Annular Wall Research Articles

Right Ventricular Dimensions and Function in Isolated Left Bundle Branch Block: Is There Evidence of Biventricular Involvement?

Isolated left bundle branch block (LBBB) may be an expression of idiopathic cardiomyopathy affecting both ventricles. The present study was conducted to evaluate right ventricular (RV) dimensions and function in asymptomatic LBBB patients with mildly depressed left ventricular (LV) function. Fifteen patients with asymptomatic LBBB in whom coronary artery disease, hypertension, and valvular pathology was excluded were studied. Fifteen healthy volunteers and 15 idiopathic dilated cardiomyopathy LBBB patients served as controls. RV long axis and tricuspid annulus diameter were obtained, as were tricuspid annular plane systolic excursion (TAPSE) and peak systolic velocity (Sm) of the RV free wall annulus. Tricuspid regurgitation (TR) jets (peak TR jets) were used for RV pressure assessment. RV dimensions were comparable between the asymptomatic LBBB patients and controls. RV functions of healthy volunteers and asymptomatic LBBB patients were similar (TAPSE: 24 +/- 3 and 24 +/- 4 mm, Sm: 13 +/- 2 and 13 +/- 3 cm/s, respectively), whereas functional parameters in idiopathic dilated cardiomyopathy patients were significantly reduced (TAPSE: 19 +/- 5 mm, Sm: 9 +/- 2 cm/s, both P < 0.01 by analysis of variance [ANOVA]). For the three groups combined, a significant inverse correlation between RV pressure (peak TR jets) and RV function (Sm) was observed (r =-0.52, P = 0.017). In patients with an asymptomatic LBBB, RV dimensions and function are within normal range. The present study suggests that screening of RV functional parameters in asymptomatic LBBB patients is not useful for identification of an early-stage cardiomyopathy, and RV dysfunction is merely a consequence of increased RV loading conditions caused by left-sided heart failure and does not indicate a generalized cardiomyopathy affecting both ventricles.

Catheter Ablation of Ventricular Tachycardia After Repair of Congenital Heart Disease

Catheter ablation of ventricular tachycardia (VT) after repair of congenital heart disease can be difficult because of nonmappable VTs and complex anatomy. Insights into the relation between anatomic isthmuses identified by delineating unexcitable tissue using substrate mapping techniques and critical reentry circuit isthmuses might facilitate ablation. Sinus rhythm voltage mapping of the right ventricle was performed in 11 patients with sustained VT after repair of congenital heart disease. Unexcitable tissue from patch material, valve annulus, or dense fibrosis, identified from bipolar voltage (<0.5 mV) and pacing threshold (>10 mA), was defined as an anatomic isthmus boundary bordering 4 isthmuses between (1) the tricuspid annulus and scar/patch in the anterior right ventricular outflow, (2) the pulmonary annulus and right ventricular free wall scar/patch, (3) the pulmonary annulus and septal scar/patch, and (4) the septal scar/patch and tricuspid annulus. The reentry circuit isthmuses of all induced 15 VTs (mean cycle length, 276+/-78 ms; 73% poorly tolerated), identified by activation, entrainment, and/or pace mapping, were located in an anatomic isthmus (11 of 15 VTs in anatomic isthmus 1). Transecting the anatomic isthmuses by ablation lesions abolished all VTs. During 30.4+/-29.3 months of follow-up, 91% of patients remained free of VT. Reentry circuit isthmuses in VT late after repair of congenital heart disease are located within anatomically defined isthmuses bordered by unexcitable tissue. The boundaries can be identified with 3-dimensional substrate mapping and connected by ablation lines during sinus rhythm. These findings should facilitate catheter and surgical ablation of stable and unstable VTs.

Bone pathology inpsoriatic arthritis

Objective. To study different variants of osteolysis in pts with psoriatic arthritis (PA) and to reveal their relationship with other clinico-radiological features of joint damage. Material and methods. 370 pts with definite PA having different variants of joint damage were included. Radiological examination of bones and joints (in some cases large picture frame) was performed. Morphological evaluation of synovial biopsies was done in 34 pts with PA and 10 pts with rheumatoid arthritis (RA). Results. Different types of osteolysis were revealed in 80 (21,6%) pts. Osteolytic variant of joint damage was present in 29 pts. 33 pts had acral, 48 — intra-articular osteolysis and 16 - true bone atrophy. Frequency and intensity of bone resorption were associated with severity of PA. Acral osteolysis correlated with arthritis of distal interphalangeal joints and onychodystrophy. Intra-articular osteolysis was most often present in distal interphalangeal joints of hands and metacarpophalangeal joints (39,6% and 41,7% respectively). Characteristic feature of PA was combination of prominent resorption with formation of bone ankylosis and periosteal reaction. Ankylosis was present in 33,3% of pts with intra-articular osteolysis and in 60% of pts with combination of different osteolysis variants. Systemic reaction of microcirculation in synovial biopsies was most prominent in osteolytic variant: marked thickening of capillary and venule basal membrane with high level of acid phosphatase, increased capillary and precapillary blood flow with stasis features, vascular lymphocyte and macrophage infiltration, productive vasculitis with annular wall thickening, thrombovasculitis and villi deep layer sclerosis. Conclusion. Different variants of osteolysis show bone involvement in PA. Acral and intra- articular osteolysis association with bone ankylosis and periostitis proves their common pathogenetic entity.

Optimal design and modeling of annular photocatalytic wall reactors

The performance of photocatalytic reactors is largely conditioned by their configuration. In particular, photocatalytic wall reactors are affected by configuration-linked factors such as diffusive resistances, reactor radiation incidence and absorption efficiencies, and by the amount of photocatalytic surface area that is effectively irradiated. In this paper, the effect of different configurations and design variables on the performance of annular photocatalytic reactors was analyzed. With this purpose, a complete reactor model was developed and solved, taking into account single- and multi-annular configurations, different reactor dimensions, and three flow patterns. The model was successfully validated against experimental results for the photocatalytic oxidation of perchloroethylene (PCE) in a multi-annular reactor. From the simulation results, it was possible to conclude that the unfavorable effect of the diffusive resistances on the reactor performance could be reduced by constructing photocatalytic annular wall reactors of small annular width and large photocatalytic surface area. Besides, the multi-annular configuration is more effective in using the radiative energy fed into the reactor than the single-annulus reactor configuration. According to the results obtained for PCE photocatalytic degradation, among all the studied reactor configurations the most efficient one is that with its annuli interconnected in a series pattern.

Numerical simulation of the effects of secondary flow and boundary retention on contaminant dispersion

The secondary flow and dispersion of a tracer substance in a fluid flowing through a curved tube are studied numerically. The system consists of an infinitely long conduit defined by two concentric curved circular pipes. Thus the two phases correspond to a flowing fluid phase and the annular wall comprised of a stationary homogenous medium. The solute is soluble in the annular region and is assumed to satisfy a linear equilibrium relationship at the interface. Flow in the fluid phase is calculated using the finite difference scheme as described by Collins and Dennis [9]. The scheme is of second order accuracy with respect to grid sizes over the entire laminar flow region and reveals the asymptotic nature of the solution for large values of Dean number D. Further, a central difference scheme is used to solve the convection diffusion equation in both the phases with the condition that the injective solute is highly soluble in the wall layer according to a linear equilibrium relationship at the interface. Results for small Dean number are first verified with our earlier results (Jayaraman et al. [17]) which were based on Dean's solution [12,13]. The numerical calculations are then extended for larger Dean number and Schmidt number. The results are consistent with experimental results that the influence of secondary flows on dispersion is reduced if the tracer is very soluble in the wall. It is found that the effective longitudinal diffusivity falls below its straight tube value by an amount, which depends on the absorption coefficient, Dean number and the diffusivity in the wall. For large Dean number dispersion becomes negligible.

Non-Newtonian fluid flow in annular pipes and entropy generation: Temperature-dependent viscosity

Non-Newtonian fluid flow in annular pipes is considered and the entropy generation due to fluid friction and heat transfer in them is formulated. A third-grade fluid is employed to account for the non-Newtonian effect, while the Reynolds model is accommodated for temperature-dependent viscosity. Closed-form solutions for velocity, temperature, and entropy fields are presented. It is found that entropy generation number increases with reducing non-Newtonian parameter, while it is the reverse for the viscosity parameter, which is more pronounced in the region close to the annular pipe inner wall.

Correlations for maximum possible induced flow rates and heat transfer parameters in open-ended vertical eccentric annuli

Fully developed laminar free convection in open-ended vertical eccentric annuli is studied under the boundary conditions of heating one of the annulus walls with uniform heat flux while the other wall is kept at ambient temperature. Correlations are developed by a regression analysis on the numerical solutions for the momentum equation using an analytical solution of the coupled energy equation. The developed correlations give the maximum possible induced flow rates and heat transfer parameters as functions of the geometric parameters, namely, the annulus eccentricity and radius ratio.

Idiopathic ventricular arrhythmias originating from the tricuspid annulus: Prevalence, electrocardiographic characteristics, and results of radiofrequency catheter ablation

Idiopathic ventricular tachycardias (VTs) and premature ventricular contractions (PVCs) arising from the tricuspid annulus have been reported. The purpose of this study was to clarify the prevalence and characteristics of VT/PVCs originating from the tricuspid annulus. The ECG characteristics and results of radiofrequency (RF) catheter ablation were analyzed in 454 patients with idiopathic VT/PVCs. Thirty-eight (8%) patients had VT/PVCs arising from the tricuspid annulus: 28 VT/PVCs (74%) originated from the septal portion of the tricuspid annulus and the remaining 10 (26%) from the free wall of the tricuspid annulus. QRS duration and Q-wave amplitude in each of leads V1-V3 were greater in VT/PVCs arising from the free wall of the tricuspid annulus than those from the septum of the tricuspid annulus (all P < .01). "Notching" of the QRS complex was observed more often in VT/PVCs arising from the free wall of the tricuspid annulus than those from the septum of the tricuspid annulus (P < .01). A Q wave in lead V1 was observed more often in VT/PVCs arising from the septum of the tricuspid annulus than those from the free wall of the tricuspid annulus (P < .005). R-wave transition occurred beyond lead V3 more often in VT/PVCs arising from the free wall of the tricuspid annulus than those from the septum of the tricuspid annulus (P < .005). RF catheter ablation eliminated 90% of the VT/PVCs arising from the free wall of the tricuspid annulus but only 57% of the VT/PVCs arising from septum of the tricuspid annulus. Idiopathic VT/PVCs arising from tricuspid annulus are not rare, and the detailed origin can be determined by ECG analysis. The preferential site of origin was the septum but also could be the free wall of the tricuspid annulus.

Chronic suppurative otitis media following paediatric cochlear implantation

The objective of this study was to report and discuss the management of chronic suppurative otitis media (CSOM) following cochlear implantation in children. The study was a retrospective review of 650 patients receiving an implant at two paediatric tertiary referral centres for cochlear implantation. Nine patients were identified who developed CSOM following cochlear implantation (incidence 1.38%). The mean time interval between implantation and symptom development was 3.66 years (range 2–8 years) and the mean time interval between implantation and CSOM surgery was 5.02 years (range 2.2–8 years). All patients presented with otorrhoea and/or abscess formation over the implant site. Two patients underwent a modified radical mastoidectomy and seven underwent a combined approach tympanoplasty, three of whom required posterior canal wall reconstruction with cortical bone and one with cartilage. In four cases it was possible to remove the cholesteatoma without removing the implant. All but two patients were fitted with a contralateral implant. In the explanted ears the cochlear implant electrode was cut at the cochleostomy site, which was then covered with muscle. Chronic suppurative otitis media following cochlear implantation may occur either as a result of a posterior canal wall defect related to surgery or possibly de novo. Attempts should be made to save the implant, but explantation with reimplantation of the contralateral ear may be the only option. In these cases the intracochlear part of the electrode array should be left in situ to facilitate possible future reimplantation. Surgical options for management of CSOM should be individualized and may include both canal-wall up and canal-wall down techniques. To reduce the incidence of CSOM following implantation the authors recommend: (1) prompt treatment and careful follow-up of patients with a history of otitis media with effusion, (2) avoidance of excessive thinning of the posterior canal wall during mastoidectomy and (3) reconstruction of any accidental trauma to the annulus or posterior canal wall during posterior tympanotomy. Copyright © 2006 John Wiley & Sons, Ltd.

Modified Semicircular Constricting Annuloplasty (Sagban's Annuloplasty) in Severe Functional Tricuspid Regurgitation: Alternative Surgical Technique and Its Mid-Term Results

De Vega annuloplasty is one of the most effective methods used in surgical correction of functional tricuspid regurgitation (FTR). Physiologic annular motions are protected by De Vega annuloplasty. However, recurrent tricuspid regurgitation secondary to Bowstring (Guitar string) phenomenon may be seen after De Vega annuloplasty as a result of gliding (jiggle) effect. The aim of this new annuloplasty was to prevent Bowstring phenomenon seen in De Vega annuloplasty. Twenty-five patients with severe FTR secondary to the left-sided valvular heart disease were included in this study. Modified semicircular constricting annuloplasty (Sagban's annuloplasty): The procedure is performed utilizing 0 and 2-0 polypropylene sutures. At first, 0 and 2-0 polypropylene sutures are fixed and knotted at anteroseptal and posteroseptal comissural regions (named as anchoring points). 2-0 Polypropylene sutures which come from anchoring points in clockwise and counterclockwise direction are used to encircle the free wall annulus as well as 0 polypropylene sutures in spiral fashion (spiral annulary suture technique). When both sutures get to the anteroposterior comissural region (tying point), they are passed through plastic snares. After the annuloplasty is completed, with the heart beating and the pulmonary artery clamped, competency of the valve is tested by injecting saline into the right ventricular chamber before the adjusting suture is tied. In this annuloplasty, 0 polypropylene sutures are used for reduction and constriction, 2-0 polypropylene sutures are used for the fixation of 0 polypropylene sutures in annular level. FTR improved totally in 16 patients (66.7%), 4 patients (16.7%) had first degree, 3 patients (12.5%) had second degree, and only 1 patient (4.2%) had third degree residual tricuspid regurgitation in an average follow-up period of 17.8 months. One patient died from low cardiac output in early postoperative period. There is no risk of recurrent regurgitation secondary to Bowstring phenomenon in this alternative annuloplasty technique and this annuloplasty is cost-effective and performed easily.

Rotated, circular arc models of stress in silos applied to core-flow and vertical rat-holes

Rotated, circular arc geometry models have been developed to describe core-flow and vertical rat-holes in cylindrical hoppers and silos. The conceptual problem of the variation of incremental element thickness has been overcome, resulting in models of greater theoretical rigour. Models have been developed in an average stress and point stress form. Analysis shows that stresses vary with vessel radius through an arc angle parameter, ε, as well as with bed depth. The models indicate that conditions at a rat-hole annulus wall are quite different from the mean stress or wall stress and this has implications for stability and flow. A modified failure criterion, based upon azimuthal stress has been used to assess the stability of deep rat-holes, and a range of rat-hole stability determined, which is dependent upon material properties and vessel diameter. Predicted stress distributions are functions of assumed internal stress distribution relationships. More physical data are required in this area to enable reliable modelling.

Reproducibility of CT Measurements of Aortic Valve Calcification, Mitral Annulus Calcification, and Aortic Wall Calcification in the Multi-Ethnic Study of Atherosclerosis

Extracoronary calcifications may have clinical significance. The error in extracoronary calcification measurements is still unknown. Accurate quantification of calcifications of the aortic valve (AVC), mitral annulus (MAC), and aortic wall (AWC) may be possible by using cardiac computed tomography (CT). We sought to establish the interscan, interobserver, and intraobserver reproducibility of these measures in all cardiac CT scans in the Multi-Ethnic Study of Atherosclerosis. We measured extracoronary calcifications in 100 randomly selected participants to assess interobserver, interscan, and intraobserver variability. Two scans were available for analysis in 99 of these participants, and we quantified thoracic aorta and valvular calcifications. Mean interscan variability of AVC was 9.7% +/- 11.4% and 8% +/- 10.3% for Agatston and volume scores, with variability of the median at 6.4% and 5.5%, respectively (P > .05). MAC inter-reader variability was 8.2% and 8.9%, with interscan variability of 28% and 33% and intrareader variability of 4% and 4.1%, respectively. For AWC, inter-reader variability was 3%-7.1%, interscan variability was 17%-18%, and intrareader variability was 0.4%-1.4%. AVC, MAC, and AWC measurements are sufficiently reproducible to allow serial investigations over a time suitable for clinical studies.

Aortic Valve Replacement with the Medtronic Freestyle Xenograft Using the Subcoronary Implantation Technique

Aortic Valve Replacement with the Medtronic Freestyle Xenograft Using the Subcoronary Implantation Technique

Intralamellar relationships within the collagenous architecture of the annulus fibrosus imaged in its fully hydrated state

The anisotropic, inhomogeneous, multiply collagenous architecture of the annulus reflects the complex pattern of mainly tensile stresses developed in this region of the disc during normal function. Structural and mechanical responses of fully hydrated in-plane sections taken from within single lamellae of the outer annulus of healthy bovine caudal discs have been investigated using a micromechanical technique in combination with simultaneous high-resolution differential interference contrast optical imaging. Responses both along and across (i.e. transverse to) the primary direction of the mono-array of collagen fibres were studied. Stretching along the alignment direction revealed a biomechanical response consistent with the behaviour of an array whose overall strength is governed primarily by the strength of embedding of the fibres in the vertebral endplates, rather than from interfibre cohesion along their length. The mono-aligned array, even when lacerated, is highly resistant to any further tearing across the alignment direction. Although not visible in the relaxed mono-arrays, transverse stretching revealed a highly complex set of interconnecting structures embodying hierarchical relationships not previously revealed. It is suggested that these structures might play an important role in the containment under pressure of the nuclear contents. The dramatic differences in rupture behaviour observed along vs. across the primary fibre direction are consistent with the known clinical consequences arising from varying degrees of annular wall damage, and might also explain various types of disc herniation. The lamellar architecture of the healthy disc revealed by this investigation provides an important reference framework for exploring structural changes associated with disc trauma and degeneration.

Failure strength of the bovine caudal disc under internal hydrostatic pressure

The structure of the disc is both complex and inhomogeneous, and it functions as a successful load-bearing organ by virtue of the integration of its various structural regions. These same features also render it impossible to assess the failure strength of the disc from isolated tissue samples, which at best can only yield material properties. This study investigated the intrinsic failure strength of the intact bovine caudal disc under a simple mode of internal hydrostatic pressure. Using a hydraulic actuator, coloured hydrogel was injected under monitored pressure into the nucleus through a hollow screw insert which passed longitudinally through one of the attached vertebrae. Failure did not involve vertebra/endplate structures. Rather, failure of the disc annulus was indicated by the simultaneous manifestation of a sudden loss of gel pressure, a flood of gel colouration appearing in the outer annulus and audible fibrous tearing. A mean hydrostatic failure pressure of 18±3 MPa was observed which was approximated as a thick-wall hoop stress of 45±7 MPa. The experiment provides a measurement of the intrinsic strength of the disc using a method of internal hydrostatic loading which avoids any disruption of the complex architecture of the annular wall. Although the disc in vivo is subjected to a much more complex pattern of loading than is achieved using simple hydrostatic pressurization, this latter mode provides a useful tool for investigating alterations in intrinsic disc strength associated with prior loading history or degeneration.

Feasibility of using interstitial ultrasound for intradiscal thermal therapy: a study in human cadaver lumbar discs

Application of heat in the spine using resistive wire heating devices is currently being used clinically for minimally invasive treatment of discogenic low back pain. In this study, interstitial ultrasound was evaluated for the potential to heat intradiscal tissue more precisely by directing energy towards the posterior annular wall while avoiding vertebral bodies. Two single-element directional applicator design configurations were tested: a 1.5 mm OD direct-coupled (DC) applicator which can be implanted directly within the disc, and a catheter-cooled (CC) applicator which is inserted in a 2.4 mm OD catheter with integrated water cooling and implanted within the disc. The transducers were sectored to produce 90° spatial heating patterns for directional control. Both applicator configurations were evaluated in four human cadaver lumbar disc motion segments. Two heating protocols were employed in this study in which the temperature measured 5 mm away from the applicator was controlled to either T = 52 °C, or T > 70 °C for the treatment period. These temperatures (thermal doses) are representative of those required for thermal necrosis of in-growing nociceptor nerve fibres and disc cellularity alone, or with coagulation and restructuring of annular collagen in the high-temperature case. Steady-state temperature maps, and thermal doses (t43) were used to assess the thermal treatments. Results from these studies demonstrated the capability of controlling temperature distributions within selected regions of the disc and annular wall using interstitial ultrasound, with minimal vertebral end-plate heating. While directional heating was demonstrated with both applicator designs, the CC configuration had greater directional heating capabilities and offered better temperature control than the DC configuration, particularly during the high-temperature protocol. Further, ultrasound energy was capable of penetrating within the highly attenuating disc tissue to produce more extensive radial thermal penetration, lower maximum intradiscal temperature, and shorter treatment times than can be achieved with current clinical intradiscal heating technology. Thus, interstitial ultrasound offers potential as a more precise and faster heating modality for the clinical management of low back pain.

Liquid Vortex Shielding for Fusion Energy Applications

Swirling liquid vortices can be used in fusion chambers to protect their first walls and critical elements from the harmful conditions resulting from fusion reactions. The beam tube structures in heavy ion fusion (HIF) must be shielded from high energy particles, such as neutrons, x-rays and vaporized coolant, that will cause damage. Here an annular wall jet, or vortex tube, is proposed for shielding and is generated by injecting liquid tangent to the inner surface of the tube both azimuthally and axially. Its effectiveness is closely related to the vortex tube flow properties. 3-D particle image velocimetry (PIV) is being conducted to precisely characterize its turbulent structure. The concept of annular vortex flow can be extended to a larger scale to serve as a liquid blanket for other inertial fusion and even magnetic fusion systems. For this purpose a periodic arrangement of injection and suction holes around the chamber circumference are used, generating the layer. Because it is important to match the index of refraction of the fluid with the tube material for optical measurement like PIV, a low viscosity mineral oil was identified and used that can also be employed to do scaled experiments of molten salts at high temperature.

Maximum possible induced flow rates in open‐ended vertical eccentric annuli with uniform heat flux

PurposeObtaining the maximum possible flow rates that can be induced by free convection in open‐ended vertical eccentric annuli under fundamental thermal boundary conditions of the fourth kind (heating or cooling one of the annulus walls with a uniform heat flux while keeping the other wall at ambient temperature). Obtaining the maximum possible flow rates that can be induced by free convection in open‐ended vertical eccentric annuli under fundamental thermal boundary conditions of the fourth kind (heating or cooling one of the annulus walls with a uniform heat flux while keeping the other wall at ambient temperature).Design/methodology/approachThe fully‐developed laminar free convection momentum equation has been solved numerically using an analytical solution of the governing energy equation.FindingsResults are presented to show the effect of the annulus radius ratio and the dimensionless eccentricity on the induced flow rate, the total heat absorbed by the fluid, and the fully developed Nusselt numbers on the two boundaries of the annulus for a fluid of Prandtl number 0.7.Practical implicationsApplications of the obtained results can be of value in the heat‐exchanger industry, in cooling of underground electric cables, and in cooling small vertical electric motors and generators.Originality/valueThe paper presents a solution that is not available in the literature for the problem of fully developed free convection in open‐ended vertical eccentric annular channels under thermal boundary conditions of the fourth kind. Also presents the maximum possible induced flow rates, the total heat absorbed by the fluid, and the Nusselt numbers on the two boundaries of the annulus. The effects of N and E (the radius ratio and eccentricity, respectively) on these results are presented. Such results are very much needed for design purposes of heat transfer equipment.

Annulus wall temperatures and heat transfer coefficients in aeroengine compressors deduced from engine measurements

Surface-mounted thermocouples were located on the annulus walls of every stator stage in both core compressors of a large civil aeroengine. The relationships of the steady state wall temperatures to the compressor inlet and exit air temperatures are shown, as is their variation with engine rotational speed. The transient response of the thermocouples to fast engine throttle manoeuvres was measured, for acceleration to full power, deceleration to idle and for both acceleration and deceleration to two intermediate power levels. Heat transfer coefficients are deduced from the matching of a thermal finite element model to the measured transients and are expressed as factors with respect to the standard free-disc formula. The variations in the factors through the compressor and through the speed range are shown. The advantages and disadvantages of using an alternative standard formula, based on duct flow, are discussed. Finally, the importance of understanding the transient local air temperature response arriving at a compressor stage due to upstream slugging is shown.

Entropy Analysis for Non-Newtonian Fluid Flow in Annular Pipe: Constant Viscosity Case

In the present study, non-Newtonian flow in annular pipe is considered. The analytical solution for velocity and temperature fields is presented while entropy generation due to fluid friction and heat transfer is formulated. The third grade fluid with constant properties is accommodated in the analysis. It is found that reducing non-Newtonian parameter increases maximum velocity magnitude and maximum temperature in the annular pipe. Total entropy generation number attains high values in the region close to the inner wall of the annular pipe, which becomes significant for low non-Newtonian parameters. Increasing Brinkman number enhances entropy generation number, particularly in the region close to the annular pipe inner wall.