Zeitschriftenartikel: „Flow shunting“

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Smolich, Joseph J., Kelly R. Kenna, Michael M. H. Cheung und Jonathan P. Mynard. „Brief asphyxial state following immediate cord clamping accelerates onset of left-to-right shunting across the ductus arteriosus after birth in preterm lambs“. Journal of Applied Physiology 128, Nr. 2 (01.02.2020): 429–39. http://dx.doi.org/10.1152/japplphysiol.00559.2019.

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Reversal of shunting across the ductus arteriosus from right-to-left to left-to-right is a characteristic feature of the birth transition. Given that immediate cord clamping (ICC) followed by an asphyxial cord clamp-to-ventilation (CC-V) interval may augment left ventricular (LV) output and central blood flows after birth, we tested the hypothesis that an asphyxial CC-V interval accelerates the onset of postnatal left-to-right ductal shunting. High-fidelity central blood flow signals were obtained in anesthetized preterm lambs (gestation 128 ± 2 days) after ICC followed by a nonasphyxial (∼40 s, n = 9) or asphyxial (∼90 s, n = 9) CC-V interval before mechanical ventilation for 30 min after birth. Left-to-right ductal flow segments were related to aortic isthmus and descending aortic flow profiles to quantify sources of ductal shunting. In the nonasphyxial group, phasic left-to-right ductal shunting was initially minor after birth, but then rose progressively to 437 ± 164 ml/min by 15 min ( P < 0.001). However, in the asphyxial group, this shunting increased from 24 ± 21 to 199 ± 93 ml/min by 15 s after birth ( P < 0.001) and rose further to 471 ± 190 ml/min by 2 min ( P < 0.001). This earlier onset of left-to-right ductal shunting was supported by larger contributions ( P < 0.001) from direct systolic LV flow and retrograde diastolic discharge from an arterial reservoir/windkessel located in the descending aorta and its major branches, and associated with increased pulmonary arterial blood flow having a larger ductal component. These findings suggest that the duration of the CC-V interval after ICC is an important modulator of left-to-right ductal shunting, LV output and pulmonary perfusion at birth. NEW & NOTEWORTHY This birth transition study in preterm lambs demonstrated that a brief (∼90 s) asphyxial interval between umbilical cord clamping and ventilation onset resulted in earlier and greater left-to-right shunting across the ductus arteriosus after birth. This greater shunting 1) resulted from an increased left ventricular output associated with a higher systolic left-to-right ductal flow and increased retrograde diastolic discharge from a lower body arterial reservoir/windkessel, and 2) was accompanied by greater lung perfusion after birth.

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Javlé, P., J. Yates, H. G. Kynaston, K. F. Parsons und S. A. Jenkins. „Hepatosplanchnic haemodynamics and renal blood flow and function in rats with liver failure“. Gut 43, Nr. 2 (01.08.1998): 272–79. http://dx.doi.org/10.1136/gut.43.2.272.

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Background—Massive liver necrosis, characteristic of acute liver failure, may affect hepatosplanchnic haemodynamics, and contribute to the alterations in renal haemodynamics and function.Aims—To investigate the relation between hepatosplanchnic haemodynamics, including portal systemic shunting, and renal blood flow and function in rats with acute liver failure.Methods—Liver failure was induced in male Wistar rats by intraperitoneal injection of 1.1 g/kg ofd(+)-galactosamine hydrochloride. The parameters assessed included: systemic, hepatosplanchnic, and renal blood flow (57Co microsphere method); portal-systemic shunting and intrarenal shunting (consecutive intrasplenic, intraportal, or renal arterial injections of 99mTc methylene diphosphonate and99mTc albumin microspheres); arterial blood pressure and portal pressure; renal function; and liver function (liver function tests and 14C aminopyrine breath test).Results—Progressive liver dysfuntion was accompanied by the development of a hyperdynamic circulation, a highly significant decrease in renal blood flow and function, and an increase in intrarenal shunting 36, 42, and 48 hours after administration of d-galactosamine. The alterations in renal blood flow and function were accompanied by significant increases in portal pressure, portal venous inflow, and intrahepatic portal systemic shunting in galactosamine treated rats compared with controls. There was a significant correlation between changes in renal blood flow and changes in portal pressure, intrahepatic portal systemic shunting, and deterioration in liver function (r=0.8, p<0.0001).Conclusions—The results of this study suggest that both increased intrahepatic portal systemic shunting and hepatocyte impairment may contribute to alterations in renal haemodynamics and function.

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Shepherd, A. P., und J. W. Kiel. „A model of countercurrent shunting of oxygen in the intestinal villus“. American Journal of Physiology-Heart and Circulatory Physiology 262, Nr. 4 (01.04.1992): H1136—H1142. http://dx.doi.org/10.1152/ajpheart.1992.262.4.h1136.

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This report describes a mathematical model of the countercurrent shunting (CCS) of O2 in the intestinal villus. The anatomic basis for the model is the close proximity of the arteriole and venule between which O2 is free to diffuse. The model divides the villus into four segments from base to tip. Steady-state equations describe the convective and diffusive fluxes of O2 in the arteriolar, capillary, and tissue compartments within each segment. Longitudinal diffusion along the length of the villus is assumed to be negligible. Simulations with the model led to the following observations: 1) CCS shifted the VO2 vs. blood flow curve down and to the right, slightly impairing VO2 at a given blood flow; 2) the base-to-tip PO2 gradient caused by the tissue O2 consumption was reduced by CCS; 3) when blood flow was reduced, the base-to-tip PO2 gradient increased until the tip PO2 fell to zero and then fell with further flow reductions; 4) lowering blood flow initially caused slight increases in shunting but further decreases in flow reduced shunting; 5) in the blood flow range in which VO2 was flow independent, increasing the O2 demand or decreasing the intervascular distance increased shunting because of the greater arteriole-to-capillary O2 concentration gradient and the decreased diffusion distance, respectively; and 6) lowering the hemoglobin's P50 to simulate fetal blood caused slight reductions in shunting and reduced VO2 at a given flow. In summary, the model confirms the potentially deleterious effects of CCS on intestinal oxygenation, and, in contrast to assertions in the literature, it shows that a base-to-tip PO2 gradient is not prima facie evidence of counter-current shunting.

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Zierer, Andreas, Spencer J. Melby, Rochus K. Voeller und Marc R. Moon. „Interatrial shunt for chronic pulmonary hypertension: differential impact of low-flow vs. high-flow shunting“. American Journal of Physiology-Heart and Circulatory Physiology 296, Nr. 3 (März 2009): H639—H644. http://dx.doi.org/10.1152/ajpheart.00496.2008.

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The purpose of the present study was to determine for the first time the qualitative and quantitative impact of varying degrees of interatrial shunting on right heart dynamics and systemic perfusion in subjects with chronic pulmonary hypertension (CPH). Eight dogs underwent 3 mo of progressive pulmonary artery banding, following which right atrial and ventricular end-systolic and end-diastolic pressure-volume relations were calculated using conductance catheters. An 8-mm shunt prosthesis was inserted between the superior vena cava and left atrium, yielding a controlled model of atrial septostomy. Data were obtained 1) preshunt or “CPH”; 2) “Low-Flow” shunt; and 3) “High-Flow” shunt (occluding superior vena cava forcing all flow through the shunt). With progressive shunting, right ventricular pressure fell from 72 ± 19 mmHg (CPH) to 54 ± 17 mmHg (Low-Flow) and 47 ± 17 mmHg (High-Flow) ( P < 0.001). Cardiac output increased from 1.5 ± 0.3 l/min at CPH to 1.8 ± 0.4 l/min at Low-Flow (286 ± 105 ml/min, 15% of cardiac output; P < 0.001), but returned to 1.6 ± 0.3 l/min at High-Flow (466 ± 172 ml/min, 29% of cardiac output; P = 0.008 vs. Low-Flow, P = 0.21 vs. CPH). There was a modest rise in systemic oxygen delivery from 252 ± 46 ml/min at CPH to 276 ± 50 ml/min at Low-Flow ( P = 0.07), but substantial fall to 222 ± 50 ml/min at High-Flow ( P = 0.005 vs. CPH, P < 0.001 vs. Low-Flow). With progressive shunting, bichamber contractility did not change ( P = 0.98), but the slope of the right atrial end-diastolic pressure volume relation decreased ( P < 0.04), consistent with improved compliance. This study demonstrated that Low-Flow interatrial shunting consistently improved right atrial mechanics and systemic perfusion in subjects with CPH, while High-Flow exceeded an “ideal shunt fraction”.

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Smolich, Joseph J., Kelly R. Kenna und Jonathan P. Mynard. „Retrograde lower body arterial reservoir discharge underlies rapid reversal of ductus arteriosus shunting after early cord clamping at birth in preterm lambs“. Journal of Applied Physiology 120, Nr. 4 (15.02.2016): 399–407. http://dx.doi.org/10.1152/japplphysiol.00794.2015.

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Arterial reservoir (“windkessel”) function, whereby a part of left ventricular (LV) output is stored in elastic arteries during systole and discharged in diastole, is a well-established physiological phenomenon. However, its role in rapid reversal (to left-to-right) and a systolic-to-diastolic shift of shunting across the ductus arteriosus after birth is unknown. To address this question, ductal and aortic isthmus flows were measured with high-fidelity transit-time probes in six anesthetized preterm fetal lambs before and after cord clamping and subsequent early mechanical ventilation and for 30 min postbirth. Descending aortic flow was calculated as the sum of isthmus and ductal flows. Left-to-right ductal flow profiles were related to those of the isthmus and descending aorta, with upper body arterial reservoir discharge indicated by forward diastolic isthmus flow, and retrograde lower body arterial reservoir discharge by negative diastolic descending aortic flow. Left-to-right ductal shunting appeared immediately after cord clamping ( P < 0.001), due entirely to newly emergent retrograde lower body reservoir discharge, and rose with ventilation via increased lower body reservoir discharge ( P < 0.005), supplemented by upper body reservoir discharge after 45 s ( P < 0.025) and LV systolic flow after 3 min ( P = 0.025). The contribution of lower body reservoir discharge to left-to-right ductal shunting fell to 55 ± 8% at ≥15 min ( P < 0.001) but remained higher ( P < 0.002) than LV systolic flow (33 ± 8%) or upper body reservoir discharge (12 ± 5%). These results suggest that retrograde lower body arterial reservoir discharge plays a key role in rapid reversal and a systolic-to-diastolic shift of ductal shunting after cord clamping and early ventilation at birth.

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Diller, Gerhard-Paul, Astrid E. Lammers, Sheila G. Haworth, Konstantinos Dimopoulos, Graham Derrick, Philipp Bonhoeffer, Michael A. Gatzoulis und Darrel P. Francis. „A modelling study of atrial septostomy for pulmonary arterial hypertension, and its effect on the state of tissue oxygenation and systemic blood flow“. Cardiology in the Young 20, Nr. 1 (Februar 2010): 25–32. http://dx.doi.org/10.1017/s1047951109991855.

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AbstractAtrial septostomy is performed in patients with severe pulmonary arterial hypertension, and has been shown to improve symptoms, quality of life and survival. Despite recognized clinical benefits, the underlying pathophysiologic mechanisms are poorly understood. We aimed to assess the effects of right-to-left shunting on arterial delivery of oxygen, mixed venous content of oxygen, and systemic cardiac output in patients with pulmonary arterial hypertension and a fixed flow of blood to the lungs. We formulated equations defining the mandatory relationship between physiologic variables and delivery of oxygen in patients with right-to-left shunting. Using calculus and computer modelling, we considered the simultaneous effects of right-to-left shunting on physiologies with different pulmonary flows, total metabolic rates, and capacities for carrying oxygen. Our study indicates that, when the flow of blood to the lungs is fixed, increasing right-to-left shunting improves systemic cardiac output, arterial blood pressure, and arterial delivery of oxygen. In contrast, the mixed venous content of oxygen, which mirrors the average state of tissue oxygenation, remains unchanged. Our model suggests that increasing the volume of right-to-left shunting cannot compensate for right ventricular failure. Atrial septostomy in the setting of pulmonary arterial hypertension, therefore, increases the arterial delivery of oxygen, but the mixed systemic saturation of oxygen, arguably the most important index of tissue oxygenation, stays constant. Our data suggest that the clinically observed beneficial effects of atrial septostomy are the result of improved flow of blood rather than augmented tissue oxygenation, provided that right ventricular function is adequate.

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Mascalchi, M., G. Arnetoli, D. Inzitari, G. Dal Pozzo, F. Lolli, D. Caramella und C. Bartolozzi. „Cine-MR Imaging of Aqueductal CSF Flow in Normal Pressure Hydrocephalus Syndrome before and after CSF Shunt“. Acta Radiologica 34, Nr. 6 (November 1993): 586–92. http://dx.doi.org/10.1177/028418519303400612.

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Reproducibility of the aqueductal CSF signal intensity on a gradient echo cine-MR sequence exploiting through plane inflow enhancement was tested in 11 patients with normal or dilated ventricles. Seven patients with normal pressure hydrocephalus (NPH) syndrome were investigated with the sequence before and after CSF shunting. Two patients exhibiting central flow void within a hyperintense aqueductal CSF improved after surgery and the flow void disappeared after shunting. One patient with increased maximum and minimum aqueductal CSF signal as compared to 18 healthy controls also improved and the aqueductal CSF signal was considerably decreased after shunting. Three patients with aqueductal CSF values similar to those in the controls did not improve, notwithstanding their maximum aqueductal CSF signals decreasing slightly after shunting. No appreciable aqueductal CSF flow related enhancement consistent with non-communicating hydrocephalus was found in the last NPH patient who improved after surgery. Cine-MR with inflow technique yields a reproducible evaluation of flow-related aqueductal CSF signal changes which might help in identifying shunt responsive NPH patients. These are likely to be those with hyperdynamic aqueductal CSF or aqueductal obstruction.

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Ordia, Joe I., Ronald W. Mortara und Edward L. Spatz. „Audible cerebrospinal fluid flow through a ventriculoperitoneal shunt“. Journal of Neurosurgery 67, Nr. 3 (September 1987): 460–62. http://dx.doi.org/10.3171/jns.1987.67.3.0460.

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Smolich, Joseph J., Kelly R. Kenna und Jonathan P. Mynard. „Antenatal betamethasone augments early rise in pulmonary perfusion at birth in preterm lambs: role of ductal shunting and right ventricular outflow distribution“. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 316, Nr. 6 (01.06.2019): R716—R724. http://dx.doi.org/10.1152/ajpregu.00318.2018.

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The glucocorticosteroid betamethasone is routinely administered via maternal intramuscular injection to enhance fetal lung maturation before anticipated preterm birth. Although antenatal betamethasone increases fetal pulmonary arterial (PA) blood flow, whether this agent alters the contribution of 1) right ventricular (RV) output or 2) left-to-right shunting across the ductus arteriosus to rises in PA blood flow after preterm birth is unknown. To address this question, anesthetized control ( n = 7) and betamethasone-treated ( n = 7) preterm fetal lambs (gestation 127 ± 1 days, means ± SD) were instrumented with aortic, pulmonary, and left atrial catheters as well as ductus arteriosus and left PA flow probes to calculate RV output, with hemodynamics measured for 30 min after cord clamping and mechanical ventilation. Mean PA blood flow was higher in betamethasone-treated than in control lambs over the initial 10 min after birth ( P < 0.05). This higher PA flow was accompanied by 1) a greater pulmonary vascular conductance ( P ≤ 0.025), 2) a larger proportion of RV output passing to lungs ( P ≤ 0.01), despite a fall in this output, and 3) earlier reversal and a greater magnitude ( P ≤ 0.025) of net ductal shunting, due to the combination of higher left-to-right ( P ≤ 0.025) and lesser right-to-left phasic shunting ( P ≤ 0.025). These results suggest that antenatal betamethasone augments the initial rise in PA blood flow after birth in preterm lambs, with this augmented rise supported by the combination of 1) a greater redistribution of RV output toward the lungs and 2) a faster and larger reversal in net ductal shunting underpinned not only by greater left-to-right, but also by lesser right-to-left phasic shunting.

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Hawkins, P. A., M. R. DeJoseph und R. A. Hawkins. „Eliminating metabolic abnormalities of portacaval shunting by restoring normal liver blood flow“. American Journal of Physiology-Endocrinology and Metabolism 270, Nr. 6 (01.06.1996): E1037—E1042. http://dx.doi.org/10.1152/ajpendo.1996.270.6.e1037.

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Portacaval shunting causes a variety of anatomic, metabolic, and physiological changes. However, it has not been determined whether, and to what degree, these changes are permanent after a sustained period of shunting. We prepared three groups of rats for study of the recovery process. One group had side-to-side shunts for 3 wk, one group had side-to-side shunts for 2 wk followed by the restoration of normal liver circulation for 1 wk, and one group (control) had sham operations. Side-to-side shunting causes liver atrophy, increased plasma ammonia, altered plasma and brain amino acid spectra, decreased plasma glucose, and increased transport of neutral amino acids across the blood-brain barrier. After restoration of the normal pattern of liver circulation by shunt repair, the liver regained its normal size within 1 day. All abnormalities associated with liver dysfunction disappeared with the exception of plasma glucose, which remained approximately 15% lower than control values.

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Dagenais, M., G. Pomier-Layrargues, B. Rocheleau, L. Giroux und P. M. Huet. „Systemic and splanchnic haemodynamic effects of pentifylline in rats with portal hypertension“. Clinical Science 83, Nr. 1 (01.07.1992): 41–45. http://dx.doi.org/10.1042/cs0830041.

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1. The systemic and splanchnic haemodynamic effects of pentifylline (40 mg/kg body weight intravenously) were assessed in rats with portal hypertension associated either with CCl4-induced cirrhosis (n= 13) or portal vein ligation (n=13). 2. Heparinized catheters were placed into the portal vein, inferior vena cava, aorta and left ventricle with exits from the neck. Haemodynamic studies were performed 4 h after consciousness was regained. Cardiac output and regional blood flows were measured using radiolabelled microspheres and the reference sample method in seven rats in each group; portal-systemic shunting was measured using microsphere injection in the ileo-colic vein in six rats in each group. 3. Forty-five minutes after injection, pentifylline had no effect on mean arterial pressure, cardiac output, peripheral resistance, portal venous flow, hepatic artery flow or portal-systemic shunting in either group of rats with portal hypertension. The drug lowered portal pressure (−18%) in cirrhotic rats, but not in portal-vein-ligated rats. 4. These data demonstrate that pentifylline lowers portal pressure in cirrhotic rats without affecting portal venous flow and portal-systemic shunting; this effect is possibly mediated by changes in intrahepatic resistance related to the effects of pentifylline on blood viscosity and/or on intrahepatic vasomotor tone.

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Kluckow, Martin, und Nick Evans. „Ductal shunting, high pulmonary blood flow, and pulmonary hemorrhage“. Journal of Pediatrics 137, Nr. 1 (Juli 2000): 68–72. http://dx.doi.org/10.1067/mpd.2000.106569.

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Dethloff, Thomas J., Gitte Moos Knudsen und Fin Stolze Larsen. „Cerebral Blood Flow Autoregulation in Experimental Liver Failure“. Journal of Cerebral Blood Flow & Metabolism 28, Nr. 5 (05.12.2007): 916–26. http://dx.doi.org/10.1038/sj.jcbfm.9600589.

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Patients with acute liver failure (ALF) display impairment of cerebral blood flow (CBF) autoregulation, which may contribute to the development of fatal intracranial hypertension, but the pathophysiological mechanism remains unclear. In this study, we examined whether loss of liver mass causes impairment of CBF autoregulation. Four rat models were chosen, each representing different aspects of ALF: galactosamine (GIN) intoxication represented liver necrosis, 90% hepatectomy (PH×90) represented reduction in liver mass, portacaval anastomosis (PCA) represented shunting of blood/toxins into the systemic circulation thus mimicking intrahepatic shunting in ALF, PCA + NH3 provided information about the additional effects of hyperammonemia Rats were intubated and sedated with pentobarbital. We measured CBF with laser Doppler, intracranial pressure (ICP) was measured in the fossa posterior and registered with a pressure transducer, brain water was measured using the wet-to-dry method, and cerebral glutamine/glutamate was measured enzymatically. The CBF autoregulatory index in both the GIN and PH×90 groups differed significantly from the control group. Conversely, CBF autoregulation was intact in the PCA and PCA + NH3 groups despite high arterial ammonia, high cerebral glutamine concentration, and increased CBF and ICP. Increased water content of the brainstem or cerebellum was not associated with defective CBF autoregulation. In conclusion, impairment of CBF autoregulation is not caused by brain edema/high ICP. Nor does portacaval shunting or hyperammonemia impair autoregulation. Rather, massive liver necrosis and reduced liver mass are associated with loss of CBF autoregulation.

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Katz, S. A., und E. O. Feigl. „Little carbon dioxide diffusional shunting in coronary circulation“. American Journal of Physiology-Heart and Circulatory Physiology 253, Nr. 3 (01.09.1987): H614—H625. http://dx.doi.org/10.1152/ajpheart.1987.253.3.h614.

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The magnitude of CO2 countercurrent diffusional trapping (net diffusion from coronary venous to coronary arterial vessels) in the myocardium was determined. The left main coronary artery was pump perfused with a modified Gregg cannula in open-chest, heart-blocked, anesthetized dogs. Coronary venous PCO2, pH, and PO2 were simultaneously measured with a rapidly responding continuous electrode-cuvette system. Coronary venous CO2 concentration was calculated from the electrode outputs and a corresponding hemoglobin determination. After a step change in coronary flow, the amount of CO2 washed out or retained by the perfused myocardium was determined from the resulting coronary venous CO2 concentration changes. Analysis of the data with a compartmental mass balance model indicated that CO2 washouts and retentions were best fit with a model in which 80% of the myocardial CO2 resides in the interstitial and intracellular compartments and the remaining 20% in vascular compartments. The maximal diffusional trapping compatible with the data resulted in a modest end-capillary-to-end-venous CO2 concentration ratio of 1.02 to 1.04 at resting coronary flows. It is concluded that diffusional trapping of myocardial CO2 was below the detection limits of the experiment and that at normal coronary blood flow rates there is little CO2 diffusional trapping.

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Hargrove, M., A. O’Donnell und T. Aherne. „Differences in displayed pump flow compared to measured flow under varying conditions during simulated cardiopulmonary bypass“. Perfusion 23, Nr. 4 (Juli 2008): 227–30. http://dx.doi.org/10.1177/0267659108100458.

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Errors in blood flow delivery due to shunting have been reported to reduce flow by, potentially, up to 40–83% during cardiopulmonary bypass. The standard roller-pump measures revolutions per minute and a calibration factor for different tubing sizes calculates and displays flow accordingly. We compared displayed roller-pump flow with ultrasonically measured flow to ascertain if measured flow correlated with the heart-lung pump flow reading. Comparison of flows was measured under varying conditions of pump run duration, temperature, viscosity, varying arterial/venous loops, occlusiveness, outlet pressure, use of silicone or polyvinyl chloride (PVC) in the roller race, different tubing diameters, and use of a venous vacuum-drainage device.

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Bautista-Rodriguez, Carles, Javier Rodriguez-Fanjul, Julio Moreno Hernando, Javier Mayol und Jose Maria Caffarena-Calvar. „Patent Ductus Arteriosus Banding for Circular Shunting After Pulmonary Valvuloplasty“. World Journal for Pediatric and Congenital Heart Surgery 8, Nr. 5 (19.09.2016): 643–45. http://dx.doi.org/10.1177/2150135116655122.

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We report two cases of newborns with critical pulmonary stenosis having intact ventricular septum, who underwent pulmonary valve balloon valvuloplasty followed by banding of a patent ductus arteriosus. Transcatheter pulmonary valvuloplasty was performed one week after delivery. Following the procedure, both developed “circular shunting” as a consequence of left-to-right ductal flow and pulmonary regurgitation. This in turn caused increased blood flow into a dysfunctional right ventricle and low systemic cardiac output syndrome. The PDA banding was performed urgently as a rescue measure in order to restore systemic flow while still maintaining some duct-dependent pulmonary blood flow. This approach resolved the circular shunting. Outcome was favorable in both the patients.

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Zhao, Rong, Pei Yu Ren und Lin Chen. „Optimization of Tour Line Structure Flow Assignment Model: Based on Resort Environment Pressure“. Advanced Materials Research 926-930 (Mai 2014): 3866–69. http://dx.doi.org/10.4028/www.scientific.net/amr.926-930.3866.

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To set up a resort’s equilibrium tourist flow assignment model, the tour line features of the tourists are considered. This model firstly initiates a tourist equilibrium distribution model for the resort and then gets an optimal approximate solution when a tourist group reaches a certain scale. Next, the resort’s tourist equilibrium shunting model is built and an optimal approximate solution is provided from the present resort tourist distribution. By analyzing the results, it is found that this model is able to realize the resort’s dynamic shunting steadily, to effectively lower the resort’s congestion and to reduce the ecological environment pressure.

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Hoekstra, A. „Artificial Shunting of Cerebrospinal Fluid“. International Journal of Artificial Organs 17, Nr. 2 (Februar 1994): 107–11. http://dx.doi.org/10.1177/039139889401700208.

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A compact three-stage shunt valve system (Orbis Sigma™ Valve) which operates as a flow regulator within certain differential pressure values has been clinically evaluated in the treatment of hydrocephalus. Clinical trials were performed in 134 cases, covering 128 patients aged from 1 day to 79 years with a mean age at implantation of 11.4 years. One-third of the implants was performed to replace failed DP shunts. Using actuarial statistics, 83.9% of the shunts continued to adequately manage hydrocephalus at three years. Overdrainage occurred in 2 cases (1.5%) and insufficient drainage occurred in four cases (3%). Compared with literature for conventional DP shunts, the incidence of these phenomena is extremely low. Based on the results summarized in this paper and those already reported in the literature, the OSV appears to address the overdrainage limitations of conventional shunts.

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Berger, John P., Ganesh Raveendran, David H. Ingbar und Maneesh Bhargava. „Hypoxia: An Unusual Cause with Specific Treatment“. Case Reports in Pulmonology 2015 (2015): 1–5. http://dx.doi.org/10.1155/2015/956341.

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Hypoxia is a well-recognized consequence of venous admixture resulting from right to left intracardiac shunting. Right to left shunting is usually associated with high pulmonary artery pressure or alteration in the direction of blood flow due to an anatomical abnormality of the thorax. Surgical or percutaneous closure remains controversial; however it is performed frequently for patients presenting with clinical sequela presumed to be resulting from paradoxical embolization secondary to right to left shunting. We report two patients with hypoxia and dyspnea due to right to left shunting through a patent foramen ovale (PFO) and venous admixture in the absence of elevated pulmonary artery pressures or other predisposing conditions like pneumonectomy or diaphragmatic weakness. Percutaneous closures of the PFOs with the self-centering Amplatzer device resulted in resolution of hypoxia and symptoms related to it.

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Meyer, John S., Yasuhisa Kitagawa, Norio Tanahashi, Hisao Tachibana, Prasab Kandula, David A. Cech, Guy L. Clifton und James E. Rose. „Evaluation of treatment of normal-pressure hydrocephalus“. Journal of Neurosurgery 62, Nr. 4 (April 1985): 513–21. http://dx.doi.org/10.3171/jns.1985.62.4.0513.

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✓ Ten patients with dementia due to normal-pressure hydrocephalus were evaluated prospectively according to a planned, longitudinal protocol for 4 to 12 months. Information recorded at each visit included clinical history, medical and neurological examination, psychometric scoring by Mini-Mental Status Questionnaire, measurement of ventricular size and local cerebral blood flow, and partition coefficients (local lambda changes) (lλ) by xenon contrast computerized tomography scanning. Cerebrospinal fluid shunting was carried out in eight cases. Serial evaluations were repeated at intervals up to 8 months after shunting, and demonstrated that the ventricles decreased in size and periventricular hypodensities decreased. White matter lλ values and blood flows and cortical gray matter flows progressively increased for 3 months after shunting, and remained increased except for one case complicated by chronic alcoholism. Clinical recovery correlated with improved cerebral perfusion. There were returns of urinary continence and improvements in gait and usually in activities of daily living. Mentation was the last factor to improve. Factors negatively influencing cerebral perfusion and clinical recovery were shunt failures and various contributing causes of dementia.

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Al-Sabeq, Basil, Sabe De und Ryan Davey. „A case of ruptured sinus of Valsalva aneurysm and reversible flow-induced pulmonary hypertension“. Pulmonary Circulation 8, Nr. 2 (26.02.2018): 204589401876065. http://dx.doi.org/10.1177/2045894018760656.

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Pulmonary hypertension (PH) in adults with congenital heart disease (CHD) and significant systemic-to-pulmonary shunting is a significant cause of morbidity and mortality. Its pathophysiology is incompletely understood, but involves a flow-induced pulmonary arteriopathy characterized by endothelial cell dysfunction and vascular remodeling that alters pulmonary arterial vasoreactivity. There is a paucity of literature linking PH with left-to-right shunting due to ruptured sinus of Valsalva aneurysms (SOVA). We present a unique case of reversible, flow-associated PH due to a ruptured congenital right SOVA fistulizing into the right atrium (RA), with emphasis on non-invasive and invasive assessment of pulmonary hemodynamics before and after surgical intervention.

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Del Bigio, Marc R., und J. Edward Bruni. „Changes in periventricular vasculature of rabbit brain following induction of hydrocephalus and after shunting“. Journal of Neurosurgery 69, Nr. 1 (Juli 1988): 115–20. http://dx.doi.org/10.3171/jns.1988.69.1.0115.

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✓ Hydrocephalus was induced in rabbits by injection of silicone oil into the cisterna magna. At 1 and 8 weeks postinjection the rabbits were either sacrificed or treated by cerebrospinal fluid shunting for 1 week. Blood vessel profiles in the periventricular neuropil were examined by light microscopy. In the caudate nucleus, septal area, and corpus callosum, hydrocephalus caused a reduction in the number of capillaries but no changes were observed in the number of larger blood vessels. Shunting reduced the size of the ventricles to normal and the number of capillaries increased if hydrocephalus was present for 1 week prior to shunting. If hydrocephalus was present for 8 weeks prior to shunting, the number of capillaries did not increase. These observations support the concept that collapse of capillaries may account for the decreased cerebral blood flow that has been measured in hydrocephalic brains.

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Malvin, G. M., J. W. Hicks und E. R. Greene. „Central vascular flow patterns in the alligator Alligator mississipiensis“. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 269, Nr. 5 (01.11.1995): R1133—R1139. http://dx.doi.org/10.1152/ajpregu.1995.269.5.r1133.

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Many different flow patterns have been described through the central circulation of crocodilian reptiles. We tested the hypothesis that the vagus nerve stimulation promotes right-to-left (R-L) shunting in the alligator. Flow patterns were investigated before and during stimulation of the intact left vagus nerve using three methods. 1) Atrial and aortic PO2 were measured simultaneously and continuously by gas probes. 2) Atrial outflows were tracked with a blood tracer (helium). 3) Flows were assessed with echocardiography. Four different flow patterns were observed before vagal stimulation: left ventricular (LV) blood flowed into both the right (RAo) and left (LAo) aortas, whereas right ventricular (RV) blood flowed only into the LAo; both aortas received a mixture of LV and RV blood; only LV blood perfused both aortas; and RV blood flowed into both aortas, but LV blood flowed only into the RAo. During vagal stimulation, both aortas received a mixture of LV and RV blood in half of the animals, and in the other half, both aortas received RV blood, but LV blood flowed only into the RAo. Doppler and contrast echocardiography demonstrated swirling flow in the foramen of Panizza and the base of the LAo during systole. These data indicate that vagal stimulation either maintains or produces R-L shunting, flow patterns are variable, and blood can swirl in the foramen of Panizza and LAo base.

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Gangemi, Michelangelo, Francesco Maiuri, Simona Buonamassa, Giuseppe Colella und Enrico de Divitiis. „Endoscopic Third Ventriculostomy in Idiopathic Normal Pressure Hydrocephalus“. Neurosurgery 55, Nr. 1 (01.07.2004): 129–34. http://dx.doi.org/10.1227/01.neu.0000126938.12817.dc.

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Abstract OBJECTIVE: To define the role and indications for an endoscopic third ventriculostomy (ETV) in patients with idiopathic normal pressure hydrocephalus (INPH). A series of 25 patients treated by endoscopic technique was analyzed, and the results were compared with those of 14 studies reporting patients treated by shunting. METHODS: Twenty-five patients with INPH were treated by ETV from January 1994 through December 2000. All were younger than 75 years of age, had a preoperative clinical history of 1 year or less, had prevalence of gait disturbance with scarce or mild dementia, had marked ventricular enlargement on magnetic resonance imaging (MRI), and had intracranial pressure values ranging from 8 to 12 mm Hg. All were studied by a phase-contrast MRI flow study 1 month after ETV. The 14 reviewed series of patients treated by shunting (all published after 1980) each include more than 25 patients, for a total of 777 patients. RESULTS: The overall rate of neurological improvement after ETV in our series was 72% (including two patients reoperated on because of absence of flow in the MRI scan); this percentage is slightly higher than that found in the 14 series of shunted patients (66%). Gait disturbance showed a high rate of improvement when compared with other symptoms, both in our ETV study and in other shunting series. Postoperative complications occurred only in one patient (4%) with an intracerebral frontal hemorrhage and in 37.9% of patients from the series including shunted patients. CONCLUSION: In patients with INPH showing short duration of symptoms, prevalence of gait disturbance, and slight mental impairment, ETV provides similar results to those of shunting. We suggest performing ETV in these patients and reserving shunting only for those who do not improve after ETV, despite the presence of cerebrospinal fluid flow through the ventriculostomy on MRI flow studies. The good results after ETV in our series indirectly confirm that the cerebrospinal fluid absorption is good or at least sufficient in selected patients with INPH.

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Goldfeld, M., B. Koifman, N. Loberant, I. Krowll und M. Haj. „Distal Arterial Flow in Patients Undergoing Upper Extremity Dialysis Shunting“. American Journal of Roentgenology 175, Nr. 2 (August 2000): 513–16. http://dx.doi.org/10.2214/ajr.175.2.1750513.

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Poupon, Raoul Y. „Serum Bile Acids, Intrahepatic Shunting, and Total Hepatic Blood Flow“. Gastroenterology 88, Nr. 1 (Januar 1985): 221–22. http://dx.doi.org/10.1016/s0016-5085(85)80172-4.

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Hjortdal, Vibeke Elisabeth, Ebbe Stender Hansen, Dorthe Kjølseth, Tine Brink Henriksen, Finn Gottrup und Jens Christian Djurhuus. „Arteriovenous Shunting and Regional Blood Flow in Myocutaneous Island Flaps“. Plastic and Reconstructive Surgery 87, Nr. 2 (Februar 1991): 326–34. http://dx.doi.org/10.1097/00006534-199102000-00015.

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28

Moggio, Richard A., Peter I. Praeger, Mohan R. Sarabu, Sateesh C. Babu, Pravin M. Shah und Mohammed Z. Choudhury. „Use of the centrifugal flow pump for vena caval shunting“. Annals of Thoracic Surgery 50, Nr. 1 (Juli 1990): 146–48. http://dx.doi.org/10.1016/0003-4975(90)90112-j.

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Prokopiw, I., P. K. Dinda und I. T. Beck. „Time-related changes in microsphere entrapment in canine jejunum“. American Journal of Physiology-Gastrointestinal and Liver Physiology 256, Nr. 3 (01.03.1989): G451—G457. http://dx.doi.org/10.1152/ajpgi.1989.256.3.g451.

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To assess the validity of repeated blood flow measurements using the microsphere technique, the apparent blood flows in the anatomic layers of the jejunum were determined from the entrapment of 9-, 11.5-, and 17-micron microspheres at 1.5, 15, 30, and 60 min after their injection. The entrapment of 17-micron spheres in the mucosa plus submucosa and in the muscularis propria remained similar at all times, but these spheres migrated (P less than 0.01) from the submucosa to the mucosa. By 1.5 min, 5 +/- 2% of 11.5-micron spheres had shunted, but no subsequent shunting was observed. No migration of 11.5-micron spheres from the mucosa, submucosa or the muscularis was observed. The shunting of 9-micron spheres from the whole wall increased from 19 +/- 4% at 1.5 min to 40 +/- 4% at 60 min (P less than 0.001). These data suggest that 17-micron spheres can only fractionate the blood flow of the whole wall into that of the mucosa plus submucosa and that of the muscularis propria, while 11.5-micron spheres may measure fractional flow to the submucosa separately. The continued washout of 9-micron microspheres precludes their use for repeated blood flow measurements.

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Gardiner, Bruce S., David W. Smith, Paul M. O'Connor und Roger G. Evans. „A mathematical model of diffusional shunting of oxygen from arteries to veins in the kidney“. American Journal of Physiology-Renal Physiology 300, Nr. 6 (Juni 2011): F1339—F1352. http://dx.doi.org/10.1152/ajprenal.00544.2010.

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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 Po2. The model predicts that AV oxygen shunting is quantitatively significant and estimates how much kidney V̇o2 must change, in the face of altered renal blood flow, to maintain cortical tissue Po2 at a stable level. It is demonstrated that oxygen shunting increases as renal V̇o2 or arterial Po2 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 V̇o2 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 Po2 when arterial Po2 changes, but renders the cortex and perhaps also the medulla susceptible to hypoxia when oxygen delivery falls or consumption increases.

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Butler, D. G., und G. Y. Oudit. „Corpuscles of Stannius and blood flow regulation in freshwater North American eels, Anguilla rostrata LeSueur“. Journal of Endocrinology 145, Nr. 1 (April 1995): 181–94. http://dx.doi.org/10.1677/joe.0.1450181.

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Abstract Cardiac output (CO), heart rate (HR), stroke volume (SV), dorsal aortic blood flow (DABF), dorsal aortic blood pressure (PDA) and plasma electrolytes were monitored in stanniectomized and sham-operated freshwater eels over a 3-week period; branchial shunting and systemic resistance (RSYS) were estimated. DABF was significantly reduced by 45% from 11·72±0·48 (control) to 6·55±0·41 (n=6; day 21) ml.min−1.kg−1 within 3 weeks after the removal of the corpuscles of Stannius. This large reduction in blood flow was due to a 25% decrease in CO and a 100% increase in estimated branchial shunting which preceded the fall in CO. CO was decreased from 16·07 ±0·31 (control) to 11·91 ±1 (n=6; day 21) ml.min−1.kg−1 through a reduction in SV; there was no significant change in HR. Estimated branchial shunting, a relative measure of branchial arterio-venous blood flow, corresponded to 2·53±0·18 ml.min−1.kg−1 (control; n=12), which represents 16% of baseline CO. Ventral and dorsal aortic pulse flows also decreased following stanniectomy. The decrease in DABF occurred in conjunction with a reduction in PDA which was measured for 12 days in a separate group of eels. Baseline PDA (3·03 ±0·1 kPa) significantly decreased by 15% to 2·55 ±0·13 kPa 4 days after stanniectomy. However, this fall in PDA was transient and accompanied by an elevation in derived RSYS. These results support the hypothesis that the corpuscles of Stannius are closely linked to cardiovascular regulation in freshwater eels. Electrolyte changes (hypercalcemia, hypomagnesia, hyperkalemia and hyponatremia) were temporally coupled to the changes in blood flows. Impaired cardiovascular function and altered patterns of blood flow to osmoregulatory organs such as the gills, kidney and skin may have led to some or all of the electrolyte disturbances which followed stanniectomy. Journal of Endocrinology (1995) 145, 181–194

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Kanemaru, Kazuya, Masayuki Ezura, Yoshihisa Nishiyama, Takashi Yagi, Hideyuki Yoshioka, Yuichiro Fukumoto, Toru Horikoshi und Hiroyuki Kinouchi. „Anchor Coil Technique for Arteriovenous Fistula Embolization“. Interventional Neuroradiology 20, Nr. 3 (01.01.2014): 283–86. http://dx.doi.org/10.15274/inr-2014-10054.

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We describe a case of arteriovenous fistula (AVF) successfully treated by coil embolization with an anchor coil inserted in the varix to facilitate dense packing at the shunting site. AVF of the left anterior choroidal artery (AChoA) draining into the ipsilateral basal vein of Rosenthal was incidentally found in a newborn female. A single detachable coil was inserted as an anchor into the varix adjacent to the shunt, and the microcatheter was pulled back to the shunting point. Three more detachable coils were delivered at the shunting point without migration under the support of the anchor coil, and the AVF was successfully obliterated with preservation of AChoA blood flow. The anchor coil technique can reduce the risk of coil migration and the number of coils required.

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Harringer, W., C. Fernandez-del Castillo, D. W. Rattner, J. L. Guerrero, A. L. Warshaw und G. J. Vlahakes. „Evaluation and validation of microsphere technique for determination of pancreatic blood flow“. American Journal of Physiology-Gastrointestinal and Liver Physiology 265, Nr. 3 (01.09.1993): G587—G594. http://dx.doi.org/10.1152/ajpgi.1993.265.3.g587.

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The purpose of this study was to evaluate the radiolabeled microsphere technique for pancreatic blood flow measurements. Using a canine model with an isolated pancreatic circulation, we assessed the shunting of 11- and 15-microns-diam microspheres in the pancreas, correlated pancreatic blood flow measurements obtained with the microsphere technique with those made with an ultrasonic flow probe, and determined the effects of high doses of microspheres on pancreatic blood flow and its measurement. Microspheres of 11 microns demonstrate significant shunting through the pancreatic microcirculation with underestimation of pancreatic blood flow of approximately 10% compared with results obtained with 15-microns microspheres. There is a close linear relationship between flow results obtained with 15-microns microspheres and with an ultrasonic flow probe for both the resting (r = 0.85) and the secretin-stimulated pancreas (r = 0.97). Left atrial injections of very large doses of 15-microns microspheres (50 x 10(6)) caused an acute transient reduction of pancreatic blood flow (to 39% of baseline flow) with a return to baseline values within 2 min. The accuracy of flow results and absence of physiological changes after repeated injections support the use of 15-microns microspheres for pancreatic blood flow measurements.

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Atkar, Mst Khorseda, und Md Tajul Islam. „A Bypassing Technique for the Remedy of Portal Hypertension through Extra Hepatic Portal Vein Obstruction by CFD Analysis“. GANIT: Journal of Bangladesh Mathematical Society 38 (14.01.2019): 89–104. http://dx.doi.org/10.3329/ganit.v38i0.39789.

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Extra-hepatic portal vein obstruction (EHPVO) is the blockage to the flow of blood in the portal vein before reaches to the liver. EHPVO is the common cause of portal hypertension in children in the most Asian countries. Examination reveals that the presence of block in the main portal vein may be responsible for the shrinkage of vein with manifold pernicious complication. The “shunt” policy is a fruitful source of restoration of the hepatic portal flow. This study shows that a new approach of bypassing (or shunting) to the blocked (thrombosed) region of the portal vein is a significant way of reducing portal hypertension and restoration of blood circulation. We studied EHPVO case through computational fluid dynamics (CFD) analysis by considering partial block formation and side to side shunt scheme inside the main portal vein. The constitutive equation for non-Newtonian fluidand energy equation are solved by control volume technique. Our study reveals that the shunting technique is strongly effective for the reconstitution of portal venous flow to the liver with lower tissue stress and rapid regression of clinical signs of portal hypertension. This new technique may potentially applicable for medication of EHPVO when shunting procedures are indicated. GANIT J. Bangladesh Math. Soc.Vol. 38 (2018) 89-104

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Thomson, J. D. R., J. Forster und J. L. Gibbs. „Cyanosis due to diastolic right-to-left shunting across a ventricular septal defect in a patient with repaired tetralogy of Fallot and pulmonary atresia“. Cardiology in the Young 9, Nr. 5 (September 1999): 506–8. http://dx.doi.org/10.1017/s1047951100005436.

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AbstractCyanosis as a result of right-to-left shunting across a ventricular septal defect is commonly encountered in patients with congenital heart disease when systolic pressure in the right ventricle exceeds that in the left ventricle. Reported is the case of a child who remained cyanosed after surgical correction of pulmonary atresia despite right ventricular systolic pressure being lower than left ventricular pressure. Colour-flow Doppler showed a residual ventricular septal defect, with right-to-left shunting in diastole alone.

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Yen, Philip. „ASD and VSD Flow Dynamics and Anesthetic Management“. Anesthesia Progress 62, Nr. 3 (01.09.2015): 125–30. http://dx.doi.org/10.2344/0003-3006-62.3.125.

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Abstract Atrial septal defects and ventricular septal defects are often encountered in patients presenting for treatment under anesthesia. The flow mechanisms for both defects are predominantly left to right shunting prior to long-term maladaptive changes that may occur. Close examination of the shunt dynamics demonstrates a minor right to left shunt that occurs as well. The article discusses these dynamics and the impact on an anesthetic plan.

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Andersson, T., L. Kihlström und M. Söderman. „Regression of a Flow-Related Ophthalmic Artery Aneurysm after Treatment of a Frontal DAVS“. Interventional Neuroradiology 10, Nr. 3 (September 2004): 265–68. http://dx.doi.org/10.1177/159101990401000310.

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We report a case of a frontal dural arteriovenous shunt or fistula (DAVS) adjacent to the left side of the cribriform plate, with bilateral supply from multiple arteries, the most prominent being the dural branches originating from the anterior ethmoidal artery coming from the left ophthalmic artery. Before treatment there was an eight mm flow-related arterial aneurysm proximally on the left ophthalmic artery. After transarterial embolization of the DAVS with N-butyl cyanoacrylate and polyvinyl alcohol, minimal shunting still remained. At follow-up angiography six months after the treatment, the shunt was obliterated and the ophthalmic artery aneurysm had regressed completely. Our case illustrates that complete obliteration of a DAVS may be achieved even though arteriovenous shunting remains at the end of the procedure. Furthermore, a flow-related arterial aneurysm, may not warrant any specific treatment. Elimination of the high flow situation can lead to complete regression of these aneurysms.

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Harwin, Joelle, Mark D. Sugi, Steven W. Hetts, Miles B. Conrad und Michael A. Ohliger. „The Role of Liver Imaging in Hereditary Hemorrhagic Telangiectasia“. Journal of Clinical Medicine 9, Nr. 11 (21.11.2020): 3750. http://dx.doi.org/10.3390/jcm9113750.

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Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant vascular disorder characterized by spontaneous epistaxis, telangiectasia, and visceral vascular malformations. Hepatic vascular malformations are common, though a minority are symptomatic. Symptoms are dependent on the severity and exact type of shunting caused by the hepatic malformation: Arteriosystemic shunting leads to manifestations of high output cardiac failure, and arterioportal shunting leads to portal hypertension. Radiologic imaging, including ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI), is an important tool for assessing liver involvement. Doppler ultrasonography is the first-line screening modality for HHT-related liver disease, and it has a standardized scale. Imaging can determine whether shunting is principally to the hepatic vein or the portal vein, which can be a key determinant of patients’ symptoms. Liver-related complications can be detected, including manifestations of portal hypertension, focal liver masses as well as ischemic cholangiopathy. Ultrasound and MRI also have the ability to quantify blood flow through the liver, which in the future may be used to determine prognosis and direct antiangiogenic therapy.

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Henry, G. William, Enrique Criado, Carol L. Lucas, José I. Ferreiro, Belinda Ha, Sheri L. Carroll und Benson R. Wilcox. „The effect of left-to-right intracardiac shunting on the distribution of pulmonary arterial axial velocities determined by an intraluminal pulsed Doppler technique“. Cardiology in the Young 4, Nr. 2 (April 1994): 136–41. http://dx.doi.org/10.1017/s1047951100002079.

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AbstractThe distribution of axial velocities in the pulmonary artery must be determined to describe accurately the flow in the pulmonary artery. Previous studies in our laboratory have demonstrated the complexity of the velocity profile in the pulmonary trunk and the branch pulmonary arteries with normal and altered pulmonary blood flow. These findings have demonstrated a skewed, parabolic mean velocity profile in the pulmonary trunk under normal hemodynamic conditions. To determine the effect of left-to-right intracardiac shunting on the distribution of axial velocities in the pulmonary artery, an animal model of atrial and ventricular shunting was used. In both models, the distribution of mean axial velocities remained skewed and parabolic with the higher mean velocities recorded toward the anterior wall.

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INANIR, S., M. UNLU, B. OKUDAN, C. ALATAS und H. ALKIM. „Quantitative evaluation of blood-flow and arteriovenous shunting in diabetic limb“. Journal of Nuclear Cardiology 2, Nr. 2 (März 1995): S121. http://dx.doi.org/10.1016/s1071-3581(05)80566-5.

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Itkin, Maxim, Scott O. Trerotola, S. William Stavropoulos, Aalpen Patel, Jeffrey I. Mondschein, Michael C. Soulen, Catherine M. Tuite et al. „Portal Flow and Arterioportal Shunting after Transjugular Intrahepatic Portosystemic Shunt Creation“. Journal of Vascular and Interventional Radiology 17, Nr. 1 (Januar 2006): 55–62. http://dx.doi.org/10.1097/01.rvi.0000191362.75969.f6.

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Jalan, Rajiv, David E. Newby, Steven W. M. Olde Damink, Doris N. Redhead, Peter C. Hayes und Alistair Lee. „Acute changes in cerebral blood flow and metabolism during portasystemic shunting“. Liver Transplantation 7, Nr. 3 (März 2001): 274–78. http://dx.doi.org/10.1053/jlts.2001.22181.

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Goelz, R., G. Mielke, M. Gonser und M. Schöning. „Prenatal assessment of shunting blood flow in vein of Galen malformations“. Ultrasound in Obstetrics and Gynecology 8, Nr. 3 (01.09.1996): 210. http://dx.doi.org/10.1046/j.1469-0705.1996.08030210.x.

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Davies, Nicholas, Fadi Nuwayhid und Jens J. Froelich. „Idiopathic high-flow priapism due to bilateral internal pudendal artery shunting“. ANZ Journal of Surgery 86, Nr. 12 (24.07.2014): 1059–61. http://dx.doi.org/10.1111/ans.12802.

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Goh, Dayeel, Robert A. Minns, Steven D. Pye und A. James W. Steers. „Cerebral blood flow velocity changes after ventricular taps and ventriculoperitoneal shunting“. Child's Nervous System 7, Nr. 8 (Dezember 1991): 452–57. http://dx.doi.org/10.1007/bf00263188.

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Zierer, Andreas, Spencer J. Melby, Rochus K. Voeller, Paul Steendijk und Marc R. Moon. „INTERATRIAL SHUNT FOR CHRONIC PULMONARY HYPERTENSION: DIFFERENTIAL IMPACT OF LOW-FLOW VS HIGH-FLOW SHUNTING“. Chest 132, Nr. 4 (Oktober 2007): 487B. http://dx.doi.org/10.1378/chest.132.4_meetingabstracts.487b.

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Kramer, Kim, Heather J. McCrea, Cheryl Fischer und Jeffrey P. Greenfield. „Establishing successful cerebrospinal fluid flow for radioimmunotherapy“. Journal of Neurosurgery: Pediatrics 9, Nr. 3 (März 2012): 316–19. http://dx.doi.org/10.3171/2011.12.peds11433.

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Successful delivery of intraventricular radioimmunotherapy is contingent on adequate CSF flow. The authors present a patient with medulloblastoma in whom obstructed CSF flow was causing hydrocephalus, which was initially corrected by implantation of a programmable shunting device. While managing the hydrocephalus, an endoscopic third ventriculostomy (ETV) needed to be performed in a collapsed ventricular system to ensure adequate radioimmunotherapy distribution. This 18-month-old patient with medulloblastoma involving leptomeningeal dissemination presented for intraventricular radioimmunotherapy. A CSF 111In-DTPA scintigraphy study obtained through the existing programmable ventriculoperitoneal shunt demonstrated activity in the lateral and third ventricles, but no activity over the cerebral convexities or spinal canal, consistent with obstruction at the level of the cerebral aqueduct. By maximization of ventricular size in a controlled setting, the patient was able to undergo a trial of ETV through very small ventricles. A postoperative CINE MR imaging study confirmed patent ETV. The pressure settings on the shunt were kept at the highest opening pressure (200 mm H2O) to maximize flow through the stoma and improve the distribution of CSF throughout the subarachnoid space. The CSF flow scintigraphy study was again performed, this time with tracer activity demonstrated down the thecal sac at 3 hours, and symmetrically over the cerebral convexities at 24 hours. The patient began weekly intraventricular administration of 131I-3F8 therapy. Successful rerouting of CSF flow for the purpose of therapeutic radioisotope administration is possible. Endoscopic third ventriculostomy can be considered in patients with programmable shunting devices; normal or slit ventricles do not preclude successful ETV.

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Espinosa, Gaudencio, Rivaldo Tavares, Felippe Fonseca, Alessandra Collares, Marina Lopes, Jose Luis Fonseca und Rafael Steffan. „Proximal endovascular blood flow shunt for thoracoabdominal aortic aneurism without total aortic clamping“. Revista do Colégio Brasileiro de Cirurgiões 42, Nr. 3 (Juni 2015): 189–92. http://dx.doi.org/10.1590/0100-69912015003011.

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<p>The authors present a surgical approach to type III and IV Crawford aneurysms that does not need total aortic clamping, which allows the more objective prevention of direct ischemic damage, as well as its exclusion by the endoprosthesis implantation, shunting the flow to the synthetic graft.</p>

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Ley, K., J. U. Meyer, M. Intaglietta und K. E. Arfors. „Shunting of leukocytes in rabbit tenuissimus muscle“. American Journal of Physiology-Heart and Circulatory Physiology 256, Nr. 1 (01.01.1989): H85—H93. http://dx.doi.org/10.1152/ajpheart.1989.256.1.h85.

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Leukocyte distribution was studied in 58 arterioles and capillaries constituting eight networks in the fascia adjacent to the rabbit tenuissimus muscle. Fluorescence video microscopy (acridine red) and digital image processing were used to visualize the leukocytes. Leukocyte concentration in the transverse arterioles leaving the muscle proper to irrigate the fascia was significantly elevated to 143 +/- 13% (mean +/- SE) of the systemic count. Leukocytes were found to further accumulate along the arteriolar tree, reaching 244 +/- 16% of systemic in the most remote branches. Leukocyte accumulation in the connective tissue can be calculated to lead to a decrease of leukocyte concentration in muscle capillaries to 89% of the systemic value. This shunting effect may be important in preventing leukocyte-induced capillary obstruction. At individual arteriolar bifurcations, leukocytes were found to preferentially enter the downstream branch with higher flow rate (regression coefficient 1.11 +/- 0.04, n = 100). This preferential distribution is quantitatively sufficient to account for the observed leukocyte distribution in the network.

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Khoury, Michael, Michael Kallile, Joseph May und Rajesh Punn. „Systemic hypertension in an infant with unrepaired tetralogy of Fallot: case report“. Cardiology in the Young 23, Nr. 5 (13.11.2012): 746–48. http://dx.doi.org/10.1017/s1047951112001837.

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AbstractPatients with severe right ventricular outflow tract obstruction in tetralogy of Fallot typically have right-to-left shunting, resulting in low pulmonary blood flow and cyanosis. Here we present the case of an infant with tetralogy of Fallot and severe pulmonary valve stenosis, complicated by systemic hypertension, the presence of which altered flow dynamics and possibly prevented cyanosis.

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