The effect of blood viscoelasticity on pulsatile flow in stationary and axially moving tubes

An analytical solution for pulsatile flow of a generalized Maxwell fluid in straight rigid tubes, with and without axial vessel motion, has been used to calculate the effect of blood viscoelasticity on velocity profiles and shear stress in flows representative of those in the large arteries. Measured bulk flow rate Q waveforms were used as starting points in the calculations for the aorta and femoral arteries, from which axial pressure gradient delta P waves were derived that would reproduce the starting Q waves for viscoelastic flow. The delta P waves were then used to calculate velocity profiles for both viscoelastic and purely viscous flow. For the coronary artery, published delta P and axial vessel acceleration waveforms were used in a similar procedure to determine the separate and combined influences of viscoelasticity and vessel motion. Differences in local velocities, comparing viscous flow to viscoelastic flow, were in all cases less than about 2% of the peak local velocity. Differences in peak wall shear stress were less than about 3%. In the coronary artery, wall shear stress differences between viscous and viscoelastic flow were small, regardless of whether axial vessel motion was included. The shape of the wall shear stress waveform and its difference, however, changed dramatically between the stationary and moving vessel cases. The peaks in wall shear stress difference corresponded with large temporal gradients in the combined driving force for the flow.     

Fetal branch pulmonary arterial vascular impedance during the second half of pregnancy

OBJECTIVE: Our purpose was to establish normal physiologic parameters in the fetal proximal and distal branch pulmonary arterial vascular impedance during the second half of pregnancy and to analyze relationships between proximal and distal pulmonary arterial blood velocity waveforms. STUDY DESIGN: In this cross-sectional study 100 uncomplicated singleton pregnancies were studied by pulsed color Doppler techniques between 18 and 41 weeks of gestation (median 30 weeks). Both right and left proximal (immediately after the bifurcation of the main pulmonary artery) and distal (beyond the first bifurcation of the branch pulmonary artery) pulmonary artery blood velocity waveforms were recorded and pulsatility index values were calculated. Peak systolic velocities and time-to-peak-velocity intervals were measured. Time-to-peak-velocity intervals were also analyzed at the level of aortic and pulmonary valves and at the ductus arteriosus. Right and left pulmonary artery diameters and right lung length were measured. RESULTS: In both right and left proximal and distal pulmonary arteries pulsatility index values decreased (p < 0.0001) and the peak systolic velocities (p < 0.003) and time-to-peak-velocity intervals (p < 0.0001) increased during the second half of pregnancy. In the proximal pulmonary arteries the pulsatility index values decreased linearly until 34 to 35 weeks of gestation and in the distal pulmonary arteries until 31 weeks of gestation. Thereafter they remained unchanged. In pulmonary arteries time-to-peak-velocity intervals were shorter (p < 0.01) than at the pulmonary valve level. There were no significant differences between the right or left pulmonary arteries in the pulsatility index values, peak systolic velocities, time-to-peak-velocity intervals, or pulmonary artery diameters. In the proximal pulmonary arteries the pulsatility index values (p < 0.02) and peak systolic velocities (p < 0.0001) were higher and time-to-peak-velocity intervals (p < 0.0001) were longer than in the distal pulmonary arteries. There was a 2.5-fold increase in pulmonary artery diameters and right lung length. CONCLUSIONS: Fetal branch pulmonary arterial vascular impedance decreases significantly during the second half of pregnancy. The linear decrease in vascular impedance during the second trimester and in the beginning of the third trimester may be related to the growth of the lung and the increase in the number of resistance vessels. During the latter part of the third trimester pulmonary vascular impedance does not decrease further.     

Radiofluorinated L-m-tyrosines: new in-vivo probes for central dopamine biochemistry

PURPOSE: Recent information indicates that large, sustained wall shear stress gradients are a dominant hemodynamic parameter associated with the location and severity of atherosclerosis and myointimal hyperplasia. This study computes the spatial values of wall shear stresses and their gradients for three carotid artery bifurcation geometries. METHODS: A computational fluid dynamics program was used to solve the transient two-dimensional partial differential equations that describe fluid flow. Blood was treated as both a Newtonian and a non-Newtonian incompressible fluid. Solutions for the velocities, wall shear stresses, and wall shear-stress gradients were obtained for three carotid bifurcation geometries: a normal carotid bifurcation (similar to a primarily reconstructed carotid endarterectomy), a patch-reconstructed carotid endarterectomy, and a gradually tapered, low-angle carotid bifurcation (no carotid bulb). RESULTS: Computed velocity profiles closely match published experimental ones. Disturbed flow velocities are largest in the bulb segment of the normal carotid bifurcation. Peak and minimum wall shear stresses and peak shear stress gradients occurred in the lateral internal carotid artery wall. These were binodal in the normal or primarily reconstructed carotid artery, localized at the distal end of the patch-reconstructed carotid bifurcation, and minimal in the smooth, tapered carotid bifurcation. Wall shear stresses and their gradients were slightly higher for non-Newtonian than Newtonian fluids in the normal carotid artery but were similar in the other two geometric configurations. CONCLUSION: These results indicate that flow disturbances in general and wall shear stress gradients in particular are markedly reduced in carotid artery bifurcations that are smooth and gradually tapered and do not have a bulb. Abrupt geometric wall changes such as those occurring in the normal carotid bulb and at the distal end of a patch-reconstruction after carotid endarterectomy are harbingers of disturbed flow and high wall shear stress gradients. These results suggest that carotid endarterectomy reconstruction geometry characterized by a gradually tapered internal carotid artery may minimize the hemodynamically induced component of early myointimal hyperplasia and thrombosis and late atherosclerotic restenosis.     

Shear stress in cerebral arteries supplying arteriovenous malformations

Arteries supplying cerebral arteriovenous malformations (AVMs) are known to dilate with time. These changes are reversible, and the feeders have been shown to slowly decrease in calibre after removal of the AMV. There is evidence that arteries alter their internal diameters in response to sustained changes of blood flow so that shear stress is kept constant. This implies that blood flow-induced shear stress might be the driving force for remodelling of the cerebral vascular network in the presence of an AVM, and for reversion of these changes after radical operation. The objective of this study is to examine the hypothesis that the shear stress in cerebral arteries supplying AMVs is of the same magnitude as in arteries supplying normal brain tissue in spite of larger blood flow rate. Fifteen patients with supratentorial cerebral AVMs admitted for endovascular treatment were examined with transcranial Doppler ultrasound in the distal Willisian vessels. Vessel calibres were measured in angiograms with magnification correction. Shear stress was estimated assuming a constant value for blood viscosity. Corresponding arteries in the cerebral hemisphere with AVM and in the contralateral one were compared in pairs. Thirty-four pairs of homonymous arteries were studied. The arteries on the AVM side presented larger calibres, higher axial blood flow velocities, lower pulsatility index and larger blood flow rates than the contralateral side. There was a clear positive correlation between blood flow velocities and vessel calibres. The estimates of shear stress did not differ significantly in corresponding arteries of both hemispheres (p = 0.18). The results indicate a precise adjustment of cerebral arterial calibre and blood flow-induced shear stress that presumably induces the progressive dilation of AVM feeders, and the slow regression of the vessel calibres to average dimensions after removal of the lesion. Each vessel seems to remodel itself in response to long-term changes in blood flow rate so that the vessel calibre is reshaped to maintain a constant level of wall shear stress.     

How the left lung is perfused after ligating the left pulmonary artery in the pig at birth: clinical implications for the hypoperfused lung

The left pulmonary artery and ductus arteriosus were ligated in 14 pigs at birth. Animals were sacrificed at intervals from 2 to 24 weeks of age. In the right lung the pulmonary artery and in the left, either the distal pulmonary artery, bronchial arteries or both were injected. The fixed lung specimens were studied by arteriography, dissection and microscopic examination of serial and random sections of lung tissue. The bronchial arterial circulation to, and within the right lung appeared normal and was similar to that described in the human lung. In the left lung, the bronchial arterial circulation hypertrophied rapidly during the first 2 weeks, and large anastomoses between pulmonary and systemic circulations were found at the same sites as in the normal pig lung. The position and structural characteristics of the anastomosing arteries is described in the different types of broncho-pulmonary connection. In most animals aged 16 weeks or more, peripheral bronchial arteries immediately proximal to the anastomotic sites, developed intimal and medial proliferation. The left lung continued to grow although in all animals it was small. The axial pulmonary artery and its branches became smaller with age. These findings help explain how the lung is perfused and grows in children with congenital heart disease and an acquired collateral pulmonary arterial circulation.     

Doppler-velocity waveforms in ductus venosus in normal and small-for-gestational-age fetuses

OBJECTIVE: To investigate blood-flow patterns in ductus venosus in growth-retarded fetuses. METHODS: Reference ranges of ductus venosus flow velocities were constructed from a cross-sectional study of 179 normal fetuses between 16 to 38 weeks' gestation. and the ductus venosus flow-velocity waveforms in 11 small-for-gestational-age (SGA) fetuses were compared with normal patterns. RESULTS: Of 179 pregnant women who were possible subjects, 175 were employed for the analysis, and ductus venosus flow-velocity waveforms were obtained in 197 out of 211 examinations (success rate = 93.4%). The peak forward velocities during (a) ventricular systoles, (b) the lowest forward velocities during atrial contractions, and (c) the time-averaged velocities all linearly increased as gestational ages increased [respectively: (a) slope, 1.135; constant, 31.720; (b) slope, 1.154; constant, 1.557; (c) slope, 1.240; constant, 19.386]. Peak forward velocities during ventricular systoles and time-averaged velocities in the SGA group did not differ from those of the normal group. Three SGA fetuses with abnormal flow in the umbilical artery showed a marked reduction of the lowest velocities during atrial contractions in the ductus venosus, and two of them showed no forward velocity at all. CONCLUSION: The Doppler-velocity waveforms of ductus venosus showed a marked reduction of the end diastolic flow, especially in SGA fetuses with abnormal umbilical artery flows.     

Effects of curvature and stenosis-like narrowing on wall shear stress in a coronary artery model with phasic flow

To gain insight into the details of intracoronary flow we have used computational fluid dynamic techniques to determine the velocity and wall shear stress distributions in both steady- and phasic-flow models of a curved coronary artery with several degrees of stenosis. The steady-flow Reynolds number was 500 and the peak phasic flow Reynolds number was 700. Without stenosis and at 25% (area) stenosis wall shear stress and velocities are higher at the outer wall than the inner wall but retain the same direction as the superimposed flow. At higher stenoses laminar flow separation occurs and the inner wall is exposed to shear stresses that vary widely, both temporally and spatially.     

Atrially based pericardial tunnel for central pulmonary artery construction

Discontinuity of central intrapericardial pulmonary arteries requires reconstruction of a pulmonary artery confluence before cavopulmonary connection, whether this connection be by bidirectional Glenn or Fontan procedure. Reconstruction of the central pulmonary arteries has previously been described using material of poor or no growth potential. A method is described for central pulmonary artery reconstruction that provides growth potential and is based on previous experience with Fontan lateral tunnel construction.     

Blood flow in pulmonary and bronchial arteries in acute experimental pneumonia and pulmonary embolism

Acute lobar pneumonia and pulmonary embolism were induced in rabbits and the blood flow in the pulmonary artery and bronchial arteries was determined using isotopic microspheres. In acute pneumonia the pulmonary artery flow to the involved lung was reduced 8.5 times and the bronchial artery flow was reduced 5.0 times compared to flow in the normal lung. In acute pulmonary embolism, both the pulmonary artery flow (2.3 times) and the bronchial artery flow (2.5 times) were also reduced. For all animals, the reduction in pulmonary artery flow paralleled the reduction in bronchial artery flow (r=0.65).     

Numerical study on the effect of steady axial flow development in the human aorta on local shear stresses in abdominal aortic branches

The three-dimensional flow through a rigid model of the human abdominal aorta complete with iliac and renal arteries was predicted numerically using the steady-state Navier Stokes equations for an incompressible. Newtonian fluid. The model adapted for our purposes was determined from data obtained from cine-CT images taken of a glass chamber that was constructed based on anatomical averages. The iliac arteries had a bifurcation angle of approximately 35 and a branch-to-trunk area ratio of 1.27. whereas the renal arteries had left and right branch angles of 40 and an area ratio of 0.73. The numerical tool FLOW3D (AEA Industrial Technology, Oxfordshire, UK) utilized body-fitted coordinates and a finite volume discretization procedure. Purely axial velocity profiles were introduced at the entrance of the model for a range of cardiac outputs. The four-branch numerical model developed for this investigation produced flow and shear conditions comparable to those found in other reported works. The total wall shear stress distribution in the iliac and renal arteries followed standard trends. with maximum shear stresses occurring in the apex region and lower shear stresses occurring along the lateral walls. Shear stresses and flow rate ratios in the downstream arteries were more effected by inlet Re than the upstream arteries. These results will be used to compare further simulations which take into effect the rotational component of flow which is present in the aortic arch.     

Use of colour and spectral Doppler ultrasound examination in gynaecology

Objective: To review and sum up the published literature on gynecological Doppler ultrasound examination. Methods: Publications on gynecological Doppler ultrasound examination already known by the author, publications found in the bibliographic database Medline, and publications found in the reference lists of available studies were read, and relevant information was extracted and summarized. Results: Reference data representative of normal findings at transvaginal color and spectral Doppler ultrasound examination of the uterine and ovarian arteries have been established in healthy pre- and post-menopausal women and in normal early pregnancies. Blood flow velocities in the uterine and ovarian arteries change during the normal menstrual cycle and are very different in pre- and post-menopausal women. Lower blood flow velocities and higher pulsatility index (PI) values have been recorded in the ovarian arteries after the menopause. Uterine artery blood flow velocities increase and uterine artery PI values and resistance index (RI) values decrease with gestational age in the first trimester. There is not yet an established role of the gynecological Doppler ultrasound examination in clinical practice. It remains unclear whether the gynecological Doppler ultrasound examination contributes substantially to the clinical management of early pregnancy complications or infertility problems, to the differential diagnosis of pelvic masses or uterine pathology. Conclusions: Large prospective studies-preferably randomized controled trials-are needed to determine the clinical value of the gynecological Doppler ultrasound examination. Copyright 1997 Elsevier Science Ireland Ltd.     

Double-Averaged Open-Channel Flows with Small Relative Submergence

We investigate the turbulent structure of shallow open channel flows where the flow depth is too small (compared with the roughness height) to form a logarithmic layer but large enough to develop an outer layer where the flow is not directly influenced by the roughness elements. Since the log layer is not present, the displacement height d, which defines the position of the zero plane, and the shear velocity u* cannot be found by fitting the velocity data to the log law. However, these parameters are still very important because they are used for scaling flow statistics for the outer and roughness layers. In this paper we propose an alternative procedure for evaluating d in laboratory conditions, where d is found from additional experiments with the fully developed log layer. We also point out the appropriate procedure for evaluating the shear velocity u* for flows with low submergence. These procedures are applied to our own laboratory flume experiments with uniform sphere roughness, where velocities were measured using Particle Image Velocimetry. Results were interpreted within the framework of the double-averaged Navier–Stokes equations and include mean velocities, turbulence intensities, Reynolds stresses, and form-induced normal and shear stresses. The data collapse well and show that in flows without a developed log layer the structure of turbulence in the outer layer remains similar to that of flows with a log layer. This means that even though the roughness layer in the experiments reported herein was sufficiently high to prevent the development of the log layer, influence of the bed roughness did not spread further up into the outer layer. Furthermore, the results show that flow statistics do not depend on relative submergence except for the form-induced stresses which increase when relative submergence decreases.     

Maternal renal artery blood flow velocimetry in normal and hypertensive pregnancies

OBJECTIVE: To investigate the effect of normal pregnancy and hypertensive disorders of pregnancy on the maternal renal artery Doppler blood flow velocity indices. METHODS: The patient material consisted of 30 normal pregnant women, 29 women with pregnancy induced hypertension, 43 women with preeclampsia and 22 pregnant women with chronic hypertension. Blood flow velocities in the segmental renal arteries from the right kidney were analysed by pulsed and color Doppler. The systolic/diastolic (s.d.) ratio, resistance index (RI) and pulsatility index (PI) were used for Doppler waveform analysis. RESULTS: In all of the groups of hypertensive pregnant women renal artery Doppler indices were significantly lower compared to the normal pregnant women group. There was a significant negative relationship between renal artery PI and mean arterial pressure in the preeclampsia group and in the chronic hypertension group. CONCLUSION: The present results demonstrate that the mechanism of renal autoregulation in preeclampsia might be altered, leaving glomerulus unprotected from increased blood pressure. It seems that the concept of renal vasoconstriction in preeclampsia might be disputed and needs further investigation.     

Fibrosing mediastinitis causing pulmonary arterial hypertension without pulmonary venous hypertension. Clinical and necropsy observations

Clinical and morphologic observations are described in two patients with severe pulmonary arterial hypertension without pulmonary venous hypertension from fibrosing mediastinitis. In one patient, both main pulmonary arteries and one major pulmonary vein were severely narrowed by dense fibrous tissue; in the second patient, only the right main pulmonary artery was severely narrowed. Both patients had normal intrapulmonary arteries and normal pulmonary parenchyma. Of nine previously described necropsy patients with pulmonary hypertension due to fibrosing mediastinitis, seven had severe narrowing of multiple large pulmonary veins and in six of them the pulmonary hypertension was entirely due to pulmonary venous obstruction. In one other patient, the pulmonary hypertension was due to obstruction of one main pulmonary artery and several large pulmonary veins. Each of these seven previously described patients had severe changes in the small intrapulmonary arteries. Of the other two previously described patients with pulmonary hypertension from fibrosing mediastinitis, one had severe narrowing of only the main right pulmonary artery, and the other, of both main pulmonary arteries. Thus, although pulmonary arterial hypertension in patients with fibrosing mediastinitis is usually due to obstruction of multiple large pulmonary veins and to severe secondary changes in small intrapulmonary arteries, fibrosing mediastinitis can cause severe pulmonary hypertension by obstructing the right or both main pulmonary arteries.     

Duplex sonography of renal arteries as a diagnostic tool in hypertensive children

Computed duplex sonography was used to examine the renal arteries in 36 hypertensive children and adolescents (ages 4-17 years) with arterial hypertension of either renal or non-renal origin. Time-averaged flow velocities, maximum blood flow velocities as well as absolute renal blood flow and renal blood flow per gram kidney weight were measured. Normal flow velocities and normal to elevated renal blood flow volume was found in patients with acute glomerulonephritis and those with signs of chronic glomerulonephritis onset. Patients having advanced stages of chronic glomerulonephritis, on the other hand, were characterized by lower levels of all parameters. Unilateral renal artery stenosis was diagnosed correctly in four patients, although one intra-renal artery stenosis escaped imaging. Scarred kidneys exhibited low-normal or reduced flow velocities and renal blood flow volumes corresponded roughly to kidney size and preservation of normal kidney structure. Hypertension in some patients with normal kidneys showed a tendency to cause higher renal blood flow without consistent acceleration of blood flow velocities. We conclude that duplex sonography is a suitable primary diagnostic tool in measuring blood flow velocities and absolute renal blood flow volume in hypertensive children, thus facilitating the choice of the next diagnostic step.     

Collateral blood supply through the ophthalmic artery: a steal phenomenon analyzed by color Doppler imaging

OBJECTIVE: This study aimed to evaluate the retrobulbar circulatory effects of reversed ophthalmic artery flow (ROAF) on the ophthalmic artery branches by means of color Doppler imaging. DESIGN: The design was a case-controlled study. PARTICIPANTS: Among 56 consecutive patients with severe (>70% stenosis) occlusive carotid artery disease, 15 patients (26.8%) with ROAF were identified. The control group consisted of 15 patients with similar degrees of carotid artery stenosis and forward ophthalmic artery flow. INTERVENTION: Arteriography and measurement of the retrobulbar hemodynamic parameters with color Doppler imaging were performed. MAIN OUTCOME MEASURES: Blood flow velocities and resistive index in the ophthalmic, central retinal, and temporal short posterior ciliary arteries were measured. RESULTS: Arteriography confirmed the diagnosis of ROAF in all 15 patients. There was no patient with ROAF diagnosed by arteriography and not diagnosed by color Doppler imaging. The frequency of bilateral severe occlusive carotid artery disease was significantly higher in the ROAF group (40%) compared to the control group (6.6%) (P = 0.04). Patients with ROAF showed significantly reduced vascular resistance in the ophthalmic artery (P = 0.03), higher vascular resistance, and lower blood flow velocities in the central retinal and temporal short posterior ciliary arteries (P < 0.05). CONCLUSION: This study suggests that patients with ROAF show a steal phenomenon, characterized by a shunt to the low-resistance intracranial circuit and reduction of retrobulbar blood flow.     

Protein phosphatase mRNA expression in Purkinje cells of staggerer and reeler mutant mice

Orthotopic heart transplantation (OHT) with bicaval and pulmonary venous anastomoses avoids the large atrial anastomoses of the standard biatrial technique. To determine whether the bicaval technique improves atrial performance, we used Doppler echocardiography to study 13 patients with bicaval OHT, 15 with biatrial OHT, and 8 normal subjects. All were in sinus rhythm and free of rejection. Left atrial size, transmitral (M) and late diastolic (A) mitral flow velocity integrals were measured. Atrial transport (A/M, %) and atrial ejection force (kilodynes, calculated from peak A-wave velocity and mitral orifice area) were assessed. Left atrial dimensions in the bicaval (4.3 +/- 0.5 cm) and biatrial groups (4.9 +/- 0.9 cm) were larger than in controls (3.3 +/- 0.8 cm, p < 0.05). Left atrial transport (37% +/- 12% and 35% +/- 12%) and ejection force (14.1 +/- 6.9 kdyne and 10.2 +/- 7.8 kdyne) were similar in the bicaval group and controls (p not significant) but were significantly lower in the biatrial group (20% +/- 19% and 3.6 +/- 4.0 kdynes, p < 0.05). The bicaval and pulmonary venous technique of OHT produces more physiologic atrial function compared with the biatrial technique as evidenced by greater atrial ejection force and more normal atrial transport.     

Value of intraplacental villous artery Doppler measurements in severe preeclampsia

Blood flow velocity waveforms were recorded by color Doppler ultrasound from intraplacental villous and umbilical arteries in 20 normal and 23 severe preeclamptic pregnancies. The results of the resistance index measurements in intraplacental villous arteries were 0.51 +/- 0.037 and 0.55 +/- 0.052 in healthy controls and preeclamptics respectively, which was not significantly different. Resistance indices showed a decrease through the umbilical cord from fetus to placenta in both groups. We also noted that Doppler examination of the umbilical cord might be an early indicator of fetal compromise. Detectable intraplacental villous flows were in normal limits even in patients with abnormally high umbilical resistance indices and failure to detect villous artery color Doppler flow signals is probably associated with fetal compromise. We conclude that Doppler measurements from the intraplacental arteries cannot be used in clinical management of patients with severe preeclampsia.     

Evaluation of a commercially available reverse transcription-PCR assay for diagnosis of enteroviral infection in archival and prospectively collected cerebrospinal fluid specimens

BACKGROUND: In the Fontan circulation, energy consumption at the cavopulmonary connection is crucial. Our hypothesis was that a modification of the standard Norwood variant of cavopulmonary connection with an extended anastomosis would improve hydrodynamics. METHODS: The in vitro hydrodynamics of two different Perspex glass models resembling the Norwood variant of cavopulmonary connection (model I) and the modification (model II) were analyzed in a mock circulation at nonpulsatile flows of 2 to 5 L/min to simulate rest and exercise. The pulmonary flow split was varied to imitate varying lung resistances. Inferior-to-superior caval flow ratio and size of models were increased to simulate growth. RESULTS: The pulmonary flow was preferentially directed to the left lung in model I and was better balanced in model II. Power losses increased exponentially with total flow in both models and were markedly higher in model I. These differences were attenuated in the larger models. Anastomotic turbulences were larger in model I. Power losses in both models were relatively insensitive to changes in pulmonary flow split. CONCLUSIONS: The proposed modification of the Norwood variant of cavopulmonary connection seems to be hydrodynamically advantageous and warrants further evaluation.     

Assessment of the Effectiveness of a Constructed Compound Channel River Restoration Project on an Incised Stream

Compound channels are often constructed in restoration projects on rivers and streams that have been channelized or are deeply incised. This design allows for flow over a wider cross-sectional area during high flows and is expected to reduce both flow velocities and bed-shear stresses in the channel during high flows. Using a compound channel restoration project on Tassajara Creek as a case study, the effectiveness of a constructed compound channel in reducing channel velocities and bed-shear stresses during high flow events was tested in two ways. First, since this is an a posteriori analysis, postproject surveys and assessments of the project are used to demonstrate the geomorphic and ecological benefits of the constructed compound channel for reducing further channel incision, improving channel stability, and enhancing native riparian vegetation, while still providing conveyance capacity for design flood flows. Second, the effectiveness of a constructed compound channel in reducing channel velocities and bed-shear stresses during high flow events is evaluated using both the one-dimensional (1D) model, HEC-RAS, and the three-dimensional (3D) numerical model, UnTRIM. This analysis demonstrates that the 1D analysis does not accurately portray the benefits of the compound channel, and is therefore not a suitable tool for evaluating the effectiveness of compound channel designs. These results demonstrate the advantages of using a 3D model and make a strong case for the implementation of more detailed hydrodynamic modeling in evaluating the suitability of restoration alternatives to improve the planning and design of river restoration projects.