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Concept: Shunt

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PURPOSE OF REVIEW: This review provides an evidence-based comparison of aqueous shunts in common use. RECENT FINDINGS: Aqueous shunts are being used with increasing frequency in the surgical management of glaucoma. Recent retrospective studies and prospective clinical trials have compared the outcomes of different shunt designs. Larger end-plate size is associated with greater intraocular pressure (IOP) reduction, but there may be an upper limit beyond which a further increase in plate surface area does not contribute beneficially to pressure control. The biocompatibility of plate material may also influence shunt efficacy. The flow restrictor of the Ahmed glaucoma valve provides an added level of safety by reducing the risk of postoperative hypotony, but this implant also appears to have a higher incidence of bleb encapsulation. SUMMARY: Several aqueous shunts are commercially available, and all have been shown to be safe and effective in lowering IOP. Studies comparing aqueous shunts have provided valuable information to assist in surgical decision-making in similar patient groups.

Concepts: Clinical trial, Surgery, Effectiveness, Intraocular pressure, Ophthalmology, Glaucoma valve, Limit superior and limit inferior, Shunt

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Object Overdrainage of CSF remains an unsolved problem in shunt therapy. The aim of the present study was to evaluate treatment options on overdrainage-related events enabled by the new generation of adjustable gravity-assisted valves. Methods The authors retrospectively studied the clinical course of 250 consecutive adult patients with various etiologies of hydrocephalus after shunt insertion for different signs and symptoms of overdrainage. Primary and secondary overdrainage were differentiated. The authors correlated the incidence of overdrainage with etiology of hydrocephalus, opening valve pressure, and patient parameters such as weight and size. Depending on the severity of overdrainage, they elevated the opening pressure, and follow-up was performed until overdrainage was resolved. Results The authors found 39 cases (15.6%) involving overdrainage-related problems-23 primary and 16 secondary overdrainage. The median follow-up period in these 39 patients was 2.1 years. There was no correlation between the incidence of overdrainage and any of the following factors: sex, age, size, or weight of the patients. There was also no statistical significance among the different etiologies of hydrocephalus, with the exception of congenital hydrocephalus. All of the “complications” could be resolved by readjusting the opening pressure of the valve in one or multiple steps, avoiding further operations. Conclusions Modern adjustable and gravity-assisted valves enable surgeons to set the opening pressure relatively low to avoid underdrainage without significantly raising the incidence of overdrainage and to treat overdrainage-related clinical and radiological complications without surgical intervention.

Concepts: Medicine, Surgery, Cerebrospinal fluid, Hydrocephalus, Valve, Etiology, Shunt

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BACKGROUND: Many adults with repaired tetralogy of Fallot have had prior Blalock-Taussig shunts. These shunts may theoretically hinder growth and development of the ipsilateral arm. METHODS: We prospectively enrolled consecutive patients with tetralogy of Fallot in a cross-sectional study to measure arm length and assess handgrip strength. Bilateral handgrip strength was quantified by a dynamometer in a standing position after instructing patients to clench each hand tightly in succession. The maximum force achieved, in kilograms, was measured. RESULTS: A total of 80 consecutive adults with tetralogy of Fallot, aged 36.0±12.5years, 49% female, were prospectively enrolled. Thirty-eight (47.5%) patients had prior Blalock-Taussig shunts at a median age of 1.0year. Twenty-one (55.3%) were left-sided and 23 (60.5%) were classic shunts. All but six patients with right-sided shunts and one without a prior shunt were right-handed. The shunts were present for a median of 4.0years prior to takedown during corrective surgery. The arm ipsilateral to the shunt was significantly shorter than the contralateral arm (71.5±6.1 versus 73.6±5.6cm, P<0.0001). Handgrip strength was significantly weaker on the ipsilateral versus contralateral side (median [IQR], 26.5 [14.0-41.5] versus 31.0 [18.0-46.0] kg, P<0.0001) and the ipsilateral-to-contralateral handgrip ratio was lower with classic versus modified shunts (median [IQR], 1.05 [1.02-1.14] versus 1.19 [1.07-1.33] kg, P=0.0541). CONCLUSION: In patients with tetralogy of Fallot, Blalock-Taussig shunts may impair normal development of the ipsilateral arm with repercussions in adulthood that include shorter limb length and reduced handgrip strength. These changes are most pronounced in patients with classic end-to-side anastomoses.

Concepts: Measurement, Mass, Tetralogy of Fallot, International System of Units, Kilogram, Adult, SI base unit, Shunt

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There is controversy over the ability of transjugular intrahepatic portosystemic shunts (TIPS) to increase survival times of patients with cirrhosis and refractory ascites. The high rate of shunt dysfunction with the use of uncovered stents counteracts the benefits of TIPS. We performed a randomized controlled trial to determine the effects of TIPS with stents covered with polytetrafluoroethylene in these patients.

Concepts: Time, Randomized controlled trial, Cirrhosis, Ascites, Hepatorenal syndrome, Transjugular intrahepatic portosystemic shunt, Shunt

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Balloon-occluded retrograde transvenous obliteration (BRTO) is an effective and minimally invasive treatment for isolated gastric varices (GVs) that is usually performed through a gastrorenal shunt (GRS) or gastrocaval shunt (GCS). However, there are some cases in which GVs drain mainly into the left pericardiophrenic vein without an accessible GRS or GCS. This brief report presents four cases of GVs without a GRS/GCS treated by BRTO through the pericardiophrenic vein. BRTO was successfully performed with the use of flexible balloon catheters without any complications in all four patients, and the GVs were completely obliterated.

Concepts: Minimally invasive, Shunt

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The aim of the study was to compare the radiological indicators of effectiveness for hydrocephalus treatment in children operated on under the third year of age with the use of shunt insertion (SI) and endoscopic third ventriculostomy (ETV). The effectiveness was considered in terms of postoperative neurodevelopment in correlation to pre- and postoperative radiological findings.

Concepts: Neurosurgery, Hydrocephalus, Neural development, Neurodevelopmental disorder, Shunt

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Patients with elevated filling pressures are at increased risk of adverse cardiovascular (CV) outcomes. Structural interventions to lower elevated either left or right atrial filling pressures are gaining attention. Studies in heart failure show that lowering left atrial pressure may reduce CV events while improving functional capacity. In recognition of this, trials are ongoing studying the effects of percutaneously implanted interatrial shunt devices (IASD). The preliminary results of IASD implantation suggest that periprocedural complications are rare and midterm safety good. Although both haemodynamic and functional parameters improve after IASD implantation, study designs, including sample size and duration, preclude definite conclusions regarding potential efficacy. In this paper, we briefly summarise current knowledge in the field, and give a perspective on the data needed to make interatrial device shunt therapy a part of our armamentarium in patients with heart failure or pulmonary hypertension and increased filling pressure.

Concepts: Blood, Cardiology, Heart, Circulatory system, Pulmonary artery, Atrium, Pressure, Shunt

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Cyclic recruitment and derecruitment of atelectasis can occur during mechanical ventilation, especially in injured lungs. Experimentally, cyclic recruitment and derecruitment can be quantified by respiration-dependent changes in PaO2 (ΔPaO2), reflecting the varying intrapulmonary shunt fraction within the respiratory cycle. This study investigated the effect of inspiration to expiration ratio upon ΔPaO2 and Horowitz index.

Concepts: Pulmonology, Pneumonia, Respiratory physiology, Acute respiratory distress syndrome, Mechanical ventilation, Pulmonary contusion, Shunt, Pulmonary shunt

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Synthetic graft materials are commonly used for shunts and cardiovascular reconstruction in neonates but are prone to thrombosis and scarring. Umbilical vein is a potential source of autologous, endothelialized tissue for neonatal shunts and tissue reconstruction but requires preservation prior to implantation.

Concepts: Pregnancy, Blood, Fetus, Umbilical vein, Vein, Embryology, Veins, Shunt

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OBJECTIVE Infants with severe hydrocephalus and extreme macrocephaly typically undergo CSF diversion early in life, which can result in significant cranial deformity due to CSF overdrainage. In this scenario, overlap of the cranial plates can precede the development of secondary synostosis and/or severe, permanent cranial deformity. As a result, extensive cranial vault remodeling is sometimes undertaken later in life, which is often challenging and has been associated with mortality and a high morbidity rate. The authors have previously described a technique for early postnatal cranial vault reduction and fixation (CVRF), in which the calvarial bones are stabilized using absorbable fixation plates in the neonatal period, in an attempt to facilitate patient positioning, simplify hydrocephalus management, and improve cosmesis. Here, the authors describe their institutional experience managing patients with extreme neonatal hydrocephalus with CSF diversion, with and without CVRF, over the past 12 years. METHODS The authors retrospectively reviewed the charts of infants with extreme hydrocephalus (head circumference > 49 cm) treated at their children’s hospital with ventriculoperitoneal shunting, with or without CVRF, between 2005 and 2017. Data collected included age, sex, etiology of hydrocephalus, type of CVRF performed (anterior, posterior, or combined), follow-up duration, orbitofrontal circumference, craniometric measurements, intraoperative blood loss, operative duration, and postoperative complications. Developmental data were collected using the third edition of the Ages and Stages Questionnaire. Photographic imaging was used to demonstrate esthetic outcomes, and family questionnaires were used to evaluate satisfaction with the esthetic outcome. RESULTS Eleven patients with extreme neonatal hydrocephalus underwent CSF shunting; 5 underwent shunting alone and 6 patients underwent shunting and CVRF. For patients who underwent shunting and CVRF, the median age at CVRF was 6 days and the median interval between shunt placement and CVRF was 2.5 days. The mean extent of calvarial vault volume reduction was 44.5% (± 3.9%). The mean duration of the CVRF procedure was 108 minutes, and 5 of 6 patients required intraoperative transfusion. Of the 5 patients who underwent shunting alone, 3 developed severe cranial deformities. Of 6 patients who underwent shunting and CVRF, 1 had a poor cosmetic outcome. In the shunting-alone group, 2 patients died and 1 required extensive cranial vault correction at 10 years of age. One patient in the shunting and CVRF group also died. CONCLUSIONS CVRF in combination with CSF shunting in the neonatal period can simplify the treatment of the rare case of severe hydrocephalic macrocephaly and leads to cosmetic outcomes that are considered good by their families.

Concepts: Childbirth, Infant, Arithmetic mean, Cerebrospinal fluid, Hydrocephalus, Outcome, Infancy, Shunt