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Residual Flow (residual + flow)
Selected AbstractsUpstream migration of Atlantic salmon at a power station on the River Nidelva, Southern NorwayFISHERIES MANAGEMENT & ECOLOGY, Issue 3 2003E. B. Thorstad Abstract The upstream migration of 17 radio-tagged adult Atlantic salmon, Salmo salar L., past hydroelectric developments on the River Nidelva, Southern Norway, was examined. Salmon migrated quickly from the site of release in the lower part of the river up to the tunnel outlet of Rygene power station, but were substantially delayed at the outlet. The salmon stayed in the outlet area for 0,71 days (median = 20), and mainly took up a position inside the dark power station tunnel. Water discharge in the tunnel was 57,176 m3 s,1, while residual flow in the river between the outlet and the dam 2.5 km further upstream was 3 m3 s,1. Ten salmon passed the outlet and entered the residual flow stretch, but none passed the dam. Six of the 10 salmon returned to the tunnel outlet. No major migration barriers were identified in the residual flow stretch, suggesting lack of motivation among the salmon to migrate due to either low water discharge compared with the main river, or several minor migration barriers along the river stretch. [source] MRA of intracranial aneurysms embolized with platinum coils: A vascular phantom study at 1.5T and 3TJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 1 2008Shingo Kakeda Abstract Purpose To analyze the influence of matrix and echo time (TE) of three-dimensional time-of-flight (3D TOF) magnetic resonance angiography (MRA) on the depiction of residual flow in aneurysms embolized with platinum coils at 1.5T and 3T. Materials and Methods A simulated intracranial aneurysm of the vascular phantom was loosely packed to maintain the patency of some residual aneurysmal lumen with platinum coils and connected to an electromagnetic flow pump with pulsatile flow. MRAs were obtained altering the matrix and TE of 3D TOF sequences at 1.5T and 3T. Results The increased spatial resolution and the shorter TE offered better image quality at 3T. For the depiction of an aneurysm remnant, the high-spatial-resolution 3T MRA (matrix size of 384 × 224 and 512 × 256) with a short TE of ,3.3 msec were superior to the 1.5T MRA obtained with any sequences. Conclusion 3T MRA is superior to 1.5T MRA for the assessment of aneurysms embolized with platinum coils; the combination of the 512 × 256 matrix and short TE (3.3 msec or less) seems feasible at 3T. J. Magn. Reson. Imaging 2008;28:13,20. © 2008 Wiley-Liss, Inc. [source] Residual Flow Signals Predict Complete Recanalization in Stroke Patients Treated With TPAJOURNAL OF NEUROIMAGING, Issue 1 2003Lise A. Labiche MD ABSTRACT Background. Residual blood flow around thrombus prior to treatment predicts success of coronary thrombolysis. The authors aimed to correlate the presence of residual flow signals in the middle cerebral artery (MCA) with completeness of recanalization after intravenous tissue plasminogen activator (TPA). Methods. The authors studied consecutive patients treated with intravenous TPA therapy who had a proximal MCA occlusion on pretreatment transcranial Doppler (TCD). Patients were continuously monitored for 2 hours after TPA bolus. Absent residual flow signals correspond to the thrombolysis in brain ischemia (TIBI) 0 grade, and the presence of residual flow signals was determined as TIBI 1-3 flow grades. Complete recanalization was defined as flow improvement to TIBI grades 4-5. Results. Seventy-five patients with a proximal MCA occlusion had median pre-bolus NIHSS 16 (85% with ,10 points). TPA bolus was given at 141 ± 56 minutes (median 120 minutes). Complete recanalization was observed in 25 (33%), partial in 23 (31%), and no early recanalization was seen in 27 (36%) patients within 2 hours after TPA bolus. Only 19% with absent residual flow signals (TIBI grade 0, n= 26) on pretreatment TCD had complete early recanalization. If pretreatment TCD showed the presence of any residual flow (TIBI 1-3, n= 49), 41% had complete recanalization within 2 hours of TPA bolus (P = .03). Conclusions. Patients with detectable residual flow signals before IV TPA bolus are twice as likely to have early complete recanalization. Those with no detectable residual flow signals have less than 20% chance for complete early recanalization with intravenous TPA and may be candidates for intra-arterial therapies. [source] Transarterial Coil Embolization of Patent Ductus Arteriosus in Small Dogs with 0.025-Inch Vascular Occlusion Coils: 10 CasesJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 3 2004Daniel F. Hogan Patent ductus arteriosus (PDA) is the most common congenital cardiac disease in the dog and generally leads to severe clinical signs, including left-sided congestive heart failure. Historically, definitive treatment consisted of surgical ligation; however, the use of vascular occlusion devices by minimally invasive techniques has gained popularity in veterinary medicine during the past decade. Adequate vascular access is a major limiting factor for these minimally invasive techniques, precluding their use in very small dogs. The clinical management of PDA with 0.025-in vascular occlusion coils in a minimally invasive transarterial technique in 10 dogs is described. The dogs were small (1.38 ± 0.22 kg), were generally young (6.70 ± 5.74 months), and had small minimal ductal diameters (1.72 ± 0.81 mm from angiography). Vascular access was achieved, and coil deployment was attempted in all dogs with a 3F catheter uncontrolled release system. Successful occlusion, defined as no angiographic residual flow, was accomplished in 8 of 10 (80%) dogs. Successful occlusion was not achieved in 2 dogs (20%), and both dogs experienced embolization of coils into the pulmonary arterial tree. One of these dogs died during the procedure, whereas the other dog underwent a successful surgical correction. We conclude that transarterial PDA occlusion in very small dogs is possible with 0.025-in vascular occlusion coils by means of a 3F catheter system and that it represents a viable alternative to surgical ligation. The risk of pulmonary arterial embolization is higher with this uncontrolled release system, but this risk may decrease with experience. [source] Maximizing residual flow under an arc destructionNETWORKS: AN INTERNATIONAL JOURNAL, Issue 4 2001Y. P. Aneja Abstract In this paper, we consider two problems related to single-commodity flows on a directed network. In the first problem, for a given s , t flow, if an arc is destroyed, all the flow that is passing through that arc is destroyed. What is left flowing from s to t is the residual flow. The objective is to determine a flow pattern such that the residual flow is maximized. We provide a strongly polynomial algorithm for this problem, called the maximum residual flow problem, and consider various extensions of this basic model. In the second problem, known as the "most vital arc" problem, the objective is to remove an arc so that the maximal flow on the residual network is as small as possible. Results are also derived which help implement an efficient scheme for solving this problem. © 2001 John Wiley & Sons, Inc. [source] Transcranial ultrasound in clinical sonothrombolysis (TUCSON) trial,ANNALS OF NEUROLOGY, Issue 1 2009Carlos A. Molina MD Objective Microspheres (,S) reach intracranial occlusions and transmit energy momentum from an ultrasound wave to residual flow to promote recanalization. We report a randomized multicenter phase II trial of ,S dose escalation with systemic thrombolysis. Methods Stroke patients receiving 0.9mg/kg tissue plasminogen activator (tPA) with pretreatment proximal intracranial occlusions on transcranial Doppler (TCD) were randomized (2:1 ratio) to ,S (MRX-801) infusion over 90 minutes (Cohort 1, 1.4ml; Cohort 2, 2.8ml) with continuous TCD insonation, whereas controls received tPA and brief TCD assessments. The primary endpoint was symptomatic intracerebral hemorrhage (sICH) within 36 hours after tPA. Results Among 35 patients (Cohort 1 = 12, Cohort 2 = 11, controls = 12) no sICH occurred in Cohort 1 and controls, whereas 3 (27%, 2 fatal) sICHs occurred in Cohort 2 (p = 0.028). Sustained complete recanalization/clinical recovery rates (end of TCD monitoring/3 month) were 67%/75% for Cohort 1, 46%/50% for Cohort 2, and 33%/36% for controls (p = 0.255/0.167). The median time to any recanalization tended to be shorter in Cohort 1 (30 min; interquartile range [IQR], 6) and Cohort 2 (30 min; IQR, 69) compared to controls (60 min; IQR, 5; p = 0.054). Although patients with sICH had similar screening and pretreatment systolic blood pressure (SBP) levels in comparison to the rest, higher SBP levels were documented in sICH+ patients at 30 minutes, 60 minutes, 90 minutes, and 24,36 hours following tPA bolus. Interpretation Perflutren lipid ,S can be safely combined with systemic tPA and ultrasound at a dose of 1.4ml. Safety concerns in the second dose tier may necessitate extended enrollment and further experiments to determine the mechanisms by which microspheres interact with tissues. In both dose tiers, sonothrombolysis with ,S and tPA shows a trend toward higher early recanalization and clinical recovery rates compared to standard intravenous tPA therapy. Ann Neurol 2009;66:28,38 [source] Transcatheter closure of high-risk muscular ventricular septal defects with the CardioSEAL occluder: Initial report from the CardioSEAL VSD RegistryCATHETERIZATION AND CARDIOVASCULAR INTERVENTIONS, Issue 5 2007D. Scott Lim MD Abstract Objectives: The CardioSEAL VSD registry was created to track safety of the device to close high-risk Ventricular Septal Defect (VSD). Background: This is the first report from the multi-centered CardioSEAL VSD registry reviewing demographics and initial results. Methods: Centers recruited patients with VSD who were high-risk for surgery due to medical condition or anatomic features. Results: 18 centers contributed data on 55 high-risk patients who had 61 VSD-occlusion procedures, with age of range of 5 days to 65 years and using one to six devices. Implantation approach was transvenous in 48, perventricular in five, and by combined approach in two patients. Ninety-two percent of intended VSD device implants were judged successful. Twenty-two patients had single VSD closed by single device in 18 and by two devices in four patients. All patients <8 kg underwent perventricular device implantation. Thirty-three patients had multiple VSDs which were closed by a single device in 23, and multiple devices in 10. At discharge echocardiography showed total residual flow through all VSDs in which devices were used was classified as "Small" or less in 74%, "More than small" in 11%, and "Uncertain" in 15%. Eight major adverse events occurred in 5/61 cases (8% event rate), with 3/81 devices embolized (4% embolization rate), 5/81 devices surgically explanted (6% explant rate), and no deaths judged to be procedure-related. Conclusion: This initial report from the multi-centered CardioSEAL VSD registry demonstrates the safety of the device to close high-risk VSDs. © 2007 Wiley-Liss, Inc. [source] Catheter closure of atrial septal defects with deficient inferior vena cava rim under transesophageal echo guidance,CATHETERIZATION AND CARDIOVASCULAR INTERVENTIONS, Issue 1 2009K.S. Remadevi MD Abstract Objectives: To describe the case selection, imaging considerations, technique, and results of catheter closure of atrial septal defects (ASD) with deficient inferior vena cava (IVC) rim. Background: Transcatheter closure with Amplatzer septal occluder (ASO) has become standard treatment for most secundum ASDs. Defects with deficient IVC rim continue to be challenging to image and close in the catheterization laboratory. Methods: Records of 12 patients with deficient IVC rim (<5 mm), who underwent catheter closure (April 2007 to June 2008) were reviewed. General anesthesia and transesophageal echo (TEE) guidance was used in all. The IVC rim was imaged at 70°,90° with retroflexion of the TEE probe, in addition to the conventional views. Devices 1,4 mm > maximal ASD size were selected. Deployment was accomplished either from the left atrium, left upper or from the right pulmonary veins. Results: The median age was 5.5 (2.5,27) years and median weight was 19.5 (9-65) kg. The defects measured 16,32 mm and 18,36 mm septal occluders were used. The median fluoroscopic time was 13.1 (4.2,32.7) min. Initial device selection was revised in four patients. Two patients had residual flows at IVC margin. The device embolized to right ventricular outflow tract in one patient. This was retrieved, and a larger device was deployed. No other complications were observed immediately or on follow-up (median 6; range 1,14 months). Conclusions: Transcatheter closure of ASDs with deficient IVC rim is feasible under TEE guidance. The modified retroflexed view allows adequate imaging of IVC rim through TEE. © 2008 Wiley-Liss, Inc. [source] | ||||||||||