt, esophageal varices and ascites resolved, and abdominal pain improved in cases 1 and 2. In addition, embolization enabled to perform transcatheter arterial chemoembolization in case 3. This procedure is a useful tool to improve various symptoms due to A-P shunt and to continue treatments for HCCs. PMID:18219909

  12. Arterio-venous shunts or low oxygen utilization?

    PubMed

    Rozin, Alexander P

    2010-02-01

    An idea of arteriovenous shunts (AVS) was proposed for explanation of dynamic regulation of oxygenation and venous hyperoxia. A formula enabling calculation of AVS and real CO2 production has recently been derived by comparing data of arterial and venous blood gases. Regarding venous hyperoxia, there is a need to differentiate capillary to tissue transport defect (low oxygen utilisation-LOU) from AVS, which may exist simultaneously. The AVS may be associated with normal or relatively high oxygen utilization from the capillary vessels and increased CO2 production. AVS is proposed to carry protective and 'stealing' properties including renal, cardiac, and pulmonary hemodynamic. Calculations of the AVS may be important for dynamic assessment of vascular and metabolic status and in emergency medicine. PMID:20026514

  13. Loop gain of a spacecraft switched shunt power system

    NASA Astrophysics Data System (ADS)

    Wu, Keng

    1994-10-01

    A novel approach of deriving the loop gain of a spacecraft switched shunt power system is presented. The system hardware elements contain both the analog and the digital components. Transfer functions of the analog circuits are easily identified employing the conventional approach. Gain function of the digital block is however conceived following a quite unconventional route. The digital gain is shown to include the effects of comparator thresholds, digital clock, shift register, sinusoidal amplitude, and ac frequency. The dependence of the digital gain on voltage thresholds, clocking period, and the integrational property of threshold comparator is expected. The dependence on sinusoidal amplitude contradicts the traditional concept of small signal analysis. The overall loop gain in the analytic form yields a computational result that matches the actual measurement very well. This fact proves, to some extent, the validity of the digital gain function and the basis of its derivation.

  14. Microwave power heterojunction bipolar transistors fabricated with thermal shunt bathtub

    SciTech Connect

    Bozada, C.A.; Barlage, D.W.; Barrette, J.P.

    1995-12-31

    Heterojunction bipolar transistor devices and circuits were fabricated using thermal shunt and bathtub thermal management techniques. Broadband cascode MMICs exhibited 10 - 14 dB gain at an output power of 2.5 - 3.0 Watts across 7 - 11 GHz. A 200 {mu}m{sup 2} common-emitter unit cell achieved 7 - 8 dB linear power gain and 40% power-added efficiency at a noise power ratio (NPR) of 18 dBc at 12 GHz. Under single tone measurements at 12 GHz, the unit cell achieved 52% power-added efficiency, with 9.5 dB linear gain, 8 dB power gain and 240 mW output power at 5 V bias.

  15. Shunt Diode Designs in Li/cf Shuttle Batteries

    NASA Technical Reports Server (NTRS)

    Miller, D.; Higgins, R.

    1984-01-01

    Although Li/CF cells and batteries have an excellent safety record, they are included with other battery systems that require additional safety precautions. One precaution suggested is the inclusion of shunt diodes into these batteries. The benefits of this addition are examined. All cells tested at elevated temperatures vent regardless of length of time between being fully discharged and reversed or inclusion of the diode in the system. Cells discharged at ambient temperatures all show a relatively quick reversal, but stabilize at voltages that are high enough that the diodes are not functioning. Cells tested at depressed temperatures reverse the deepest of all cells tested, with the deepest reversal occurring very early in the test and voltages recovering to above -0.60 volts near the end of the tests. Anode limited cells will eliminate the venting during hot reversal.

  16. Shunt diode designs in Li/CF Shuttle batteries

    NASA Astrophysics Data System (ADS)

    Miller, D.; Higgins, R.

    1984-09-01

    Although Li/CF cells and batteries have an excellent safety record, they are included with other battery systems that require additional safety precautions. One precaution suggested is the inclusion of shunt diodes into these batteries. The benefits of this addition are examined. All cells tested at elevated temperatures vent regardless of length of time between being fully discharged and reversed or inclusion of the diode in the system. Cells discharged at ambient temperatures all show a relatively quick reversal, but stabilize at voltages that are high enough that the diodes are not functioning. Cells tested at depressed temperatures reverse the deepest of all cells tested, with the deepest reversal occurring very early in the test and voltages recovering to above -0.60 volts near the end of the tests. Anode limited cells will eliminate the venting during hot reversal.

  17. Electro-clinical follow-up of shunted hydrocephalic children.

    PubMed

    Varfis, G; Berney, J; Beaumanoir, A

    1977-01-01

    In a survey of 29 hydrocephalic children treated by ventriculoatrial shunt (Holter valve) with a follow-up of 4 years, EEG records before the operation and at least once a year thereafter, the authors can support the view that an epileptogenic focus has developed around the place of insertion of the ventricular catheter in 19 cases, leading to epileptic seizures in 17 up to now. Thus the incidence of convulsions in this particular group of patients is 0.59 (17/29), the limits of confidence 95% being 0.39-0.76. The irritative abnormalities occur usually during the second year after the operation and the delay for the onset of clinical seizures is variable. The age at operation seems to influence the occurrence of the epileptogenic scar. The type of hydrocephalus and especially the presence of an associated cerebral focal lesion can be of importance in the development of clinical seizures. PMID:405183

  18. Emphysematous pyonephrosis associated with extrahepatic portosystemic shunt in a dog

    PubMed Central

    LIM, Jongsu; YOON, Youngmin; JUNG, Dongin; YEON, Seongchan; LEE, Heechun

    2015-01-01

    A 16-month-old intact female Maltese dog was referred for examination of depression and vomiting. Ultrasonography revealed dilated right renal pelvis containing echogenic fluid with free gas. A hyperechoic material suspected of urolith was identified in the right ureter. Computed tomography revealed emphysematous change of the right kidney associated with ureteral obstruction and extrahepatic portosystemic shunt (EHPSS). Ureteronephrectomy and surgical correction were performed for the EHPSS. Escherichia coli was isolated from pus from the right kidney. Quantitative analysis revealed that the urolith was an ammonium urate stone. After 5 months follow-up, no complication was observed. This is the first report of emphysematous pyonephrosis associated with EHPSS in a dog. PMID:26668166

  19. Carotid Baroreceptor Stimulation and Arteriovenous Shunts for Resistant Hypertension.

    PubMed

    Paivanas, Nicholas; Bisognano, John D; Gassler, John P

    2015-01-01

    Pharmacologic therapy for hypertension is effective for the majority of patients with hypertension, but there is a subset of the population with treatment-resistant hypertension who cannot achieve their blood pressure goal despite taking multiple medications. Since these patients are at increased risk of cardiovascular disease and end-organ damage, additional therapies must be considered. This review discusses several novel interventional therapies-including baroreflex activation therapy, baroreceptor stenting, and creation of an arteriovenous shunt-that may provide alternative options for blood pressure control in those with treatment-resistant hypertension. All of these therapies remain investigational, and each has its own strengths and weaknesses that will be critical to assess as they come to market. PMID:27057291

  20. Sequential Switching Shunt Maximum Power Point Regulator (S3MPPR)

    NASA Astrophysics Data System (ADS)

    Blanes, J. M.; Garrigos, A.; Carrasco, J. A.; Weinberg, A. H.; Ejea, J. B.; Sanchis, E.; Farreres, A.; Maset, E.; Soto, A.; de la Cruz, F.

    2011-10-01

    This paper presents the implementation of a Sequential Switching Shunt Maximum Power Point Regulator (S3MPPR). The S3MPPR is the evolution of the traditional S3R where the fixed reference, used by the main error amplifier, is replaced by an MPPT voltage reference. With this variation, the system corresponds to a non-regulated bus topology but with the dynamic characteristics of a regulated one and with the ability to track the MPP of the solar array. This work focuses on this topic, studying the best way to implement the S3MPPR in a geostationary telecommunication satellite. In order to validate the proposal, a 1.6 kW prototype has been implemented and many tests have been carried out with the prototype, all of them showing the good behaviour of the converter.

  1. A SQUID gradiometer module with large junction shunt resistors

    NASA Astrophysics Data System (ADS)

    Qiu, Yang; Liu, Chao; Zhang, Shu-Lin; Zhang, Guo-Feng; Wang, Yong-Liang; Li, Hua; Zeng, Jia; Kong, Xiang-Yan; Xie, Xiao-Ming

    2014-08-01

    A dual-washer superconducting quantum interference device (SQUID) with a loop inductance of 350 pH and two on-washer integrated input coils is designed according to conventional niobium technology. In order to obtain a large SQUID flux-to-voltage transfer coefficient, the junction shunt resistance is selected to be 33 Ω. A vertical SQUID gradiometer module with a baseline of 100 mm is constructed by utilizing such a SQUID and a first-order niobium wire-wound antenna. The sensitivity of this module reaches about 0.2 fT/(cm·Hz1/2) in the white noise range using a direct readout scheme, i.e., the SQUID is directly connected to an operational amplifier, in a magnetically shielded room. Some magnetocardiography (MCG) measurements with a sufficiently high signal-to-noise ratio (SNR) are demonstrated.

  2. Role of Glyoxylate Shunt in Oxidative Stress Response.

    PubMed

    Ahn, Sungeun; Jung, Jaejoon; Jang, In-Ae; Madsen, Eugene L; Park, Woojun

    2016-05-27

    The glyoxylate shunt (GS) is a two-step metabolic pathway (isocitrate lyase, aceA; and malate synthase, glcB) that serves as an alternative to the tricarboxylic acid cycle. The GS bypasses the carbon dioxide-producing steps of the tricarboxylic acid cycle and is essential for acetate and fatty acid metabolism in bacteria. GS can be up-regulated under conditions of oxidative stress, antibiotic stress, and host infection, which implies that it plays important but poorly explored roles in stress defense and pathogenesis. In many bacterial species, including Pseudomonas aeruginosa, aceA and glcB are not in an operon, unlike in Escherichia coli In P. aeruginosa, we explored relationships between GS genes and growth, transcription profiles, and biofilm formation. Contrary to our expectations, deletion of aceA in P. aeruginosa improved cell growth under conditions of oxidative and antibiotic stress. Transcriptome data suggested that aceA mutants underwent a metabolic shift toward aerobic denitrification; this was supported by additional evidence, including up-regulation of denitrification-related genes, decreased oxygen consumption without lowering ATP yield, increased production of denitrification intermediates (NO and N2O), and increased cyanide resistance. The aceA mutants also produced a thicker exopolysaccharide layer; that is, a phenotype consistent with aerobic denitrification. A bioinformatic survey across known bacterial genomes showed that only microorganisms capable of aerobic metabolism possess the glyoxylate shunt. This trend is consistent with the hypothesis that the GS plays a previously unrecognized role in allowing bacteria to tolerate oxidative stress. PMID:27036942

  3. Staged Transcatheter Treatment of Portal Hypoplasia and Congenital Portosystemic Shunts in Children

    SciTech Connect

    Bruckheimer, Elchanan Dagan, Tamir; Atar, Eli; Schwartz, Michael; Kachko, Ludmila; Superina, Riccardo; Amir, Gabriel; Shapiro, Rivka; Birk, Einat

    2013-12-15

    Purpose: Congenital portosystemic shunts (CPSS) with portal venous hypoplasia cause hyperammonemia. Acute shunt closure results in portal hypertension. A transcatheter method of staged shunt reduction to afford growth of portal vessels followed by shunt closure is reported. Methods: Pressure measurements and angiography in the CPSS or superior mesenteric artery (SMA) during temporary occlusion of the shunt were performed. If vessels were diminutive and the pressure was above 18 mmHg, a staged approach was performed, which included implantation of a tailored reducing stent to reduce shunt diameter by {approx}50 %. Recatheterization was performed approximately 3 months later. If the portal pressure was below 18 mmHg and vessels had developed, the shunt was closed with a device. Results: Six patients (5 boys, 1 girl) with a median age of 3.3 (range 0.5-13) years had CPSS portal venous hypoplasia and hyperammonemia. Five patients underwent staged closure. One patient tolerated acute closure. One patient required surgical shunt banding because a reducing stent could not be positioned. At median follow-up of 3.8 (range 2.2-8.4) years, a total of 21 procedures (20 transcatheter, 1 surgical) were performed. In all patients, the shunt was closed with a significant reduction in portal pressure (27.7 {+-} 11.3 to 10.8 {+-} 1.8 mmHg; p = 0.016), significant growth of the portal vessels (0.8 {+-} 0.5 to 4.0 {+-} 2.4 mm; p = 0.037), and normalization of ammonia levels (202.1 {+-} 53.6 to 65.7 {+-} 9.6 {mu}mol/L; p = 0.002) with no complications. Conclusion: Staged CPSS closure is effective in causing portal vessel growth and treating hyperammonemia.

  4. Percutaneous Transjugular Direct Porto-caval Shunt in Patients with Budd-Chiari Syndrome

    SciTech Connect

    Quateen, A.; Pech, M.; Berg, T.; Bergk, A.; Podrabsky, P.; Felix, R.; Ricke, J.

    2006-08-15

    The purpose of the study was to evaluate the feasibility and effectiveness of direct porto-caval shunts in patients with Budd-Chiari syndrome (BCS) in whom there is no access to the hepatic veins during transjugular intrahepatic portosystemic shunt (TIPSS). We included six consecutive patients with fulminant/acute Budd-Chiari syndrome (mean age: 35 years) in whom a conventional TIPSS was not possible due to inaccessible hepatic veins. We performed a direct porto-caval shunt via a transhepatic approach. Patients were followed up by means of clinical examination, laboratory investigations, and Doppler ultrasound. TIPSS implantation from the inferior vena cava (IVC) was successful in all six patients (100%). The median transhepatic shunt length was 9 cm (8-10 cm). No procedure-related complications were observed in our patients. Early shunt occlusion occurred in three out of six patients (50%). In all three of these patients, the stent used to stabilize the shunt ended 1-2 cm before reaching the IVC. All occlusions were successfully recanalized. One of these patients developed recurrent early shunt as well as mesenteric and splenic vein occlusions. She died 7 days after TIPSS placement due to an unmanageable coagulation disorder. The remaining five patients were followed up by planned clinical examination and laboratory investigations (mean follow-up time was 15 months; patient 1 was followed up for 13 months, patient 2 for 14 months, patient 3 for 15 months, and patients 4 and 5 for 16 months) and all displayed a complete and durable resolution of liver failure and ascites without reintervention. In patients with acute liver failure originating from BCS and inaccessible hepatic veins, a direct transhepatic porto-caval shunt can be performed safely and effectively under ultrasound guidance. Future studies in larger patient groups should investigate if the patency of transcaval TIPSS with long transhepatic shunt segments is similar compared to conventional TIPSS via

  5. Tunable acoustic waveguide based on vibro-acoustic metamaterials with shunted piezoelectric unit cells

    NASA Astrophysics Data System (ADS)

    Kwon, Byung-Jin; Jung, Jin-Young; Lee, Dooho; Park, Kwang-Chun; Oh, Il-Kwon

    2015-10-01

    We propose a new class of acoustic waveguides with tunable bandgaps (TBs) by using vibro-acoustic metamaterials with shunted periodic piezoelectric unit cells. The unit metamaterial cells that consist of a single crystal piezoelectric transducer and an electrical shunt circuit are designed to induce a strong vibro-acousto-electrical coupling, resulting in a tunable acoustic bandgap as well as local structural resonance and Bragg scattering bandgaps. The present results show that the TB frequency can be actively controlled and the transmission loss of the acoustic wave can be greatly improved by simply changing the inductance values in the shunt circuit.

  6. Primary ventriculo-peritoneal shunts in treatment of hydrocephalus associated with myelomeningocele

    PubMed Central

    Stark, G. D.; Drummond, M. B.; Poneprasert, S.; Robarts, F. H.

    1974-01-01

    In 50 children suffering from open myelomeningocele, a ventriculo-peritoneal shunt was employed as the primary procedure for control of hydrocephalus. In 11 cases the system was ultimately replaced by a ventriculo-atrial shunt, though this may not always have been necessary. In the remaining 39 patients satisfactory control of hydrocephalus was achieved. Obstruction, particularly of the peritoneal catheter, occurred frequently in the first 6 months but no revisions were required after 2 years. It is concluded that while ventriculo-peritoneal and ventriculo-atrial shunts achieve comparable success in controlling hydrocephalus, the former, due to the relatively innocuous complications, offers significant long-term advantages. PMID:4593818

  7. Intracranial hypotension after syringopleural shunting in posttraumatic syringomyelia: Case report and review of the literature.

    PubMed

    Summers, Johanne C; Vellore, Yagnesh; Chan, Patrick C H; Rosenfeld, Jeffrey V

    2015-01-01

    We report a case of a 45-year-old male with a syringopleural shunt who developed intracranial hypotension. The patient presented with 2 weeks history of worsening headache and back pain, on a background of having had a syringopleural shunt inserted for a thoracic posttraumatic syrinx. Computerized tomography imaging of the brain revealed bilateral subdural fluid collections. Magnetic resonance imaging appearances of spinal and intracranial pachymeningeal enhancement confirmed intracranial hypotension. We present a rare case of intracranial hypotension secondary to syringopleural shunting in a patient with posttraumatic syringomyelia. PMID:25972956

  8. Waste Package Neutron Absorber, Thermal Shunt, and Fill Gas Selection Report

    SciTech Connect

    V. Pasupathi

    2000-01-28

    Materials for neutron absorber, thermal shunt, and fill gas for use in the waste package were selected using a qualitative approach. For each component, selection criteria were identified; candidate materials were selected; and candidates were evaluated against these criteria. The neutron absorber materials evaluated were essentially boron-containing stainless steels. Two candidates were evaluated for the thermal shunt material. The fill gas candidates were common gases such as helium, argon, nitrogen, carbon dioxide, and dry air. Based on the performance of each candidate against the criteria, the following selections were made: Neutron absorber--Neutronit A978; Thermal shunt--Aluminum 6061 or 6063; and Fill gas--Helium.

  9. A Case of Discontinued Proximal Limb of a Ventriculoperitoneal Shunt With Patent Fibrous Tract.

    PubMed

    Bermo, Mohammed; Leung, Alan S; Matesan, Manuela

    2016-06-01

    Radionuclide shuntogram is important in the evaluation of cerebrospinal fluid (CSF) shunts complications such as mechanical failure, malpositioning, pseudocyst, or overdrainage. We present here a case of congenital hydrocephalus and posterior fossa cyst with multiple shunt procedures and revisions with breakage of the proximal tube of the ventriculoperitoneal shunt but preserved CSF drainage through the patent fibrous tract. Careful correlation with SPECT/CT images helped confirm the breakage and exclude CSF leak outside of the tract, which was suspected on planar images. PMID:26914568

  10. Treatment of Syringomyelia due to Chiari Type I Malformation with Syringo-Subarachnoid-Peritoneal Shunt

    PubMed Central

    Akakın, Akın; Yılmaz, Baran; Kılıç, Türker

    2015-01-01

    Chiari type I malformation is a tonsillar herniation more than 3 mm from the level of foramen magnum, with or without concurrent syringomyelia. Different surgical treatments have been developed for syringomyelia secondary to Chiari's malformations: craniovertebral decompression with or without plugging of the obex, syringo-subarachnoid, syringo-peritoneal, and theco-peritoneal shunt placement. Shunt placement procedures are useful for neurologically symptomatic large-sized syrinx. In this paper, authors define the first successful treatment of a patient with syringomyelia due to Chiari type I malformation using a pre-defined new technique of syringo-subarachnoid-peritoneal shunt with T-tube system. PMID:25932303

  11. Testing of cerebrospinal compensatory reserve in shunted and non-shunted patients: a guide to interpretation based on an observational study.

    PubMed Central

    Czosnyka, M; Whitehouse, H; Smielewski, P; Simac, S; Pickard, J D

    1996-01-01

    OBJECTIVE--To design a computerised infusion test to compensate for the disadvantages of Katzman's lumbar infusion method: inadequate accuracy of estimation of the resistance to cerebrospinal fluid outflow and poor predictive value in normal pressure hydrocephalus. METHODS--Accuracy was improved by intracranial pressure signal processing and model analysis for measurement of cerebrospinal compensatory variable. These include the CSF outflow resistance, brain compliance, pressure-volume index, estimated sagittal sinus pressure, CSF formation rate, and other variables. Infusion may be made into the lumbar space, ventricles, or, when assessing shunt function in vivo, the shunt chamber. RESULTS AND CONCLUSIONS--The computerised test has been used for five years in a multicentre study in 350 hydrocephalic patients of various ages, aetiologies, and states of cerebrospinal compensation. The principles of using the test to characterise different types of CSF circulatory disorders in patients presenting with ventricular dilatation, including brain atrophy and normal and high pressure hydrocephalus, are presented and illustrated. Previous studies showed a positive correlation between cerebrospinal compensatory variables and the results of shunting, but such a prediction remains difficult in idiopathic normal pressure hydrocephalus, particularly in elderly patients. The technique is helpful in the assessment of shunt malfunction, including posture-related overdrainage, over-drainage related to the nocturnal B wave activity, and proximal or distal shunt obstruction. The appendix presents an introduction of the mathematical modelling of CSF pressure volume-compensation included in computerised infusion test software. Images PMID:8778261

  12. Optimizing the Shunting Schedule of Electric Multiple Units Depot Using an Enhanced Particle Swarm Optimization Algorithm

    PubMed Central

    Jin, Junchen

    2016-01-01

    The shunting schedule of electric multiple units depot (SSED) is one of the essential plans for high-speed train maintenance activities. This paper presents a 0-1 programming model to address the problem of determining an optimal SSED through automatic computing. The objective of the model is to minimize the number of shunting movements and the constraints include track occupation conflicts, shunting routes conflicts, time durations of maintenance processes, and shunting running time. An enhanced particle swarm optimization (EPSO) algorithm is proposed to solve the optimization problem. Finally, an empirical study from Shanghai South EMU Depot is carried out to illustrate the model and EPSO algorithm. The optimization results indicate that the proposed method is valid for the SSED problem and that the EPSO algorithm outperforms the traditional PSO algorithm on the aspect of optimality. PMID:27436998

  13. Optimizing the Shunting Schedule of Electric Multiple Units Depot Using an Enhanced Particle Swarm Optimization Algorithm.

    PubMed

    Wang, Jiaxi; Lin, Boliang; Jin, Junchen

    2016-01-01

    The shunting schedule of electric multiple units depot (SSED) is one of the essential plans for high-speed train maintenance activities. This paper presents a 0-1 programming model to address the problem of determining an optimal SSED through automatic computing. The objective of the model is to minimize the number of shunting movements and the constraints include track occupation conflicts, shunting routes conflicts, time durations of maintenance processes, and shunting running time. An enhanced particle swarm optimization (EPSO) algorithm is proposed to solve the optimization problem. Finally, an empirical study from Shanghai South EMU Depot is carried out to illustrate the model and EPSO algorithm. The optimization results indicate that the proposed method is valid for the SSED problem and that the EPSO algorithm outperforms the traditional PSO algorithm on the aspect of optimality. PMID:27436998

  14. A broken heart: Right-to-left shunt in the setting of normal cardiac pressures

    PubMed Central

    Gomperts, Natalie; Fowler, Robert; Horlick, Eric; McLaughlin, Peter

    2008-01-01

    A patent foramen ovale (PFO) is a common structural cardiac variant occurring in approximately 30% of the general population. Patients are usually asymptomatic because the defect is flap-like and does not permit significant left-to-right shunting. However, pathological conditions that result in cardiac rotation or higher than normal right atrial pressures can reverse the normal left atrial to right atrial pressure gradient and cause a right-to-left shunt through a PFO. If the right-to-left shunt is persistent, systemic hypoxemia or paradoxical emboli may result. The present report describes a case of refractory hypoxemia in a critically ill patient with a PFO who had a right-to-left shunt with normal right-sided cardiac pressures. PMID:18340396

  15. A broken heart: right-to-left shunt in the setting of normal cardiac pressures.

    PubMed

    Gomperts, Natalie; Fowler, Robert; Horlick, Eric; McLaughlin, Peter

    2008-03-01

    A patent foramen ovale (PFO) is a common structural cardiac variant occurring in approximately 30% of the general population. Patients are usually asymptomatic because the defect is flap-like and does not permit significant left-to-right shunting. However, pathological conditions that result in cardiac rotation or higher than normal right atrial pressures can reverse the normal left atrial to right atrial pressure gradient and cause a right-to-left shunt through a PFO. If the right-to-left shunt is persistent, systemic hypoxemia or paradoxical emboli may result. The present report describes a case of refractory hypoxemia in a critically ill patient with a PFO who had a right-to-left shunt with normal right-sided cardiac pressures. PMID:18340396

  16. Congenital extrahepatic portosystemic shunt complicated by the development of hepatocellular carcinoma.

    PubMed

    Sharma, Ruchi; Suddle, Abid; Quaglia, Alberto; Peddu, Praveen; Karani, John; Satyadas, Thomas; Heaton, Nigel

    2015-10-01

    Congenital extrahepatic portosystemic shunt, also known as Abernethy malformation, is a rare congenital malformation. It causes shunting of blood through a communication between the portal and systemic veins such as a patent ductus venous. We report 3 cases of Abernethy malformation complicated by the development of hepatocellular carcinoma. Additionally, we comprehensively reviewed all previously reported cases and highlighted common features that may help in early diagnosis and appropriate management. Patients with Abernethy malformation may have an increased propensity to develop hepatocellular carcinoma. All 5 previously reported cases, plus the three of our patients, have a type 1 (complete) shunt suggesting a role for absent portal blood flow in the pathogenesis of hepatocellular carcinoma. Congenital extrahepatic portosystemic shunt should be sought for in cases with raised serum ammonia, hepatic encephalopathy or hepatocellular carcinoma in the absence of cirrhosis. PMID:26459734

  17. Clotting Problems with the Teflon-Silastic Arteriovenous Shunt in Patients on Regular Haemodialysis

    PubMed Central

    Papadimitriou, M.; Carroll, R. N. P.; Kulatilake, A. E.

    1969-01-01

    Episodes of clotting that occurred in 22 patients on regular haemodialysis were studied over a six-month period. The venous pressure during dialysis and the radiology of the Teflon-Silastic arteriovenous shunt were found to be satisfactory guides for the management of the shunt. The failure of the shunt during the early stage was mainly due to technical reasons. Histological study of the excised vessels in removed long-term shunts showed that these had failed because of rigidity and thickening of the vessel wall due to calcium and iron deposits or chronic inflammation, or both. ImagesFig. 1Fig. 2Fig. 3Fig. 4Fig. 5Fig. 6Fig. 7Fig. 8Fig. 9Fig. 10Fig. 11 PMID:5776208

  18. What are the implications of the spontaneous spleno-renal shunts in liver cirrhosis?

    PubMed Central

    2009-01-01

    Background Although significant advances are expected to be made in the assessment of the portal hypertension-related complications, the prognostic role of spleno-renal shunts has not been fully explored so far. Clarifying this aspect could help tackle the life-treating events occurring in patients suffering from liver cirrhosis. The aim of the study was to analyze the relationships between the spleno-renal shunts presence at doppler ultrasound and the liver cirrhosis complications. Methods Design: eighty one patients out of 129 formed the study population (35 females). Chronic liver damage in these patients was caused by HCV (66), HBV (2), alcohol abuse (2) or unknown etiology, likely non-alcoholic steatohepatitis (11). Setting: two Liver Units of university/primary hospitals in Southern Italy. Main outcome measures: grading of esofageal varices; detection of ascites: assessment of hepatic encephalopathy; evaluation of liver cirrhosis severity; tracking hepatocellular carcinoma; doppler features of spleno-renal shunts and splenic flow velocity; spleen longitudinal diameter at sonography. Results The prevalence of spleno-renal shunts was 18.5%, without no difference concerning the etiology (HCV versus non-HCV, p = 0.870); the prevalence of hepatocellular carcinoma in patients with spleno-renal shunts was superior to that of patients without them (Pearson Chi-square, p = 0.006, power of sample size 74%), also after adjustment for liver decompensation (p = 0.024). The median score of hepatic encephalopathy in patients with and without spleno-renal shunts was similar, i.e., 0 (range, 0-2) versus 0 (0 - 3), p = 0.67. The median splenic vein flow velocity in patients with spleno-renal shunts was significantly inferior to that of patients without them, i.e., 13 cm/sec (95% confidence intervals, 6-18) versus 21 cm/sec (17-24), p < 0.0001. By far the largest percentage of large esophageal varices was in patients without spleno-renal shunts (p = 0.005). In contrast, the

  19. Superconducting FCL using a combined inducted magnetic field trigger and shunt coil

    DOEpatents

    Tekletsadik, Kasegn D.

    2007-10-16

    A single trigger/shunt coil is utilized for combined induced magnetic field triggering and shunt impedance. The single coil connected in parallel with the high temperature superconducting element, is designed to generate a circulating current in the parallel circuit during normal operation to aid triggering the high temperature superconducting element to quench in the event of a fault. The circulating current is generated by an induced voltage in the coil, when the system current flows through the high temperature superconducting element.

  20. Mycotic pulmonary artery aneurysm: an unusual complication of ventriculo-atrial shunt

    PubMed Central

    Gelfand, Elliot T.; Callaghan, John C.

    1981-01-01

    A 23-year-old man with a previous ventriculo-atrial shunt for a pinealoma developed a febrile illness and heart murmur. The condition was thought to be caused by subacute bacterial endocarditis. Further investigation, however, revealed a mycotic left pulmonary artery aneurysm, which was treated by means of a left pneumonectomy with cardiopulmonary bypass. Such an aneurysm represents yet another complication of ventriculo-atrial shunting for hydrocephalus. Images PMID:15216218

  1. Experimental Percutaneous Extrahepatic Portacaval Shunt Creation by Transjugular Approach in Swine

    SciTech Connect

    Seong, Chang Kyu; Pavcnik, Dusan Uchida, Barry T.; Anai, Hiroshi; Timmermans, Hans; Niyyati, Mahtab; Corless, Christopher L.; Correa, Luiz O.; Keller, Frederick S.; Roesch, Josef

    2005-06-15

    The purpose of the study was to evaluate the feasibility of the creation of a percutaneous extrahepatic portacaval shunt (PEPS) in swine by a transjugular approach and to find a suitable stent-graft to use in PEPS. In 12 swine, the extrahepatic portal vein (PV) was entered from the inferior vena cava (IVC) by a needle system introduced from the transjugular approach. A catheter introduced through the transhepatic approach served as a target. Five types of stent-graft consisting of homemade Z stents and a polytetrafluoethylene cover were explored for PEPS creation. Eight animals had follow-up venograms up to 6 weeks or until the shunt became severely stenotic. Gross and histologic examinations were performed after the final follow-up venography. The PV punctures and stent-graft placement were difficult, but the PEPS was established in all animals. In four animals, the stent-graft failed to adequately cover the tract, causing severe hemorrhage. Only two shunts remained patent up to 6 weeks. The other shunts exhibited severe stenosis or occlusion. At gross examination, all shunts traversed the liver parenchyma of the caudate lobe surrounding the IVC. The extravascular PEPS portion was 4 mm to 2 cm long. All shunts entered the PV close to the splenomesenteric junction and exhibited neointimal formation. Shunt stenoses were caused by neointimal hyperplasia and occlusions by a superimposed thrombus. PEPS can be created by the transjugular approach in swine, but only the PV shunt entrance is extrahepatic. None of the tested rigid stent-grafts were suitable for PEPS creation. A short flexible stent-graft with flanged ends is suggested for further exploration.

  2. Acute Budd-Chiari syndrome: Treatment with transjugular intrahepatic portosystemic shunt

    SciTech Connect

    Strunk, Holger M.; Textor, Jochen; Brensing, Karl-August; Schild, Hans H.

    1997-07-15

    The case of a 28-year-old man with acute Budd-Chiari syndrome due to veno-occlusive disease is reported. Transjugular intrahepatic portosystemic shunt (TIPS) was performed after upper gastrointestinal endoscopy, duplex sonographic and abdominal computed tomographic examination, inferior cavogram with hepatic venous catheterization, and transvenous biopsy. A 10-mm parenchymal tract was created. The patient did well after the procedure; ascites resolved and liver function improved markedly. The shunt has remained patent up to now for 6 months.

  3. Palliative embolisation for intrapulmonary shunting in lepidic predominant adenocarcinoma of the lung

    PubMed Central

    Tan, Joanne Yue-Ai; Walters, Darren L.; Poon, Karl; Zimmerman, Paul; Aldons, Pat

    2015-01-01

    Lepidic predominant adenocarcinoma (LPA) (formerly known as bronchioalveolar carcinoma) has rarely been reported to cause refractory hypoxia with intrapulmonary shunting [1–7]. We describe a case who underwent the palliative strategy of intravascular right lower pulmonary artery embolisation with an 18 mm Amplatzer II vascular plug to reduce intrapulmonary shunting. This is the first report we are aware of using this minimally invasive procedure to treat this condition. PMID:26236621

  4. Optimal Surgical Management Using a Classic Blalock-Taussig Shunt for an Infected Pseudoaneurysm After a Modified Blalock-Taussig Shunt Procedure.

    PubMed

    Okada, Noritaka; Murayama, Hiroomi; Hasegawa, Hiroki

    2016-05-01

    We present 2 cases of a 3-month-old girl and boy who were diagnosed with an infected pseudoaneurysm 2 months after undergoing left-sided modified Blalock-Taussig shunt (mBTS) operations for pulmonary atresia. Because the shunts in both cases were nearly obstructed, they underwent a 2-stage surgical approach: classic BTS operations through a right thoracotomy to establish sufficient pulmonary flow and infected graft removal through a median sternotomy after close observation of the state of the aneurysms. By utilizing autologous tissue from a different thoracic entry, both patients were successfully managed and recovered without any recurrence of infection. PMID:27106441

  5. Standard Trabeculectomy and Ex-PRESS Miniature Glaucoma Shunt: A Comparative Study and Literature Review

    PubMed Central

    Zunz, Eran; Tzur, Rotem; Kurtz, Shimon; Shemesh, Gabi

    2015-01-01

    Purpose: The aim of this study was to compare the efficacy and safety between standard trabeculectomy and the Ex-PRESS shunt implantation. Methods: A retrospective review of the records of 100 eyes of 100 patients who underwent trabeculectomy or Ex-PRESS shunt implantation between July 2010 and June 2012 was conducted. Of these, 61 (61%) eyes underwent trabeculectomy and 39 (39%) eyes underwent Ex-PRESS shunt implantation. Demographic information, glaucoma type, surgical details, preoperative, and postoperative data including intraocular pressure (IOP), number of medications, reoperation, and occurrence of any complications were recorded. Results: No differences in IOP reduction or number of postoperative IOP-lowering medications were demonstrated between the 2 procedures. Success rates were 86.9% for trabeculectomy and 84.6% for Ex-PRESS shunt. Rates of failure and hypotony were not significantly different between the groups. No parameter was correlated with success or failure of any procedure. Conclusions: Standard trabeculectomy and Ex-PRESS shunt have similar efficacy and safety profiles. As the Ex-PRESS shunt is considerably more expensive, its use may be unjustified, especially as a primary procedure. PMID:24633088

  6. Bedside nuclear probe for detection and quantification of left to right intracardiac shunts.

    PubMed Central

    Gould, B A; Turner, J; Keeling, D H; Ring, N J; Cox, R R; Marshall, A J

    1988-01-01

    A cadmium telluride nuclear probe with an Elscint gamma camera was used to detect and measure left to right intracardiac shunts at the bedside in 34 patients. Fifteen also had right heart catheterisation and oximetric measurement of the shunt. For the nuclear technique 740 MBq (20 mCi) of technetium-99m pertechnetate was injected into the right antecubital vein and the pulmonary to systemic flow ratio (QP:QS) was measured by the gamma variate technique. Data were not obtained in four patients because the nuclear probe failed in three patients and one storage disc was corrupted. Data from the gamma camera were lost in another patient. When the size of the shunt measured by the nuclear probe was compared with that measured by the oximetric technique the mean difference (SD of mean difference) was 0.36 (SD 0.78) and when it was compared with the gamma camera it was 0.08 (SD 0.67). Analysis of scatter plots showed that the larger the shunt, the larger the discrepancy. Twenty four of 29 data sets showed complete agreement between the nuclear probe and gamma camera on the size of the shunt. Any differences were small. These data indicate that left to right intracardiac shunts may be measured accurately by a nuclear probe at the bedside in either the coronary care unit or outpatient department. PMID:2835974

  7. Prevention options for ventriculoperitoneal shunt infections: a retrospective analysis during a five-year period

    PubMed Central

    Wu, Xing; Liu, Qin; Jiang, Xiaofei; Zhang, Tao

    2015-01-01

    Shunt infection is the most common and dreaded complication in patients with hydrocephalus. For the purpose of reducing the high morbidity and mortality, how to prevent is a vital step. A retrospective analysis of 384 CSF cerebrospinal fluid (CSF) shunt procedures was undertaken from 2006 to 2010 in our neurosurgery department. Infection diagnosis was established by subjecting the CSF to biochemical and microbiological parameters. The patients’ demographic and clinical characteristics, various treatment procedures and outcome were evaluated. The infection rate of ventriculoperitoneal (VP) shunt was 12.5% in 2006, which dropped to 2% and stabilized at lower level from 2008. The most common causes of hydrocephalus were traumatic injury and brain tumor. Fever and consciousness disturbance were the major clinical symptoms. Gram-negative rods episodes was the most frequently isolated microorganisms accounting for 58%, followed by S. aureus , S. epidermidis and Staphylococcus haemolyticus. With the removal of shunt and intravenous antibiotics therapy, 82% of the patients survived. Majority of the isolates were sensitive to the carbopenem antibiotics and vancomycin. The mean length of hospital stay was 47 days. Prompt shunt removal and perioperative antibiotic prophylaxis seems to be essential for the survival of patients with VP shunt infection. PMID:26770643

  8. Effect of rapamycin on hepatic osteodystrophy in rats with portasystemic shunting

    PubMed Central

    van der Merwe, Schalk W; Conradie, Maria M; Bond, Robert; Olivier, Brenda J; Fritz, Elongo; Nieuwoudt, Martin; Delport, Rhena; Slavik, Tomas; Engelbrecht, Gert; Kahn, Del; Shephard, Enid G; Kotze, Maritha J; de Villiers, Nico P; Hough, Stephen

    2006-01-01

    AIM: To study if T-cell activation related to portasystemic shunting causes osteoclast-mediated bone loss through RANKL-dependent pathways. We also investigated if T-cell inhibition using rapamycin would protect against bone loss in rats. METHODS: Portasystemic shunting was performed in male Sprague-Dawley rats and rapamycin 0.1 mg/kg was administered for 15 wk by gavage. Rats received powderized chow and supplemental feeds to prevent the effects of malnutrition on bone composition. Weight gain and growth was restored after surgery in shunted animals. At termination, biochemical parameters of bone turnover and quantitative bone histology were assessed. Markers of T-cell activation, inflammatory cytokine production, and RANKL-dependent pathways were measured. In addition, the roles of IGF-1 and hypogonadism were investigated. RESULTS: Portasystemic shunting caused low turnover osteoporosis that was RANKL independent. Bone resorbing cytokine levels, including IL-1, IL-6 and TNFα, were not increased in serum and TNFα and RANKL expression were not upregulated in PBMC. Portasystemic shunting increased the circulating CD8+ T-cell population. Rapamycin decreased the circulating CD8+ T-cell population, increased CD8+ CD25+ T-regulatory cell population and improved all parameters of bone turnover. CONCLUSION: Osteoporosis caused by portasystemic shunting may be partially ameliorated by rapamycin in the rat model of hepatic osteodystrophy. PMID:16874862

  9. Transvenous retrograde portography for identification and characterization of portosystemic shunts in dogs.

    PubMed

    Miller, Matthew W; Fossum, Theresa W; Bahr, Anne M

    2002-12-01

    Transvenous retrograde portography for identification and characterization of portosystemic shunts in dogs A method for transvenous retrograde portography (TRP) in dogs suspected to have a portosystemic shunt (PSS) and results in 20 dogs are described. For TRP, dogs were anesthetized and positioned in left lateral recumbency A dual-lumen balloon-tipped catheter was inserted into the right jugular vein and advanced into the azygos vein. The balloon was inflated to occlude the azygos vein, and contrast material was injected during fluoroscopic evaluation. The catheter was then positioned in the caudal vena cava just cranial to the diaphragm. The balloon was again inflated to occlude the vena cava, and contrast material was again injected. Once a shunt was identified, selective catheterization was attempted with a guide wire and angled catheter. A PSS was identified in 18 of the 20 dogs. In 10 of the 18, the shunt vessel could be selectively catheterized, allowing measurement of portal pressures while the shunt was occluded with the balloon. In 1 dog, results of TRP were normal, but subsequent exploratory celiotomy revealed a single extrahepatic PSS, which was surgically attenuated. The other dog in which results of TRP were normal did not have a macroscopic PSS. In dogs suspected to have a PSS, TRP may be a useful adjunctive diagnostic test that is less invasive than operative mesenteric vein portography and allows measurement of portal pressures before and after temporary shunt occlusion. PMID:12479329

  10. Mechanism for measurement of flow rate of cerebrospinal fluid in hydrocephalus shunts.

    PubMed

    Rajasekaran, Sathish; Kovar, Spencer; Qu, Peng; Inwald, David; Williams, Evan; Qu, Hongwei; Zakalik, Karol

    2014-01-01

    The measurement of the flow rate of cerebrospinal fluid (CSF) or existence of CSF flow inside the shunt tube after shunt implant have been reported as tedious process for both patients and doctors; this paper outlines a potential in vitro flow rate measurement method for CSF in the hydrocephalus shunt. The use of implantable titanium elements in the shunt has been proposed to allow for an accurate temperature measurement along the shunt for prediction of CSF flow rate. The CSF flow velocity can be deduced by decoupling the thermal transfer in the measured differential time at a pair of measurement spots of the titanium elements. Finite element analyses on the fluidic and thermal behaviors of the shunt system have been conducted. Preliminary bench-top measurements on a simulated system have been carried out. The measured flow rates, ranging from 0.5 mm/sec to 1.0 mm/sec, which is clinically practical, demonstrate good agreements with the simulation results. PMID:25570411

  11. Integrated fuel cell stack shunt current prevention arrangement

    DOEpatents

    Roche, Robert P.; Nowak, Michael P.

    1992-01-01

    A fuel cell stack includes a plurality of fuel cells juxtaposed with one another in the stack and each including a pair of plate-shaped anode and cathode electrodes that face one another, and a quantity of liquid electrolyte present at least between the electrodes. A separator plate is interposed between each two successive electrodes of adjacent ones of the fuel cells and is unified therewith into an integral separator plate. Each integral separator plate is provided with a circumferentially complete barrier that prevents flow of shunt currents onto and on an outer peripheral surface of the separator plate. This barrier consists of electrolyte-nonwettable barrier members that are accommodated, prior to the formation of the integral separator plate, in corresponding edge recesses situated at the interfaces between the electrodes and the separator plate proper. Each barrier member extends over the entire length of the associated marginal portion and is flush with the outer periphery of the integral separator plate. This barrier also prevents cell-to-cell migration of any electrolyte that may be present at the outer periphery of the integral separator plate while the latter is incorporated in the fuel cell stack.

  12. Oculo-peritoneal shunt: draining aqueous humor to the peritoneum.

    PubMed

    Maldonado-Junyent, Ana; Maldonado-Bas, Arturo; Gonzalez, Andrea; Pueyrredón, Francisco; Maldonado-Junyent, María; Maldonado-Junyent, Arturo; Rodriguez, Diego; Bulacio, Mariano

    2015-01-01

    In 2010, there were estimated to be approximately 60.5 million people with glaucoma. This number is expected to increase to 79.6 million by 2020. In 2010, there were 8.4 million people with bilateral blindness caused by glaucoma, and this number is expected in increase to 11.2 million by 2020. Filtering implants are special devices that have been developed to reduce intraocular pressure in patients with refractory glaucoma. The success rate of these implants is relatively low, and they continue to fail over time. To avoid failure caused by the formation of scar tissue around the implants, attempts have been made to drain the aqueous humor to various sites, including the venous system, lacrimal sac, sinuses, and conjunctival fornix. Recently, a system to shunt aqueous humor from the anterior chamber to the peritoneum has been developed. The surgical technique involved in this system is a modification of the technique currently used by neurosurgeons for the treatment of hydrocephalus. We present the first case operated using this technique. PMID:25945537

  13. Cellular and shunt conductances of toad bladder epithelium.

    PubMed

    Gordon, L G

    1978-12-29

    Toad urinary bladders were mounted in Ussing-type chambers and volt-age-clamped. At nonzero voltages only, small fluctuations in current, delta I, and therefore in tissue conductance, delta Gt, were detected. These fluctuations were caused by the smooth muscle of the underlying tissue which could be monitored continuously and simultaneously with the current, I. Inhibition of the smooth muscle contraction with verapamil (2 X 10(-5) M) abolished the fluctuations in I and Gt. Amiloride (10(-4) M) had no significant effect on the magnitude of delta Gt, oxytocin increased Gt without affecting delta Gt, and mucosal hypertonicity produced by mannitol increased delta Gt. These results are consistent with the hypothesis that two parallel pathways exist for passive current flow across the toad urinary bladder: one, the cellular pathway, was not affected by smooth muscle activity; the other, the paracellular pathway, was the route whose conductance was altered by the action of the smooth muscle. Thus the relationship between the cellular and shunt conductances of the epithelium of the toad urinary bladder, under a variety of conditions, can be investigated by utilizing the effects of the movement of the smooth muscle. PMID:110941

  14. Hyperglucagonemia and hyperkinetic circulation after portocaval shunt in the rat

    SciTech Connect

    Kravetz, D.; Arderiu, M.; Bosch, J.; Fuster, J.; Visa, J.; Casamitjana, R.; Rodes, J.

    1987-02-01

    The study was aimed at investigating whether increased portal venous inflow (PVI) after portocaval shunt (PCS) in the rat is the result of selective splanchnic vasodilatation or whether it is part of a generalized circulatory disturbance. Rats with PCS and sham-operated controls were studied 2 wk after surgery by measuring cardiac output (CO), PVI, and hepatic artery flow (HAF) with radioactive microspheres (V Cr and UC). Plasma glucagon (GL) was measured by radioimmunoassay. PCS rats had increased CO and reduced arterial pressure and total peripheral resistance. PVI was markedly increased, but this appeared to be part of a generalized circulatory disturbance, since when PVI is expressed as percent of CO no difference is observed between PCS and sham-operated rats, indicating the absence of a preferential splanchnic vasodilatation. GL increased after PCS, and significant correlations were observed between GL and CO and between GL and PVI. HAF increased after PCS but did not compensate the loss of portal flow, evidence by a lower total hepatic flow in PCS rats. These results suggest that PCS induces a hyperkinetic circulatory state in which increased PVI represents its splanchnic manifestation and that increased GL release may be in part responsible for these hemodynamic changes.

  15. Effects of isradipine and other calcium antagonists on arteriovenous-shunt flow in anesthetized rabbits and cats

    SciTech Connect

    Hof, R.P.

    1989-04-17

    The effects of vasodilators on arteriovenous (AV)-shunt flow was investigated in anesthetized cats and rabbits, using the tracer microsphere method. In cats, the calcium antagonist isradipine reduced AV-shunt flow; verapamil showed a similar tendency and nicardipine was without effect. Dihydralazine strongly increased, but nitroglycerin and dipyridamole decreased AV-shunt flow. In rabbits, the effects of isradipine and verapamil were similar to those seen in cats. Sodium nitroprusside had no effect, whereas prazosin, minoxidil, and the potassium-channel activator cromakalim increased AV-shunt flow. The contrasting effects of drugs sharing the same mechanism of action suggest that target-tissue selectivity is more important than the mechanism of action. An increase of AV-shunt flow is unlikely to be beneficial but could be associated with a number of undesirable side effects. It might negatively affect migraine sufferers and, if AV-shunt dilatation shows no tolerance development, it represents an unnecessary hemodynamic burden for the heart.

  16. Ventriculo-bipleural shunt as last resort in a 4-year-old child in whom a VP and VA shunt failed.

    PubMed

    Ratliff, Miriam; Unterberg, Andreas; Bächli, Heidi

    2016-03-01

    The authors present the unusual case of a 4-year-old boy who had a complex history of posthemorrhagic hydrocephalus and who underwent more than 40 surgeries related to this condition. In the course of trying to treat his condition, ventriculoperitoneal, ventriculoatrial, and ventriculopleural shunts were inserted and failed. The child presented with a dysfunction of his shunt system. A ventriculopleural shunt was inserted, but within days the patient developed dyspnea as a clinical symptom of pleural effusion that required repeated thoracentesis. A bipleural drainage system was inserted, and no relevant pleural effusions developed during the follow-up period. Although the authors' experience is based on a single case, they do suggest bipleural drainage in patients with clinically relevant pleural effusions when the more common alternatives are not a good choice. Bipleural drainage might particularly be an option in children, who are prone to pleural effusion because of the smaller absorbing pleural surface. The authors reviewed the English-language literature on PubMed dating back to 1952. To their knowledge, this is the only published case in which a patient was treated with a ventriculo-bipleural shunt. PMID:26613270

  17. The Budd-Chiari syndrome. Treatment by mesenteric-systemic venous shunts.

    PubMed Central

    Cameron, J L; Herlong, H F; Sanfey, H; Boitnott, J; Kaufman, S L; Gott, V L; Maddrey, W C

    1983-01-01

    Twelve patients with the Budd-Chiari syndrome have been managed surgically. Ten of the patients were female, two were male, with a mean age of 40 years. Three of the patients had polycythemia vera, two had pre-existing cirrhosis, one had ingested estrogens, one had an occult tumor, and in four there were no associated factors. Ten patients presented with ascites and two with bleeding esophageal varices. The diagnosis was confirmed in all 12 patients by liver biopsy and hepatic vein catheterization. Inferior vena cavography revealed the abdominal vena cava to be thrombosed in six patients. The superior mesenteric vein was used to decompress the congested liver in all 12 patients. In five patients, a mesocaval shunt (MCS) was performed and in seven patients, a mesoatrial shunt (MAS) was carried out. There were four hospital deaths (two MCS, two MAS). One late death (MAS) occurred from liver failure following shunt thrombosis. Two additional patients (one MCS, one MAS) re-developed ascites immediately following surgery and angiography revealed a thrombosed shunt. Ascites has been controlled with a LeVeen shunt in these two patients, but liver biopsies showed progression to cirrhosis. The remaining five patients (three MAS, two MCS) did well, and angiography revealed patent shunts. Two of these patients, however, re-developed ascites at 4 and 10 months following MAS and required a second MAS. Follow-up ranges from 6 to 68 months. In three of the patients (two MCS, one MAS) with patent shunts, liver biopsy shows a remarkable return toward normal liver architecture and histology. Images Fig. 1. Fig. 2. Fig. 3. Fig. 4. Fig. 5. Fig. 6. Fig. 7. PMID:6615056

  18. T1-201 per rectum: A noninvasive method for evaluating portosystemic shunt

    SciTech Connect

    Verdickt, X.; Reding, P.; Tshiamala, P.; Ham, H.R.

    1984-01-01

    Portosystemic shunt is one of the most important complications of liver cirrhosis. Unfortunately, current methods for detecting and quantifying this shunt are either non-specific or associated with significant morbidity. The aim of this work was to evaluate the clinical value of a new non-traumatic method which consisted of administrating T1-201 per rectum and monitoring the absorbed activity using a camera and a computer system. The method assumes that in the absence of portosystemic shunt, most of the absorbed activity will be fixed in the liver while in the presence of this shunt, some of the activity will be fixed in the myocardium. The ratio of heart to liver activity can therefore be used to evaluate the importance of the portosystemic shunt. 34 subjects have been studied. The ratio of heart to liver activity at the 25th minute after the tracer administration is higher in patients with liver cirrhosis (n=22, m=.9, s.d.=.37) than in patients with steatosis (n=10, m=.28, s.d.=.03). In two healthy subjects investigated the H/L ratio was .27 and .30. The reproducibility of the test was evaluated in 8 subjects and showed a good reproducibility (mean of difference =.03, range=.01 to .07). Patients with esophageal varices had always a high H/L ratio while some patients with liver cirrhosis without esophageal varices had also high H/L ratio, probably due to the presence of intrahepatic shunt. The authors' results showed the value of this new non-traumatic test for detecting and quantifying extra- as well as intrahepatic portosystematic shunt.

  19. The internal mammary artery as a shunt in a noncyanotic infant with hemitruncus: surgical and anesthetic management.

    PubMed

    Mahan, Vicki L; Stevens, Randy M; Mesia, Cesar I; Schwartz, Roy E; Moulick, Achintya N

    2016-08-01

    The internal mammary artery (IMA) has been used as a systemic-to-pulmonary artery shunt in selected patients with congenital heart disease. Growth and development of hypoplastic pulmonary arteries have been described. We discuss the surgical and anesthetic management of an infant with an atretic-thrombosed right pulmonary artery originating from the ascending aorta in whom the IMA was used to create a systemic-to-pulmonary artery shunt after failure of a previous shunt and later successful pulmonary artery reconstruction. The IMA should be considered as an alternative conduit in patients requiring a systemic-to-pulmonary artery shunt for growth of pulmonary arteries. PMID:27290936

  20. Post-TIPS Hepatic Encephalopathy Treated by Occlusion Balloon-Assisted Retrograde Embolization of a Coexisting Spontaneous Splenorenal Shunt

    SciTech Connect

    Shioyama, Yasukazu; Matsueda, Kiyoshi; Horihata, Koushi; Kimura, Masashi; Nishida, Norifumi; Kishi, Kazushi; Terada, Masaki; Sato, Morio; Yamada, Ryusaku

    1996-11-15

    A 51-year-old man with posthepatitis cirrhosis underwent a transjugular intrahepatic portosystemic shunt (TIPS) for bleeding of recurrent esophageal varices. The patient had a coexisting, spontaneous, splenorenal shunt. He subsequently developed hepatic encephalopathy, presumably due to excessive portosystemic shunting. Since medical management resulted in no significant improvement, the splenorenal shunt was embolized from the jugular vein approach via renal vein access during temporary balloon occlusion. Within a few days, the patient's hepatic encephalopathy resolved. Twelve months later the patient showed no recurrence of encephalopathy and had maintained a patent TIPS.

  1. Right-to-left shunt is common in chronic migraine.

    PubMed

    Nahas, S J; Young, W B; Terry, R; Kim, A; Van Dell, T; Guarino, A J; Silberstein, S D

    2010-05-01

    Our aim was to determine the prevalence of right-to-left shunt (RtLS) in patients with chronic migraine (CM), and to correlate the presence and grade of RtLS with aura and neurological symptoms, and duration and severity of disease. The prevalence of RtLS in migraine without aura is similar to that of the general population (between 20 and 35%). In migraine with aura, the prevalence is much higher (approximately 50%). The prevalence in CM, with or without aura, is unknown. Consecutive patients between the ages of 18 and 60 years with CM attending a tertiary care specialty headache clinic over an 8-week period were eligible. There were 131 patients in the study. A structured diagnostic interview was performed. Bubble transcranial Doppler with Valsalva manoeuvre determined RtLS presence and grade. Sixty-six percent (86/131) of patients had RtLS, a statistically significantly greater rate than those reported in the general population and in migraine with or without aura (P < 0.001). There was no difference in RtLS rate or grade between those with and those without aura. Specific headache features and the presence of neurological symptoms were similar between those with and those without RtLS. Compared with both the general population and the episodic migraine population (with and without aura), patients with CM, with or without aura, are more likely to have RtLS. The clinical implications of our findings need to be determined. PMID:19732069

  2. [Repeat endovascular interventions after transjugular intrahepatic portosystemic shunt (tips) procedures].

    PubMed

    Shipovskiĭ, V N; Tsitsiashvili, M Sh; Saakian, A M; Monakhov, D V; Khuan, Ch; Nechaev, A I

    2010-01-01

    The authors share their experience with transjugular intrahepatic portosystemic shunt (TIPS) procedures preformed in a total of fifty-nine patients diagnosed with and hence operated on for class B and C hepatocirrhosis (according to the Child-Turcotte-Pugh classification), portal hypertension, grade 3 varicosely dilated oesophageal veins, or ascites. Of these, there were 12 women and 47 men (average age 56.3 years). Three types of stents were used: matrix stents (PERICO), self-expanding (ZA-stents, OptiMedsinus-SuperFlex- Visualstents, Zilverstents, SMART), and coated self-expanding stents (Gore Viatorr TIPS Endoprosthesis). Six (11 %) TIPS procedures ended in failure. Of the remaining 53 successful TIPS attempts, thirteen patients developed an in-stent thrombosis at various terms postoperatively, with one patient having experienced it twice Within four postoperative days, thrombosis occurred in three patients, at terms varying from one month to three months in five patients, and from 6 to 12 months in a further five patients. More often thromboses were encountered with the matrix stents (n = 3) 23.0% (PERICO) and self-expanding stents (n = 8) in 61.0% (OptiMed sinus-SuperFlex-Visual). Thromboses were clinically manifested by oesophageal variceal haemorrhage. An in-stent thrombosis was confirmed by means of ultrasonographic duplex scanning (lack of arterial blood flow). The primary stent patency rate following TIPS procedures amounted to 67%. with the secondary assisted graft patency rate equalling 89%. Restoration of the stent's lumen after TIPS procedures by means of endovascular recanalization, rheolytic thrombectomy, balloon angioplasty, and a stent-in-stent technique appears to be a minimally invasive, rather efficient method and virtually the only way to preserve the stent's patency. This technique makes it possible to decrease the rate of recurrent oesophageal variceal haemorrhage. PMID:21032871

  3. Transjugular intrahepatic portosystemic shunts and portal hypertension-related complications

    PubMed Central

    Siramolpiwat, Sith

    2014-01-01

    Portal hypertension (PH) plays an important role in the natural history of cirrhosis, and is associated with several clinical consequences. The introduction of transjugular intrahepatic portosystemic shunts (TIPS) in the 1980s has been regarded as a major technical advance in the management of the PH-related complications. At present, polytetrafluoroethylene-covered stents are the preferred option over traditional bare metal stents. TIPS is currently indicated as a salvage therapy in patients with bleeding esophageal varices who fail standard treatment. Recently, applying TIPS early (within 72 h after admission) has been shown to be an effective and life-saving treatment in those with high-risk variceal bleeding. In addition, TIPS is recommended as the second-line treatment for secondary prophylaxis. For bleeding gastric varices, applying TIPS was able to achieve hemostasis in more than 90% of patients. More trials are needed to clarify the efficacy of TIPS compared with other treatment modalities, including cyanoacrylate injection and balloon retrograde transvenous obliteration of gastric varices. TIPS should also be considered in bleeding ectopic varices and refractory portal hypertensive gastropathy. In patients with refractory ascites, there is growing evidence that TIPS not only results in better control of ascites, but also improves long-term survival in appropriately selected candidates. In addition, TIPS is a promising treatment for refractory hepatic hydrothorax. However, the role of TIPS in the treatment of hepatorenal and hepatopulmonary syndrome is not well defined. The advantage of TIPS is offset by a risk of developing hepatic encephalopathy, the most relevant post-procedural complication. Emerging data are addressing the determination the optimal time and patient selection for TIPS placement aiming at improving long-term treatment outcome. This review is aimed at summarizing the published data regarding the application of TIPS in the management of

  4. Transjugular intrahepatic portosystemic shunts and portal hypertension-related complications.

    PubMed

    Siramolpiwat, Sith

    2014-12-01

    Portal hypertension (PH) plays an important role in the natural history of cirrhosis, and is associated with several clinical consequences. The introduction of transjugular intrahepatic portosystemic shunts (TIPS) in the 1980s has been regarded as a major technical advance in the management of the PH-related complications. At present, polytetrafluoroethylene-covered stents are the preferred option over traditional bare metal stents. TIPS is currently indicated as a salvage therapy in patients with bleeding esophageal varices who fail standard treatment. Recently, applying TIPS early (within 72 h after admission) has been shown to be an effective and life-saving treatment in those with high-risk variceal bleeding. In addition, TIPS is recommended as the second-line treatment for secondary prophylaxis. For bleeding gastric varices, applying TIPS was able to achieve hemostasis in more than 90% of patients. More trials are needed to clarify the efficacy of TIPS compared with other treatment modalities, including cyanoacrylate injection and balloon retrograde transvenous obliteration of gastric varices. TIPS should also be considered in bleeding ectopic varices and refractory portal hypertensive gastropathy. In patients with refractory ascites, there is growing evidence that TIPS not only results in better control of ascites, but also improves long-term survival in appropriately selected candidates. In addition, TIPS is a promising treatment for refractory hepatic hydrothorax. However, the role of TIPS in the treatment of hepatorenal and hepatopulmonary syndrome is not well defined. The advantage of TIPS is offset by a risk of developing hepatic encephalopathy, the most relevant post-procedural complication. Emerging data are addressing the determination the optimal time and patient selection for TIPS placement aiming at improving long-term treatment outcome. This review is aimed at summarizing the published data regarding the application of TIPS in the management of

  5. External lumbar drain: A pragmatic test for prediction of shunt outcomes in idiopathic normal pressure hydrocephalus

    PubMed Central

    Chotai, Silky; Medel, Ricky; Herial, Nabeel A.; Medhkour, Azedine

    2014-01-01

    Background: The consensus on most reliable supplemental test to predict the shunt responsiveness in patients with idiopathic normal pressure hydrocephalus (iNPH) is lacking. The aim of this study is to discuss the utility of external lumbar drain (ELD) in evaluation of shunt responsiveness for iNPH patients. Methods: A retrospective review of 66 patients with iNPH was conducted. All patients underwent 4-day ELD trial. ELD-positive patients were offered ventriculoperitoneal shunt (VPS) surgery. The primary outcome evaluation parameters were gait and mini mental status examination (MMSE) assessment. The family and patient perception of improvement was accounted for in the outcome evaluation. Results: There were 38 male and 28 female with mean age of 74 years (range 45-88 years). ELD trial was positive in 86% (57/66) of patients. No major complications were encountered with the ELD trial. A total of 60 patients (57 ELD-positive, 3 ELD-negative) underwent VPS insertion. The negative ELD trial (P = 0.006) was associated with poor outcomes following shunt insertion. The positive ELD trial predicted shunt responsiveness in 96% patients (P < 0.0001, OR = 96.2, CI = 11.6-795.3). A receiver operating characteristic (ROC) curve analysis revealed that the ELD trial is reasonably accurate in differentiating shunt responder from non-responder in iNPH patients (area under curve = 0.8 ± 0.14, P = 0.02, CI = 0.52-1.0). The mean follow-up period was 12-months (range 0.3-3 years). The significant overall improvement after VPS was seen in 92% (55/60). The improvement was sustained in 76% of patients at mean 3-year follow-up. The number of comorbid conditions (P = 0.034, OR = 4.15, CI = 1.2-9.04), and a history of cerebrovascular accident (CVA) (P = 0.035, OR = 4.4, CI = 1.9-14.6) were the predictors of poor outcome following shunt surgery. Conclusion: The positive ELD test predicted shunt responsiveness in 96% of patients. With adequate technique, maximal results with minimal

  6. Complete Intestinal Obstruction and Necrosis as a Complication of a Ventriculoperitoneal Shunt in Children

    PubMed Central

    Zhao, Rui; Shi, Wei; Yu, Jianzhong; Gao, Xiaofeng; Li, Hao

    2015-01-01

    Abstract Ventriculoperitoneal (VP) shunt complications are common, but abdominal complications are rare. The objective of this report is to present 2 cases of intestinal obstruction due to a VP shunt and review the literature for data on this rare occurrence. A 4-month-old boy received surgical resection of a medulloblastoma and a VP shunt was inserted to manage progressive hydrocephalus. Two months later, he was admitted with intermittent vomiting, and plain abdominal radiography showed complete intestinal obstruction. Emergency laparotomy revealed an adhesive intestinal obstruction around the catheter, and approximately 5 cm of necrotic ileum was resected. His recovery was uneventful. In the second case, a 6-year-old boy was diagnosed with a primary nongerminomatous malignant germ cell tumor and a VP shunt was place to treat hydrocephalus. Two weeks after the first course of chemotherapy, he went into a coma; computed tomography demonstrated enlargement of the tumor and gross total resection was performed. Two weeks later, he developed abdominal distention; plain radiography showed intestinal obstruction and laparotomy revealed adhesive intestinal obstruction around the catheter with 15 cm of necrotic ileum. The necrotic bowel was resected. Unfortunately, the patient developed sepsis and despite treatment remained in a vegetative state. Medline, Central, Embase, and Google Scholar databases were searched up to May 9, 2014, using the terms VP shunt, shunting, and/or intestinal obstruction. Only cases involving children or adolescents were included. Eleven reports involving patients with abdominal complications resulting from a VP shunt for hydrocephalus were identified. The dates of the reports spanned from 1971 to 2014. Volvulus was the most common cause of VP shunt-related obstruction, and mechanical obstruction due to twisting of the catheter the second most common. Only 1 case in the literature review was related to intestinal adhesions. Treatment in most

  7. Simulations reveal adverse hemodynamics in patients with multiple systemic to pulmonary shunts.

    PubMed

    Esmaily-Moghadam, Mahdi; Murtuza, Bari; Hsia, Tain-Yen; Marsden, Alison

    2015-03-01

    For newborns diagnosed with pulmonary atresia or severe pulmonary stenosis leading to insufficient pulmonary blood flow, cyanosis can be mitigated with placement of a modified Blalock-Taussig shunt (MBTS) between the innominate and pulmonary arteries. In some clinical scenarios, patients receive two systemic-to-pulmonary connections, either by leaving the patent ductus arteriosus (PDA) open or by adding an additional central shunt (CS) in conjunction with the MBTS. This practice has been motivated by the thinking that an additional source of pulmonary blood flow could beneficially increase pulmonary flow and provide the security of an alternate pathway in case of thrombosis. However, there have been clinical reports of premature shunt occlusion when more than one shunt is employed, leading to speculation that multiple shunts may in fact lead to unfavorable hemodynamics and increased mortality. In this study, we hypothesize that multiple shunts may lead to undesirable flow competition, resulting in increased residence time (RT) and elevated risk of thrombosis, as well as pulmonary overcirculation. Computational fluid dynamics-based multiscale simulations were performed to compare a range of shunt configurations and systematically quantify flow competition, pulmonary circulation, and other clinically relevant parameters. In total, 23 cases were evaluated by systematically changing the PDA/CS diameter, pulmonary vascular resistance (PVR), and MBTS position and compared by quantifying oxygen delivery (OD) to the systemic and coronary beds, wall shear stress (WSS), oscillatory shear index (OSI), WSS gradient (WSSG), and RT in the pulmonary artery (PA), and MBTS. Results showed that smaller PDA/CS diameters can lead to flow conditions consistent with increased thrombus formation due to flow competition in the PA, and larger PDA/CS diameters can lead to insufficient OD due to pulmonary hyperfusion. In the worst case scenario, it was found that multiple shunts can lead to

  8. Hypoxia and GABA shunt activation in the pathogenesis of Alzheimer's disease.

    PubMed

    Salminen, Antero; Jouhten, Paula; Sarajärvi, Timo; Haapasalo, Annakaisa; Hiltunen, Mikko

    2016-01-01

    We have previously observed that the conversion of mild cognitive impairment to definitive Alzheimer's disease (AD) is associated with a significant increase in the serum level of 2,4-dihydroxybutyrate (2,4-DHBA). The metabolic generation of 2,4-DHBA is linked to the activation of the γ-aminobutyric acid (GABA) shunt, an alternative energy production pathway activated during cellular stress, when the function of Krebs cycle is compromised. The GABA shunt can be triggered by local hypoperfusion and subsequent hypoxia in AD brains caused by cerebral amyloid angiopathy. Succinic semialdehyde dehydrogenase (SSADH) is a key enzyme in the GABA shunt, converting succinic semialdehyde (SSA) into succinate, a Krebs cycle intermediate. A deficiency of SSADH activity stimulates the conversion of SSA into γ-hydroxybutyrate (GHB), an alternative route from the GABA shunt. GHB can exert not only acute neuroprotective activities but unfortunately also chronic detrimental effects which may lead to cognitive impairment. Subsequently, GHB can be metabolized to 2,4-DHBA and secreted from the brain. Thus, the activation of the GABA shunt and the generation of GHB and 2,4-DHBA can have an important role in the early phase of AD pathogenesis. PMID:26617286

  9. The Value of Programmable Shunt Valves for the Management of Subdural Collections in Patients with Hydrocephalus

    PubMed Central

    Alexiou, George A.; Mihos, Evaggelos; Fotakopoulos, George; Voulgaris, Spyridon

    2013-01-01

    Background. The aim of the present study was to assess the value of electromagnetic programmable shunt valves for the treatment of subdural collections. Methods. Adult patients with hydrocephalus of various causes that were treated with programmable shunt valves during the last ten years were retrospectively studied. In 127 patients, 139 electromagnetic programmable shunt valves were implanted. Results. A nontraumatic subdural fluid collection was detected in 12 patients. The treatment of these patients consisted of reprogramming of the valve's opening pressure. In 5 patients small subdural hematomas were detected; 4 of these patients were treated by raising the opening pressure alone and one patient required surgical drainage and change of the pressure setting. Traumatic chronic subdural hematomas were detected in 6 patients. These patients were treated by surgical drainage and readjustment of the valve's opening pressure. Conclusion. The ability to treat a shunt-related complication, such as a subdural fluid collection, by reprogramming the valve's opening pressure to a higher setting is an advantage over nonprogrammable valves, and it enables the opening pressure to be slowly lowered once the fluid collection is reabsorbed. Based on our results, we believe that programmable shunt valves should be preferred. PMID:24453855

  10. Quantitative measurement of intrapulmonary and extrapulmonary right-to-left shunt.

    PubMed

    Jones, H A; Stradling, J R; Clark, J C; Davies, E E; Rozkovec, A

    1983-05-01

    We have developed a new technique that enables the shunting of blood from the right to the left side of the circulation to be partitioned into a cardiac and a lung component. The effects of recirculation are minimal, and the method does not require on-line data analysis. Quantitative estimates of these components have been made in two normal dogs and in five patients with raised pulmonary arterial pressures, some of whom were known to have a patent foramen ovale. The results were compared with oxygen shunt measured during air breathing. A poorly soluble gas, nitrogen, radiolabelled with 13N in solution is injected first into a central vein while matched samples of blood are drawn from the pulmonary artery and the aorta. A second solution containing 13N is injected into the right ventricle and sampled from the aorta only. Standardized gamma-counting techniques were used to analyze both the injected radioactivity and the radioactivity in the samples. These two measurements enable us to calculate the total right-to-left shunt, the pulmonary shunt, and by subtraction the extrapulmonary cardiac shunt. PMID:6863103

  11. Efficacy of Doppler Ultrasonography for Assessment of Transjugular Intrahepatic Portosystemic Shunt Patency

    SciTech Connect

    Kimura, Masashi; Sato, Morio; Kawai, Nobuyuki; Tanaka, Kayo; Sonomura, Tetsuo; Shioyama, Kazushi; Kishi, Yasukazu; Terada, Masaki; Yamada, Ryusaku

    1996-11-15

    Purpose: To assess the efficacy of Doppler ultrasonography (US) as a noninvasive method for monitoring patency of the transjugular intrahepatic portosystemic shunt (TIPS). Methods: Twenty-nine patients who had received TIPS for bleeding esophagogastric varices and/or refractory ascites with portal hypertension underwent Doppler US studies within 2 weeks after TIPS. Further studies were performed in 15 of them at 6 months, in 9 at 1 year, and in 4 at 2 years for a total of 57 US studies. The US findings were compared with the angiographic findings obtained at the same time. Results: In 45 of the 57 studies, shunt patency was found by Doppler US, correlating to 44 patencies and one occlusion on angiography. Doppler signal in the shunt could not be detected in 12 studies resulting in the diagnosis of shunt occlusion. This correlated with angiographic occlusion in 8 studies and patency in the remaining 4. All angiographically patent shunts that were occluded by Doppler US had various degrees of stenosis. A number of technical factors were found to be responsible for Doppler US false-positive or false-negative diagnoses, some related to the type of stent used. The Doppler US sensitivity was therefore 92%, the specificity 89%. Conclusion: Doppler US is a reliable noninvasive method to evaluate patency of TIPS.

  12. [Lymphangiomyomatosis with chylous ascites treatment successfully by peritoneo-venous shunting].

    PubMed

    Kimura, M; Morikawa, T; Takeuchi, K; Furuie, H; Fukimura, M; Mikami, R; Kakuta, Y; Kawamura, S; Tashiro, Y

    1996-05-01

    A 49-year-old woman was admitted to our hospital because of coughing and dyspnea. A chest roentogenogram showed emphysematous changes and a diffuse reticular shadow. A high-resolution CT scan of the chest showed many small cysts throughout the lungs. Lymphangiomyomatosis was diagnosed after examination of a specimen obtained by transbronchial biopsy. Abdominal distention due to chylous ascites developed during the hospital stay despite anti-estrogen therapy. Because the ascites was resistant to conservative therapy, we decided to begin peritoneo-venous shunting with a Denver Shunt system. After the operation, the abdominal distention was controlled for 1 year and 11 months, at which time the patient died of respiratory and heart failure with pneumonia. At autopsy, the shunt was patent and functional although about 900 ml of serous ascites fluid was present. An adenocarcinoma was found in the upper lobe of the right lung, but it may not have been related to the lymphangiomyomatosis. Peritoneovenous shunting with a Denver Shunt can be used to treat chylous ascites due to lymphangiomyomatosis when conservative therapy is insufficient. PMID:8753114

  13. Radionuclide quantitation of right-to-left intracardiac shunts in children

    SciTech Connect

    Peter, C.A.; Armstrong, B.E.; Jones, R.H.

    1981-09-01

    A simple, noninvasive method for measurement of right-to-left intracardiac shunts would enhance the management of patients with congenital heart disease. This study describes application of data processing techniques used previously in dye-indicator curves to data recorded during the initial transit of radioactive bolus through the central circulation. Radionuclide angiocardiograms were performed in 20 children, mean age 30 months, immediately after cardiac catheterization for congenital heart disease. The radionuclide data recorded over the carotid artery were used to replace arterial sampling required for dye indicators, and forward triangles were fitted to calculate the right-to-left shunt in an approach similar to that of Wood for indicator-dilution curves. Ten of the children had right-to-left shunts by Fick and radionuclide measurement, and 10 of the children with septal defects had no right-to-left shunt by either technique. Both the radionuclide and Fick measurements correlated well (r . 0.95). Therefore, radionuclide angiocardiographic data may be used for accurate calculation of right-to-left shunts in small children, eliminating the need for arterial sampling.

  14. The relationship of subarachnoid hemorrhage and the need for postoperative shunting.

    PubMed

    Vale, F L; Bradley, E L; Fisher, W S

    1997-03-01

    The incidence of chronic hydrocephalus requiring shunting after aneurysmal subarachnoid hemorrhage (SAH) is not precisely known. The authors investigated whether the need for ventriculoperitoneal (VP) shunting can be predicted by initial Hunt and Hess grade or Fisher computerized tomography score. One hundred eight patients who presented with SAH and underwent 116 surgical procedures for aneurysm clipping were evaluated retrospectively to determine the incidence of chronic hydrocephalus. Chronic hydrocephalus was defined as clinically and radiographically demonstrated hydrocephalus that lasted 2 weeks or longer after the original hemorrhage and that required shunting. All SAH patients were managed in a similar fashion with induced hypervolemia, relative hemodilution, and hypertension complemented by a course of calcium channel blockers. The majority of patients underwent perioperative extracranial ventricular drainage to allow intraoperative brain relaxation and to assist intracranial pressure management. The overall mortality rate of the study group was 17%. Of the surviving patients, 20% underwent VP shunt placement secondary to chronic hydrocephalus. There were no statistically significant relationships between chronic hydrocephalus and patient age or gender, aneurysm type and size, or use of a perioperative drain. There was a high clinical correlation between chronic hydrocephalus and admission Hunt and Hess grades and Fisher grades (p < 0.05). All of the patients who survived a second bleeding episode and almost 46% of the patients who presented with intraventricular hemorrhage required placement of a VP shunt. The authors present predictive tables of chronic hydrocephalus based on the patient's admission Hunt and Hess grade and Fisher classification. PMID:9046303

  15. Constitutively active endothelial Notch4 causes lung arteriovenous shunts in mice

    PubMed Central

    Jelin, Eric B.; Ng, Jennifer; Wu, Jianfeng; Carlson, Timothy R.; Wu, Xiaoqing; Looney, Mark R.; Wang, Rong A.

    2010-01-01

    Lung arteriovenous (AV) shunts or malformations cause significant morbidity and mortality in several distinct clinical syndromes. For most patients with lung AV shunts, there is still no optimal treatment. The underlying molecular and cellular etiology for lung AV shunts remains elusive, and currently described animal models have insufficiently addressed this problem. Using a tetracycline-repressible system, we expressed constitutively active Notch4 (Notch4*) specifically in the endothelium of adult mice. More than 90% of mice developed lung hemorrhages and respiratory insufficiency and died by 6–7 wk after gene expression began. Vascular casting and fluorescent microsphere analysis showed evidence of lung AV shunts in affected mice. Cessation of Notch4* expression reversed these pathophysiological effects. Assessment of the vascular morphology revealed enlarged, tortuous vessels in the lungs that resembled arteriovenous malformations. By using whole lung organ culture, we demonstrated the effects of constitutively active Notch4 on the lung vasculature to be a primary lung phenomenon. Together, our results indicate the importance of Notch signaling in maintaining the lung vasculature and offer a new, reliable model with which to study the pathobiology of lung arteriovenous shunts and malformations. PMID:19933399

  16. A 25-year experience with total portosystemic shunts and reappraisal of colon exclusion.

    PubMed

    Talman, E A; Johns, T N; Regan, W W

    1983-05-01

    The results of 43 total shunt procedures for bleeding esophageal varices performed consecutively at two community hospitals from 1956 to 1981 are reviewed. Of 15 patients with immediate preoperative bilirubins greater than 2.0 mg/dl, 11 died following shunt surgery. Of 28 other shunted patients with immediate preoperative bilirubins of less than 2.0 mg/dl, there was only one in-hospital death, thus substantiating the contention that the last preoperative serum bilirubin value is the best predictor of operative mortality. Of ten patients with appreciable ascites verified at the time of operation, there were only two survivors, and both of these had preoperative bilirubins of less than 2.0 mg/dl. Twenty-nine of the 31 patients who left the hospital were still living at least one year after operation. All 23 patients operated on prior to 1977 were available for 5-year follow-up, and there were 14 survivors (60%). Thirteen of the 31 patients (42%) manifested some degree of hepatic encephalopathy, as interpreted by necessity for protein restriction and either Neomycin or Lactulose. Incapacitating post-shunt hepatic encephalopathy developed in one patient who required recurrent hospitalizations for episodic coma. This patient underwent a total abdominal colectomy and ileorectal anastomosis, with elimination of all episodes of encephalopathy for the subsequent 4 1/2 years. The previous 16 cases in the literature of surgical treatment of post-shunt encephalopathy are reviewed, and the efficacy of such colon exclusion is reassessed. PMID:6601935

  17. Emergency management of an acute tension pneumocephalus following ventriculoperitoneal shunt surgery for normal pressure hydrocephalus.

    PubMed

    Aydoseli, Aydın; Akcakaya, Mehmet Osman; Aras, Yavuz; Boyali, Osman; Unal, Omer Faruk

    2013-01-01

    Tension pneumocephalus is a rare and life threatening complication of intracranial surgical procedures, and requires immediate recognition and surgical intervention. Tension pneumocephalus following ventriculoperitoneal shunt surgery is extremely rare and commonly seen as a delayed complication. To our knowledge, early postoperative tension pneumocephalus after shunt surgery was reported only in one other publication. We present a case of acute tension pneumocephalus following ventriculoperitoneal shunt surgery for normal pressure hydrocephalus, which was managed well with close neurological follow-up and rapid surgical intervention. The use of the portable CT scanner in this case saved significant time, without the transport of the patient to the radiology unit, made early surgical intervention possible, and prevented morbidity and mortality. PMID:24101285

  18. Comparative study of two structures of shunt active filter suppressing particular harmonics

    NASA Astrophysics Data System (ADS)

    Benchaita, L.; Salem Nia, A.; Saadate, S.

    1998-07-01

    This paper deals with the study of shunt active filters used for suppressing particular harmonics generated by nonlinear loads in utility distribution power systems. Both structures of shunt active filter, voltage source active filter (VSAF) and current source active filter (CSAF), are considered. The analytical study of specific harmonics identification in a given spectrum is first presented. For simulation as well as experimentation the nonlinear load is a conventional three phase thyristor rectifier and harmonics 5 and 7 are selected to be eliminated by active filter. The whole system consisting of the ac power supply network, the SCR rectifier and the shunt active filter (VSAF/CSAF) is then simulated. The simulation results are discussed and the efficiency of the two kinds of active filter are compared. Finally, for the first structure, VSAF, the simulation results are confirmed by experimental test realized by means of a fully digital control active power filter developed in our laboratory.

  19. Delayed-onset endophthalmitis associated with Ex-PRESS mini glaucoma shunt®.

    PubMed

    Ahmed, Yasir; Pathengay, Avinash; Flynn, Harry W; Isom, Ryan

    2012-01-01

    The authors describe a 92-year-old man who developed delayed-onset endophthalmitis secondary to Bacillus sp. in his left eye 3 years after placement of an Ex-PRESS mini glaucoma shunt (Optonol Ltd., Neve Ilan, Israel). Seidel testing was positive over the Ex-PRESS mini glaucoma shunt. The patient underwent vitreous tap followed by intravitreal injections of vancomycin (1 mg/0.1 mL), ceftazadime (2.25 mg/0.1 mL), and dexamethasone (0.4 mg/0.1 mL), along with subconjunctival injection of vancomycin and tobramycin. The last recorded visual acuity was 3/200 in the left eye. With a 1-month follow-up, this case illustrates successful treatment with a vitreous tap and injection of intravitreal antibiotics. Vitrectomy and removal of the Ex-PRESS mini glaucoma shunt were not performed. PMID:22785601

  20. A 100 GHz Josephson mixer using resistively-shunted Nb tunnel junctions

    NASA Technical Reports Server (NTRS)

    Schoelkopf, R. J.; Phillips, T. G.; Zmuidzinas, J.

    1993-01-01

    The authors describe preliminary mixer results using resistively shunted Nb/AlO(x)/Nb tunnel junctions in a 100-GHz waveguide mixer mount. The mixer utilizes robust, lithographically defined devices which have nonhysteretic I-V curves. A receiver temperature of 390 K (DSB) has been obtained with a conversion loss of -6.5 dB. The receiver's behavior agrees qualitatively with the behavior predicted by the resistively shunted junction model. Substantial improvements in performance are expected with the use of better-optimized shunted junctions, and numerical simulations suggest that, if devices with higher ICRN (critical current-normal state resistance) products can be obtained, Josephson effect mixers could be competitive with SIS mixers at high frequencies.

  1. Pseudotumor cerebri in a child receiving peritoneal dialysis: recovery of vision after lumbo-pleural shunt

    PubMed Central

    Alrifai, Muhammad Talal; Al Naji, Foad; Alamir, Abdulrahman; Russell, Neville

    2011-01-01

    A 9-year-old boy with end-stage renal disease who was receiving continuous ambulatory peritoneal dialysis (CAPD) presented with acute visual loss and was found to have papilledema. Neuroimaging and cerebrospinal fluid (CSF) analysis were normal. The lumbar puncture opening pressure was 290 mm of water so the diagnosis of pseudotumor cerebri (PTC) was entertained. Medical treatment was not an option because of renal insufficiency; neither was lumbo-peritoneal shunting, because of the peritoneal dialysis. After a lumbo-pleural shunt was placed, there was marked improvement in symptoms. The lumbo-pleural shunt is a reasonable option for treatment for PTC in patients on CAPD who require a CSF divergence procedure. PMID:21911996

  2. Superiority of radionuclide over oximetric measurement of left to right shunts.

    PubMed Central

    Baker, E J; Ellam, S V; Lorber, A; Jones, O D; Tynan, M J; Maisey, M N

    1985-01-01

    In 100 children with suspected left to right shunts the ratio of pulmonary to systemic flow was measured both by oximetry and first pass radionuclide angiography. The pulmonary time activity curve from the radionuclide study was analysed by the method of gamma variate fits. There was strong correlation between the two techniques; weaker correlation was found when the shunt was at atrial rather than ventricular level. This difference can be explained only by problems with the oximetric rather than the radionuclide technique. Although there are important limitations to the radionuclide method, it is the more precise and less invasive of the two and is to be preferred when the accurate measurement of left to right shunts is required. PMID:3994867

  3. Orthodeoxia-platypnea due to intracardiac shunting--relief with transcatheter double umbrella closure.

    PubMed

    Landzberg, M J; Sloss, L J; Faherty, C E; Morrison, B J; Bittl, J A; Bridges, N D; Casale, P N; Keane, J F; Lock, J E

    1995-11-01

    The safety and efficacy of transcatheter clamshell occlusion of patent foramen ovale for relief of severe arterial desaturation and dyspnea in the upright position due to intracardiac shunting were examined in eight patients with excessive risk of surgical patent foramen ovale closure. All patients had successful reduction of intracardiac shunting with an immediate rise in oxygen saturation > or = 95% by implantation of a clamshell device on the atrial septum. Despite two early incidents of device embolization, retrieval and immediate re-implantation, and one patient with nonsustained atrial and ventricular arrhythmias, there were no adverse clinical sequelae. In follow-up evaluation transcatheter clamshell closure of patent foramen ovale has provided persistent relief from shunt-related arterial desaturation and symptomatology in all living patients. PMID:8542634

  4. Wave propagation in beams with anti-symmetric piezoelectric shunting arrays

    NASA Astrophysics Data System (ADS)

    Sheng-Bing, Chen; Gang, Wang

    2016-03-01

    Piezoelectric shunting arrays are employed to control the wave propagation in flexible beams. Contrary to conventional symmetric configuration, a substrate beam with anti-symmetric shunting arrays is investigated by adapted transfer matrix method. Compared with symmetric scheme, the anti-symmetric one demonstrates some distinctive characteristics. Primarily, the longitudinal and flexural waves are coupled, so they are correlated and must be considered simultaneously. Moreover, the attenuation of flexural wave is much stronger in anti-symmetric scenario, while the longitudinal wave demonstrates the converse side. As a result, the anti-symmetric scheme can be utilized to improve the vibration isolation capability of shunting arrays. Finally, the theoretical analyses are validated by finite element simulations. Project supported by the National Natural Science Foundation of China (Grant No. 51322502).

  5. Post-Transjugular Intrahepatic Portosystemic Shunt Follow-Up and Management in the VIATORR Era.

    PubMed

    Ferral, Hector; Gomez-Reyes, Elisa; Fimmel, Claus J

    2016-03-01

    The transjugular intrahepatic portosystemic shunt (TIPS) is a non-selective portosystemic shunt created using endovascular techniques. The first TIPS was performed in Germany in 1988. The VIATORR self-expandable PTFE covered stent-graft (WL Gore, Flagstaff AZ) was approved by the FDA for a TIPS application in December of 2004. This stent-graft offers excellent shunt patency rates and it is possible that it has a beneficial effect on patient survival. Patient surveillance and post-procedural management have changed after the introduction of this stent-graft. This article presents the current management strategies that are followed at our Institution for patients who have undergone a TIPS procedure with a VIATORR stent graft including imaging follow-up, management of encephalopathy, medical management and nutritional aspects. PMID:26997092

  6. Cerebral venous thrombosis complicated by hemorrhagic infarction secondary to ventriculoperitoneal shunting.

    PubMed

    Son, Won-Soo; Park, Jaechan

    2010-10-01

    While a delayed intracerebral hemorrhage at the site of a ventricular catheter has occasionally been reported in literature, a delayed hemorrhage caused by venous infarction secondary to ventriculoperitoneal shunting has not been previously reported. In the present case, a 68-year-old woman underwent ventriculoperitoneal shunting through a frontal burr hole, and developed a hemorrhagic transformation of venous infarction on the second postoperative day. This massive venous infarction was caused by bipolar coagulation and occlusion of a large paramedian cortical vein in association with atresia of the rostral superior sagittal sinus. Thus, to eliminate the risk of postoperative venous infarction, technical precautions to avoid damaging surface vessels in a burr hole are required under loupe magnification in ventriculoperitoneal shunting. PMID:21113365

  7. A Shunt Model of the Inner Medullary Nephron with Pre-Bend Transitions

    NASA Astrophysics Data System (ADS)

    Gonzalez, M. T.; Hegarty, A. F.; Thomas, S. R.

    2009-09-01

    Mathematical models of the renal medulla face the problem of representing water and solute transfer among tens of thousands of nephrons and blood vessels of various lengths, arranged in countercurrent fashion. Published models fall into two broad categories with respect to this issue: multi-nephron models, which explicitly represent a large number of individual nephrons, or lumped models with virtual shunts that represent the turning back of nephrons and vessels at varying depths. Shunt models have the advantage of a compact description and relatively rapid execution time but are ill-suited to faithfully represent features such as prebend transitions of epithelial permeabilities in nephrons of different lengths. A new shunt model approach that can accommodate pre-bend transitions of nephrons at all medullary depths is presented in this work together with the results of simulation of predicted flows and concentrations.

  8. A mathematical model of diffusional shunting of oxygen from arteries to veins in the kidney.

    PubMed

    Gardiner, Bruce S; Smith, David W; O'Connor, Paul M; Evans, Roger G

    2011-06-01

    To understand how arterial-to-venous (AV) oxygen shunting influences kidney oxygenation, a mathematical model of oxygen transport in the renal cortex was created. The model consists of a multiscale hierarchy of 11 countercurrent systems representing the various branch levels of the cortical vasculature. At each level, equations describing the reactive-advection-diffusion of oxygen are solved. Factors critical in renal oxygen transport incorporated into the model include the parallel geometry of arteries and veins and their respective sizes, variation in blood velocity in each vessel, oxygen transport (along the vessels, between the vessels and between vessel and parenchyma), nonlinear binding of oxygen to hemoglobin, and the consumption of oxygen by renal tissue. The model is calibrated using published measurements of cortical vascular geometry and microvascular Po(2). The model predicts that AV oxygen shunting is quantitatively significant and estimates how much kidney Vo(2) must change, in the face of altered renal blood flow, to maintain cortical tissue Po(2) at a stable level. It is demonstrated that oxygen shunting increases as renal Vo(2) or arterial Po(2) increases. Oxygen shunting also increases as renal blood flow is reduced within the physiological range or during mild hemodilution. In severe ischemia or anemia, or when kidney Vo(2) increases, AV oxygen shunting in proximal vascular elements may reduce the oxygen content of blood destined for the medullary circulation, thereby exacerbating the development of tissue hypoxia. That is, cortical ischemia could cause medullary hypoxia even when medullary perfusion is maintained. Cortical AV oxygen shunting limits the change in oxygen delivery to cortical tissue and stabilizes tissue Po(2) when arterial Po(2) changes, but renders the cortex and perhaps also the medulla susceptible to hypoxia when oxygen delivery falls or consumption increases. PMID:21367922

  9. Deconvolution analysis in radionuclide quantitation of left-to-right cardiac shunts.

    PubMed

    Alderson, P O; Douglass, K H; Mendenhall, K G; Guadiani, V A; Watson, D C; Links, J M; Wagner, H N

    1979-06-01

    A poor bolus injection results in an unsatisfactory quantitative radionuclide angiocardiogram in as many as 20% of children with possible, left-to-right (L-R) cardiac shunts. Deconvolution analysis was applied to similar studies in experimental animals to determine whether dependence on the input bolus could be minimized. Repeated good-bolus, prolonged (greater than 2.5 sec), or multiple-peak injections were made in four normal dogs and seven dogs with surgically created atrial septal defects (ASD). QP/QS was determined using the gamma function. The mean QP/QS from ten good-bolus studies in each animal was used as the standard for comparison. In five trials in normal animals, where a prolonged or double-peak bolus led to a shunt calculation (QP/QS greater than 1.2 : 1), deconvolution resulted in QP/QS = 1.0. Deconvolution improved shunt quantitation in eight of ten trials in animals that received a prolonged bolus. The correlation between the reference QP/QS and the QP/QS calculated from uncorrected bad bolus studies was only 0.39 (p greater than 0.20). After deconvolution using a low pass filter, the correlation improved significantly (r = 0.77, p less than 0.01). The technique gave inconsistent results with multiple-peak bolus injections. Deconvolution analysis in these studies is useful in preventing normals from being classified as shunts, and in improving shunt quantitation after a prolonged bolus. Clinical testing of this technique in children with suspected L-R shunts seems warranted. PMID:536823

  10. Cross-sectional imaging of thoracic and abdominal complications of cerebrospinal fluid shunt catheters.

    PubMed

    Bolster, Ferdia; Fardanesh, Reza; Morgan, Tara; Katz, Douglas S; Daly, Barry

    2016-04-01

    This study aims to review the imaging findings of distal (thoracic and abdominal) complications related to ventriculo-peritoneal (VP), ventriculo-pleural (VPL), and ventriculo-atrial (VA) cerebrospinal fluid (CSF) shunt catheter placement. Institution review board-approved single-center study of patients with thoracic and abdominal CSF catheter-related complications on cross-sectional imaging examinations over a 14-year period was performed. Clinical presentation, patient demographics, prior medical history, and subsequent surgical treatment were recorded. The presence or absence of CSF catheter-related infection and/or acute hydrocephalus on cross-sectional imaging was also recorded. There were 81 distal CSF catheter-related complications identified on 47 thoracic or abdominal imaging examinations in 30 patients (age 5-80 years, mean 39.3 years), most often on CT (CT = 42, MRI = 1, US = 4). Complications included 38 intraperitoneal and 11 extraperitoneal fluid collections. Extraperitoneal collections included nine abdominal wall subcutaneous (SC) pseudocysts associated with shunt migration and obesity, an intrapleural pseudocyst, and a breast pseudocyst. There were also two large VPL-related pleural effusions, a fractured catheter in the SC tissues, and a large VA shunt thrombus within the right atrium. Ten patients (33.3 %) had culture-positive infection from CSF or shunt catheter samples. Ten patients (33.3 %) had features of temporally related acute or worsening hydrocephalus on neuroimaging. In four of these patients, the detection of thoracic and abdominal complications on CT preceded and predicted the findings of acute hydrocephalus on cranial imaging. Thoracic and abdominal complications of CSF shunts, as can be identified on CT,  include shunt infection and/or obstruction, may be both multiple and recurrent, and may be predictive of concurrent acute intracranial problems. PMID:26610766

  11. Electrospun polyurethane as an alternative ventricular catheter and in vitro model of shunt obstruction

    PubMed Central

    Suresh, Supraja

    2015-01-01

    Intracranial pressure and volume vary considerably between hydrocephalic patients, and with age, health and haemodynamic status; if left untreated, intracranial pressure rises and the ventricular system expands to accommodate the excess cerebrospinal fluid, with significant morbidity and mortality. Cerebrospinal fluid shunts in use today have a high incidence of failure with shunt obstruction being the most serious. Conventional proximal shunt catheters are made from poly(dimethyl)siloxane, the walls of which are perforated with holes for the cerebrospinal fluid to pass through. The limited range of catheters, in terms of material selection and flow distribution, is responsible in large part for their poor performance. In this study, we present an alternative design of proximal catheter made of electrospun polyether urethane, and evaluate its performance in the presence of glial cells, which are responsible for shunt blockage. The viability and growth of cells on catheter materials such as poly(dimethyl)siloxane and polyurethane in the form of cast films, microfibrous mats and porous sponges were studied in the presence of proteins present in cerebrospinal fluid after 48 h and 96 h in culture. The numbers of viable cells on each substrate were comparable to untreated poly(dimethyl)siloxane, both in the presence and absence of serum proteins found in cerebrospinal fluid. A cell culture model of shunt obstruction was developed in which cells on electrospun polyether urethane catheters were subjected to flow during culture in vitro, and the degree of obstruction quantified in terms of hydraulic permeability after static and perfusion culture. The results indicate that a catheter made of electrospun polyether urethane would be able to maintain cerebrospinal fluid flow even with the presence of cells for the time period chosen for this study. These findings have implications for the design and deployment of microporous shunt catheter systems for the treatment of

  12. Electrospun polyurethane as an alternative ventricular catheter and in vitro model of shunt obstruction.

    PubMed

    Suresh, Supraja; Black, Richard A

    2015-02-01

    Intracranial pressure and volume vary considerably between hydrocephalic patients, and with age, health and haemodynamic status; if left untreated, intracranial pressure rises and the ventricular system expands to accommodate the excess cerebrospinal fluid, with significant morbidity and mortality. Cerebrospinal fluid shunts in use today have a high incidence of failure with shunt obstruction being the most serious. Conventional proximal shunt catheters are made from poly(dimethyl)siloxane, the walls of which are perforated with holes for the cerebrospinal fluid to pass through. The limited range of catheters, in terms of material selection and flow distribution, is responsible in large part for their poor performance. In this study, we present an alternative design of proximal catheter made of electrospun polyether urethane, and evaluate its performance in the presence of glial cells, which are responsible for shunt blockage. The viability and growth of cells on catheter materials such as poly(dimethyl)siloxane and polyurethane in the form of cast films, microfibrous mats and porous sponges were studied in the presence of proteins present in cerebrospinal fluid after 48 h and 96 h in culture. The numbers of viable cells on each substrate were comparable to untreated poly(dimethyl)siloxane, both in the presence and absence of serum proteins found in cerebrospinal fluid. A cell culture model of shunt obstruction was developed in which cells on electrospun polyether urethane catheters were subjected to flow during culture in vitro, and the degree of obstruction quantified in terms of hydraulic permeability after static and perfusion culture. The results indicate that a catheter made of electrospun polyether urethane would be able to maintain cerebrospinal fluid flow even with the presence of cells for the time period chosen for this study. These findings have implications for the design and deployment of microporous shunt catheter systems for the treatment of

  13. Robust glycogen shunt activity in astrocytes: Effects of glutamatergic and adrenergic agents.

    PubMed

    Walls, A B; Heimbürger, C M; Bouman, S D; Schousboe, A; Waagepetersen, H S

    2009-01-12

    The significance and functional roles of glycogen shunt activity in the brain are largely unknown. It represents the fraction of metabolized glucose that passes through glycogen molecules prior to entering the glycolytic pathway. The present study was aimed at elucidating this pathway in cultured astrocytes from mouse exposed to agents such as a high [K+], D-aspartate and norepinephrine (NE) known to affect energy metabolism in response to neurotransmission. Glycogen shunt activity was assessed employing [1,6-13C]glucose, and the glycogen phosphorylase inhibitor 1,4-dideoxy-1,4-imino-D-arabinitol (DAB) to block glycogen degradation. The label intensity in lactate, reflecting glycolytic activity, was determined by mass spectrometry. In the presence of NE a substantial glycogen shunt activity was observed, accounting for almost 40% of overall glucose metabolism. Moreover, when no metabolic stimulant was applied, a compensatory increase in glycolytic activity was seen when the shunt was inhibited by DAB. Actually the labeling in lactate exceeded that obtained when glycolysis and glycogen shunt both were operational, i.e. supercompensation. A similar phenomenon was seen when astrocytes were exposed to D-aspartate. In addition to glycolysis, tricarboxylic acid (TCA) cycle activity was monitored, analyzing labeling by mass spectrometry in glutamate which equilibrates with alpha-ketoglutarate. Both an elevated [K+] and D-aspartate induced an increased TCA cycle activity, which was altered when glycogen degradation was inhibited. Thus, the present study provides evidence that manipulation of glycogen metabolism affects both glycolysis and TCA cycle metabolism. Altogether, the results reveal a highly complex interaction between glycogenolysis and glycolysis, with the glycogen shunt playing a significant role in astrocytic energy metabolism. PMID:19000744

  14. Occam's razor in the management of ventriculoperitoneal shunt dysfunction: Diagnosis and management of an unusual pediatric case.

    PubMed

    Dadlani, Ravi; Dadlani, Reena; Ghosal, Nandita; Hegde, Alangar

    2015-01-01

    Ventriculoperitoneal (VP) shunt surgery is probably the commonest surgical procedure in neurosurgery. Belying its technical simplicity is the myriad complications associated with it. Shunt malfunction is a common complication associated with this surgery, second only to shunt related infections, which may be associated with it. Sterile cerebrospinal fluid (CSF) eosinophilia (CE) has been reported with VP shunts, which may or may not be related to the dysfunction. Eosinophilia in the CSF has also been associated with a number of other conditions including parasitic infestations in the brain. This may be unrelated to the shunt surgery. We present a case of a child, operated earlier for hydrocephalus, who presented with sub-acute loss of vision and bilateral oculomotor paresis. CSF from a chamber tap revealed eosinophilia. The commonest presenting symptom of shunt malfunction is raised intracranial pressure. There are no reports in the literature of VP shunt malfunction presenting with bilateral oculomotor paresis and decreased visual acuity. The associated CE complicated the clinical picture, especially since the initial brain radiology was normal. We discuss the clinical differential diagnosis of this very interesting presentation, management dilemmas and outcome in this child. This rare clinical presentation was found to be the result of a shunt malfunction and not due to any rare parasitic infestation of the brain. Occam's razor dictates that the simplest explanation in a given situation is usually the most accurate, as is seen in this case. PMID:25972962

  15. Subcutaneous tumor growth complicating the positioning of Denver shunt and intrapleural port-à-cath in mesothelioma patients.

    PubMed

    van Ooijen, B; Eggermont, A M; Wiggers, T

    1992-12-01

    Patients with malignant ascites and malignant pleural fluid from abdominal or pleural mesothelioma underwent the positioning of Denver type peritoneovenous shunt or intrapleural catheter. They developed tumor growth in the subcutaneous tissue surrounding the devices throughout their courses. Neoplastic seeding is a potential complication of the positioning of shunts and catheters in cavities filled with fluid rich in tumor cells. PMID:1478300

  16. Semi-active control of piezoelectric coating's underwater sound absorption by combining design of the shunt impedances

    NASA Astrophysics Data System (ADS)

    Sun, Yang; Li, Zhaohui; Huang, Aigen; Li, Qihu

    2015-10-01

    Piezoelectric shunt damping technology has been applied in the field of underwater sound absorption in recent years. In order to achieve broadband echo reduction, semi-active control of sound absorption of multi-layered piezoelectric coating by shunt damping is significant. In this paper, a practical method is proposed to control the underwater sound absorption coefficients of piezoelectric coating layers by combining design of the shunt impedance that allows certain sound absorption coefficients at setting frequencies. A one-dimensional electro-acoustic model of the piezoelectric coating and the backing is established based on the Mason equivalent circuit theory. First, the shunt impedance of the coating is derived under the constraint of sound absorption coefficient at one frequency. Then, taking the 1-3 piezoelectric composite coating as an example, the sound absorption properties of the coating shunted to the designed shunt impedance are investigated. Next, on the basis of that, an iterative method for two constrained frequencies and an optimizing algorithm for multiple constrained frequencies are provided for combining design of the shunt impedances. At last, an experimental sample with four piezoelectric material layers is manufactured, of which the sound absorption coefficients are measured in an impedance tube. The experimental results show good agreement with the finite element simulation results. It is proved that a serial R-L circuit can control the peak frequency, maximum and bandwidth of the sound absorption coefficient and the combining R-L circuits shunted to multiple layers can control the sound absorption coefficients at multiple frequencies.

  17. Method of removing the effects of electrical shorts and shunts created during the fabrication process of a solar cell

    DOEpatents

    Nostrand, Gerald E.; Hanak, Joseph J.

    1979-01-01

    A method of removing the effects of electrical shorts and shunts created during the fabrication process and improving the performance of a solar cell with a thick film cermet electrode opposite to the incident surface by applying a reverse bias voltage of sufficient magnitude to burn out the electrical shorts and shunts but less than the break down voltage of the solar cell.

  18. Percutaneous Punctured Transcatheter Device Closure of Residual Shunt after Ventricular Septal Defect Repair

    PubMed Central

    2016-01-01

    Ventricular septal defects (VSDs) are estimated to account for 20 to 30% of all congenital heart defects (CHDs). Although a residual shunt is the most common complication of VSD surgery, a second operation that applies the surgical repair method is very difficult because it can increase the possibility of uncontrolled bleeding and the severity of tissue adhesion. Here, we present the first case of percutaneous punctured transcatheter device closure of a residual shunt after VSD repair as a novel method to further develop for the treatment of children with congenital heart disease. PMID:27293910

  19. Palliative ventriculoperitoneal shunt in a pediatric patient with recurrent metastatic medulloblastoma.

    PubMed

    Schiff, Deborah; Kline, Cassie; Meltzer, Hal; Auger, JoAnne

    2009-04-01

    The authors present a case report of a pediatric patient with recurrent metastatic medulloblastoma who demonstrated significant clinical improvement after placement of a palliative ventriculoperitoneal (VP) shunt. They also review the medical literature that supports palliative surgical management of hydrocephalus and intracranial hypertension (ICH) caused by leptomeningeal (LM) spread of malignancy. The burdens and benefits of an invasive surgical procedure must always be weighed carefully, especially at end-of-life. Yet for some patients with LM spread and ICH, VP shunting may improve their quality of life, although their prognosis remains poor. PMID:19327082

  20. Pancreaticoportal Fistula and Disseminated Fat Necrosis After Revision of a Transjugular Intrahepatic Portosystemic Shunt

    SciTech Connect

    Klein, Seth J. Saad, Nael; Korenblat, Kevin; Darcy, Michael D.

    2013-04-15

    A 59-year old man with alcohol related cirrhosis and portal hypertension was referred for transjugular intrahepatic portosystemic shunt (TIPS) to treat his refractory ascites. Ten years later, two sequential TIPS revisions were performed for shunt stenosis and recurrent ascites. After these revisions, he returned with increased serum pancreatic enzyme levels and disseminated superficial fat necrosis; an iatrogenic pancreaticoportal vein fistula caused by disruption of the pancreatic duct was suspected. The bare area of the TIPS was subsequently lined with a covered stent-graft, and serum enzyme levels returned to baseline. In the interval follow-up period, the patient has clinically improved.

  1. Posterior Reversible Encephalopathy Syndrome and Subarachnoid Hemorrhage After Lumboperitoneal Shunt for Fulminant Idiopathic Intracranial Hypertension.

    PubMed

    Fok, Anthony; Chandra, Ronil V; Gutman, Matthew; Ligtermoet, Matthew; Seneviratne, Udaya; Kempster, Peter

    2016-06-01

    A 33-year-old woman presented with severe visual loss from fulminant idiopathic intracranial hypertension. Her lumbar puncture opening pressure was 97 cm H2O. Soon after lumboperitoneal shunt surgery, she had a generalized tonic-clonic seizure. Magnetic resonance imaging demonstrated frontal subarachnoid hemorrhage (SAH) and neuroimaging findings consistent with posterior reversible encephalopathy syndrome (PRES). We hypothesize that an abrupt drop in intracranial pressure after lumboperitoneal shunting led to maladjustment of cerebral vascular autoregulation, which caused SAH and PRES. PMID:26919070

  2. How a left-to-right shunt may protect against haemodynamic deterioration in restrictive cardiomyopathy.

    PubMed

    Van Mieghem, Nicolas; Daenen, Wim; Budts, Werner

    2005-06-01

    Today, more and more children with complex heart lesions and underlying cardiomyopathies reach adulthood. This results in a wide range of new clinical problems encountered in later life. In particular, idiopathic restrictive cardiomyopathy is initially treated by medication to reduce symptoms, but at end-stage disease, heart or heart-lung transplantation becomes unavoidable. We describe the case of a patient with restrictive cardiomyopathy and a persistent extra-cardiac left-to-right shunt, where we hypothesize that the shunt may protect against haemodynamic deterioration in end-stage restrictive cardiomyopathie. PMID:15999476

  3. Implementation of FFT Algorithm using DSP TMS320F28335 for Shunt Active Power Filter

    NASA Astrophysics Data System (ADS)

    Patel, Pinkal Jashvantbhai; Patel, Rajesh M.; Patel, Vinod

    2016-07-01

    This work presents simulation, analysis and experimental verification of Fast Fourier Transform (FFT) algorithm for shunt active power filter based on three-level inverter. Different types of filters can be used for elimination of harmonics in the power system. In this work, FFT algorithm for reference current generation is discussed. FFT control algorithm is verified using PSIM simulation results with DLL block and C-code. Simulation results are compared with experimental results for FFT algorithm using DSP TMS320F28335 for shunt active power filter application.

  4. Percutaneous Mesocaval Shunt Creation in a Patient with Chronic Portal and Superior Mesenteric Vein Thrombosis

    SciTech Connect

    Bercu, Zachary L. Sheth, Sachin B.; Noor, Amir; Lookstein, Robert A. Fischman, Aaron M. Nowakowski, F. Scott Kim, Edward Patel, Rahul S.

    2015-10-15

    The creation of a transjugular intrahepatic portosystemic shunt (TIPS) is a critical procedure for the treatment of recurrent variceal bleeding and refractory ascites in the setting of portal hypertension. Chronic portal vein thrombosis remains a relative contraindication to conventional TIPS and options are limited in this scenario. Presented is a novel technique for management of refractory ascites in a patient with hepatitis C cirrhosis and chronic portal and superior mesenteric vein thrombosis secondary to schistosomiasis and lupus anticoagulant utilizing fluoroscopically guided percutaneous mesocaval shunt creation.

  5. Resolution of severe hepato-pulmonary syndrome following transjugular portosystemic shunt procedure

    PubMed Central

    Wallace, Michael C; James, Alan L; Marshall, Martin; Kontorinis, Nickolas

    2012-01-01

    The hepato-pulmonary syndrome (HPS) is a relatively common complication of hepatic disease that leads to hypoxaemia and dyspnoea secondary to pulmonary shunting. A number of pharmacological therapies have been trialled, yet liver transplantation remains the only definitive treatment. The use of a transjugular intrahepatic portosystemic shunt (TIPS) to reduce portal hypertension and improve oxygenation remains controversial in HPS due to the lack of large clinical series or randomised controlled trials. We present a case of HPS successfully treated with TIPS and review the relevant literature. PMID:22669921

  6. Meso-Rex shunt for immediate portal revascularization in pediatric liver transplantation: first report.

    PubMed

    Rivera, Jairo; Fusaro, Fabio; de Magnée, Catherine; Clapuyt, Philippe; Reding, Raymond

    2012-09-01

    We describe the case of a 13-month-old girl transplanted for biliary atresia with PV hypoplasia. She received the left liver lobe of her mother and presented intraoperative portal thrombosis. Because of technical reasons, the opportunity to have conventional PV reconstruction using the donor left PV stump was lost. Immediate conversion to a meso-Rex shunt, using the recipient jugular vein as a bridge between the superior mesenteric vein and the graft Rex recessus, allowed excellent portal revascularization of the transplant. We suggest that synchronous meso-Rex shunt may constitute a valid alternative to truncal PV anastomosis during pediatric LT. PMID:21923884

  7. A new method for palliation of malignant obstructive jaundice utilizing a peritoneo-venous shunt pump.

    PubMed

    Araki, K; Kure, M; Kobayasi, M; Sugito, M; Ogata, T

    1994-02-01

    A new simple palliative method for use in malignant obstructive jaundice is presented. This method is particularly effective in the prevention of ascending infections. The method consists of interposing a one-way flow shunt pump (peritoneo-venous shunt pump) between a bile catheter and a jejunal catheter. Four patients were treated with this new method. Jaundice improved significantly in all patients. They had a much better quality of life with no serious complications during the terminal course. This less invasive and safe procedure is preferred for patients who have extrahepatic biliary obstruction due to incurable malignant tumors. PMID:7513676

  8. Current diagnosis and management of post-transjugular intrahepatic portosystemic shunt refractory hepatic encephalopathy.

    PubMed

    Pereira, Keith; Carrion, Andres F; Martin, Paul; Vaheesan, Kirubahara; Salsamendi, Jason; Doshi, Mehul; Yrizarry, Jose M

    2015-12-01

    Transjugular intrahepatic portosystemic shunt has evolved into an important option for management of complications of portal hypertension. The use of polytetrafluoroethylene covered stents enhances shunt patency. Hepatic encephalopathy (HE) remains a significant problem after TIPS placement. The approach to management of patients with refractory hepatic encephalopathy typically requires collaboration between different specialties. Patient selection for TIPS requires careful evaluation of risk factors for HE. TIPS procedure-related technical factors like stent size, attention to portosystemic pressure gradient reduction and use of adjunctive variceal embolization maybe important. Conservative medical therapy in combination with endovascular therapies often results in resolution or substantial reduction of symptoms. Liver transplantation is, however, the ultimate treatment. PMID:26332169

  9. Temporary axillary-carotid shunting for unusual instances of carotid stenosis.

    PubMed

    Shumacker, H B; Isch, J H; Jolly, W W

    1976-07-01

    A method has been developed which entails the introduction of the larger end of a Javid shunt tube in the axillary artery and the other in the internal carotid with only momentary interruption of blood flow. The method of closing the incision after the thromboendarterectomy almost entirely eliminates a second period of carotid occlusion. This procedure may be useful in unusual instances in which it is believed advantageous to avoid even the relatively short occlusion periods usually necessary when using the standard intraluminal shunt technique. PMID:936041

  10. Cavo-pulmonary shunt: from the first experiments to clinical practice.

    PubMed

    Konstantinov, I E; Alexi-Meskishvili, V V

    1999-09-01

    The cavo-pulmonary anastomosis is often referred to as Glenn shunt today. The concept of cavo-pulmonary shunting, however, was developed independently by many surgeons. While the work of some of them is widely recognized, the pioneering contributions of many others fall into oblivion. Nonetheless, each of them contributed something original and precious to the total sum of our modern knowledge. It seems timely, as we enter the new millennium, to give due credit to those individuals who put their minds and efforts into helping sick children. These people deserve recognition. PMID:10510029

  11. Resolution of severe hepato-pulmonary syndrome following transjugular portosystemic shunt procedure.

    PubMed

    Wallace, Michael C; James, Alan L; Marshall, Martin; Kontorinis, Nickolas

    2012-01-01

    The hepato-pulmonary syndrome (HPS) is a relatively common complication of hepatic disease that leads to hypoxaemia and dyspnoea secondary to pulmonary shunting. A number of pharmacological therapies have been trialled, yet liver transplantation remains the only definitive treatment. The use of a transjugular intrahepatic portosystemic shunt (TIPS) to reduce portal hypertension and improve oxygenation remains controversial in HPS due to the lack of large clinical series or randomised controlled trials. We present a case of HPS successfully treated with TIPS and review the relevant literature. PMID:22669921

  12. Performance of organics and nitrogen removal in subsurface wastewater infiltration systems by intermittent aeration and shunt distributing wastewater.

    PubMed

    Pan, Jing; Yuan, Fang; Yu, Long; Huang, Linli; Fei, Hexin; Cheng, Fan; Zhang, Qi

    2016-07-01

    Organics and nitrogen removal in four subsurface wastewater infiltration systems (SWISs), named SWIS A (without intermittent aeration and shunt distributing wastewater), SWIS B (with intermittent aeration), SWIS C (with shunt distributing wastewater) and SWIS D (with intermittent aeration and shunt distributing wastewater) was investigated. High average removal rates of 92.3% for COD, 90.2% for NH4-N and 88.1% for TN were achieved simultaneously in SWIS D compared with SWIS A, B and C. The excellent TN removal of SWIS D was due to intermittent aeration provided sufficient oxygen for nitrification in upper matrix and the favorable anoxic or anaerobic environment for denitrification in subsequent matrix, and moreover, shunt distributing wastewater provided sufficient carbon source for denitrification process. The results indicated that intermittent artificial aeration combined with shunt distributing wastewater could achieve high organics and nitrogen removal in SWISs. PMID:27039353

  13. Successful living donor liver transplant in a child with Abernethy malformation with biliary atresia, ventricular septal defect and intrapulmonary shunting.

    PubMed

    Singhal, Ashish; Srivastava, Ajitabh; Goyal, Neerav; Vij, Vivek; Wadhawan, Manav; Bera, Motilal; Gupta, Subash

    2009-12-01

    Congenital portosystemic shunts are the anomalies in which the mesenteric venous drainage bypasses the liver and drains directly into the systemic circulation. This is a report of a rare case of LDLT in a four-yr old male child suffering with biliary atresia (post-failed Kasai procedure) associated with (i) a large congenital CEPSh from the spleno-mesentric confluence to the LHV, (ii) intrapulmonary shunts, (iii) perimembranous VSD. The left lobe graft was procured from the mother of the child. Recipient IVC and the shunt vessel were preserved during the hepatectomy, and the caval and shunt clamping were remarkably short while performing the HV and portal anastomosis. Post-operative course was uneventful; intrapulmonary shunts regressed within three months after transplantation and currently after 18 months following transplant child is doing well with normal liver functions. CEPSh has been extensively discussed and all the published cases of liver transplantation for CEPSh were reviewed. PMID:19254272

  14. Risk factors for first cerebrospinal fluid shunt infection: findings from a multi-center prospective cohort study

    PubMed Central

    Simon, Tamara D.; Butler, Jerry; Whitlock, Kathryn B.; Browd, Samuel R.; Holubkov, Richard; Kestle, John R.W.; Kulkarni, Abhaya V.; Langley, Marcie; Limbrick, David D.; Mayer-Hamblett, Nicole; Tamber, Mandeep; Wellons, John C.; Whitehead, William E.; Riva-Cambrin, Jay

    2014-01-01

    Objective To quantify the extent to which revision(s) of cerebrospinal fluid (CSF) shunt are associated with increased risk of CSF shunt infection, after adjusting for patient factors that may contribute to infection risk. Study design We used the HCRN registry to assemble a large prospective six center cohort of 1,036 children undergoing initial CSF shunt placement between April 2008 and January 2012. The primary outcome of interest was first CSF shunt infection. Data for initial CSF shunt placement and all subsequent CSF shunt revisions prior to first CSF shunt infection, where applicable, were obtained. The risk of first infection was estimated using a multivariable Cox proportional hazard model accounting for patient characteristics and CSF shunt revisions, and is reported using hazard ratios (HR) with 95% confidence intervals (CI). Results Of the 102 children who developed first infection within 12 months of placement, 33 (32%) followed one or more CSF shunt revisions. Baseline factors independently associated with risk of first infection included: gastrostomy tube (HR 2.0, 95% CI: 1.1, 3.3), age 6–12 months (HR 0.3, 95% CI: 0.1, 0.8), and prior neurosurgery (HR 0.4, 95% CI: 0.2, 0.9). After controlling for baseline factors, infection risk was most significantly associated with the need for revision (1 revision vs. none, HR 3.9, 95% CI: 2.2, 6.5; ≥2 revisions, HR 13.0, 95% CI: 6.5, 24.9). Conclusions This study quantifies the elevated risk of infection associated with shunt revisions observed in clinical practice. To reduce risk of infection risk further work should optimize revision procedures. PMID:24661340

  15. Co-Localization of GABA Shunt Enzymes for the Efficient Production of Gamma-Aminobutyric Acid via GABA Shunt Pathway in Escherichia coli.

    PubMed

    Pham, Van Dung; Somasundaram, Sivachandiran; Park, Si Jae; Lee, Seung Hwan; Hong, Soon Ho

    2016-04-28

    Gamma-aminobutyric acid (GABA) is a non-protein amino acid, which is an important inhibitor of neurotransmission in the human brain. GABA is also used as the precursor of biopolymer Nylon-4 production. In this study, the carbon flux from the tricarboxylic acid cycle was directed to the GABA shunt pathway for the production of GABA from glucose. The GABA shunt enzymes succinate-semialdehyde dehydrogenase (GabD) and GABA aminotransferase (GabT) were co-localized along with the GABA transporter (GadC) by using a synthetic scaffold complex. The co-localized enzyme scaffold complex produced 0.71 g/l of GABA from 10 g/l of glucose. Inactivation of competing metabolic pathways in mutant E. coli strains XBM1 and XBM6 increased GABA production 13% to reach 0.80 g/l GABA by the enzymes co-localized and expressed in the mutant strains. The recombinant E. coli system developed in this study demonstrated the possibility of the pathway of the GABA shunt as a novel GABA production pathway. PMID:26838342

  16. Photoacoustic microscopy of arteriovenous shunts and blood diffusion in early-stage tumors

    NASA Astrophysics Data System (ADS)

    Yeh, Chenghung; Liang, Jinyang; Zhou, Yong; Hu, Song; Sohn, Rebecca E.; Arbeit, Jeffrey M.; Wang, Lihong V.

    2016-02-01

    Angiogenesis in a tumor region creates arteriovenous (AV) shunts that cause an abnormal venous blood oxygen saturation (sO2) distribution. Here, we applied optical-resolution photoacoustic microscopy to study the AV shunting in vivo. First, we built a phantom to image sO2 distribution in a vessel containing converged flows from two upstream blood vessels with different sO2 values. The phantom experiment showed that the blood from the two upstream vessels maintained a clear sO2 boundary for hundreds of seconds, which is consistent with our theoretical analysis using a diffusion model. Next, we xenotransplanted O-786 tumor cells in mouse ears and observed abnormal sO2 distribution in the downstream vein from the AV shunts in vivo. Finally, we identified the tumor location by tracing the sO2 distribution. Our study suggests that abnormal sO2 distribution induced by the AV shunts in the vessel network may be used as a new functional benchmark for early tumor detection.

  17. Study of Anterior Chamber Aqueous Tube Shunt by Fourier-Domain Optical Coherence Tomography

    PubMed Central

    Jiang, Chunhui; Li, Yan; Huang, David; Francis, Brian A.

    2012-01-01

    Purpose. This cross-sectional, observational study used Fourier-domain optical coherence tomography (OCT) to examine the position, patency, and the interior entrance site of anterior chamber (AC) aqueous tube shunts. Methods. The OCT, slitlamp biomicroscopy, and gonioscopy findings of 23 eyes of 18 patients with AC shunts were collected and compared. Results. OCT images demonstrated the shunt position and patency in all 23 eyes, and the details of the AC entrance in 16 eyes. The position of the tube varied, with the majority (14/23) on the surface of the iris. The exact position of the AC entrance relative to Schwalbe's line (SL) could be determined in 9 eyes (posterior to SL in 7 eyes, anterior in 2 eyes). At the AC entrance, growth of fibrous scar tissue was present between the tube and the corneal endothelium in all 16 eyes in which the entrance could be clearly visualized. It's a new finding that could not be visualized by slitlamp examination or lower resolution OCT. Conclusion. Compared to slitlamp examination, Fourier-domain OCT of AC tube shunts provided more detailed anatomic information regarding the insertion level relative to SL, scar tissue between the tube and the corneal endothelium, and patency of the tube opening. PMID:22778909

  18. Computer simulation of magnetization-controlled shunt reactors for calculating electromagnetic transients in power systems

    SciTech Connect

    Karpov, A. S.

    2013-01-15

    A computer procedure for simulating magnetization-controlled dc shunt reactors is described, which enables the electromagnetic transients in electric power systems to be calculated. It is shown that, by taking technically simple measures in the control system, one can obtain high-speed reactors sufficient for many purposes, and dispense with the use of high-power devices for compensating higher harmonic components.

  19. Low-dose acetylsalicylic acid and bleeding risks with ventriculoperitoneal shunt placement.

    PubMed

    Kamenova, Maria; Croci, Davide; Guzman, Raphael; Mariani, Luigi; Soleman, Jehuda

    2016-09-01

    OBJECTIVE Ventriculoperitoneal (VP) shunt placement is a common procedure for the treatment of hydrocephalus following diverse neurosurgical conditions. Most of the patients present with other comorbidities and receive antiplatelet therapy, usually acetylsalicylic acid (ASA). Despite its clinical relevance, the perioperative management of these patients has not been sufficiently investigated. The aim of this study was to compare the peri- and postoperative bleeding complication rates associated with ASA intake in patients undergoing VP shunt placement. METHODS Of 172 consecutive patients undergoing VP shunt placement between June 2009 and December 2015, 40 (23.3%) patients were receiving low-dose ASA treatment. The primary outcome measure was bleeding events in ASA users versus nonusers, whereas secondary outcome measures were postoperative cardiovascular events, hematological findings, morbidity, and mortality. A subgroup analysis was conducted in patients who discontinued ASA treatment for < 7 days (n = 4, ASA Group 1) and for ≥ 7 days (n = 36, ASA Group 2). RESULTS No statistically significant difference for bleeding events was observed between ASA users and nonusers (p = 0.30). Cardiovascular complications, surgical morbidity, and mortality did not differ significantly between the groups either. Moreover, there was no association between ASA discontinuation regimens (< 7 days and ≥ 7 days) and hemorrhagic events. CONCLUSIONS Given the lack of guidelines regarding perioperative management of neurosurgical patients with antiplatelet therapy, these findings elucidate one issue, showing comparable bleeding rates in ASA users and nonusers undergoing VP shunt placement. PMID:27581316

  20. Effects of Ground Equalization on the Electrical Performance of Asymmetric CPW Shunt Stubs

    NASA Technical Reports Server (NTRS)

    Dib, Nihad; Gupta, Minoo; Ponchak, George; Katehi, Linda

    1993-01-01

    A hybrid technique is used to study the effects of ground equalization on the electrical performance of CPW shunt stubs. Extensive experiments have been performed and the results are in good agreement with theoretical data. The advantages of using air-bridges in CPW circuits as opposed to bond-wires are also discussed.

  1. Model for Calculating Electrolytic Shunt Path Losses in Large Electrochemical Energy Conversion Systems

    NASA Technical Reports Server (NTRS)

    Prokopius, P. R.

    1976-01-01

    Generalized analysis and solution techniques were developed to evaluate the shunt power losses in electrochemical systems designed with a common or circulating electrolyte supply. Sample data are presented for a hypothetical bulk energy storage redox system, and the general applicability of the analysis technique is discussed.

  2. Transjugular Intrahepatic Portosystemic Shunt Placement in Patients with Cirrhosis and Concomitant Portal Vein Thrombosis

    SciTech Connect

    Ha, Thuong G. Van Hodge, Justin; Funaki, Brian; Lorenz, Jonathan; Rosenblum, Jordan; Straus, Christopher; Leef, Jeff

    2006-10-15

    Purpose. To determine the safety and efficacy of transjugular intrahepatic portosystemic shunt (TIPS) creation in patients with liver cirrhosis complicated by thrombosed portal vein. Methods. This study reviewed 15 cases of TIPS creation in 15 cirrhotic patients with portal vein thrombosis at our institution over an 8-year period. There were 2 women and 13 men with a mean age of 53 years. Indications were refractory ascites, variceal hemorrhage, and refractory pleural effusion. Clinical follow-up was performed in all patients. Results. The technical success rate was 75% (3/4) in patients with chronic portal vein thrombosis associated with cavernomatous transformation and 91% (10/11) in patients with acute thrombosis or partial thrombosis, giving an overall success rate of 87%. Complications included postprocedural encephalopathy and localized hematoma at the access site. In patients with successful shunt placement, the total follow-up time was 223 months. The 30-day mortality rate was 13%. Two patients underwent liver transplantation at 35 days and 7 months, respectively, after TIPS insertion. One patient had an occluded shunt at 4 months with an unsuccessful revision. The remaining patients had functioning shunts at follow-up. Conclusion. TIPS creation in thrombosed portal vein is possible and might be a treatment option in certain patients.

  3. Racial and socioeconomic disparities in outcomes following pediatric cerebrospinal fluid shunt procedures.

    PubMed

    Attenello, Frank J; Ng, Alvin; Wen, Timothy; Cen, Steven Y; Sanossian, Nerses; Amar, Arun P; Zada, Gabriel; Krieger, Mark D; McComb, J Gordon; Mack, William J

    2015-06-01

    OBJECT Racial and socioeconomic disparities within the US health care system are a growing concern. Despite extensive research and efforts to narrow such disparities, minorities and economically disadvantaged patients continue to exhibit inferior health care outcomes. Disparities in the delivery of pediatric neurosurgical care are understudied. Authors of this study examine the impact of race and socioeconomic status on outcomes following pediatric CSF shunting procedures. METHODS Discharge information from the 2000, 2003, 2006, and 2009 Kids' Inpatient Database for individuals (age < 21 years) with a diagnosis of hydrocephalus who had undergone CSF shunting procedures was abstracted for analysis. Multivariate logistic regression analyses, adjusting for patient and hospital factors and annual CSF shunt procedure volume, were performed to evaluate the effects of race and payer status on the likelihood of inpatient mortality and nonroutine hospital discharge (that is, not to home). RESULTS African American patients (p < 0.05) had an increased likelihood of inpatient death and nonroutine discharge compared with white patients. Furthermore, Medicaid patients had a significantly higher likelihood of nonroutine discharge (p < 0.05) as compared with privately insured patients. CONCLUSIONS Findings in this study, which utilized US population-level data, suggest the presence of racial and socioeconomic status outcome disparities following pediatric CSF shunting procedures. Further studies on health disparities in this population are warranted. PMID:25791773

  4. Catheterobronchial fistula due to vena cava superior thrombosis as a late complication of ventriculoatrial shunt.

    PubMed

    Parízek, J; Nytra, T; Zemánková, M; Eliás, P; Sercl, M; Nĕmecková, J; Jakubec, J

    1994-09-01

    A case of a catheterobronchial fistula as a rare late complication of a ventriculoatrial shunt is reported. The ventriculoatrial shunt was implanted in a 4-month-old boy suffering from extreme postinfectious hydrocephalus. During the following years, twelfth nerve palsy on the right, vertebralgias, and salty taste sensations in the mouth associated with intermittent coughing and swelling of the neck and supraclavicular region on the right side developed. Valvography established a diagnosis of fistula 12 years after the implantation of a shunt. Ultrasonography of the neck and mediastinum and contrast-enhanced dynamic computed tomographic scanning demonstrated a catheterobronchial fistula to the subsegmental bronchus of the anterior segment of the right upper lung lobe, a thrombosis of the right internal jugular and both right and left brachiocephalic veins and the superior vena cava, and an extensive collateral venous system mainly draining into the azygos vein. Normalization of cerebrospinal fluid and blood flow and pressure allowed extraction of the "atrial" catheter without complications. One year after surgery the boys is in good health and without signs of shunt dependence. PMID:7842439

  5. Hepatic and renal metabolism before and after portasystemic shunts in patients with cirrhosis.

    PubMed Central

    Owen, O E; Mozzoli, M A; Reichle, F A; Kreulen, T H; Owen, R S; Boden, G; Polansky, M

    1985-01-01

    Hepatic cirrhosis with portal hypertension and gastroesophageal hemorrhage is a disease complex that continues to be treated by surgical portasystemic shunts. Whether or not a reduction or diversion of portal blood flow to the liver adversely affects the ability of the liver to maintain fuel homeostasis via gluconeogenesis, glycogenolysis, and ketogenesis is unknown. 11 patients with biopsy-proven severe hepatic cirrhosis were studied before and after distal splenorenal or mesocaval shunts. Hepatic, portal, and renal blood flow rates and glucose, lactate, pyruvate, glycerol, amino acids, ketone bodies, free fatty acids, and triglyceride arteriovenous concentration differences were determined to calculate net precursor-product exchange rates across the liver, gut, and kidney. The study showed that hepatic contribution of glucose and ketone bodies and the caloric equivalents of these fuels delivered to the blood was not adversely affected by either a distal splenorenal or mesocaval shunt. In addition to these general observations, isolated findings emerged. Mesocaval shunts reversed portal venous blood and functionally converted this venous avenue into hepatic venous blood. The ability of the kidney to make a substantial net contribution of ketone bodies to the blood was also observed. PMID:4044831

  6. An improved reservoir for the flushing test to diagnose shunt insufficiency.

    PubMed

    Schlosser, Hans-Georg; Crawack, Hans-Joachim; Miethke, Christoph; Knitter, Thoralf; Zeiner, Andreas; Sprung, Christian

    2016-09-01

    OBJECTIVE Reservoirs integrated into hydrocephalus shunts are commonly used for the removal of CSF and for intra-ventricular pressure measurement. Pumping with the reservoir to diagnose shunt sufficiency is still a matter of controversy. The authors describe an improved flushing device and its characteristic features in vitro and in vivo. METHODS The flushing reservoir is constructed with a sapphire ball in a cage as a nonresistance valve to also enable the detection of distal occlusions. The most important reservoir parameters were investigated in vitro, simulating total and partial proximal and distal shunt occlusions. Then the expected advantages were assessed in vivo by evaluating the pump test data of 360 implanted reservoirs. The results were compared with those found in the literature. RESULTS The optimization of the technical parameters of the device, such as the high stroke volume in combination with moderate suction force, are obvious advantages compared with other flushing devices. Total occlusion of the ventricular catheter and the valve could be assessed with high certainty. The detection of a total obstruction of the peritoneal catheter or any partial obstruction is also possible, depending on its exact grade and location. CONCLUSIONS Shunt obstructions can be assessed using the pumping test. The reservoir construction presented here provides a clear enhancement of that diagnostic test. PMID:27581310

  7. AB227. Our experience of T-shaped shunt for the treatment of ischemic priapism

    PubMed Central

    Tang, Yuxin; Tan, Zhengyu; Zhou, Jun; Peng, Dongyi; Gan, Yu; Yang, Jianfu; He, Leye; Wang, Yong

    2016-01-01

    Objective To explore the efficacy of T-shaped shunt operation for the treatment of ischemic priapism. Methods We retrospectively studied nine patients with ischemic priapism. All patients were given preoperative MRI examination, T-shaped shunt operation and heparin saline flushing were performed when conservative therapy failed, a wedge biopsy of corpus cavernosum were done during the operation for tissue diagnosis. Results All patients had satisfactory outcome of the T-shaped shunt surgery except two patients who were diagnosed as malignant priapism, one was due to perineal neuroendocrine carcinoma and he refused taking further therapy and died 3 months later; the other was caused by penile epithelioid sarcoma and then accepted partial resection of penis; during 6–12 months follow-up, five cases developed erectile dysfunction. Conclusions MRI appears to be valuable for the management of ischemic priapism. Although T-shaped shunt operation has advantages of simple operation, less complications and satisfactory efficacy, it is not suitable for the patient of ischemic priapism which is caused by tumor. A wedge biopsy of corpus cavernosum during operation is helpful to confirm malignant priapism.

  8. Liquid breathing - Prevention of pulmonary arterial-venous shunting during acceleration.

    NASA Technical Reports Server (NTRS)

    Sass, D. J.; Ritman, E. L.; Caskey, P. E.; Banchero, N.; Wood, E. H.

    1972-01-01

    Dependent pulmonary atelectasis, arterial-venous shunting, and downward displacement of the heart caused by the gravitational-inertial force environment were prevented in dogs breathing oxygenated liquid fluorocarbon in a whole-body water-immersion respirator. Partial closure of the major airways during part of the expiratory phase of liquid respiration was a significant problem initially but was minimized in subsequent studies.

  9. Multiple acquired extrahepatic portosystemic shunts secondary to veno-occlusive disease in a young German shepherd

    PubMed Central

    Fredholm, Dan

    2009-01-01

    An 11-month-old German shepherd presented with behavioral abnormalities. Histopathologic analysis of liver biopsies taken during exploratory laparotomy revealed veno-occlusive disease caused by fibrosis of the hepatic central veins leading to secondary portal hypertension, development of shunting vessels, and hepatic encephalopathy. The fibrosis was likely congenital in origin. PMID:19794875

  10. Tube shunt coverage with gamma-irradiated cornea allograft (VisionGraft)

    PubMed Central

    Ekici, Feyzahan; Moster, Marlene R; Cvintal, Victor; Hu, Wanda D; Waisbourd, Michael

    2015-01-01

    Purpose To investigate the clinical outcomes of tube shunt coverage using sterile gamma-irradiated cornea allograft. Patients and methods The Wills Eye Hospital Glaucoma Research Center retrospectively reviewed the medical records of 165 patients who underwent glaucoma tube shunt procedures using sterile gamma-irradiated cornea allograft (VisionGraft) between December 2012 and November 2013. Demographic characteristics, type of tube shunt, and position were noted. Complications were recorded at 1 day; 1 week; 1, 3, 6, and 12 months; and on the final postoperative visit. Results One hundred and sixty-nine eyes of 165 patients were included. The mean follow-up time was 4.8±3.5 (ranging from 1 to 16) months. There was no evidence of immunological reaction, infection, or exposure in 166 eyes (98.2%). Three eyes (1.8%) experienced graft or tube exposure within the first 3 postoperative months. Two of the cases had underlying diseases: bullous pemphigoid and chronic allergic conjunctivitis. Conclusion Coverage of tube shunts using gamma-irradiated cornea allograft had a low exposure rate and was well tolerated. The graft can be stored long term at room temperature and has an excellent postoperative cosmetic appearance. PMID:25995612

  11. Nonbacterial Thrombotic Endocarditis Associated with the Use of a Peritoneovenous Shunt

    PubMed Central

    Kaplansky, Michael; Reyes, Cesar V.

    1987-01-01

    The following report concerns a case of nonbacterial thrombotic endocarditis that developed in a patient being treated with a LeVeen peritoneovenous shunt for intractable ascites secondary to Laënnec's cirrhosis. To the best of our knowledge, such an association has not been previously described. (Texas Heart Institute Journal 1987; 14:215-218) Images PMID:15229744

  12. [Peritoneojugular shunt in the treatment of idiopathic ascites in the hemodialyzed patient: a clinical case].

    PubMed

    Massari, R; Marinelli, S; Fulgente, R; Summa, R

    1995-01-01

    The case of an uremic patient receiving dialytic treatment, who also had an hydiopatic ascites, probably due to peritoneal hyper-waterproofing, is described. Peritoneo-venous shunt was positioned with good result. Generally, similar clinical situations such a therapy is as valid as other commonly used methods. PMID:8706186

  13. [Isolated left ventricular--right atrial shunt after blunt chest trauma (author's transl)].

    PubMed

    Kreuzer, E; Beyer, J

    1978-12-01

    A case of left-ventricular-right-atrial septal defect secundary to blunt chest trauma is described. The etiology of this type of septal defect, e. g. congenital, following aortic and mitral valve replacement, endocarditis and trauma, is discussed. Early defect closure is recommended in the presence of significant shunt volume. PMID:751280

  14. Stent Angioplasty of Closed Mesocaval Shunt in a Patient with Budd-Chiari Syndrome

    SciTech Connect

    Sancak, Tanzer; Karagulle, Ayse Tuba; Bilgic, Sadik; Sanlidilek, Umman; Yerdel, Mehmet Ali

    2002-08-15

    Budd-Chiari syndrome (BCS) is an uncommon disorder caused by hepatic venous outflow obstruction. It is characterized by ascites, hepatomegaly and abdominal pain. Percutaneous intervention shave recently been used for the treatment of BCS. We present a case of BCS with a closed mesocaval shunt which was reopened with a self-expandable metallic stent.

  15. High-energy phosphate metabolism in a neonatal model of hydrocephalus before and after shunting.

    PubMed

    da Silva, M C; Drake, J M; Lemaire, C; Cross, A; Tuor, U I

    1994-10-01

    The authors studied the effects of hydrocephalus on the high-energy phosphate metabolism of the brain and the impact of ventriculoperitoneal (VP) shunting on these changes in an experimental model of hydrocephalus. High-energy phosphate metabolism was analyzed using in vivo magnetic resonance (MR) imaging and 31P MR spectroscopy. Hydrocephalus was produced in 34 1-week-old kittens by cisternal injection of 0.05 ml of a 25% kaolin solution. Sixteen litter mates were used as controls. A VP shunt with a distal slit valve was implanted in 17 of the 34 hydrocephalic animals 10 days after induction of hydrocephalus. Both MR imaging and 31P MR spectroscopy were obtained 1 and 3 weeks after either kaolin or distilled water injection. Untreated hydrocephalic animals had marked dilatation of the lateral ventricles and periventricular edema. Magnetic resonance spectroscopy showed a significant decrease in the energy index ratio of phosphocreatine (PCR): inorganic phosphate (PI) and an increase in the PI:adenosine triphosphate (ATP) ratio. There was a direct correlation between the decrease in the energy index and ventricular size. Compared with preoperative scans, shunted animals showed no periventricular edema, and the ventricles decreased in size. Also, PCR:PI and PI:ATP ratios were within the levels of controls. This study suggests that neonatal hydrocephalus results in a mild hypoxic/ischemic insult that is treatable by VP shunting. PMID:7931588

  16. Optimally tuned resonant negative capacitance for piezoelectric shunt damping based on measured electromechanical impedance

    NASA Astrophysics Data System (ADS)

    Salloum, Rogério; Heuss, Oliver; Götz, Benedict; Mayer, Dirk

    2015-04-01

    In this paper, a new tuning method for shunt damping with a series resistance, inductance and negative capacitance is proposed and its validity is investigated. It is based on the measured electromechanical impedance of a piezoelectric system, which is represented through an equivalent electrical circuit that takes into account the characteristics of the piezoelectric transducer and the host structure. Afterwards, an additional circuit representing the shunt is connected and the Norton equivalent impedance is obtained at the terminals that represent the mechanical mode of interest. During the tuning process, the optimal shunt parameters are found by minimizing the maximum absolute value of the Norton equivalent impedance over a defined frequency range through a numerical optimization. Taking benefit from the analogy between electrical impedance and mechanical admittance, the minimization of different mechanical responses (displacement, velocity or acceleration) is also proposed and the different optimum shunt parameters obtained are compared. In view of real technical applications, this method allows the integration of a real negative capacitance circuit, i.e., a negative impedance converter, rather than an ideal component. It is thus possible to use the impedance of this circuit and optimize the individual component values. Since this method is based on one simple measurement, it can be applied to arbitrary structures without the need of complex dynamic tests or expensive finite elements calculations. Finally, an experimental analysis is carried out in order to compare the damping performance of the proposed method and the conventional analytical method that minimizes a mechanical frequency response function.

  17. A Multi-Mode Blade Damping Control using Shunted Piezoelectric Transducers with Active Feedback Structure

    NASA Technical Reports Server (NTRS)

    Choi, Benjamin; Morrison, Carlos; Min, James

    2009-01-01

    The Structural Dynamics and. Mechanics branch (RXS) is developing smart adaptive structures to improve fan blade damping at resonances using piezoelectric (PE) transducers. In this presentation, only one shunted PE transducer was used to demonstrate active control of multi-mode blade resonance damping on a titanium alloy (Ti-6A1-4V) flat plate model, regardless of bending, torsion, and 2-stripe modes. This work would have a significant impact on the conventional passive shunt damping world because the standard feedback control design tools can now be used to design and implement electric shunt for vibration control. In other words, the passive shunt circuit components using massive inductors and. resistors for multi-mode resonance control can be replaced with digital codes. Furthermore, this active approach with multi patches can simultaneously control several modes in the engine operating range. Dr. Benjamin Choi presented the analytical and experimental results from this work at the Propulsion-Safety and. Affordable Readiness (P-SAR) Conference in March, 2009.

  18. Negative capacitance shunt damping system with optimized characteristics for use with piezoelectric transducers

    NASA Astrophysics Data System (ADS)

    Pohl, Martin

    2014-03-01

    For ecologic sustainability and decreasing reserves of fossile energy sources, fuel efficiency is a major concern especially for passenger aircraft. Therefore, lightweight structures made from carbon fiber plastics offer great potential. But when used for panel-like structures, they have the disadvantage of lower damping and coincidence frequencies compared to conventional differential metal constructions. Both aspects lead to an increased vibration level and by this a higher noise radiation. Because of this, special noise and vibration treatment is needed to ensure passenger cabin comfort. Besides passive damping and active structural acoustic control (ASAC), piezoelectric shunt damping is investigated. Due to its broadband performance, the negative capacitance shunt can be used for multimode systems with varying eigenfrequencies. These shunts are usually built with operational amplifiers and passive components as resistors and capacitors. This setup is sufficient for laboratory tests at low excitation levels. In fact, it is not capable of accessing the full voltage amplitude of common piezoelectric transducers, because most operational amplifiers only deliver +/-15V maximum output voltage. Therefore an improved setup is presented in this paper, which addresses the specific voltage requirements of a common piezoelectric transducer to achieve best performance. It comprises a tailored power source and an appropriate concept for the negative capacitance shunt hardware. This new hardware only uses standard operational amplifiers together with a high voltage power amplifier to cover the whole operating range of a piezoelectric transducer. A demonstrator board is developed and experimentally investigated at a test structure. Finally, the results are compared to a conventional setup.

  19. Percutaneous In Utero Thoracoamniotic Shunt Creation for Fetal Thoracic Abnormalities Leading to Non-Immune Hydrops

    PubMed Central

    White, Sarah B.; Tutton, Sean M.; Rilling, William S.; Kuhlmann, Randall S.; Peterson, Erika L.; Wigton, Thomas R.; Ames, Mary B.

    2015-01-01

    Purpose In a fetus, rare, fetal thoracic abnormalities can cause mediastinal shift and vena cava obstruction resulting in fetal hydrops and intra-uterine fetal demise. This series describes a trans-abdominal, trans-uterine Seldinger based percutaneous approach to create a shunt for treatment of these fetal abnormalities. Material and Methods Five fetuses presented with non-immune fetal hydrops due to fetal thoracic abnormalities causing severe mass effect. Under direct ultrasound guidance, an 18 G needle was used to access the malformation. Through a peel away sheath, a customized pediatric transplant 4.5 French double J ureteral stent was advanced; the leading loop was placed in the fetal thorax and the trailing end left outside the fetal thorax within the amniotic cavity. Results Seven thoracoamniotic shunts were successfully placed in 5 fetuses, with one shunt immediately replaced due to displacement during the procedure and the second not functioning at follow-up requiring insertion of a second shunt. All fetuses had successful decompression of the thoracic malformation, allowing lung re-expansion and resolution of hydrops. Three of 5 mothers had meaningful (> 7 days) prolongation of their pregnancies. All pregnancies were maintained to > 30 weeks, with a range of 30 weeks 1 day to 37 weeks 2 days. There were no maternal complications. Conclusions Seldinger based percutaneous approach to draining fetal thoracic abnormalities is feasible and can allow for prolongation of pregnancy, antenatal lung development and ultimately result in fetal survival. PMID:24702750

  20. Periodic shunted arrays for the control of noise radiation in an enclosure

    NASA Astrophysics Data System (ADS)

    Casadei, Filippo; Dozio, Lorenzo; Ruzzene, Massimo; Cunefare, Kenneth A.

    2010-08-01

    This work presents numerical and experimental investigations of the application of a periodic array of resistive-inductive (RL) shunted piezoelectric patches for the attenuation of broadband noise radiated by a flexible plate in an enclosed cavity. A 4×4 lay-out of piezoelectric patches is bonded to the surface of a rectangular plate fully clamped to the top face of a rectangular cavity. Each piezo-patch is shunted through a single RL circuit, and all shunting circuits are tuned at the same frequency. The response of the resulting periodic structure is characterized by frequency bandgaps where vibrations and associated noise are strongly attenuated. The location and extent of induced bandgaps are predicted by the application of Bloch theorem on a unit cell of the periodic assembly, and they are controlled by proper selection of the shunting circuit impedance. A coupled piezo-structural-acoustic finite element model is developed to evaluate the noise reduction performance. Strong attenuation of multiple panel-controlled modes is observed over broad frequency bands. The proposed concept is tested on an aluminum plate mounted in a wooden box and driven by a shaker. Experimental results are presented in terms of pressure responses recorded using a grid of microphones placed inside the acoustic box.

  1. Manipulating waves by distilling frequencies: a tunable shunt-enabled rainbow trap

    NASA Astrophysics Data System (ADS)

    Cardella, Davide; Celli, Paolo; Gonella, Stefano

    2016-08-01

    In this work, we propose and test a strategy for tunable, broadband wave attenuation in electromechanical waveguides with shunted piezoelectric inclusions. Our strategy is built upon the vast pre-existing literature on vibration attenuation and bandgap generation in structures featuring periodic arrays of piezo patches, but distinguishes itself for several key features. First, we demystify the idea that periodicity is a requirement for wave attenuation and bandgap formation. We further embrace the idea of ‘organized disorder’ by tuning the circuits as to resonate at distinct neighboring frequencies. In doing so, we create a tunable ‘rainbow trap’ (Tsakmakidis et al 2007 Nature 450 397–401) capable of attenuating waves with broadband characteristics, by distilling (sequentially) seven frequencies from a traveling wavepacket. Finally, we devote considerable attention to the implications in terms of packet distortion of the spectral manipulation introduced by shunting. This work is also meant to serve as a didactic tool for those approaching the field of shunted piezoelectrics, and attempts to provide a different perspective, with abundant details, on how to successfully design an experimental setup involving resistive-inductive shunts.

  2. Shunt-Enhanced, Lead-Driven Bifurcation of Epilayer GaAs based EEC Sensor Responsivity

    NASA Astrophysics Data System (ADS)

    Solin, Stuart; Werner, Fletcher

    2015-03-01

    The results reported here explore the geometric optimization of room-temperature EEC sensor responsivity to applied bias by exploring contact geometry and location. The EEC sensor structure resembles that of a MESFET, but the measurement technique and operation distinguish the EEC sensor significantly; the EEC sensor employs a four-point resistance measurement as opposed to a two-point source-drain measurement and is operated under both forward and reverse bias. Under direct forward bias, the sensor distinguishes itself from a traditional FET by allowing current to be injected from the gate, referred to as a shunt, into the active layer. We show that the observed bifurcation in EEC sensor response to direct reverse bias depends critically on measurement lead location. A dramatic enhancement in responsivity is achieved via a modification of the shunt geometry. A maximum percent change of 130,856% of the four-point resistance was achieved under a direct reverse bias of -1V using an enhanced shunt design, a 325 fold increase over the conventional EEC square shunt design. This result was accompanied by an observed bifurcation in sensor response, driven by a rotation of the four-point measurement leads. S. A. S is a co-founder of and has a financial interest in PixelEXX, a start-up company whose mission is to market imaging arrays.

  3. [The Codman Medos programmable shunt valve. Evaluation of 53 implantations in 50 patients].

    PubMed

    Belliard, H; Roux, F X; Turak, B; Nataf, F; Devaux, B; Cioloca, C

    1996-01-01

    Fifty three Codman Medos programmable valves were implanted in 50 patients (28 men and 22 women) aged 5 to 77 years, from April 1992 to February 1994. They presented with a hydrocephalus 43 times, an arachnoid cyst three times and a CSF leakage four times. The aims of this study were: a) to test the reliability of this equipment, in current use as well as its eventual advantages, inconveniences and restraints, b) to determine its best indications. Follow-up ranged from 12 to 36 months (average = 22 months). Five patients were lost for follow-up. One patient died from a post-operative sepsis. Four died from their disease. Infectious complications concerned 6 patients (11%). A radio-clinical overdrainage syndrome appeared in 9 patients with slit-ventricles, 5 of them associated with sub-dural collections. All these cases were treated with shunt reprogrammings. While 43 pressure settings over 53 were satisfactory in the immediate post-operative period, it appeared that only 38% of shunts had required one only setting when the study period was over. A certain number of pressure adjustments malfunctioned: 6 times, post-operative X-ray controls showed pressures significantly different from the figures which had been selected (difference from -30 mm H2O to + 70 mm H2O); pressure readjustments were effective and accurate for five of them, but one shunt had to be changed; 15 deprogrammings were detected during long term follow-up, 9 of them after MR1. Pressure programming was readjusted only on patients presenting with clinical signs, i-e mainly for those having a pressure difference > +/-30 mm H2O. As a conclusion, the authors consider that such a shunt can be very useful in some precise indications as: NPH, multioperated hydrocephalus, arachnoid and porencephalic cysts, some spontaneous or iatrogenic CSF leakages, temporary shunts necessitating a progressive withdrawal. Because of a) the cost of this equipment, b) the specific restraints (X-rays controls, programmer), and

  4. Piezoelectric Shunt Vibration Damping of F-15 Panel under High Acoustic Excitation

    NASA Technical Reports Server (NTRS)

    Wu, Shu-Yau; Turner, Travis L.; Rizzi, Stephen A.

    2000-01-01

    At last year's SPIE symposium, we reported results of an experiment on structural vibration damping of an F-15 underbelly panel using piezoelectric shunting with five bonded PZT transducers. The panel vibration was induced with an acoustic speaker at an overall sound pressure level (OASPL) of about 90 dB. Amplitude reductions of 13.45 and 10.72 dB were achieved for the first and second modes, respectively, using single- and multiple-mode shunting. It is the purpose of this investigation to extend the passive piezoelectric shunt-damping technique to control structural vibration induced at higher acoustic excitation levels, and to examine the controllability and survivability of the bonded PZT transducers at these high levels. The shunting experiment was performed with the Thermal Acoustic Fatigue Apparatus (TAFA) at the NASA Langley Research Center using the same F-15 underbelly panel. The TAFA is a progressive wave tube facility. The panel was mounted in one wall of the TAFA test section using a specially designed mounting fixture such that the panel was subjected to grazing-incidence acoustic excitation. Five PZT transducers were used with two shunt circuits designed to control the first and second modes of the structure between 200 and 400 Hz. We first determined the values of the shunt inductance and resistance at an OASPL of 130 dB. These values were maintained while we gradually increased the OASPL from 130 to 154 dB in 6-dB steps. During each increment, the frequency response function between accelerometers on the panel and the acoustic excitation measured by microphones, before and after shunting, were recorded. Good response reduction was observed up to the 148dB level. The experiment was stopped at 154 dB due to wire breakage from vibration at a transducer wire joint. The PZT transducers, however, were still bonded well on the panel and survived at this high dB level. We also observed shifting of the frequency peaks toward lower frequency when the OASPL

  5. The C-shunt Flux Qubit: A New Generation of Superconducting Flux Qubit

    NASA Astrophysics Data System (ADS)

    Birenbaum, Jeffrey Scott

    While quantum computation has the potential to revolutionize the scientific community, to date no architecture has been developed which offers the necessary combination of high coherence times and massive scalability. Superconducting flux qubits satisfy the second requirement well but to date useful devices are limited to coherence times of typically only a few mus. In this dissertation we examine the possibilities of improving the coherence performance of the flux qubit to the levels required for fault-tolerant quantum computation. We find that coherence times for many devices are limited by photon-induced quasiparticles and mitigation of these quasiparticles increases coherence times by more than a factor of two. Beyond this, however, we find little improvement in flux qubit performance compared to prior results. Despite improved fabrication techniques and varied device designs we find flux qubit coherence times are still typically below 5 mus. Furthermore, wide device-to-device variations are observed which prevent effective scaling of the flux qubit to quantum information circuits. Based on the proposal by You, et al. we develop of a capacitively-shunted version of the flux qubit called the C-shunt flux qubit. With the addition of a capacitive shunt across the small junction of the flux qubit we are able to reduce the amplitude sensitivity to both charge and flux noise by more than a factor of three. The result is a predicted ten-fold enhancement in the coherence times compared to the unshunted flux qubit. At the same time we preserve much of the anharmonicity of the flux qubit resulting in a device with coherence times comparable to modern transmons but with a factor of four better anharmonicity and more flexible coupling configurations. By using a high-quality MBE aluminum shunt process on an annealed sapphire substrate coupled with a more conventional electron-beam-evaporated aluminum Josephson junction process we fabricate hybrid C-shunt flux qubits. We

  6. Blood volume and body fluid compartments in lambs with aortopulmonary left-to-right shunts.

    PubMed Central

    Gratama, J W; Dalinghaus, M; Meuzelaar, J J; Gerding, A M; Koers, J H; Zijlstra, W G; Kuipers, J R

    1992-01-01

    A left-to-right shunt is accompanied by an increased plasma and blood volume. Since this is likely realized through renin/aldosterone-mediated salt and water retention, other body fluid compartments may be changed too. Therefore, we studied blood volume and body fluid compartments by a single-injection, triple-indicator dilution technique in nine 8-wk-old lambs with an aortopulmonary left-to-right shunt (55 +/- 3% of left ventricular output; mean +/- SEM) and in 11 control lambs, 2.5 wk after surgery. Systemic blood flow was maintained at the same level as in control lambs, but the aortic pressure of the shunt lambs was lower. Blood volume in shunt lambs was larger than in control lambs (110 +/- 6 vs. 84 +/- 7 ml/kg, P < 0.001) through an increase in plasma volume, which correlated significantly with the magnitude of the left-to-right shunt (r = 0.81, P < 0.01). Red blood cell volume was equal to that of control lambs. Evidence was obtained that the increase in plasma volume was induced by a transient increase in renin (8.0 +/- 2.2 vs. 1.6 +/- 0.2 nmol.l-1.h-1; P < 0.02) and aldosterone (0.51 +/- 0.14 vs. 0.24 +/- 0.09 nmol/liter) concentrations. Interstitial water volume, however, was not significantly different from that in control lambs. The amount of intravascular protein was significantly higher than in control lambs (5.0 +/- 0.3 vs. 3.5 +/- 0.2 g/kg body mass, P < 0.001). There were no significant differences in intracellular and total body water volumes between the two groups. We conclude that the increased amount of intravascular protein confines the fluid retained by the kidneys to the vascular compartment. PMID:1430202

  7. Reduced clearance of proteins labeled with diisopropylfluorophosphate in portacaval-shunted rats.

    PubMed

    Dienel, Gerald A; Cruz, Nancy F

    2014-12-01

    Portacaval shunting is a model for hepatic encephalopathy that causes chronic hyperammonemia, disruption of metabolic, signaling, and neurotransmitter systems, and progressive morphological changes. Exposure of cultured cells to ammonia raises intralysosomal pH and inhibits proteolysis, and the present study tested the hypothesis that proteolytic capacity is diminished in portacaval-shunted rats. Proteins were labeled in vivo with tracer doses of diisopropylfluorophosphate (DFP) and clearance of label was assayed. This approach labeled proteins independent of protein synthesis, which is reported to be altered in shunted rats, and avoided complications arising from re-utilization of labeled amino acids that causes underestimation of degradation rate. Characterization of DFP labeling showed that protein labeling was fast, about 50% of the label was released during a 24 h interval, labeling by DFP metabolites was negligible, inhibition of brain acetylcholinesterase was not detectable, and labeling by [(3)H]- and [(14)C]DFP was equivalent. To assay degradative capacity, proteins were first labeled with [(3)H]DFP, followed by labeling with [(14)C]DFP that was given 24 or 72 h later. The (3)H/(14)C ratio in each animal was used as a relative measure of removal of (3)H-labeled proteins. (3)H/(14)C ratios were generally significantly higher in portacaval-shunted rats than in controls, consistent with reduced proteolytic capacity. Assays of amino acid incorporation into brain protein generally replicated literature reports, supporting the conclusion that protein synthesis unlikely to be markedly inhibited and amino acid recycling influences calculated protein synthesis rates in shunted rats. Therapeutic strategies to reduce ammonia level would help normalize lysosomal functions and protein and lipid turnover. PMID:24154686

  8. Metallurgical Effects of Shunting Current on Resistance Spot-Welded Joints of AA2219 Sheets

    NASA Astrophysics Data System (ADS)

    Jafari Vardanjani, M.; Araee, A.; Senkara, J.; Jakubowski, J.; Godek, J.

    2016-06-01

    Shunting effect is the loss of electrical current via the secondary circuit provided due to the existence of previous nugget in a series of welding spots. This phenomenon influences on metallurgical aspects of resistance spot-welded (RSW) joints in terms of quality and performance. In this paper RSW joints of AA2219 sheets with 1 mm thickness are investigated metallurgically for shunted and single spots. An electro-thermal finite element analysis is performed on the RSW process of shunted spot and temperature distribution and variation are obtained. These predictions are then compared with experimental micrographs. Three values of 5 mm, 20 mm, and infinite (i.e., single spot) are assumed for welding distance. Numerical and experimental results are matching each other in terms of nugget and HAZ geometry as increasing distance raised nugget size and symmetry of HAZ. In addition, important effect of shunting current on nugget thickness, microstructure, and Copper segregation on HAZ grain boundaries were discovered. A quantitative analysis is also performed about the influence of welding distance on important properties including ratio of nugget thickness and diameter (r t), ratio of HAZ area on shunted and free side of nugget (r HA), and ratio of equivalent segregated and total amount of Copper, measured in sample (r Cu) on HAZ. Increasing distance from 5 mm to infinite, indicated a gain of 111.04, -45.55, and -75.15% in r t, r HA, and r Cu, respectively, while obtained ratios for 20 mm welding distance was suitable compared to single spot.

  9. Risk Factors for Thrombosis, Overshunting and Death in Infants after Modified Blalock-Taussig Shunt

    PubMed Central

    Küçük, Mehmet; Özdemir, Rahmi; Karaçelik, Mustafa; Doksöz, Önder; Karadeniz, Cem; Yozgat, Yılmaz; Meşe, Timur; Sarıosmanoğlu, Nejat

    2016-01-01

    Background The Modified Blalock-Taussig shunt procedure can provide increased flow of blood to the lungs for babies born with certain congenital heart defects. We evaluated 44 subjects under 2 years of age who had a Modified Blalock-Taussig shunt (MBTS) procedure performed from 2009-2013, to investigate risk factors for thrombosis, overshunting and death. Methods The study subjects included in our investigation were severely cyanotic newborns with pulmonary stenosis or atresia and duct dependent circulation, and infants having Tetralogy of Fallot with small pulmonary arteries who underwent a MBTS procedure in our facility from 2009-2013. We duly noted patient preoperative characteristics such as hemoglobin, hematocrit, mean platelet volume, prothrombin time and partial thromboplastin time. Our study investigated the risk factors for post-operative overcirculation, thrombosis and death. Results The age and weight of patients in our study at the time of procedure ranged from 1 day to 20 months old (median 12 days), and 2.4 kg to 12 kg (mean 4.6 kg), respectively. A total of 8 patients died following surgery, and. 4 (9.1%) had shunt thrombosis, of which one died during shunt revision. Partial thromboplastin time was 28.7 seconds in patients with thrombosis, and 35 in all other patients (p = 0.04). Overcirculation was detected in 5 patients; shunt size/body weight was 1.25 in patients who had overcirculation, and 1.06 in all other patients. Conclusions It is important to assess risk factors associated with the MBTS operation. The results of our study suggest that a preoperative low aPTT value may be an indicator for thrombosis in infants who have undergone MBTS surgery. PMID:27274175

  10. A physical framework for implementing virtual models of intracranial pressure and cerebrospinal fluid dynamics in hydrocephalus shunt testing.

    PubMed

    Venkataraman, Pranav; Browd, Samuel R; Lutz, Barry R

    2016-09-01

    OBJECTIVE The surgical placement of a shunt designed to resolve the brain's impaired ability to drain excess CSF is one of the most common treatments for hydrocephalus. The use of a dynamic testing platform is an important part of shunt testing that can faithfully reproduce the physiological environment of the implanted shunts. METHODS A simulation-based framework that serves as a proof of concept for enabling the application of virtual intracranial pressure (ICP) and CSF models to a physical shunt-testing system was engineered. This was achieved by designing hardware and software that enabled the application of dynamic model-driven inlet and outlet pressures to a shunt and the subsequent measurement of the resulting drainage rate. RESULTS A set of common physiological scenarios was simulated, including oscillations in ICP due to respiratory and cardiac cycles, changes in baseline ICP due to changes in patient posture, and transient ICP spikes caused by activities such as exercise, coughing, sneezing, and the Valsalva maneuver. The behavior of the Strata valve under a few of these physiological conditions is also demonstrated. CONCLUSIONS Testing shunts with dynamic ICP and CSF simulations can facilitate the optimization of shunts to be more failure resistant and better suited to patient physiology. PMID:27203135

  11. Sonographic detection of intrapulmonary shunting of venous gas bubbles during exercise after diving in a professional diver.

    PubMed

    Obad, Ante; Palada, Ivan; Ivancev, Vladimir; Valic, Zoran; Fabijanic, Damir; Brubakk, Alf O; Dujic, Zeljko

    2007-10-01

    We report a case of right-to-left intrapulmonary (IP) shunting of venous gas bubbles at a high level of exercise after diving. The diagnosis was made using a 4-chamber view of the heart via echocardiography during exercise. This case is the first in which we could find evidence of IP shunt recruitment during exercise after diving, and the bubble grade was the highest ever seen in our laboratory. Venous bubbles crossing over through IP shunts during exercise after diving is a very rare event. PMID:17676615

  12. Vascular plug-assisted retrograde transvenous obliteration of portosystemic shunts for refractory hepatic encephalopathy: a case report.

    PubMed

    Park, Jonathan K; Cho, Sung-Ki; Kee, Stephen; Lee, Edward W

    2014-01-01

    While balloon-assisted retrograde transvenous obliteration (BRTO) has been used for two decades in Asia for the management of gastric variceal bleeding, it is still an emerging therapy elsewhere. Given the shunt closure brought about by the procedure, BRTO has also been used for the management of portosystemic encephalopathy with promising results. Modified versions of BRTO have been developed, including plug-assisted retrograde transvenous obliteration (PARTO), where a vascular plug is deployed within a portosystemic shunt. To our knowledge, we present the first North American case of PARTO in the setting of a large splenorenal shunt for the management of portosystemic encephalopathy. PMID:24744943

  13. Stability of Programmable Shunt Valve Settings with Simultaneous Use of the Optune Transducer Array: A Case Report

    PubMed Central

    Chan, Andrew K; Winkler, Ethan A; Viner, Jennifer A; Taylor, Jennie W; McDermott, Michael W.

    2016-01-01

    The Optune® transducer array (Novocure Ltd., Haifa, Israel) is an FDA-approved noninvasive regional therapy that aims to inhibit the growth of glioblastoma multiforme (GBM) cells via utilization of alternating electric fields. Some patients with GBM may develop hydrocephalus and benefit from subsequent shunt placement, but special attention must be paid to patients in whom programmable valves are utilized, given the potential effect of the magnetic fields on valve settings. We present the first case report illustrating the stability of programmable shunt valve settings in a neurosurgical patient undergoing therapy with the Optune device. In this study, shunt valve settings were stable over a period of five days despite Optune therapy. This is reassuring for patients with GBM who require simultaneous treatment with both the Optune device and a programmable shunt system. PMID:27551653

  14. Stability of Programmable Shunt Valve Settings with Simultaneous Use of the Optune Transducer Array: A Case Report.

    PubMed

    Chan, Andrew K; Birk, Harjus S; Winkler, Ethan A; Viner, Jennifer A; Taylor, Jennie W; McDermott, Michael W

    2016-01-01

    The Optune® transducer array (Novocure Ltd., Haifa, Israel) is an FDA-approved noninvasive regional therapy that aims to inhibit the growth of glioblastoma multiforme (GBM) cells via utilization of alternating electric fields. Some patients with GBM may develop hydrocephalus and benefit from subsequent shunt placement, but special attention must be paid to patients in whom programmable valves are utilized, given the potential effect of the magnetic fields on valve settings. We present the first case report illustrating the stability of programmable shunt valve settings in a neurosurgical patient undergoing therapy with the Optune device. In this study, shunt valve settings were stable over a period of five days despite Optune therapy. This is reassuring for patients with GBM who require simultaneous treatment with both the Optune device and a programmable shunt system. PMID:27551653

  15. MRI-Monitored Intra-Shunt Local Agent Delivery of Motexafin Gadolinium: Towards Improving Long-Term Patency of TIPS

    PubMed Central

    Meng, Yanfeng; Zhang, Tong; Willis, Patrick; Le, Thomas; Soriano, Stephanie; Ray, Erik; Valji, Karim; Zhang, Guixiang; Yang, Xiaoming

    2013-01-01

    Background Transjugular intrahepatic portosystemic shunt (TIPS) has become an important and effective interventional procedure in treatment of the complications related to portal hypertension. Although the primary patency of TIPS has been greatly improved due to the clinical application of cover stent-grafts, the long-term patency is still suboptimal. This study was to investigate the feasibility of using magnetic resonance imaging (MRI)-monitored intra-shunt local agent delivery of motexafin gadolinium (MGd) into shunt-vein walls of TIPS. This new technique aimed to ultimately inhibit shuntstenosis of TIPS. Methodology Human umbilical vein smooth muscle cells (SMCs) were incubated with various concentrations of MGd, and then examed by confocal microscopy and T1-map MRI. In addition, the proliferation of MGd-treated cells was evaluated. For in vivo validation, seventeen pigs underwent TIPS. Before placement of the stent, an MGd/trypan-blue mixture was locally delivered, via a microporous balloon, into eleven shunt-hepatic vein walls under dynamic MRI monitoring, while trypan-blue only was locally delivered into six shunt-hepatic vein walls as serve as controls. T1-weighted MRI of the shunt-vein walls was achieved before- and at different time points after agent injections. Contrast-to-noise ratio (CNR) of the shunt-vein wall at each time-point was measured. Shunts were harvested for subsequent histology confirmation. Principal Findings In vitro studies confirmed the capability of SMCs in uptaking MGds in a concentration-dependent fashion, and demonstrated the suppression of cell proliferation by MGds as well. Dynamic MRI displayed MGd/blue penetration into the shunt-vein walls, showing significantly higher CNR of shunt-vein walls on post-delivery images than on pre-delivery images (49.5±9.4 vs 11.2±1.6, P<0.01), which was confirmed by histology. Conclusion Results of this study indicate that MRI-monitored intra-shunt local MGd delivery is feasible and MGd

  16. Bihemispheric Paradoxical Cerebral Embolism in a Patient with Pulmonary Thromboembolism and Presumptive Fistula Right-to-Left Shunt.

    PubMed

    Zanati Bazan, Silméia Garcia; Braga, Gabriel Pereira; Luvizutto, Gustavo José; Trindade, André Petean; Pontes-Neto, Octávio Marques; Bazan, Rodrigo

    2016-06-01

    We report a case of a bihemispheric paradoxical cerebral embolism in a patient with pulmonary thromboembolism and presumptive pulmonary arteriovenous fistula. The echocardiogram showed no intracardiac shunt, and the transcranial Doppler (TCD) revealed spontaneous microembolic signals in the middle cerebral arteries (MCAs), and late passage of a higher number of microembolic signals in the MCAs, compatible with right-to-left shunt (RLS). The TCD and the echocardiogram were useful for identifying the RLS when rapid neurological deterioration occurred. PMID:27105566

  17. [Unilateral Posterior Reversible Encephalopathy Syndrome after Ventriculo-Peritoneal Shunt for Normal Pressure Hydrocephalus Following Subarachnoid Hemorrhage: A Case Report].

    PubMed

    Sato, Hiroyuki; Koizumi, Takayuki; Sato, Daisuke; Endo, Shin; Kato, Syunichi

    2016-06-01

    The patient, a 79-year-old man, experienced a Hunt & Kosnik grade IV subarachnoid hemorrhage, presenting with sudden-onset coma and severe left hemiplegia. We performed cranial clipping surgery for a ruptured aneurysm on the right middle cerebral artery the same day. Post-operative recovery proceeded smoothly, with gradual improvements in disturbed consciousness and left hemiplegia. Three weeks post-operation, CT revealed low-density areas in the right frontal and temporal lobe, believed to be due to subarachnoid hemorrhage, as well as hydrocephaly. We then performed a lumbo-peritoneal (L-P) shunt for the hydrocephaly. Two months later, the patient experienced shunt occlusion, and we performed a ventriculo-peritoneal (V-P) shunt revision (pressure: 6 cm H(2)O). Headaches, severe decline in cognitive function, and worsened left hemiplegia were observed seven weeks post-shunt revision. Cranial CT revealed widespread low-density areas in right posterior cerebral white matter. We suspected unilateral posterior reversible encephalopathy syndrome (PRES) after performing cranial MRI and cerebral angiography. Increasing the set pressure of the shunt improved the symptoms and radiographic findings. PRES is typically bilateral, and unilateral incidents are rare. This is the first report of unilateral PRES secondary to shunt operation. Its unilaterality appears to have been caused by unilateral brain damage or adhesions to the brain surface from the subarachnoid cerebral hemorrhage. Overdrainage post-shunt can also induce PRES. Diagnosis of PRES is more difficult in unilateral cases;practitioners must keep PRES in mind as a rare complication post-shunt operation. PMID:27270150

  18. Intra-abdominal metastasis of an intracranial germinoma via ventriculo-peritoneal shunt in a 13-year-old female.

    PubMed

    Murray, Matthew J; Metayer, Lucy E; Mallucci, Conor L; Hale, Juliet P; Nicholson, James C; Kirollos, Ramez W; Burke, G A Amos

    2011-12-01

    A 13-year-old patient presented with massive intra-abdominal metastasis and spontaneous acute tumour lysis syndrome, 17-months after VP shunt placement for metastatic pineal germinoma treated with cranio-spinal-irradiation. Hyperhydration/rasburicase improved renal function, allowing chemotherapy with subsequent surgery. The patient remains event-free 34-months later. Risk of intra-abdominal metastasis from VP shunts is discussed. PMID:21501064

  19. Center effect and other factors influencing temporization and shunting of cerebrospinal fluid in preterm infants with intraventricular hemorrhage

    PubMed Central

    Riva-Cambrin, Jay; Shannon, Chevis N.; Holubkov, Richard; Whitehead, William E.; Kulkarni, Abhaya V.; Drake, James; Simon, Tamara D.; Browd, Samuel R.; Kestle, John R. W.; Wellons, John C.

    2012-01-01

    Object There is little consensus regarding the indications for surgical CSF diversion (either with implanted temporizing devices [reservoir or subgaleal shunt] or shunt alone) in preterm infants with posthemorrhagic hydrocephalus. The authors determined clinical and neuroimaging factors associated with the use of surgical CSF diversion among neonates with intraventricular hemorrhage (IVH), and describe variations in practice patterns across 4 large pediatric centers. Methods The use of implanted temporizing devices and conversion to permanent shunts was examined in a consecutive sample of 110 neonates surgically treated for IVH related to prematurity from the 4 clinical centers of the Hydrocephalus Clinical Research Network (HCRN). Clinical, neuroimaging, and so-called processes of care factors were analyzed. Results Seventy-three (66%) of the patients underwent temporization procedures, including 50 ventricular reservoir and 23 subgaleal shunt placements. Center (p < 0.001), increasing ventricular size (p = 0.04), and bradycardia (p = 0.07) were associated with the use of an implanted temporizing device, whereas apnea, occipitofrontal circumference (OFC), and fontanel assessments were not. Implanted temporizing devices were converted to permanent shunts in 65 (89%) of the 73 neonates. Only a full fontanel (p < 0.001) and increased ventricular size (p = 0.002) were associated with conversion of the temporizing devices to permanent shunts, whereas center, OFCs, and clot characteristics were not. Conclusions Considerable center variability exists in neurosurgical approaches to temporization of IVH in prematurity within the HCRN; however, variation between centers is not seen with permanent shunting. Increasing ventricular size—rather than classic clinical findings such as increasing OFCs—represents the threshold for either temporization or shunting of CSF. PMID:22546024

  20. The early serological detection of colonisation by Staphylococcus epidermidis of ventriculo-atrial shunts.

    PubMed

    Holt, R

    1980-01-01

    Simple quantitative serological tests demonstrating Staphylococcus epidermidis agglutinins and C-reactive protein were used for the early detection of ventriculo-atrial shunt colonization by this organism. Tests in normal children and adults in various age groups throughout life confirmed Bayston's ovservations that those tested attained a titre up to 1:160 TO S. epidermidis agglutinogen. In contrast, the titre in children with colonised shunts and in adults with S. epidermidis endocarditis, both conditions which are usually accompanied by bacteraemia, rose to much higher levels, sometimes up to 1:5120. The routine combination of both tests has proven to be of considerable diagnostic value, particularly in early or recent colonisation. PMID:7372358

  1. Gate assisted turn-off thyristor with cathode shunts and dynamic gate

    NASA Technical Reports Server (NTRS)

    Schlegel, E. S.; Page, D. J.

    1976-01-01

    A 1,000-V, 200-A gate-assisted turn-off thyristor (GATT) is described, whose design features include an interdigitated shunted cathode, a dynamic gate, a means for optimizing the carrier lifetime level, and a bypass diode. The device physics of gate-assisted turn-off are reviewed. Based on this, improvements in the design are described. It is shown that a prime failure mode can be eliminated and that the gate-assist signal voltage can be substantially decreased by employing a shunted cathode emitter. The test data show excellent turn-on characteristics due to the dynamic gate and the long perimeter of the edge of the main cathode. Turn-off times as short as 3 microsec are obtained. The combination of controlling the carrier lifetime with a precisely controlled and easily variable irradiation dose of high energy electrons with gate assist current provides for simple, precision tailoring of the device characteristics to the intended application.

  2. Impact of aortocaval shunt flow on cardiac and renal function in unilateral nephrectomized rats.

    PubMed

    Wu, Jie; Cheng, Zhong; Zhang, Mingjing; Zhu, Pengfei; Gu, Ye

    2016-01-01

    We previously reported significantly enhanced cardiac remodeling post aortocaval fistula (AV) in unilateral nephrectomized (UNX) rats. However, the relationship between the size of the AV and the cardiorenal effects in UNX rats remains unknown. In the present study, AV was induced by 20, 18 and 16 gauge needles in UNX rats to see if larger shunt would definitely induce heavier cardiac and renal damage in UNX rats. Our results demonstrated that bigger shunt size is linked with proportional more significant cardiorenal remodeling and dysfunction in UNX rats. Expression of inflammatory biomarkers including CRP, TNF-α, IL-6, IL-1β, TGF-β and MCP-1 in left kidney and heart was significantly increased in all UNX + AV groups compared to Sham rats. Inflammation might thus participate in the worsening cardiorenal functions and remodeling processes in this model. PMID:27279232

  3. Integration of Thermal Energy Harvesting in Semi-Active Piezoelectric Shunt-Damping Systems

    NASA Astrophysics Data System (ADS)

    Lubieniecki, Michał; Uhl, Tadeusz

    2015-01-01

    The opportunities to energize a broad range of devices by use of energy available almost anywhere and in many forms are almost unlimited. A major advantage of energy harvesting is the manufacture of small autonomous electronic devices with no need for power supply and maintenance. Shunt damping circuits, although unfavorably affected by the size and mass of bulky coil inductors, started to base on synthetic inductors losing their passivity. In this paper we report a study of the feasibility of powering shunt damping circuits by use of thermal energy otherwise irrevocably lost from a bearing. The heat generated in the bearing is converted thermoelectrically into electric energy which is then used to power synthetic inductance circuitry. We show that the power demand of such circuit can be satisfied by use of a thermoelectric generator paired with a moderately loaded bearing.

  4. Congenital Extrahepatic Portosystemic Shunts: Spectrum of Findings on Ultrasound, Computed Tomography, and Magnetic Resonance Imaging

    PubMed Central

    Gupta, Pankaj; Sinha, Anindita; Sodhi, Kushaljit Singh; Lal, Anupam; Debi, Uma; Thapa, Babu R.; Khandelwal, Niranjan

    2015-01-01

    Congenital extrahepatic portosystemic shunt (CEPS) is a rare disorder characterised by partial or complete diversion of portomesenteric blood into systemic veins via congenital shunts. Type I is characterised by complete lack of intrahepatic portal venous blood flow due to an end to side fistula between main portal vein and the inferior vena cava. Type II on the other hand is characterised by partial preservation of portal blood supply to liver and side to side fistula between main portal vein or its branches and mesenteric, splenic, gastric, and systemic veins. The presentation of these patients is variable. Focal liver lesions, most commonly nodular regenerative hyperplasia, are an important clue to the underlying condition. This pictorial essay covers imaging characteristics in abdominopelvic region. PMID:26858845

  5. Impact of aortocaval shunt flow on cardiac and renal function in unilateral nephrectomized rats

    PubMed Central

    Wu, Jie; Cheng, Zhong; Zhang, Mingjing; Zhu, Pengfei; Gu, Ye

    2016-01-01

    We previously reported significantly enhanced cardiac remodeling post aortocaval fistula (AV) in unilateral nephrectomized (UNX) rats. However, the relationship between the size of the AV and the cardiorenal effects in UNX rats remains unknown. In the present study, AV was induced by 20, 18 and 16 gauge needles in UNX rats to see if larger shunt would definitely induce heavier cardiac and renal damage in UNX rats. Our results demonstrated that bigger shunt size is linked with proportional more significant cardiorenal remodeling and dysfunction in UNX rats. Expression of inflammatory biomarkers including CRP, TNF-α, IL-6, IL-1β, TGF-β and MCP-1 in left kidney and heart was significantly increased in all UNX + AV groups compared to Sham rats. Inflammation might thus participate in the worsening cardiorenal functions and remodeling processes in this model. PMID:27279232

  6. On-line process analysis innovation: DiComp (tm) shunting dielectric sensor technology

    NASA Astrophysics Data System (ADS)

    Davis, Craig R.; Waldman, Frank A.

    1993-02-01

    The DiComp Shunting Dielectric Sensor (SDS) is a new patent-pending technology developed under the Small Business Innovation Research Program (SBIR) for NASA's Kennedy Space Center. The incorporation of a shunt electrode into a conventional fringing field dielectric sensor makes the SDS uniquely sensitive to changes in material dielectric properties in the KHz to MHz range which were previously detectable only at GHz measurement frequencies. The initial NASA application of the SDS for Nutrient Delivery Control has demonstrated SDS capabilities for thickness and concentration measurement of Hoagland nutrient solutions. The commercial introduction of DiComp SDS technology for concentration and percent solids measurements in dispersions, emulsions and solutions represents a new technology for process measurements for liquids in a variety of industries.

  7. Design and Implementation of Takagi-Sugeno Fuzzy Logic Controller for Shunt Compensator

    NASA Astrophysics Data System (ADS)

    Singh, Alka; Badoni, Manoj

    2015-08-01

    This paper describes the application of Takagi-Sugeno (TS) type fuzzy logic controller to a three-phase shunt compensator in power distribution system. The shunt compensator is used for power quality improvement and has the ability to provide reactive power compensation, reduce the level of harmonics in supply currents, power factor correction and load balancing. Additionally, it can also be used to regulate voltage at the point of common coupling (PCC). The paper discusses the design of TS fuzzy logic controller and its implementation based on only four rules. The smaller number of rules makes it suitable for experimental verification as compared to Mamdani fuzzy controller. A small laboratory prototype of the system is developed and the control algorithm is verified experimentally. The TS fuzzy controller is compared with the proportional integral based industrial controller and their performance is compared under a wide variation of dynamic load changes.

  8. Application of VSC-HVDC with Shunt Connected SMES for Compensation of Power Fluctuation

    NASA Astrophysics Data System (ADS)

    Linn, Zarchi; Kakigano, Hiroaki; Miura, Yushi; Ise, Toshifumi

    This paper describes the application of VSC-HVDC (High Voltage DC Transmission using Voltage Source Converter) with shunt connected SMES (Superconducting Magnetic Energy Storage) for compensation of power fluctuation caused by fluctuating power source such as photovoltaics and wind turbines. The objectives of this proposed system is to smooth out fluctuating power in one terminal side of HVDC in order to avoid causing power system instability and frequency deviation by absorbing or providing power according to the system requirement while another terminal side power is fluctuated. The shunt connected SMES charges and discharges the energy to and from the dc side and it compensates required power of fluctuation to obtain constant power flow in one terminal side of VSC-HVDC system. This system configuration has ability for power system stabilization in the case of power fluctuation from natural energy source. PSCAD/EMTDC simulation is used to evaluate the performance of applied system configuration and control method.

  9. A novel low-profile ventriculoamniotic shunt for foetal aqueductal stenosis.

    PubMed

    Chen, Yanfei; Emery, Stephen P; Maxey, Antonina P; Gu, Xinzhu; Wagner, William R; Chun, Youngjae

    2016-01-01

    This study proposed a novel ventriculoamniotic shunt device for foetal aqueductal stenosis treatment fabricated with 3Fr or 4Fr size catheters that have a longitudinal bending stiffness with kink resistance, sufficient luminal area for cerebrospinal fluid drainage and capacity for valve integration. Computational flow dynamics studies were carried out to optimise the device design, including size of the lumen and length of the device. An in vitro pressure and flow rate measurement test circuit was constructed to assess the high pressure relieving functionality of draining cerebrospinal fluid from foetal brain. Additionally, a resistance force measurement test platform was built to quantitatively evaluate the anchor performance of various geometric designs. The valve functionality was qualitatively evaluated through the visualisation of the flow patterns in the amniotic sac with injected red coloured fluid under stereomicroscopy. These in vitro results demonstrate the feasibility of the ventriculoamniotic shunt device designed for placement in the foetal brain. PMID:27004923

  10. Comparison of 2D transmon coherence for different capacitive shunt fabrication methods

    NASA Astrophysics Data System (ADS)

    Yoder, Jonilyn; Kamal, Archana; Yan, Fei; Gudmundsen, Theodore; Welander, Paul; Gustavsson, Simon; Hover, David; Kerman, Andrew; Sears, Adam; Oliver, William

    2015-03-01

    Improvements in superconducting qubit coherence times and reproducibility have been demonstrated using capacitive shunting. In this study, we present a side-by-side comparison of two distinct methods for preparing the aluminum shunt capacitor material for 2D transmon superconducting qubit devices. The first method involved in situ wafer outgassing prior to molecular beam epitaxy aluminum evaporation. The second method involved ex situ wafer annealing prior to electron gun aluminum evaporation. Materials analysis for each process will be detailed. Experimental results, including qubit coherence times and superconducting coplanar waveguide resonator internal quality factors, will be presented for representative devices prepared using both methods. This work is sponsored by the Assistant Secretary of Defense for Research and Engineering under Air Force Contract FA8721-05-0002. Opinions, interpretations, conclusions, and recommendations are those of the authors and are not necessarily endorsed by the United States Government.

  11. Atlantoaxial Rotatory Subluxation after Removal of a Ventriculoperitoneal Shunt in the Supine-Lateral Position.

    PubMed

    Hashide, Shusei; Aihara, Yasuo; Nagahara, Ayumi; Mitsuyama, Tetsuryu; Okada, Yoshikazu

    2015-01-01

    Atlantoaxial rotatory subluxation (AARS) is an uncommon disease with a greater prevalence in children than adults. So far there has only been one report of AARS after surgery related to ventriculoperitoneal (VP) shunting. We present a new case of AARS closed reduction treatment after VP shunt removal in an 8-year-old girl with wound pain on the back of her head and torticollis after surgery. Her head was rotated in the spine-lateral position during surgery. The diagnosis of AARS was established by 3D-computed tomography. The rotatory subluxation was cured after cervical traction therapy. The successful closed reduction was the consequence of early detection and conservative treatment, which are important constituents in the management of AARS. PMID:26202450

  12. On-line process analysis innovation: DiComp (tm) shunting dielectric sensor technology

    NASA Technical Reports Server (NTRS)

    Davis, Craig R.; Waldman, Frank A.

    1993-01-01

    The DiComp Shunting Dielectric Sensor (SDS) is a new patent-pending technology developed under the Small Business Innovation Research Program (SBIR) for NASA's Kennedy Space Center. The incorporation of a shunt electrode into a conventional fringing field dielectric sensor makes the SDS uniquely sensitive to changes in material dielectric properties in the KHz to MHz range which were previously detectable only at GHz measurement frequencies. The initial NASA application of the SDS for Nutrient Delivery Control has demonstrated SDS capabilities for thickness and concentration measurement of Hoagland nutrient solutions. The commercial introduction of DiComp SDS technology for concentration and percent solids measurements in dispersions, emulsions and solutions represents a new technology for process measurements for liquids in a variety of industries.

  13. Arterial and venous embolization: Declotting of dialysis shunts by direct injection of streptokinase

    SciTech Connect

    Zeit, R.M.

    1986-06-01

    During the past 33 months, thrombolysis of 79 clotted hemodialysis shunts was attempted by injecting small quantities of dilute streptokinase solution directly into the clotted shunt, followed by massage of the clot. Embolization of clot fragments in six of 79 cases (7.6%) was demonstrated angiographically. In four of the six cases embolization involved the brachial artery or its branches. In one case embolization involved an arm vein, and in one case embolization involved both the bracial artery and axillary vein. All patients remained asymptomatic, and repeat angiographic study, usually performed the following day, showed resolution of the emboli in four of five cases. The incidence of embolization in direct-injection thrombolysis reported in this study appears to be comparable to that reported in studies using the streptokinase infusion technique.

  14. Noncirrhotic Extrahepatic Portosystemic Shunt Causing Adult-Onset Encephalopathy Treated with Endovascular Closure

    PubMed Central

    Elnekave, Eldad; Belenky, Eugenia; Van der Veer, Lindsley

    2015-01-01

    A 54-year-old woman presented with a six-month history of episodic confusion and progressive ataxia. A comprehensive metabolic panel was notable for elevated values of alkaline phosphatase (161 U/L), total bilirubin (1.5 mg/dL), and serum ammonia of 300 umol/L (normal range 9–47). Hepatitis panel, relevant serological tests, tumor markers (CA-19-9, CEA), and urea cycle enzyme studies were unrevealing. Lactulose and rifaximin therapy failed to normalize serum ammonia levels. Imaging revealed a structural vascular abnormality communicating between an enlarged inferior mesenteric vein and the left renal vein, measuring 16 mm in greatest diameter. The diagnosis of congenital extrahepatic portosystemic shunt was made and endovascular shunt closure was performed using a 22 mm Amplatzer II vascular plug. Within a day, serum ammonia levels normalized. Lactulose and rifaximin were discontinued, and confusion and ataxia resolved. PMID:26199783

  15. Options Studied for Managing Space Station Solar Array Electrical Hazards for Sequential Shunt Unit Replacement

    NASA Technical Reports Server (NTRS)

    Delleur, Ann M.; Kerslake, Thomas W.; Levy, Robert K.

    2004-01-01

    The U.S. solar array strings on the International Space Station are connected to a sequential shunt unit (SSU). The job of the SSU is to shunt, or short, the excess current from the solar array, such that just enough current is provided downstream to maintain the 160-V bus voltage while meeting the power load demand and recharging the batteries. Should an SSU fail on-orbit, it would be removed and replaced with the on-orbit spare during an astronaut space walk or extravehicular activity (EVA) (see the photograph). However, removing an SSU during an orbit Sun period with input solar array power connectors fully energized could result in substantial hardware damage and/or safety risk to the EVA astronaut. The open-circuit voltage of cold solar-array strings can exceed 320 V, and warm solar-array strings could feed a short circuit with a total current level exceeding 240 A.

  16. [Pleuro-peritoneal shunt in a patient with intractable pleural effusion after cardiac surgery].

    PubMed

    Tsuji, Maiko; Yamazaki, Takenori

    2014-10-01

    A 45-year-old man experienced dyspnea on effort and was hospitalized due to severe mitral valve regurgitation and atrial fibrillation. He also had alcoholic cirrhosis. After he was stabilized, mitral valve plasty and Maze procedure were performed. The postoperative clinical course was satisfactory. During the follow-up period, he began to suffer from persistent left pleural effusion, which amounted to about 2,500 to 3,000 ml, and required intercostal tube drainage weekly. Therefore a pleuro-peritoneal shunt was implanted. The pleural effusion decreased, and he obtained significant relief from dyspnea. After one year, we confirmed that pleural effusion had not reoccurred, and removed the pleuro-peritoneal shunt. PMID:25292378

  17. [Reconstruction of pulmonary blood flow in the Norwood procedure; Blalock-Taussig shunt; from bench to surgery].

    PubMed

    Kitaichi, Takashi; Sugano, Mikio; Kinoshita, Hajime; Nakayama, Taisuke; Kurobe, Hirotsugu; Kanbara, Tamotsu; Fujimoto, Eiki; Kitagawa, Tetsuya

    2014-04-01

    Although the right-ventricle to pulmonary artery( RV-PA) shunt as a source of pulmonary blood supply of Norwood procedure has improved early outcomes, disadvantages including right ventricular dysfunction or arrhythmias have been reported. So it has been still remained controversial whether BT shunt or RV-PA conduit should be selected. We examined the influence of Blalock-Taussig( BT) shunt size on regulation of the pulmonary blood flow in experimental model of a univentricular heart to determine the specific guidelines regarding suitable shunt size in the Norwood procedure. The canine univentricular heart model with the ratio of shunt size to body weight (SS/BW) of 0.8 to 1.1 showed significant negative correlation between the pulmonary/systemic blood flow ratio( Qp/Qs)and arterial PCo2, but those with SS/BW of 1.1 to 1.4 did not. Similar phenomena were shown with the grouped data on relationship between the Qp/Qs and inspired oxygen fraction. These findings imply that when SS/BW is 0.8 to 1.1, the Qp/Qs is controllable by physiologic respiratory manipulations. In the context of our clinical experiences, SS/BW of 0.9 to 1.0 is considered a useful index for suitable BT shunt in the Norwood procedure. PMID:24917156

  18. Management of variceal hemorrhage in children with extrahepatic portal venous obstruction-shunt surgery versus endoscopic sclerotherapy.

    PubMed

    Wani, Arshad Hussain; Shah, Omar Javed; Zargar, S A

    2011-12-01

    Extrahepatic portal venous obstruction (EHPVO) is a common cause of portal hypertention in children. Esophageal variceal hemorrhage is a major cause of morbidity and mortality in these patients. For many decades, portal systemic shunts were considered as the most effective treatment of variceal hemorrhage. Endoscopic injection sclerotherapy (EIS) was first introduced for emergency management of bleeding varices and subsequently as definitive treatment to prevent recurrent hemorrhage. The purpose of the study was to compare the safety and efficacy of shunt surgery and endoscopic sclerotherapy for patients with proven esophageal variceal bleeding due to EHPVO. The study was a prospective randomized study of 61 children with bleeding esophageal varices due to EHPVO carried out jointly by the department of General Surgery and Gastroenterology at Sher-i-Kashmir Institute of Medical Sciences, Srinagar, between March 2001 and September 2003. Thirty patients received surgery and other 31 patients received EIS. Overall incidence of rebleeding was 22.6% in sclerotherapy group and 3.3% in shunt surgery group. Treatment failure occurred in 19.4% patients in sclerotherapy group and 6.7% in shunt surgery group. The rebleeding rate of sclerotherapy is significantly higher than that of shunt surgery. However, the therapy failure rate of sclerotherapy is not significantly different from that of shunt surgery. PMID:23204696

  19. Programmable shunt valves: in vitro assessment of safety of the magnetic field generated by a portable game machine.

    PubMed

    Nakashima, Koji; Nakajo, Takato; Kawamo, Michiari; Kato, Akihito; Ishigaki, Seiichiro; Murakami, Hidetomo; Imaizumi, Yohichi; Izumiyama, Hitoshi

    2011-01-01

    Cerebrospinal fluid (CSF) shunts are frequently used to treat hydrocephalus. The use of a programmable shunt valve allows physicians to easily change the opening pressure. Since patients with adjustable CSF shunt valves may use portable game machines, the permanent magnets in these machines may alter the shunt valve programmed settings or permanently damage the device. This study investigated the risk of unintentional valve adjustment associated with the use of game machines in patients with programmable CSF shunt valves. Four adjustable valves from 4 different manufacturers, Sophysa Polaris model SPV (Polaris valve), Miethke proGAV (proGAV), Codman Hakim programmable valve (CHPV), and Strata II small valve (Strata valve), were evaluated. Magnetic field interactions were determined using the portable game machine, Nintendo DS Lite (DS). The maximum distance between the valve and the DS that affected the valve pressure setting was measured by x-ray cinematography. The Polaris valve and proGAV were immune to unintentional reprogramming by the DS. However, the settings of the CHPV and Strata valves were randomly altered by the DS. Patients with an implanted shunt valve should be made aware of the risks posed by the magnetic fields associated with portable game machines and commonly used home electronics. PMID:21946726

  20. Asymptomatic Intrahepatic Portosystemic Venous Shunt: To Treat or Not To Treat?

    PubMed

    Palvanov, Arkadiy; Marder, Ruth Leah; Siegel, David

    2016-09-01

    Intrahepatic portosystemic venous shunts (IPSVSs) are rare vascular malformations. They can be asymptomatic or present with various symptoms including encephalopathy. We present two cases of IPSVS, one involving a patient presenting with altered mental status and the other discovered incidentally. While there is no question that patients presenting with symptomatic IPSVS should undergo definitive treatment, there is no consensus regarding elective therapy for asymptomatic lesions. PMID:27574389

  1. Usefulness of Transjugular Intrahepatic Portosystemic Shunt in the Management of Bleeding Ectopic Varices in Cirrhotic Patients

    SciTech Connect

    Vidal, V.; Joly, L.; Perreault, P.; Bouchard, L.; Lafortune, M.; Pomier-Layrargues, G.

    2006-04-15

    Purpose. To evaluate the safety and efficacy of transjugular intrahepatic portosystemic shunt (TIPS) in the control of bleeding from ectopic varices. Methods. From 1995 to 2004, 24 cirrhotic patients, bleeding from ectopic varices, mean age 54.5 years (range 15-76 years), were treated by TIPS. The etiology of cirrhosis was alcoholic in 13 patients and nonalcoholic in 11 patients. The location of the varices was duodenal (n = 5), stomal (n = 8), ileocolic (n = 6), anorectal (n = 3), umbilical (n = 1), and peritoneal (n 1). Results. TIPS controlled the bleeding in all patients and induced a decrease in the portacaval gradient from 19.7 {+-} 5.4 to 6.4 {+-} 3.1 mmHg. Postoperative complications included self-limited intra-abdominal bleeding (n = 2), self-limited hemobilia (n = 1), acute thrombosis of the shunt (n = 1), and bile leak treated by a covered stent (n = 1). Median follow-up was 592 days (range 28-2482 days). Rebleeding occurred in 6 patients. In 2 cases rebleeding was observed despite a post-TIPS portacaval gradient lower than 12 mmHg and was controlled by variceal embolization; 1 patient underwent surgical portacaval shunt and never rebled; in 3 patients rebleeding was related to TIPS stenosis and treated with shunt dilatation with addition of a new stent. The cumulative rate of rebleeding was 23% and 31% at 1 and 2 years, respectively. One- and 2-year survival rates were 80% and 76%, respectively. Conclusion. The present series demonstrates that bleeding from ectopic varices, a challenging clinical problem, can be managed safely by TIPS placement with low rebleeding and good survival rates.

  2. Irreversible Electroporation of a Hepatocellular Carcinoma Lesion Adjacent to a Transjugular Intrahepatic Portosystemic Shunt Stent Graft

    PubMed Central

    Jung, Ernst Michael; Wohlgemuth, Walter A.; Trabold, Benedikt; Haimerl, Michael; Schreyer, Andreas; Stroszczynski, Christian; Wiggermann, Philipp

    2013-01-01

    We report in a 65-year-old man hepatocellular carcinoma adjacent to a transjugular intrahepatic portosystemic shunt stent-graft which was successfully treated with irreversible electroporation (IRE). IRE is a new non-thermal tissue ablation technique which uses electrical pulses to induce cell necrosis by irreversible membrane poration. IRE proved to be more advantageous in the ablation of perivascular tumor with little injury to the surrounding structures. PMID:24043975

  3. Late Intrahepatic Hematoma Complicating Transjugular Intrahepatic Portosystemic Shunt for Budd-Chiari Syndrome

    SciTech Connect

    Terreni, Natalia; Vangeli, Marcello; Raimondo, Maria Luisa; Tibballs, Jonathan M.; Patch, David; Burroughs, Andrew K.

    2007-09-15

    Late intrahepatic hematoma is a rare complication of the transjugular intrahepatic portosystemic shunt (TIPS) procedure. We describe a patient with Budd-Chiari syndrome (BCS), who presented with a large inrahepatic hematoma 13 days after TIPS. Review of the literature reveals only two previous cases, both occurring in patients with BCS and presenting after a similar time interval. This potentially serious complication appears to be specific for TIPS in BCS.

  4. Preoperative detection of intrahepatic venovenous shunt treated by microwave precoagulation during right hepatectomy.

    PubMed

    Delhorme, Jean-Baptiste; Méméo, Riccardo; Marescaux, Jacques; Pessaux, Patrick

    2015-11-01

    A 53-year-old woman underwent a 2-stage right hepatectomy for bilobar metastasis of an ileal neuroendocrine carcinoma. Preoperative three-dimensional computed tomography reconstruction helped to diagnose an intrahepatic venovenous shunts from the right and middle hepatic veins to the left hepatic vein, which could cause a intraoperative bleeding. Hemostasis was performed by means of precoagulation with microwave-assisted coagulation. PMID:26558160

  5. A Right Upper Lobe Mass in the Thorax After Modified Blalock-Taussig Shunt.

    PubMed

    Manuel, Valdano; Miguel, Gade; Magalhães, Manuel Pedro; Nunes, Maria Ana; Morais, Humberto; Júnior, António Filipe

    2016-07-01

    We report an incidental finding of pseudoaneurysm in a 10-month-old boy with tetralogy of Fallot and Down syndrome who had undergone placement of a modified Blalock-Taussig shunt at age four months. Computed tomography was a determinant exam for better assessment. The lesion was successfully resected with concomitant complete repair of tetralogy of Fallot in a single-stage. The child was asymptomatic at fourth month follow-up. PMID:27358305

  6. Resting pulmonary haemodynamics and shunting: a comparison of sea-level inhabitants to high altitude Sherpas

    PubMed Central

    Foster, Glen E; Ainslie, Philip N; Stembridge, Mike; Day, Trevor A; Bakker, Akke; Lucas, Samuel J E; Lewis, Nia C S; MacLeod, David B; Lovering, Andrew T

    2014-01-01

    The incidence of blood flow through intracardiac shunt and intrapulmonary arteriovenous anastomoses (IPAVA) may differ between Sherpas permanently residing at high altitude (HA) and sea-level (SL) inhabitants as a result of evolutionary pressure to improve gas exchange and/or resting pulmonary haemodynamics. To test this hypothesis we compared sea-level inhabitants at SL (SL-SL; n = 17), during acute isocapnic hypoxia (SL-HX; n = 7) and following 3 weeks at 5050 m (SL-HA; n = 8 non-PFO subjects) to Sherpas at 5050 m (n = 14). , heart rate, pulmonary artery systolic pressure (PASP) and cardiac index (Qi) were measured during 5 min of room air breathing at SL and HA, during 20 min of isocapnic hypoxia (SL-HX; = 47 mmHg) and during 5 min of hyperoxia ( = 1.0; Sherpas only). Intracardiac shunt and IPAVA blood flow was evaluated by agitated saline contrast echocardiography. Although PASP was similar between groups at HA (Sherpas: 30.0 ± 6.0 mmHg; SL-HA: 32.7 ± 4.2 mmHg; P = 0.27), it was greater than SL-SL (19.4 ± 2.1 mmHg; P < 0.001). The proportion of subjects with intracardiac shunt was similar between groups (SL-SL: 41%; Sherpas: 50%). In the remaining subjects, IPAVA blood flow was found in 100% of subjects during acute isocapnic hypoxia at SL, but in only 4 of 7 Sherpas and 1 of 8 SL-HA subjects at rest. In conclusion, differences in resting pulmonary vascular regulation, intracardiac shunt and IPAVA blood flow do not appear to account for any adaptation to HA in Sherpas. Despite elevated pulmonary pressures and profound hypoxaemia, IPAVA blood flow in all subjects at HA was lower than expected compared to acute normobaric hypoxia. PMID:24396057

  7. Renal oxygenation: preglomerular vasculature is an unlikely contributor to renal oxygen shunting.

    PubMed

    Olgac, Ufuk; Kurtcuoglu, Vartan

    2015-04-01

    The primary aim of this study was to assess the plausibility of preglomerular arterial-to-venous oxygen shunting in the kidney. To this end, we have developed a segment-wise three-dimensional computational model that takes into account transport processes in arteries, veins, cortical tissue, and capillaries. Our model suggests that the amount of preglomerular oxygen shunting is negligible. Consequently, it is improbable that preglomerular shunting contributes to the hypothesized regulation of renal oxygenation. Cortical tissue oxygenation is more likely determined by the interplay between oxygen supply, either from the preglomerular vasculature or from capillaries, and oxygen consumption. We show that reported differences in permeability to oxygen between perfused and unperfused tissue may be explained by what we refer to as advection-facilitated diffusion. We further show that the preglomerular vasculature is the primary source of oxygen for the tissue when cortical consumption is high or renal arterial blood is highly oxygenated, i.e., under hyperoxemic conditions. Conversely, when oxygen demand in the tissue is decreased, or under hypoxemic conditions, oxygen is supplied predominantly by capillaries. PMID:25503734

  8. What is the ideal initial valve pressure setting in neonates with ventriculoperitoneal shunts?

    PubMed

    Korinth, Marcus C; Gilsbach, J M

    2002-04-01

    In order to determine the optimal valve pressure setting during the first weeks in neonates after implantation of programmable Hakim valves and to analyze the benefits and possible side effects of a new treatment protocol in this age group, we performed this prospective study. In 20 consecutive newborns less than 5 weeks of age with hydrocephalus due to various etiologies, a ventriculoperitoneal shunt with a programmable Hakim valve at an extremely low initial valve pressure setting of 30-40 mm H(2)O was implanted. This "overdrainage" was maintained, monitored by regular clinical examination and transcranial ultrasonographic imaging, until the wound healing was uneventfully completed and the permanent valve pressure setting of 100-120 mm H(2)O was chosen. In this age group, which is prone to specific noninfectious shunt complications like wound breakdown, cerebrospinal fluid (CSF) fistula and subcutaneous CSF collections, none of these complications were seen, nor were there any persisting overdrainage phenomena on transcranial ultrasonography. Initial, temporary "overdrainage" represents a simple, useful and risk-free therapy in neonates with programmable shunts which might lower the incidence of typical noninfectious complications in this age group. PMID:12006750

  9. Simultaneous Cranioplasty and Subdural-Peritoneal Shunting for Contralateral Symptomatic Subdural Hygroma following Decompressive Craniectomy

    PubMed Central

    Lin, Muh-Shi; Chen, Tzu-Hsuan; Kung, Woon-Man; Chen, Shuo-Tsung

    2015-01-01

    Background. Contralateral subdural hygroma caused by decompressive craniectomy tends to combine with external cerebral herniation, causing neurological deficits. Material and Methods. Nine patients who underwent one-stage, simultaneous cranioplasty and contralateral subdural-peritoneal shunting were included in this study. Clinical outcome was assessed by Glasgow Outcome Scale as well as Glasgow Coma Scale, muscle power scoring system, and complications. Results. Postoperative computed tomography scans demonstrated completely resolved subdural hygroma and reversed midline shifts, indicating excellent outcome. Among these 9 patients, 4 patients (44%) had improved GOS following the proposed surgery. Four out of 4 patients with lethargy became alert and orientated following surgical intervention. Muscle strength improved significantly 5 months after surgery in 7 out of 7 patients with weakness. Two out of 9 patients presented with drowsiness due to hydrocephalus at an average time of 65 days after surgery. Double gradient shunting is useful to eliminate the respective hydrocephalus and contralateral subdural hygroma. Conclusion. The described surgical technique is effective in treating symptomatic contralateral subdural hygroma following decompressive craniectomy and is associated with an excellent structural and functional outcome. However, subdural-peritoneal shunting plus cranioplasty thoroughly resolves the subdural hygroma collection, which might deteriorate the cerebrospinal fluid circulation, leading to hydrocephalus. PMID:25879062

  10. Accurate expressions for solar cell fill factors including series and shunt resistances

    NASA Astrophysics Data System (ADS)

    Green, Martin A.

    2016-02-01

    Together with open-circuit voltage and short-circuit current, fill factor is a key solar cell parameter. In their classic paper on limiting efficiency, Shockley and Queisser first investigated this factor's analytical properties showing, for ideal cells, it could be expressed implicitly in terms of the maximum power point voltage. Subsequently, fill factors usually have been calculated iteratively from such implicit expressions or from analytical approximations. In the absence of detrimental series and shunt resistances, analytical fill factor expressions have recently been published in terms of the Lambert W function available in most mathematical computing software. Using a recently identified perturbative relationship, exact expressions in terms of this function are derived in technically interesting cases when both series and shunt resistances are present but have limited impact, allowing a better understanding of their effect individually and in combination. Approximate expressions for arbitrary shunt and series resistances are then deduced, which are significantly more accurate than any previously published. A method based on the insights developed is also reported for deducing one-diode fits to experimental data.

  11. Dual-Functional Energy-Harvesting and Vibration Control: Electromagnetic Resonant Shunt Series Tuned Mass Dampers.

    PubMed

    Zuo, Lei; Cui, Wen

    2013-10-01

    This paper proposes a novel retrofittable approach for dual-functional energy-harvesting and robust vibration control by integrating the tuned mass damper (TMD) and electromagnetic shunted resonant damping. The viscous dissipative element between the TMD and primary system is replaced by an electromagnetic transducer shunted with a resonant RLC circuit. An efficient gradient based numeric method is presented for the parameter optimization in the control framework for vibration suppression and energy harvesting. A case study is performed based on the Taipei 101 TMD. It is found that by tuning the TMD resonance and circuit resonance close to that of the primary structure, the electromagnetic resonant-shunt TMD achieves the enhanced effectiveness and robustness of double-mass series TMDs, without suffering from the significantly amplified motion stroke. It is also observed that the parameters and performances optimized for vibration suppression are close to those optimized for energy harvesting, and the performance is not sensitive to the resistance of the charging circuit or electrical load. PMID:23918165

  12. Portosystemic shunting in portal hypertension: evaluation with portal scintigraphy with transrectally administered I-123 IMP

    SciTech Connect

    Kashiwagi, T.; Azuma, M.; Ikawa, T.; Takehara, T.; Matsuda, H.; Yoshioka, H.; Mitsutani, N.; Koizumi, T.; Kimura, K.

    1988-10-01

    Portosystemic shunting was evaluated with rectal administration of iodine-123 iodoamphetamine (IMP) in seven patients without liver disease and 53 patients with liver cirrhosis. IMP (2-3 mCi (74-111 MBq)) was administered to the rectum through a catheter. Images of the chest and abdomen were obtained for up to 60 minutes with a scintillation camera interfaced with a computer. In all patients, images of the liver and/or lungs were observed within 5-10 minutes and became clear with time. In patients without liver disease, only liver images could be obtained, whereas the lung was visualized with or without the liver in all patients with liver cirrhosis. The portosystemic shunt index was calculated by dividing counts of lungs by counts of liver and lung. These values were significantly higher in liver cirrhosis, especially in the decompensated stage. Transrectal portal scintigraphy with IMP appears to be a useful method for noninvasive and quantitative evaluation of portosystemic shunting in portal hypertension.

  13. Pleurovenous shunt in treating refractory nonmalignant hepatic hydrothorax: a case report.

    PubMed

    Hadsaitong, Damrong; Suttithawil, Wudthichai

    2005-12-01

    We report a case of successful, long-term pleurovenous shunt (PVS) in treating refractory nonmalignant hepatic hydrothorax. An 82-year-old woman with liver cirrhosis, hypertension complicated with chronic renal failure while on hemodialysis, presented with progressive dyspnea in association with a recurrent right-sided pleural effusion, occurring secondary to transdiaphragmatic migration of ascites. The diagnosis was established by a demonstration of (99m)Tc-sulphur colloid sequential scintigraphic scan. Despite repetitive thoracenteses and traditional medical treatment, she suffered dyspnea without relief. Denver peritoneovenous shunt was inserted into the right-sided pleural cavity to drain effusion into the subclavian vein without short- and long-term complications. Manually pumping schedule of 10 min was performed twice daily to remove pleural fluid into the venous circulation for maintaining shunt patency. After 19 months of follow-up, the patient is doing well and PVS remains patent without significant pleural effusion. PVS opens a window of opportunity and offers an alternative procedure with minimal invasiveness for high-risk patients with refractory hepatic hydrothorax. It could be an alternative treatment to other conventional surgical interventions. PMID:16291082

  14. [Alternative options for examination of the patency of peritoneo-venous shunts].

    PubMed

    Arató, Endre; Kollár, Lajos; Szilágyi, Károly; Litter, Ilona; Schmidt, Erzsébet

    2004-02-01

    For the treatment of refractory ascites we use the saphenoperitoneal shunt described by Pang in 1992 approximately 2 years. This procedure eliminates the most frequent complications of the former synthetic shunts: occlusion of the collector branches and infections as well. In addition, the use of autologous vein is cost-saving. The first Hungarian publications (K. Vincze and Z. Nagy et al.) reported good results, which are confirmed also by us, after we performed 21 operations. The publications until now usually describe the technique. This intervention is now a widely accepted one. On the other hand, just a small number of papers describe the options for the examination of patency and the follow-ups. We report about the algorithm used in our department after surgery to evaluate graft patency and surgical efficacy. A method to determine the volume of ascites developed by ourselves is described. We feel that the successful application of saphenoperitoneal shunts depends on very close follow-up. Considering that no objective method to check the patency does exist, we are sure that decisions about further operations can only be made if simultaneous diverse follow-up methods are available. PMID:15270521

  15. The history and future of transjugular intrahepatic portosystemic shunt: food for thought.

    PubMed

    Saad, Wael E

    2014-09-01

    The origins of transjugular intrahepatic portosystemic shunt (TIPS) date back to the 1960s with inadvertent portal access during the early years of transjugular cholangiography. TIPS is now the most frequently performed portal hypertension decompressive procedure performed by interventional radiologists, and has become the primary portosystemic shunt (surgical or percutaneous) performed in the United States. One of the least discussed major advantages of TIPS in the transplant era is that it is intrahepatic and thus is removed in situ during a liver transplant, while extrahepatic shunts (surgical or percutaneous) have to be ligated or revised during the liver transplantation. However, since the widespread clinical utilization of TIPS in the 1990s, it has been plagued with two major problems, namely, patency and hepatic encephalopathy. With the advent of commercially available expanded polytetraflouroethylenne (e-PTFE) covered stents a decade ago, 12- to 24-month TIPS patency has improved significantly (by ∼20-30%). However, hepatic encephalopathy (although not proven to have increased due to e-PTFE covered stents grafts) remains a significant morbidity problem. The article discusses the history of TIPS, critiques the retrospective encephalopathy data in the literature, and discusses futuristic TIPS-design ideas about the management of post-TIPS hepatic encephalopathy. PMID:25177087

  16. Homeostasis and the glycogen shunt explains aerobic ethanol production in yeast.

    PubMed

    Shulman, Robert G; Rothman, Douglas L

    2015-09-01

    Aerobic glycolysis in yeast and cancer cells produces pyruvate beyond oxidative needs, a paradox noted by Warburg almost a century ago. To address this question, we reanalyzed extensive measurements from (13)C magnetic resonance spectroscopy of yeast glycolysis and the coupled pathways of futile cycling and glycogen and trehalose synthesis (which we refer to as the glycogen shunt). When yeast are given a large glucose load under aerobic conditions, the fluxes of these pathways adapt to maintain homeostasis of glycolytic intermediates and ATP. The glycogen shunt uses glycolytic ATP to store glycolytic intermediates as glycogen and trehalose, generating pyruvate and ethanol as byproducts. This conclusion is supported by studies of yeast with a partial block in the glycogen shunt due to the cif mutation, which found that when challenged with glucose, the yeast cells accumulate glycolytic intermediates and ATP, which ultimately leads to cell death. The control of the relative fluxes, which is critical to maintain homeostasis, is most likely exerted by the enzymes pyruvate kinase and fructose bisphosphatase. The kinetic properties of yeast PK and mammalian PKM2, the isoform found in cancer, are similar, suggesting that the same mechanism may exist in cancer cells, which, under these conditions, could explain their excess lactate generation. The general principle that homeostasis of metabolite and ATP concentrations is a critical requirement for metabolic function suggests that enzymes and pathways that perform this critical role could be effective drug targets in cancer and other diseases. PMID:26283370

  17. Evaluation of peritoneovenous shunt patency with Tc-99m labeled microspheres.

    PubMed

    Madeddu, G; D'Ovidio, N G; Casu, A R; Mura, R; Costanza, C; Lai, N; LeVeen, H H

    1983-04-01

    The LeVeen peritoneovenous shunt (PVS) was investigated in 40 cirrhotic patients with refractory ascites. Five millicuries of Tc-99m-tagged human albumin microspheres (15-36 microns) were injected into the peritoneal cavity between the umbilicus and the left anterior superior iliac spine. The radiotracer was always detectable by scintigram in the lungs when the shunt was patent. In case of malfunction, by contrast, the radioactivity was either restricted to the venous tube or confined below the diaphragm for at least 4 hr. In the presence of complete obstruction, whereas the tube was not visualized after peritoneal injection, it was outlined by direct injection of 2 mCi of Tc-99m albumin microspheres into its subcutaneous tract, where it crossed the 12th rib, immediately above the valve. This technique sufficed to establish whether the site of obstruction was at the valve or in the tubing itself. In one patient, poor visualization of the tube and a delayed image of the lungs was caused by partial occlusion of the valve with fibrinoid debris. This radiotracer method proved simple, quick, and led to an immediate selective replacement when the shunt was not patent. Therefore, the use of this test is recommended for a definitive diagnosis, since there were neither false negatives nor false positives. No complications such as embolism or bacterial infection were encountered with Tc-99m human albumin microspheres, which are excellent tracers. PMID:6220137

  18. From shunting inhibition to dynamic normalization: Attentional selection and decision-making in brief visual displays.

    PubMed

    Smith, Philip L; Sewell, David K; Lilburn, Simon D

    2015-11-01

    Normalization models of visual sensitivity assume that the response of a visual mechanism is scaled divisively by the sum of the activity in the excitatory and inhibitory mechanisms in its neighborhood. Normalization models of attention assume that the weighting of excitatory and inhibitory mechanisms is modulated by attention. Such models have provided explanations of the effects of attention in both behavioral and single-cell recording studies. We show how normalization models can be obtained as the asymptotic solutions of shunting differential equations, in which stimulus inputs and the activity in the mechanism control growth rates multiplicatively rather than additively. The value of the shunting equation approach is that it characterizes the entire time course of the response, not just its asymptotic strength. We describe two models of attention based on shunting dynamics, the integrated system model of Smith and Ratcliff (2009) and the competitive interaction theory of Smith and Sewell (2013). These models assume that attention, stimulus salience, and the observer's strategy for the task jointly determine the selection of stimuli into visual short-term memory (VSTM) and the way in which stimulus representations are weighted. The quality of the VSTM representation determines the speed and accuracy of the decision. The models provide a unified account of a variety of attentional phenomena found in psychophysical tasks using single-element and multi-element displays. Our results show the generality and utility of the normalization approach to modeling attention. PMID:25448118

  19. Reduced bacterial adhesion to hydrocephalus shunt catheters mediated by cerebrospinal fluid proteins.

    PubMed Central

    Brydon, H L; Bayston, R; Hayward, R; Harkness, W

    1996-01-01

    BACKGROUND--Prosthetic infections are a major problem, requiring complex and lengthy management. The role of blood proteins in the pathogenesis of implant infection has been investigated, but research into the role of CSF protein in shunt infections has not been undertaken, even though a high CSF protein has been assumed to increase the risk of such infections. METHODS--New shunt catheters were exposed to either CSF or individual protein solutions, and the numbers of radiolabelled staphylococci that adhered to them were compared with controls that had been exposed to saline only. RESULTS--A significant reduction in bacteria adhering to the test catheter was found in each instance. Furthermore, the CSF with the highest protein content, from a patient with intraventricular haemorrhage, had the greatest inhibitory effect on bacterial adhesion. The effect of the solutions on the hydrophobicity of the silicone rubber was also investigated. The silicone rubber was more hydrophilic, and bacterial adhesion was less, with solutions containing a higher protein content, and these findings were in keeping with the current theories on the mechanism of bacterial adhesion to polymers. CONCLUSIONS--A high CSF protein content does not predispose to the development of shunt infections. PMID:8648336

  20. Anatomy of hepatic arteriolo-portal venular shunts evaluated by 3D micro-CT imaging

    PubMed Central

    Kline, Timothy L; Knudsen, Bruce E; Anderson, Jill L; Vercnocke, Andrew J; Jorgensen, Steven M; Ritman, Erik L

    2014-01-01

    The liver differs from other organs in that two vascular systems deliver its blood – the hepatic artery and the portal vein. However, how the two systems interact is not fully understood. We therefore studied the microvascular geometry of rat liver hepatic artery and portal vein injected with the contrast polymer Microfil®. Intact isolated rat livers were imaged by micro-CT and anatomic evidence for hepatic arteriolo-portal venular shunts occurring between hepatic artery and portal vein branches was found. Simulations were performed to rule out the possibility of the observed shunts being artifacts resulting from image blurring. In addition, in the case of specimens where only the portal vein was injected, only the portal vein was opacified, whereas in hepatic artery injections, both the hepatic artery and portal vein were opacified. We conclude that mixing of the hepatic artery and portal vein blood can occur proximal to the sinusoidal level, and that the hepatic arteriolo-portal venular shunts may function as a one-way valve-like mechanism, allowing flow only from the hepatic artery to the portal vein (and not the other way around). PMID:24684343

  1. Diffusive oxygen shunting between vessels in the preglomerular renal vasculature: anatomic observations and computational modeling.

    PubMed

    Gardiner, Bruce S; Thompson, Sarah L; Ngo, Jennifer P; Smith, David W; Abdelkader, Amany; Broughton, Brad R S; Bertram, John F; Evans, Roger G

    2012-09-01

    To understand how geometric factors affect arterial-to-venous (AV) oxygen shunting, a mathematical model of diffusive oxygen transport in the renal cortex was developed. Preglomerular vascular geometry was investigated using light microscopy (providing vein shape, AV separation, and capillary density near arteries) and published micro-computed tomography (CT) data (providing vessel size and AV separation; Nordsletten DA, Blackett S, Bentley MD, Ritman EL, Smith NP. IUPS Physiome Project. http://www.physiome.org.nz/publications/nordsletten_blackett_ritman_bentley_smith_2005/folder_contents). A "U-shaped" relationship was observed between the arterial radius and the distance between the arterial and venous lumens. Veins were found to partially wrap around the artery more consistently for larger rather than smaller arteries. Intrarenal arteries were surrounded by an area of fibrous tissue, lacking capillaries, the thickness of which increased from ∼5 μm for the smallest arteries (<16-μm diameter) to ∼20 μm for the largest arteries (>200-μm diameter). Capillary density was greater near smaller arteries than larger arteries. No capillaries were observed between wrapped AV vessel pairs. The computational model comprised a single AV pair in cross section. Geometric parameters critical in renal oxygen transport were altered according to variations observed by CT and light microscopy. Lumen separation and wrapping of the vein around the artery were found to be the critical geometric factors determining the amount of oxygen shunted between AV pairs. AV oxygen shunting increases both as lumen separation decreases and as the degree of wrapping increases. The model also predicts that capillaries not only deliver oxygen, but can also remove oxygen from the cortical parenchyma close to an AV pair. Thus the presence of oxygen sinks (capillaries or tubules) near arteries would reduce the effectiveness of AV oxygen shunting. Collectively, these data suggest that AV oxygen

  2. Long-term survival after emergency portacaval shunting for bleeding varices in patients with alcoholic cirrhosis.

    PubMed

    Orloff, M J; Bell, R H

    1986-01-01

    Since 1963, a prospective evaluation of the emergency portacaval shunt procedure has been conducted in 264 unselected patients with cirrhosis and bleeding varices who underwent operation within 8 hours of admission to the emergency department. Of 153 patients who underwent operation 10 or more years ago, 45 (29 percent) have survived from 10 to 22 years and their current status is known. On admission, 40 percent of the long-term survivors had jaundice, 44 percent had ascites, 13 percent had encephalopathy (with an additional 9 percent with a history of encephalopathy), 29 percent had severe muscle wasting, and 82 percent had a hyperdynamic state. There were 9 Child's class A patients, 33 Child's class B patients, and 3 Child's class C patients. At operation, all patients had portal hypertension which was reduced by the shunt to a mean corrected free portal pressure of 18 mm saline solution. The emergency portacaval shunt procedure permanently controlled variceal bleeding. None of the patients bled again from varices, and the shunt remained patent throughout life in every patient. Encephalopathy did not affect 91 percent of the patients, but was a recurrent problem in 9 percent, usually related to the use of alcohol. Lifelong abstinence from alcohol occurred in 58 percent of the long-term survivors, but 11 percent resumed regular drinking and 31 percent consumed alcohol occasionally. Liver function declined compared with preoperative function in only 18 percent of the patients, almost always because of alcohol use. Ten years after operation, 73 percent of the patients were in excellent or good condition, and 68 percent were gainfully employed or engaged in full-time housework. Comparison of the 10 to 22 year survivors with our early group of 180 patients reported previously and our recent group of 84 patients showed no significant differences in preoperative or operative data. The single factor that appeared to influence long-term survival was resumption of regular

  3. Extrahepatic portacaval shunt via a magnetic compression technique: A cadaveric feasibility study

    PubMed Central

    Yan, Xiao-Peng; Liu, Wen-Yan; Ma, Jia; Li, Jian-Peng; Lv, Yi

    2015-01-01

    AIM: To explore the anatomical feasibility of portacaval shunt using a magnetic compression technique (MCT) in cadavers. METHODS: Computed tomography (CT) images of 30 portal hypertensive patients were obtained. The diameters of the portal vein (PV), the inferior vena cava (IVC), and distance between the two structures were measured. Similar measurements were performed on 20 adult corpses. The feasibility of portacaval shunt based on those measurements was analyzed. First stage of the extrahepatic portacaval shunt using MCT was performed on five cadavers. Specifically, the PV and IVC were exposed through an abdominal incision of the cadavers. The parent magnet was introduced from the femoral vein and was delivered into the IVC by an anchor wire and a 5F Cook catheter. The daughter magnet was introduced into the PV through the splenic vein using an interventional guide wire. When the daughter magnet met the parent magnet, they automatically clipped together and the first stage of the portacaval shunt was set up. RESULTS: The average diameters of the PV and the IVC measured from the 30 CT image were 14.39 ± 2.36 mm and 18.59 ± 4.97 mm, respectively, and the maximum and minimum distances between the PV and the IVC were 9.79 ± 4.56 mm and 9.50 ± 4.79 mm, respectively. From 20 cadavers, the average diameters of the PV and the IVC were 14.48 ± 1.47 mm and 24.71 ± 2.64 mm, and the maximum and minimum distances between the PV and the IVC were 10.14 ± 1.70 mm and 8.93 ± 1.17 mm, respectively. The distances between the PV and the IVC from both the CT images and the cadavers were within the effective length of portacaval anastomosis using MCT (30.30 ± 4.19 mm). The PV and IVC are in close proximity to each other with no intervening tissues or structures in between. Simulated surgeries of the first stage using MCT on five cadavers was successfully performed. CONCLUSION: Anatomically, extrahepatic portacaval shunt employing MCT is highly feasible in humans. PMID

  4. Role of ventriculoperitoneal shunting in patients with neoplasms of the central nervous system: An analysis of 59 cases

    PubMed Central

    NIGIM, FARES; CRITCHLOW, JONATHAN F.; KASPER, EKKEHARD M.

    2015-01-01

    Approximately 1–5% of patients with cerebral metastasis and ~40% of patients with primary brain tumors suffer from hydrocephalus. These patients often exhibit a poor prognosis. The aim of the present study was to reassess the validity of ventriculoperitoneal shunting (VPS) with the assistance of the general surgeon in oncological patients. A total of 59 patients underwent first-time VPS at the Beth Israel Deaconess Medical Center (Boston, USA) between 2004 and 2012; 40 patients had hydrocephalus from brain metastasis and 19 from primary tumors. The analyzed independent variables included demographics, body mass index, past medical history, clinical presentation, indication for surgery, Karnofsky performance status (KPS) score and surgical technique; the dependent variables were postoperative symptoms and occurrence, cause and time of shunt failure. The outcomes were analyzed with the t-test and Kaplan-Meier estimates for shunt survival. The mean age of the patients was 57.2 years and the mean operative time was 50.4 min. Symptomatic palliation was achieved in 93% of the cases; patients with severe symptoms, such as debilitating headaches, nausea and vomiting, benefited significantly from VPS. The mean follow-up time was 6.3 months; complications occurred in only 7 patients (11.8%) during follow-up: 2 in the proximal shunt (1 infection and 1 obstruction), both requiring revision, 1 infection in the distal catheter requiring shunt removal, 2 cases of intracerebral bleeding that were monitored with computed tomography scans, 1 wound infection treated with antibiotics and 1 valve complication that required temporary revision. The initial and 3-month KPS scores were 65±16.4 and 75±16.0, respectively. The mean overall shunt survival was 6.4 months (range, 1.0 day-76.0 months) from the placement of the VP shunt. At 3 months after VPS, 93.5% of the patients remained alive with functioning shunts and at 1 year 87% of the shunts were still functioning. In conclusion, VPS

  5. Comparison of shunt fraction estimation using transcolonic iodine-123-iodoamphetamine and technetium-99m-pertechnetate in a group of dogs with experimentally-induced chronic biliary cirrhosis

    SciTech Connect

    Koblik, P.D.; Hornof, W.J.; Yen, C.K.; Komtebedde, J.; Breznock, E.; Fisher, P. )

    1991-01-01

    Portosystemic shunt fraction estimation using transcolonic iodine-123-iodoamphetamine (IMP) has been previously validated relative to portal vein macroaggregated albumin injections using an experimental model of cirrhosis. Transcolonic technetium-99m-pertechnetate (TcO4-) has been proposed as an alternative tracer to IMP to study portal circulation in cirrhotic patients. We compared shunt fraction estimates from paired transcolonic IMP and TcO4- studies performed on a group of dogs before and after common bile duct ligation surgery. Pertechnetate over-estimated shunt fraction in 6/7 postoperative studies relative to IMP. A good correlation between the two methods was demonstrated, however, the slope of the regression line was substantially less than 1.0 with TcO4- values reaching 100% at IMP shunt values of approximately 60%. This apparent inability to accurately assess high shunt flows may limit the quantitative aspects of TcO4- studies on patients with severe portosystemic shunting.

  6. Two Cases of Transcatheter Closure of Central Aortopulmonary Shunts: One with an Amplatzer Duct Occluder II and One with an Amplatzer Vascular Plug I

    PubMed Central

    Celebi, Ahmet; Yucel, Ilker Kemal; Kucuk, Mehmet

    2016-01-01

    When total correction is not possible in infants who have a cyanotic congenital heart disease, creation of a palliative aortopulmonary shunt is essential. A central aortopulmonary shunt is preferable, because of its technical and hemodynamic advantages. Overcirculation, thrombosis, and stenosis of the shunt are the main postoperative sequelae that necessitate urgent reintervention. Percutaneous transcatheter closure of aortopulmonary shunts can eliminate the need for reoperation and substantially decrease postoperative morbidity and mortality rates. We report our successful transcatheter closures of central aortopulmonary shunts in a 3-month-old infant and a 15-year-old girl, with use of an Amplatzer Duct Occluder II and an Amplatzer Vascular Plug I, respectively. To our knowledge, this is the first report of the transcatheter closure of central aortopulmonary shunts with these 2 devices. PMID:27303241

  7. Refractory tension pneumothorax as a result of an internally displaced thoracoamniotic shunt in an infant with a congenital pulmonary airway malformation.

    PubMed

    Law, Brenda Hiu Yan; Bratu, Ioana; Jain, Venu; Landry, Marc-Antoine

    2016-01-01

    Antenatally, congenital pulmonary airway malformation (CPAM) causing fetal hydrops can be palliated with thoracoamniotic shunts, which may become displaced in utero. We report a case of an infant born at 34 weeks gestational age with an antenatally diagnosed macrocystic lung lesion, fetal hydrops and an internally displaced thoracoamniotic shunt. The infant suffered refractory pneumothoraces despite multiple chest drains, and stabilised only after surgical resection of the lesion. Intraoperatively, the shunt was noted to form a connection between a type I CPAM and the pleural space. As the shunt was displaced internally, this complication was not immediately obvious during the initial resuscitation. In infants with large cystic lung lesions, clinicians should be aware that internally displaced thoracoamniotic shunts could contribute to refractory tension pneumothoraces and anticipate the need for advanced neonatal resuscitation, including early thoracocentesis or chest drain insertion. Furthermore, displaced shunts may require early surgical intervention. PMID:27469386

  8. Two Cases of Transcatheter Closure of Central Aortopulmonary Shunts: One with an Amplatzer Duct Occluder II and One with an Amplatzer Vascular Plug I.

    PubMed

    Celebi, Ahmet; Yucel, Ilker Kemal; Balli, Sevket; Kucuk, Mehmet

    2016-06-01

    When total correction is not possible in infants who have a cyanotic congenital heart disease, creation of a palliative aortopulmonary shunt is essential. A central aortopulmonary shunt is preferable, because of its technical and hemodynamic advantages. Overcirculation, thrombosis, and stenosis of the shunt are the main postoperative sequelae that necessitate urgent reintervention. Percutaneous transcatheter closure of aortopulmonary shunts can eliminate the need for reoperation and substantially decrease postoperative morbidity and mortality rates. We report our successful transcatheter closures of central aortopulmonary shunts in a 3-month-old infant and a 15-year-old girl, with use of an Amplatzer Duct Occluder II and an Amplatzer Vascular Plug I, respectively. To our knowledge, this is the first report of the transcatheter closure of central aortopulmonary shunts with these 2 devices. PMID:27303241

  9. Radioembolization with Y-90 Glass Microspheres: Do We Really Need SPECT-CT to Identify Extrahepatic Shunts?

    PubMed Central

    Theysohn, Jens M.; Ruhlmann, Marcus; Müller, Stefan; Dechene, Alexander; Best, Jan; Haubold, Johannes; Umutlu, Lale; Gerken, Guido; Bockisch, Andreas; Lauenstein, Thomas C.

    2015-01-01

    Purpose Selective Internal Radiation Therapy (SIRT) with 90yttrium (Y-90) is an increasingly used therapeutic option for unresectable liver malignancies. Nontarget embolization of extrahepatic tissue secondary to vascular shunting can lead to SIRT associated complications. Our aim was to assess whether extrahepatic shunts can reliably be diagnosed based on hepatic digital subtraction angiography (DSA) or whether subsequent SPECT/CT data can provide additional information. Materials and Methods 825 patients with hepatocellular carcinoma (n = 636), hepatic metastases (n = 158) or cholangiocellular carcinoma (n = 31) were retrospectively analyzed. During hepatic DSA 128 arteries causing shunt flow to gastrointestinal tissue were coilembolized (right gastric artery n = 63, gastroduodenal artery n = 29; branches to duodenum / pancreas n = 36). Technectium-99m-labeled human serum albumin (HSA) was injected in all 825 patients. SPECT/CT data was used to identify additional or remaining shunts to extrahepatic tissue. Results An unexpected uptake of HSA in extrahepatic tissue was found by SPECT/CT in 54/825 (6.5%) patients (located in stomach n = 13, duodenum n = 26, distal bowel segments n = 12, kidney n = 1, diaphragm n = 2). These patients underwent repeated DSA and newly identified shunt vessels were coilembolized in 22/54 patients, while in 12/54 patients a more distal catheter position for repeat injection of HSA was chosen. In 20/54 patients the repeated SPECT/CT data still revealed an extrahepatic HSA uptake. These patients did not receive SIRT. Conclusion Most extrahepatic shunts can be identified on DSA prior to Y-90 therapy. However, SPECT-CT data helps to identify additional shunts that were initially not seen on DSA. PMID:26335790

  10. N-butyl cyanoacrylate embolization with blood flow control of an arterioportal shunt that developed after radiofrequency ablation of hepatocellular carcinoma.

    PubMed

    Sonomura, Tetsuo; Kawai, Nobuyuki; Kishi, Kazushi; Ikoma, Akira; Sanda, Hiroki; Nakata, Kouhei; Minamiguchi, Hiroki; Nakai, Motoki; Hosokawa, Seiki; Tamai, Hideyuki; Sato, Morio

    2014-01-01

    We present a case of a patient with rapid deterioration of esophageal varices caused by portal hypertension accompanied by a large arterioportal shunt that developed after radiofrequency ablation of hepatocellular carcinoma. We used n-butyl cyanoacrylate (NBCA) as an embolic material to achieve pinpoint embolization of the shunt, because the microcatheter tip was 2 cm away from the shunt site. Under hepatic arterial flow control using a balloon catheter, the arterioportal shunt was successfully embolized with NBCA, which caused an improvement in the esophageal varices. PMID:24643464

  11. N-Butyl Cyanoacrylate Embolization with Blood Flow Control of an Arterioportal Shunt That Developed after Radiofrequency Ablation of Hepatocellular Carcinoma

    PubMed Central

    Kawai, Nobuyuki; Kishi, Kazushi; Ikoma, Akira; Sanda, Hiroki; Nakata, Kouhei; Minamiguchi, Hiroki; Nakai, Motoki; Hosokawa, Seiki; Tamai, Hideyuki; Sato, Morio

    2014-01-01

    We present a case of a patient with rapid deterioration of esophageal varices caused by portal hypertension accompanied by a large arterioportal shunt that developed after radiofrequency ablation of hepatocellular carcinoma. We used n-butyl cyanoacrylate (NBCA) as an embolic material to achieve pinpoint embolization of the shunt, because the microcatheter tip was 2 cm away from the shunt site. Under hepatic arterial flow control using a balloon catheter, the arterioportal shunt was successfully embolized with NBCA, which caused an improvement in the esophageal varices. PMID:24643464

  12. Ribosome shunting in the cauliflower mosaic virus 35S RNA leader is a special case of reinitiation of translation functioning in plant and animal systems

    PubMed Central

    Ryabova, Lyubov A.; Hohn, Thomas

    2000-01-01

    The shunt model predicts that small ORFs (sORFs) within the cauliflower mosaic virus (CaMV) 35S RNA leader and downstream ORF VII are translated by different mechanisms, that is, scanning–reinitiation and shunting, respectively. Wheat germ extract (WGE) and rabbit reticulocyte lysate (RRL) in vitro translation systems were used to discriminate between these two processes and to study the mechanism of ribosomal shunt. In both systems, expression downstream of the leader occurred via ribosomal shunt under the control of a stable stem and a small ORF preceding it. Shunting ribosomes were also able to initiate quite efficiently at non-AUG start codons just downstream of the shunt landing site in WGE but not in RRL. The short sORF MAGDIS from the mammalian AdoMetDC RNA, which conditionally suppresses reinitiation at a downstream ORF, prevented shunting if placed at the position of sORF A, the 5′-proximal ORF of the CaMV leader. We have demonstrated directly that sORF A is translated and that proper termination of translation at the 5′-proximal ORF is absolutely required for both shunting and linear ribosome migration. These findings strongly indicate that shunting is a special case of reinitiation. PMID:10766738

  13. Management of Transjugular Intrahepatic Portosystemic Shunt (TIPS)-associated Refractory Hepatic Encephalopathy by Shunt Reduction Using the Parallel Technique: Outcomes of a Retrospective Case Series

    SciTech Connect

    Cookson, Daniel T. Zaman, Zubayr; Gordon-Smith, James; Ireland, Hamish M.; Hayes, Peter C.

    2011-02-15

    Purpose: To investigate the reproducibility and technical and clinical success of the parallel technique of transjugular intrahepatic portosystemic shunt (TIPS) reduction in the management of refractory hepatic encephalopathy (HE). Materials and Methods: A 10-mm-diameter self-expanding stent graft and a 5-6-mm-diameter balloon-expandable stent were placed in parallel inside the existing TIPS in 8 patients via a dual unilateral transjugular approach. Changes in portosystemic pressure gradient and HE grade were used as primary end points. Results: TIPS reduction was technically successful in all patients. Mean {+-} standard deviation portosystemic pressure gradient before and after shunt reduction was 4.9 {+-} 3.6 mmHg (range, 0-12 mmHg) and 10.5 {+-} 3.9 mmHg (range, 6-18 mmHg). Duration of follow-up was 137 {+-} 117.8 days (range, 18-326 days). Clinical improvement of HE occurred in 5 patients (62.5%) with resolution of HE in 4 patients (50%). Single episodes of recurrent gastrointestinal hemorrhage occurred in 3 patients (37.5%). These were self-limiting in 2 cases and successfully managed in 1 case by correction of coagulopathy and blood transfusion. Two of these patients (25%) died, one each of renal failure and hepatorenal failure. Conclusion: The parallel technique of TIPS reduction is reproducible and has a high technical success rate. A dual unilateral transjugular approach is advantageous when performing this procedure. The parallel technique allows repeat bidirectional TIPS adjustment and may be of significant clinical benefit in the management of refractory HE.

  14. The effect of shunt surgery on neuropsychological performance in normal pressure hydrocephalus: a systematic review and meta-analysis.

    PubMed

    Peterson, Katie A; Savulich, George; Jackson, Dan; Killikelly, Clare; Pickard, John D; Sahakian, Barbara J

    2016-08-01

    We conducted a systematic review of the literature and used meta-analytic techniques to evaluate the impact of shunt surgery on neuropsychological performance in patients with normal pressure hydrocephalus (NPH). Twenty-three studies with 1059 patients were identified for review using PubMed, Web of Science, Google scholar and manual searching. Inclusion criteria were prospective, within-subject investigations of cognitive outcome using neuropsychological assessment before and after shunt surgery in patients with NPH. There were statistically significant effects of shunt surgery on cognition (Mini-Mental State Examination; MMSE), learning and memory (Rey Auditory Verbal Learning Test; RAVLT, total and delayed subtests), executive function (backwards digit span, phonemic verbal fluency, trail making test B) and psychomotor speed (trail making test A) all in the direction of improvement following shunt surgery, but with considerable heterogeneity across all measures. A more detailed examination of the data suggested robust evidence for improved MMSE, RAVLT total, RAVLT delayed, phonemic verbal fluency and trail making test A only. Meta-regressions revealed no statistically significant effect of age, sex or follow-up interval on improvement in the MMSE. Our results suggest that shunt surgery is most sensitive for improving global cognition, learning and memory and psychomotor speed in patients with NPH. PMID:27017344

  15. CT stereotaxy guided lateral trans-cerebellar programmable fourth ventriculo-peritoneal shunting for symptomatic trapped fourth ventricle.

    PubMed

    Sharma, R R; Pawar, S J; Devadas, R V; Dev, E J

    2001-10-01

    A trapped fourth ventricle is a rare clinico-radiological entity producing symptoms suggestive of a progressive posterior fossa mass lesion. It is mainly reported in children as a late complication of lateral ventricular shunting to relieve infantile post-meningitic or post-hemorrhagic hydrocephalus. Optional treatment of the trapped fourth ventricle remains controversial. Placement of fourth ventricular shunting via a conventional midline approach can be fraught with complications in about 40% of the patients. Authors report a successful CT Stereotaxy guided high pressure (80 mm H(2)O) programmable fourth ventriculo-peritoneal shunting via a lateral trans-cerebellar approach in a 14-year-old girl with a trapped fourth ventricle, which occurred as a late complication of ventriculo-peritoneal shunting in her infancy. Her preoperative symptoms of raised intracranial pressure, bobble-head doll syndrome and bilateral abducens palsies completely improved following the surgery. Lateral trans-cerebellar stereotactic placement of the fourth ventricular catheter and the use of high-pressure (low flow) programmable shunt (to avoid complications associated with over drainage) are beneficial in some patients with trapped fourth ventricle. PMID:11532552

  16. Chemotherapy-induced cerebrospinal fluid malabsorption in a shunted child: case report and review of the literature

    PubMed Central

    O'Halloran, Philip J; Kaliaperumal, Chandrasekaran; Caird, John

    2013-01-01

    Ventriculoperitoneal (VP) shunt insertion is one of the most common neurosurgical procedures for the treatment of chronic hydrocephalus. Although regarded as a relatively benign procedure, several complications including obstruction, infection and mechanical failure can be seen during the postoperative stage. Symptomatic sterile cerebrospinal fluid (CSF) ascites and hydrothoracies are rare complications of VP shunt surgery. The paucity of cases makes identifying the aetiological factors difficult, particularly without catheter tip migration. It is most likely that several factors interact to reduce the absorption of CSF. The authors discuss the case of a 5-year-old girl who developed CSF ascites and a pleural effusion after starting chemotherapy for a suprasellar pilocytic astrocytoma, 2 years post-VP shunt insertion, due to a secondary obstructive hydrocephalus. After the initial management of the presenting symptoms, the child's VP shunt was subsequently changed to a ventriculo-atrial shunt and the patient made an unremarkable recovery. We also review the literature pertaining to this rare complication, assessing identifiable risk factors and surgical management options. PMID:23396932

  17. Passive electrophysiological properties of aged and axotomized cat spinal cord motoneurons: the effect of cell size and electrode shunt.

    PubMed

    Engelhardt, J K; Chase, M H

    1992-07-01

    Intracellular recordings were obtained from intact and axotomized lumbar motoneurons of aged cats. The sub-threshold electrical properties of these cells were measured, including input resistance, resting membrane potential, and the first two equalizing time constants as well as their associated amplitude constants. These data were used in a semi-infinite cable model of the motoneuron to estimate the size of the shunt resistance (Rshunt) which is created when the electrode penetrates the cell membrane. The average Rshunt for intact aged cells was 5.35 +/- 1.01 M omega, while that for the axotomized aged cells was 8.93 +/- 1.20 M omega. The statistically significant difference in mean shunt magnitude did not affect the measurements of membrane time constant because this constant is independent of the shunt in this model of the motoneuron. However, the determination of cell input resistance, which is not independent of the shunt, was shown to underestimate the real cell input resistance by 23-29%. We therefore conclude that the shunt resistance is an important factor which should be taken into account when measuring input resistance. PMID:1508398

  18. Long Term Results (>5 Years) in Patients With Peritoneovenous Shunting for Intractable Ascites: Liver Function and Cancer Mortality

    PubMed Central

    Meakins, Jonathan L.; Wu, Andrew; Smadja, Claude; Bonnet, Patrick; Gouffier, Etienne; Campillo, Bernard

    1989-01-01

    This report is based on twenty-eight (26%) of 107 patients included in a protocol for prospective evaluation of elective peritoneo-venous shunting for intractable ascites in cirrhosis. These patients had no other procedures and survived more than 5 years after the operation. All patients were free of ascites except one in whom it was mild. One patient refused follow-up. Shunt patency was assessed in 23 patients. In 14 patients (60.9%), the shunt was obstructed and the superior vena cava was occluded in 5 of them. In 9 patients (39.1%), the shunt was still functioning. No clinical or biological parameters differentiated these two groups of patients. Of the 24 patients who were alcoholics, 2 abstained completely and 20 significantly reduced their drinking habits. In 25 patients, the Pugh's score improved and was A at the time of the study. Seven patients (25.9%) developed a malignant tumor of the oro-pharynx or digestive tract, all other patients were alive and in good health. This study suggests that patients with intractable ascites treated by a peritoneo-venous shunt may survive for a long period. In patients abstaining from heavy drinking, it may function as a therapeutic bridge permitting spontaneous improvement of liver function. The risk of supervening neoplasms suggests that a continuous follow-up of these patients is warranted. PMID:2487384

  19. Molecular dissection of the prototype foamy virus (PFV) RNA 5′-UTR identifies essential elements of a ribosomal shunt

    PubMed Central

    Schepetilnikov, Mikhail; Schott, Gregory; Katsarou, Konstantina; Thiébeauld, Odon; Keller, Mario; Ryabova, Lyubov A.

    2009-01-01

    The prototype foamy virus (PFV) is a nonpathogenic retrovirus that shows promise as a vector for gene transfer. The PFV (pre)genomic RNA starts with a long complex leader that can be folded into an elongated hairpin, suggesting an alternative strategy to cap-dependent linear scanning for translation initiation of the downstream GAG open reading frame (ORF). We found that the PFV leader carries several short ORFs (sORFs), with the three 5′-proximal sORFs located upstream of a structural element. Scanning-inhibitory hairpin insertion analysis suggested a ribosomal shunt mechanism, whereby ribosomes start scanning at the leader 5′-end and initiate at the downstream ORF via bypass of the central leader regions, which are inhibitory for scanning. We show that the efficiency of shunting depends strongly on the stability of the structural element located downstream of either sORFs A/A′ or sORF B, and on the translation event at the corresponding 5′-proximal sORF. The PFV shunting strategy mirrors that of Cauliflower mosaic virus in plants; however, in mammals shunting can operate in the presence of a less stable structural element, although it is greatly improved by increasing the number of base pairings. At least one shunt configuration was found in primate FV (pre)genomic RNAs. PMID:19638424

  20. Intra-Hepatic Spillage of Gallstones as a Late Complication of Laparoscopic Cholecystectomy: MR Imaging Findings

    PubMed Central

    Ragozzino, Alfonso; Puglia, Marta; Romano, Federica; Imbriaco, Massimo

    2016-01-01

    Summary Background Spillage of gallstones in the abdominal cavity may rarely occur during the course of laparoscopic cholecystectomy. Dropped gallstones in the peritoneal and extra-peritoneal cavity are usually asymptomatic. However, they may lead to abscess formation with an estimated incidence of about 0.3%. Common locations of the abscess are in the abdominal wall followed by the intra-abdominal cavity, usually in the sub-hepatic or retro-peritoneum inferior to the sub-hepatic space. Case Report We hereby describe an unusual case of infected spilled gallstones in the right sub-phrenic space, prospectively detected on abdominal MRI performed two years after laparoscopic cholecystectomy, in a patient with only a mild right-sided abdominal complaint. Conclusions This case highlights the role of MRI in suggesting the right diagnosis in cases with vague or even absent symptomatology. In our case the patient’s history together with high quality abdomen MRI allowed the correct diagnosis. Radiologists should be aware of this rare and late onset complication, even after many years from surgery as an incidental finding in almost asymptomatic patients. PMID:27471576

  1. Irinotecan drug eluting beads used as a treatment of advanced intra hepatic cholangiocarcinoma.

    PubMed

    Roch, Jean Amede; Palma-Gutierrez, John; Lapalus, Marie Georges; Paillet, Carole; Pilleul, Frank

    2008-01-01

    This report describes a 74-year-old male with unresectable intrahepatic cholangiocarcinoma (ICC). However surgical procedure is the only curative treatment, it often seems to be ineffective because of the aggressive behaviour of the disease. The role of systemic chemotherapy in the ICC is undefined with a median survival between 6.43 to 12.17 months obtained by using the combination chemotherapy of gemcitabine with cisplatin. In the present case, we performed a targeted treatment using drug eluting beads (DEB) with irinotecan (IRI) administered as transarterial-chemoembolization (TACE). After one session, the tumour vascularity decreased significantly at the one month evaluation on computed tomography (CT) scan of the liver. This case report suggested that minimally invasive transcatheter DEB embolization could be a promising, safe and effective treatment for selective patients with unresectable ICC. PMID:22470601

  2. KrasG12D and p53 mutation cause primary intra-hepatic cholangiocarcinoma

    PubMed Central

    O’Dell, Michael R.; Huang, Jing-Li; Whitney-Miller, Christa L.; Deshpande, Vikram; Rothberg, Paul; Grose, Valerie; Rossi, Randall M.; Zhu, Andrew X.; Land, Hartmut; Bardeesy, Nabeel; Hezel, Aram F.

    2012-01-01

    Intrahepatic cholangiocarcinoma (IHCC) is a primary cancer of the liver with a rising incidence and poor prognosis. Preclinical studies of the etiology and treatment of this disease are hampered by the relatively small number of available IHCC cell lines or genetically faithful animal models. Here we report the development of a genetically engineered mouse model of IHCC that incorporates two of the most common mutations in human IHCC, activating mutations of Kras (KrasG12D) and deletion of p53. Tissue-specific activation of KrasG12D alone resulted in the development of invasive IHCC with low penetrance and long latency. Latency was shortened by combining KrasG12D activation with heterozygous or homozygous deletion of p53 (mean survival of 56 weeks versus 19 weeks, respectively), which also resulted in widespread local and distant metastasis. Serial analysis showed that the murine models closely recapitulated the multistage histopathologic progression of the human disease, including the development of stroma-rich tumors and the pre-malignant biliary lesions, intraductal papillary biliary neoplasms (IPBN) and Von Meyenburg complexes (VMC; also known as biliary hamartomas). These findings establish a new genetically and histopathologically faithful model of IHCC and lend experimental support to the hypothesis that IPBN and VMC are precursors to invasive cancers. PMID:22266220

  3. Advanced concepts for a 1200-kV shunt reactor. Volume I. Exploration of new concepts for inductive shunt reactor designs for integration into a 1200-kV gas insulated substation. Final report

    SciTech Connect

    Not Available

    1981-03-27

    The objective of this program is to explore new concepts for inductive shunt reactor designs for integration into a 1200 kV gas insulated substation. The most promising design should exhibit low dimensional profile with reduced weight, lower losses, and lower noise level when compared with units of equivalent rating designed with present day technology. To meet the objectives several advanced concepts of shunt reactor design were studied. The major concepts explored in this project reactor design were studied. The major concepts explored in this project included: sulfur hexafluoride gas insulated, foil type windings, high reluctance core materials, and heat transfer via the gaseous medium. As a result of the study, a shunt reactor was designed through an application of the advanced concepts with the conclusions that the program objectives could be attained.

  4. Functional Changes of Diaphragm Type Shunt Valves Induced by Pressure Pulsation

    NASA Astrophysics Data System (ADS)

    Lee, Chong-Sun; Suh, Chang-Min; Ra, Young-Shin

    Shunt valves used to treat patients with hydrocephalus were tested to investigate influence of pressure pulsation on their flow control characteristics. Our focus was on flow dynamic and functional changes of the small and thin diaphragms in the valves that serve as the main flow control mechanism and are made from silicone elastomer. Firstly, pressure-flow control curves were compared under pulsed and steady flow (without pulsation) conditions. Secondly, functional changes of the valves were tested after a long-term continuous pulsation with a peristaltic pump. Thirdly, flushing procedures selectively conducted by neurosurgeons were simulated with a fingertip pressed on the dome of the valves. As 20cc/hr of flow rate was adjusted at a constant pressure, application of 40mmH2O of pressure pulse increased flow rate through shunt valves more than 60%. As a 90cm length silicone catheter was connected to the valve outlet, increase in the flow rate was substantially reduced to 17.5%. Pressure-flow control characteristics of some valves showed significant changes after twenty-eight days of pressure pulsation at 1.0 Hz under 50.0cc/hr of flow rate. Flushing simulation resulted in temporary decrease in the pressure level. It took three hours to fully recover the normal pressure-flow control characteristics after the flushing. Our results suggest that shunt valves with a thin elastic diaphragm as the main flow control mechanism are sensitive to intracranial pressure pulsation or pressure spikes enough to change their pressure-flow control characteristics.

  5. The Retrograde Ventriculosinusal Shunt in an Animal Experimental Model of Hydrocephalus.

    PubMed

    Pinto, Fernando Campos Gomes; Becco, Rodrigo; Alho, Eduardo Joaquim Lopes; Poli-de-Figueiredo, Luiz Francisco; Souza, Podalyro Amaral de; Oliveira, Matheus Fernandes de; Teixeira, Manoel Jacobsen

    2016-01-01

    Currently, hydrocephalus treatment is performed mainly with ventriculoperitoneal shunting. This experimental study aims at assessing whether the experimental model of hydrocephalus in dogs is applicable to the laboratory study of the retrograde ventriculosinusal shunt (RVSS). Four mongrel dogs were assessed. After randomization, the animals were divided into two groups: an experimental group that underwent the induction of hydrocephalus/RVSS and a control group, for the measurement of the mean arterial pressure, intracranial pressure and pressure in the superior sagittal sinus (SSS). The controls presented a mean arterial pressure of 68 mm Hg (71 and 65), an intracranial pressure of 163 mm H2O (149.6 and 176.8) and a pressure at the SSS of 40 mm H2O (40 and 40). The kaolin injection into the cisterna magna at a concentration of 0.3 mg/ml was capable of inducing the clinical and radiological mechanism of hydrocephalus (intracranial pressure = 250 mm H2O, pressure at the SSS = 50 mm H2O). The caliber of the SSS was 2.5 ± 1.0 mm. The fact that the SSS caliber of the dog was the same size as the external diameter of the catheter used resulted in the complete obstruction of the SSS when the catheter was inserted. We believe we could design and perform an experimental model to test the RVSS. It is applicable and feasible. The model of hydrocephalus, the surgical apparatus and the scenario were adequate, but the shunt system needs to be proportionally made to the canine anatomy. PMID:26942592

  6. Embolization of Portosystemic Shunts for Treatment of Medically Refractory Hepatic Encephalopathy

    PubMed Central

    Lynn, Amanda M.; Singh, Siddharth; Congly, Stephen E.; Khemani, Disha; Johnson, David H.; Wiesner, Russell H.; Kamath, Patrick S.; Andrews, James C.; Leise, Michael D.

    2016-01-01

    Treatment options for refractory hepatic encephalopathy (HE) are limited. Patients who fail medical management may harbor large portosystemic shunts (PSSs) which are possible therapeutic targets. This study aims to describe patient selection, effectiveness, and safety of percutaneous PSS embolization in those with medically refractory HE. A retrospective evaluation of consecutive adult patients with medically refractory HE referred for PSS embolization at a tertiary center was performed (2003–2015). Patient data collected included the type of HE, medications, Model for End-Stage Liver Disease (MELD) score, shunt type, embolization approach, and materials used. Outcomes of interest were immediate (7 days), intermediate (1–4 months), and longer-term (6–12 months) effectiveness and periprocedural safety. Effectiveness was determined based on changes in hospitalization frequency, HE medications, and symptoms. Twenty-five patients with large PSS were evaluated for shunt embolization. Five were excluded due to high MELD scores (n = 1), comorbid conditions (n = 1), or technical considerations (n = 3). Of 20 patients who underwent embolization, 13 had persistent and 7 had recurrent HE; 100% (20/20) achieved immediate improvement. Durable benefit was achieved in 100% (18/18) and 92% (11/12) at 1–4 and 6–12 months, respectively. The majority (67%; 8/12) were free from HE-related hospitalizations over 1 year; 10% developed procedural complications, and all resolved. Six developed new or worsening ascites. In conclusion, PSS embolization is a safe and effective treatment strategy that should be considered for select patients with medically refractory HE. PMID:26970243

  7. Insufficient Portal Vein Inflow in Children without Major Shunt Vessels During Living Donor Liver Transplantation.

    PubMed

    Matsuura, Toshiharu; Yoshimaru, Koichiro; Yanagi, Yusuke; Esumi, Genshiro; Hayashida, Makoto; Taguchi, Tomoaki

    2016-01-01

    BACKGROUND Liver cirrhosis is frequently accompanied by insufficient portal vein inflow (IPVF) with large portosystemic shunts. However, pediatric cases often manifested IPVF without any apparent major portosystemic shunts. Although IPVF is a very critical issue, the intraoperative assessment has not been well established. In this study, we reviewed the intraoperative approach and the outcome of the IPVF cases at our department. MATERIAL AND METHODS Eighty-three living donor liver transplantations (LDLT) were performed from 1996 to 2014. The IPVF occurred in 5 cases and necessitated some additional assessments and intraoperative PV flow modulations. We retrospectively reviewed the operative records and analyzed the risk factors and the outcome of the IPVF. RESULTS All 5 IPVF cases were biliary atresia and the mean age at LDLT was 0.74±0.19 years old. The mean recipient PV diameter was 4.3±0.8 mm and the donor IMV patch grafts were applied. To increase the PV inflow, the collaterals around the spleen were ligated in all cases. Intraoperative portal venography was performed in 1 case for selective shunt vessel ligation. In 1 case, the graft was removed and returned to the back table to prevent graft loss during the IPVF. As a result, the final PVF/GV increased to 66.4±20.0 ml/min/100 g. CONCLUSIONS IPVF is a very critical problem. Intraoperative portal venography is helpful and collateral veins ligation is crucial. In some cases, returning the graft to the back table during the PV inflow modulation can prevent graft loss. PMID:27306916

  8. Power Quality Improvement Using an Enhanced Network-Side-Shunt-Connected Dynamic Voltage Restorer

    NASA Astrophysics Data System (ADS)

    Fereidouni, Alireza; Masoum, Mohammad A. S.; Moghbel, Moayed

    2015-10-01

    Among the four basic dynamic voltage restorer (DVR) topologies, the network-side shunt-connected DVR (NSSC-DVR) has a relatively poor performance and is investigated in this paper. A new configuration is proposed and implemented for NSSC-DVR to enhance its performance in compensating (un)symmetrical deep and long voltage sags and mitigate voltage harmonics. The enhanced NSSC-DVR model includes a three-phase half-bridge semi-controlled network-side-shunt-connected rectifier and a three-phase full-bridge series-connected inverter implemented with a back-to-back configuration through a bidirectional buck-boost converter. The network-side-shunt-connected rectifier is employed to inject/draw the required energy by NSSC-DVR to restore the load voltage to its pre-fault value under sag/swell conditions. The buck-boost converter is responsible for maintaining the DC-link voltage of the series-connected inverter at its designated value in order to improve the NSSC-DVR capability in compensating deep and long voltage sags/swells. The full-bridge series-connected inverter permits to compensate unbalance voltage sags containing zero-sequence component. The harmonic compensation of the load voltage is achieved by extracting harmonics from the distorted network voltage using an artificial neural network (ANN) method called adaptive linear neuron (Adaline) strategy. Detailed simulations are performed by SIMULINK/MATLAB software for six case studies to verify the highly robustness of the proposed NSSC-DVR model under various conditions.

  9. Atrial Septal Defect Closure for Right-to-Left Shunting Following a MitraClip Repair.

    PubMed

    Al'Aref, Subhi J; Bergman, Geoffrey; Wong, S Chiu

    2016-09-01

    Percutaneous repair of the mitral valve has been widely adopted for the treatment of primary, symptomatic severe mitral regurgitation in patients at prohibitive risk for surgical intervention. We present a case of an elderly female patient with moderate-to-severe mitral regurgitation who underwent MitraClip procedure, with postprocedural course remarkable for the development of right-to-left shunting and hypoxia, for which the patient underwent a percutaneous repair of the atrial septal defect with immediate recovery of oxygen saturation. PMID:27591693

  10. A single PWM section solar array shunt switching unit with an active ripple filter

    SciTech Connect

    Cho, B.H.; Lee, D.H.

    1995-12-31

    A single pulse-width-modulation (PWM) section shunt switching unit (SSU) for multi-kilowatt space power systems is presented. Due to the output capacitance of the solar cell, the PWM section in the array draws a pulsating current, which must be suppressed with a large filter inductor for each section. Proposed design uses a single designated PWM section with an active inductance enhancement filter. This leads to drastic reduction in size and weight of the SSU compared to the existing designs for the Space Station and Earth Observation System (EOS). A prototype has been designed and tested.

  11. Effect of shunt resistance and bypass diodes on the shadow tolerance of solar cell modules

    NASA Astrophysics Data System (ADS)

    Swaleh, M. S.; Green, M. A.

    1982-01-01

    In the field, solar cell arrays are subjected to shadows from both predictable sources and such unpredictable sources as bird droppings or fallen leaves. The most obvious result of a shadow is a decrease in power output from the solar cell array. However, a more serious problem that can arise is the degradation and eventual failure of the array due to localized overheating. These difficulties can be avoided either by incorporating a relatively small shunt resistance in the solar cell design or by incorporating bypass diodes. In this paper we analyse these techniques and compare their effectiveness.

  12. Rectal variceal bleeding treated by transjugular intrahepatic portosystemic shunt. Potentials and pitfalls.

    PubMed

    Godil, A; McCracken, J D

    1997-09-01

    Bleeding from anorectal varices can be massive and life threatening. Prompt differentiation between hemorrhoids and anorectal varices is crucial in treating these patients. Many different treatments are available for bleeding anorectal varices, but none has proved efficacy. We report a case of successful transjugular intrahepatic portosystemic shunt (TIPS) in controlling massive rectal variceal bleeding in an elderly patient with primary biliary cirrhosis and portal hypertension. After TIPS, rapid decompensation of liver function and encephalopathy developed and led to her death. Although TIPS may be effective in controlling acute life-threatening bleeding from anorectal varices, it can be associated with life-threatening complications. PMID:9412951

  13. Method of making an ion beam sputter-etched ventricular catheter for hydrocephalus shunt

    NASA Technical Reports Server (NTRS)

    Banks, B. A. (Inventor)

    1984-01-01

    The centricular catheter comprises a multiplicity of inlet microtubules. Each microtubule has both a large opening at its inlet end and a multiplicity of microscopic openings along its lateral surfaces. The microtubules are perforated by an ion beam sputter etch technique. The holes are etched in each microtubule by directing an ion beam through an electro formed mesh mask producing perforations having diameters ranging from about 14 microns to about 150 microns. This structure assures a reliable means for shunting cerebrospinal fluid from the cerebral ventricles to selected areas of the body.

  14. A comprehensive theoretical and experimental study of coplanar waveguide shunt stubs

    NASA Technical Reports Server (NTRS)

    Dib, Nihad I.; Ponchak, George E.; Katehi, Linda P. B.

    1993-01-01

    A comprehensive theoretical and experimental study of straight and bent coplanar waveguide (CPW) shunt stubs is presented. In the theoretical analysis, the CPW is assumed to be inside a cavity, while, the experiments are performed on open structures. A hybrid technique was developed to analyze the CPW discontinuities which proved to be accurate since the theoretical and experimental results agree very well. The effect of the cavity resonances on the behavior of the stubs with and without air-bridges is investigated. In addition, the encountered radiation loss due to the discontinuities is evaluated experimentally.

  15. Design of the HEAO main bus shunt regulator. [High Energy Astronomical Observatory solar array

    NASA Technical Reports Server (NTRS)

    Middlebrook, R. D.; Kimble, S. G.

    1976-01-01

    The High Energy Astronomy Observatory (HEAO) is being built for NASA by an American company. The general requirements concerning the HEAO main bus regulator are examined. The bus regulated voltage is 33 V, the maximum shunt current is 45 A, and the regulator output impedance is to be less than 0.5 Ohm from dc to 100 kHz. Loop gain design considerations for the main bus regulator are discussed and a description is given of the general device configuration. Attention is also given to regulator loop design and performance.

  16. Headache during haemodialysis in a patient with shunt: a cause for concern?

    PubMed

    O'Sullivan, Padraig; Sajjad, Jahangir; Abrar, Sahibzada; Marks, Charles

    2015-01-01

    A 20-year-old woman with a functioning ventriculoperitoneal (VP) shunt consistently reported unbearable vertex headaches and nausea during the last hour of her haemodialysis (HD) sessions. After one particularly severe episode, which was associated with vomiting, restlessness and blurred vision, her team suspected that she was developing dialysis disequilibrium syndrome. She improved fully on cessation of HD, requiring simple analgaesia only, and continued dialysis three times per week. Several more distressing episodes of nausea and headaches compelled us to give intravenous mannitol during HD, resulting in temporary improvement. Subsequently, shorter and more frequent dialysis sessions along with intravenous mannitol resulted in satisfactory clinical response. PMID:25819823

  17. A new Hydrocephalus Clinical Research Network protocol to reduce cerebrospinal fluid shunt infection.

    PubMed

    Kestle, John R W; Holubkov, Richard; Douglas Cochrane, D; Kulkarni, Abhaya V; Limbrick, David D; Luerssen, Thomas G; Jerry Oakes, W; Riva-Cambrin, Jay; Rozzelle, Curtis; Simon, Tamara D; Walker, Marion L; Wellons, John C; Browd, Samuel R; Drake, James M; Shannon, Chevis N; Tamber, Mandeep S; Whitehead, William E

    2016-04-01

    OBJECT In a previous report by the same research group (Kestle et al., 2011), compliance with an 11-step protocol was shown to reduce CSF shunt infection at Hydrocephalus Clinical Research Network (HCRN) centers (from 8.7% to 5.7%). Antibiotic-impregnated catheters (AICs) were not part of the protocol but were used off protocol by some surgeons. The authors therefore began using a new protocol that included AICs in an effort to reduce the infection rate further. METHODS The new protocol was implemented at HCRN centers on January 1, 2012, for all shunt procedures (excluding external ventricular drains [EVDs], ventricular reservoirs, and subgaleal shunts). Procedures performed up to September 30, 2013, were included (21 months). Compliance with the protocol and outcome events up to March 30, 2014, were recorded. The definition of infection was unchanged from the authors' previous report. RESULTS A total of 1935 procedures were performed on 1670 patients at 8 HCRN centers. The overall infection rate was 6.0% (95% CI 5.1%-7.2%). Procedure-specific infection rates varied (insertion 5.0%, revision 5.4%, insertion after EVD 8.3%, and insertion after treatment of infection 12.6%). Full compliance with the protocol occurred in 77% of procedures. The infection rate was 5.0% after compliant procedures and 8.7% after noncompliant procedures (p = 0.005). The infection rate when using this new protocol (6.0%, 95% CI 5.1%-7.2%) was similar to the infection rate observed using the authors' old protocol (5.7%, 95% CI 4.6%-7.0%). CONCLUSIONS CSF shunt procedures performed in compliance with a new infection prevention protocol at HCRN centers had a lower infection rate than noncompliant procedures. Implementation of the new protocol (including AICs) was associated with a 6.0% infection rate, similar to the infection rate of 5.7% from the authors' previously reported protocol. Based on the current data, the role of AICs compared with other infection prevention measures is unclear

  18. The brain following transjugular intrahepatic portosystemic shunt: the perspective from neuroimaging.

    PubMed

    Chen, Hui Juan; Zheng, Gang; Wichmann, Julian L; Schoepf, U Joseph; Lu, Guang Ming; Zhang, Long Jiang

    2015-12-01

    Hepatic encephalopathy (HE) is a common complication after implantation of a transjugular intrahepatic portosystemic shunt (TIPS). Neuroimaging offers a variety of techniques for non-invasive evaluation of alterations in metabolism, as well as structural and functional changes of the brain in patients after TIPS implantation. In this article, we review the epidemiology and pathophysiology of post-TIPS HE. The potential of neuroimaging including positron emission tomography and multimodality magnetic resonance imaging to investigate the pathophysiology of post-TIPS HE is presented. We also give a perspective on the role of neuroimaging in this field. PMID:26404041

  19. Anesthetic management in children with Hurler's syndrome undergoing emergency ventriculoperitoneal shunt surgery.

    PubMed

    Gupta, Nidhi; Rath, Girija Prasad; Bala, Renu; Reddy, Bapura Kiran; Chaturvedi, Arvind

    2012-04-01

    Mucopolysaccharidoses (MPSs) are a group of lysosomal storage disorder characterized by progressive multiorgan accumulation of glycosaminoglycans. Patients with MPS I (Hurler's syndrome) present as one of the most difficult airway problems to be managed by anesthesiologists. Hydrocephalus with increased intracranial pressure is a frequent complication seen in these patients. The rarity of the syndrome accounts for the small number of case reports and anecdotal information on the intracranial manifestations of this syndrome. We describe the successful anesthetic management of 2 children with Hurler's syndrome who underwent ventriculoperitoneal shunt surgery for acute hydrocephalus. PMID:22754449

  20. Anesthetic management in children with Hurler's syndrome undergoing emergency ventriculoperitoneal shunt surgery

    PubMed Central

    Gupta, Nidhi; Rath, Girija Prasad; Bala, Renu; Reddy, Bapura Kiran; Chaturvedi, Arvind

    2012-01-01

    Mucopolysaccharidoses (MPSs) are a group of lysosomal storage disorder characterized by progressive multiorgan accumulation of glycosaminoglycans. Patients with MPS I (Hurler's syndrome) present as one of the most difficult airway problems to be managed by anesthesiologists. Hydrocephalus with increased intracranial pressure is a frequent complication seen in these patients. The rarity of the syndrome accounts for the small number of case reports and anecdotal information on the intracranial manifestations of this syndrome. We describe the successful anesthetic management of 2 children with Hurler's syndrome who underwent ventriculoperitoneal shunt surgery for acute hydrocephalus. PMID:22754449