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Numerical evaluation of incresed blood pressure due to arterial stenoses and
 

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    Numerical evaluation of incresed blood pressure due to arterial stenoses and Numerical evaluation of incresed blood pressure due to arterial stenoses and Document Transcript

    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 5, September - October (2013) © IAEME 10 NUMERICAL EVALUATION OF INCRESED BLOOD PRESSURE DUE TO ARTERIAL STENOSES AND ATROPHY OF END ORGAN Vishal V. Shukla1 , Promad M. Padole2 1 Research Scholar, Visvesvaraya National Institute of Technology, Nagpur, M.S., India, 440011 2 Professor, Visvesvaraya National Institute of Technology, Nagpur, M.S., India, 440011 ABSTRACT This paper explains and demonstrates that flow through Venturimeter is comparable to flow through stenotic artery, discarding other complicated physiological factors. In this study systolic blood pressure 120 mm of mercury is set as standard baseline in non-stenotic artery. The increasing pressure rise is found for increasing blockages. A FE Model was analysed to obtain the values of corresponding blood pressures. For 80 % Stenosis, rise of about 64% in blood pressure and about 55 % reduction of blood flow to end organ was found.The study concludes that without using any pressure or flow measuring devices, a couple of simple and handy charts can be obtained. They can be used as as a primary diagnostic tool. CFD study of blood flow through stenotic models provides easy-to-use information to doctors dealing with patients of high Blood Pressure. Keywords: Blood pressure, Blood Flow Rate, Computational Fluid Dynamics (CFD), Stenotic artery 1. INTRODUCTION Human body is a complex combination of bio-structures & bio-fluids systems. Kidney is a one of the complex organ in human body with multifarious chemical, biological and physiological mechanisms. There are two Kidneys in human body, located just below the rib cage, one on each side of the spine. The main function of kidney is to filter the blood separating impurities in the form of urine. Narrowing of blood vessels due to deposition of fatty substance or cholesterol on the inner side of arterial wall is called stenosis. Stenosis acts as an obstruction to blood flow due to reduced cross section area of blood vessel. Moreover, due to stenosis the upstream blood pressure also increases. The most common cause of secondary hypertension (blood pressure) is Renal Artery Stenosis (RAS). Hypertension is complex disorder that affects the heart, brain, blood vessels and kidneys. RAS, as shown in Fig. 1, is narrowing of the major arteries that supply blood to the kidneys, due to build up of fatty substance called plaque. The narrowing of the renal artery diminishes the blood supply to the kidney. When the kidney is deprived of normal blood supply, it shrinks in size due to atrophy. Thus INTERNATIONAL JOURNAL OF MECHANICAL ENGINEERING AND TECHNOLOGY (IJMET) ISSN 0976 – 6340 (Print) ISSN 0976 – 6359 (Online) Volume 4, Issue 5, September - October (2013), pp. 10-20 © IAEME: www.iaeme.com/ijmet.asp Journal Impact Factor (2013): 5.7731 (Calculated by GISI) www.jifactor.com IJMET © I A E M E
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 5, September - October (2013) © IAEME 11 RAS may ultimately lead to kidney failure [1, 2]. RAS reduces the blood flow through the renal artery to kidney and causes the kidney to release increased amount of the hormone renin. Renin is a powerful blood pressure regulator, initiates a series of chemical events that result in hypertension Hypertension due to RAS is known as Reno Vascular Hypertension (RVH). Based on the extent of RAS, RVH can be very severe and mostly difficult to control by medication. Elevated blood pressure in one renal artery can cause loss of filtering function and therefore damage the other kidney as well [3, 4]. Figure 1: Renal Artery Stenosis (RAS) RAS reduces efficient functioning of kidney. The deteriorated kidney function may be reversed by correcting stenosis. It is now known that many cases of RAS are under diagnosed and may present as a spectrum of other diseases based on secondary hypertension. RVH is an important consequence of RAS. Antihypertensive medical therapy fails to control RVH [5, 6]. Restoring of narrowed blood vessel with a spring like device called stent is one of the efficient mechanisms to down regulate RVH. Several investigators have reported that renal artery revascularization can stabilize or improve renal function. Over 1 to 4 years of time, stenosis often redevelops (restenosis). RAS is associated with loss of renal size. Clinical investigations till date are unable to demonstrate a relationship between severity of stenosis and renal function. Fundamentally, the kidneys require continuous flow of blood to function. Clearly, there are some biological or chemical factors that influence functioning of kidneys. But the mechanical factors like length & diameter of stenosis and intrarenal pressure also affect the renal blood flow. Several modern test procedures based on imaging techniques are available at the speciality hospitals. Some of them are: Angiography, Magnetic resonance angiography (MRA), Ultrasound etc. The machines and tooling required to one or more of the above test procedures are costly. Therefore these diagnostic test procedures are expensive. The radiologists use one of the above diagnostic test procedures at specialty hospitals for finding the exact location and severity of RAS. The general physician can predict the existence of RAS but cannot quantify the extent (percent blockage). Management of RAS consists of three possible strategies: medical management, surgical management and percutaneous therapy with balloon angioplasty and stent implantation. 2. MATERIALS AND METHODS One of the investigation [7], in their experiments on hemodynamic effects in elastic silicon rubber models, have shown that geometry, hemodynamics and vessel wall structure have a strong influence on creation of stenoses. Pressure and velocity gradients, flow behavior, velocity distribution
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 5, September - October (2013) © IAEME 12 and shear stress on the wall are very important parameters in blood flow analysis. Plaque deposits are found predominantly at arterial bends and bifurcations. Another study [8] based on the cardiovascular electronic system and crude forms of CFD model. The pressure drop of each section due to the stenosis was computed by means of an electrical circuit and a simple CFD model. Arterial stenoses in the range of 0–78% have been investigated to estimate plaque progression and wall stresses, both numerically and experimentally. However, the study presents very elementary CFD models and does not quantify the reduction in blood flow to kidney due to RAS. Blood is not a fluid but rather a suspension of particles. Blood can be assumed to be Newtonian. This is because the velocity and shear rates in the larger arteries are high. The shear rate of blood flow is found to be about 1000 sec−1 in large vessels. In large arteries, the shear stress (τ) exerted on blood elements is linear with the rate of shear, and blood behaves as a Newtonian fluid. In this range, the elastic behavior of blood becomes insignificant. The nonnewtonian behaviour is important only in small vessels (veins) and not in large size blood vessels like renal arteries. Therefore, the effect of nonnewtonian behavior of blood in renal arteries is small and negligible [9, 10, and 11]. The turbulence is not present in the cardiovascular system in physiological situations. Hence, blood flow is laminar. The viscosity of blood is patient specific but varies in the range of 3-4 mPa-s at a temperature of 370 C. the value of viscosity for blood can be taken as 3.5 mPa-S Therefore, blood is considered to be an isotropic, incompressible and homogeneous fluid with a density value of 1050 kg/m3 . 2.1 Geometric and finite element modeling Geometric modeling of object domain followed by finite element solution of respective physical phenomenon provides the better understanding of the problem at hand. It eliminates the difficulty of complex analytical problem solving procedures and hence adopted frequently by many researchers. Modeling, in combination with experimental data and analytical approach, often yields logical scientific conclusions. Two-dimensional (2-D) geometrical section of healthy and stenotic renal artery models are created, with the FEM general purpose CFD code ANSYS v 13.0 (ANSYS® Inc., USA). ANSYS is a Finite Element Analysis (FEA) system with multiple pre and post processing codes for structural, thermal and fluid flow. Finite Element Method (FEM) based and not Finite Volume Method (FVM) based CFD is used to investigate the effect of RAS on the increase in blood pressure. This is because of the inherited advantages of FEM as enlisted below: It caters to the needs of geometric flexibility. It allows applying physical boundary conditions easily and accurately. It satisfies global physical (linear) conservation laws automatically especially quadratic quantities and even for which divergence theorems are not applicable. Laplacian, divergence and gradient operators are ad-joint to each other in continuum in FEM and not in FVM. Phase speed of FEM is always more accurate than that of FVM. Based on the data collected from various sources like books and research papers, it is known that the geometry of a healthy renal artery is almost tubular (cylindrical) and symmetrical. Therefore, only a section of length (g = 16 mm), diameter (h = 8 mm) and the length of stenotic wall length (f = 8 mm), as shown in Fig. 2, is modeled. About 10 numbers of symmetrical stenotic models are created at the middle portion of geometry by creating arcs with three key points. The minimum diameter at the site of stenoses and percentage of stenoses based on diameters and areas are calculated as shown in TABLE 1.
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 5, September - October (2013) © IAEME 13 Figure 2: Sections of stenotic renal artery: a-23 %, b-44 %, c-61%, d-80 %, and e-92 % (major dimensions of section of stenotic artery; f = 8 mm; g = 16 mm; h = 8 mm). Table 1: Percentage of stenosis on the basis of area Inside diameter (mm) 8.0 7.0 6.0 5.0 4.3 4.0 3.5 3.3 3.0 2.3 % Stenosis based on the cross sectional area 0 23 44 61 71 75 80 83 86 92 In general, stenoses are specified relative to percentage of blocked areas; therefore, henceforth in this study, stenoses based on percent areas shall be followed. The mesh is built with 2-D Fluid 141 elements, each having four nodes and 4 degrees of freedom (two translational velocities: Vx & Vy) and two pressures: Px & Py). The numbers of iterations are determined by using different meshes, from coarse to progressively fine, until the inlet pressure distribution is mesh convergent within a prescribed tolerance. The total numbers of nodes are about 1374 and elements about 1301 for the healthy artery configuration i.e. with 0 % stenosis, which slightly differs for the stenotic configurations due to local mesh adaptations. The mesh for 92% stenotic section is shown magnified in the inset in Fig. 2. While meshing the artery walls are set for desired number of mesh divisions. Blood is modeled as an incompressible, homogeneous, Newtonian viscous fluid, with a specific mass of 1050 kg/m3 and a constant dynamic viscosity of 3.5X10-3 Pa-s (J.R. Torii et al., 2006; K. Hassani et al, 2007). The flow is assumed to be steady state, Laminar and adiabatic (K. Hassani et al, 2007). The rise in the pressure depends not only on the viscosity and density of the fluid but also on the extent of the stenosis. Therefore simulation of flow of water (ρ=1000Kg/m3 and µ=0.798X10-3 Pa-s) through various stenoses have also been carried out. A normal renal artery has a blood flow of about 1 LPM. Therefore to impose boundary conditions, the axial inlet velocity of 0.33 cm/s (as flow is 1 LPM through 8 mm dia. artery) is assigned in X-direction ( Vx = 0.33 cm/s) and zero transverse velocity components ( Vy = 0 cm/s)at the entrance of the vessel. The inlet velocity profile is assumed to be laminar. No slip boundary conditions are imposed on the impermeable, rigid vessel walls. Vessel walls are assumed to be rigid to simplify and analysis and also there shall be a very minor changes on the output quantities under consideration like pressure drop (∆P), frictional head loss (Hf) etc. At the outlet zero gauge pressure (equivalent to 1 atm. pressure) as a reference pressure is imposed to determine the pressure difference (∆P) between the inlet and outlet. Identical geometric models, Finite Element mesh and boundary conditions (Pressure, Velocity, Velocity-Profile and Flow
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 5, September - October (2013) © IAEME 14 Rate) are used in both the CFD investigations of water as well as blood; however viscosities and densities differ as mentioned above. The external forces, such as those due to gravity or human motion are assumed to be not significant and are neglected. Considering symmetric pressure distribution and steady state 2-D fluid flow, fluid shear stresses due to RAS are numerically analyzed. Both the fluids (blood & water) are treated as incompressible and Newtonian fluid. Two CFD analyses one each for water & blood and one experimental analysis, only for water, have been carried out to investigate the effect of blockage on the rise of pressure. The overall approach can be justified on the basis of following logic: 1. Experimental analysis of blood flow through stenotic arterial sections is not practicable; therefore, computer simulation is the only option to investigate the case of blood flow through stenotic section. 2. If the CFD results of water flow matches with the experimental results of water flow, then FE model is validated. And hence CFD results of blood flow shall be quite reliable. On the basis of the above logic, the objectives are set. (i) To establish a FEM based mathematical blood pressure model and (ii) To formulate kidney atrophy model based on stenosis. 2.2 Experimental set up Simple experimental setup was designed to investigate the effect of stenoses on the rise of pressure. The experimental setup as shown in Fig. 3 consists of a positive displacement gear pump with torque of 1.6 Nm. The outlet of the pump is connected to a polyethylene tube resembling the renal artery of diameter 8 mm and length 0.3 m connected by means of a Tee joint. One end of the Tee is attached to the polyethylene tube while the other end is connected to a vertical tube of diameter 12 mm and length 2 meters. The vertical tube acts as both a piezometer-cum-surge tank in the experiment. The experiment was carried out simply to validate the CFD model created and analysed on computer. Once the results are for water both experimental and that of computational model are found close enough, the computational model was called be satisfactorily validated [12]. Figure 3: Experimental setup to determine the effect of stenosis on rise in blood pressure: (a) nine numbers of specimens are cut from a nylon bar; (b) length of each specimen is 10 mm; (c) specimens are drilled through using various sizes of drill bits; and (d) top view of specimen (countersunk at distal ends). Following a standard Finite Element Method procedure of Modeling, meshing, assigning the material properties and applying boundary conditions, the FE model was solved.
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 5, September - October (2013) © IAEME 15 3. RESULTS AND DISCUSSION The solution was smoothly converged without any warnings and error. It is mainly because of all the parameters in the preprocessing phase were correctly attributed. Fig. 4, shows the iteration convergence of CFD solution run for blood flow through the computational model. The flow of blood through renal artery model without stenosis is Laminar (max. Re = 1003). The velocity profile as shown in Fig 5 (a) indicates highest velocity of 36.7 cm/s at middle section of artery. The velocity profile in the stenotic section with maximum blockage (92%) is shown in Fig. 5 (b). The highest velocity of 136 cm/s (Re = 938) is observed at 0.25 mm from the wall. Figure 4: CFD solution convergence for blood flow (a) (b) Figure 5: Laminar velocity profiles for blood flow through normal and blocked artery: (a) velocity profile in the section of model artery for blood flow (0% stenosis, healthy artery) and (b) velocity profile in the section of model artery for blood flow (92% stenosis, blocked artery).
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 5, September - October (2013) © IAEME 16 And as shown in Fig. 6 (a), velocity distribution fairly remains the same within the core of the renal artery. One of the important things noticed in the study is little reduction in velocities near the wall and downstream of the stenosis region and can be verified from Fig. 6 (b). (a) (b) Figure 6 (a): velocity distribution of blood flow within the tube model with maximum blockage (92% stenosis); (b): distribution of blood flow velocity vectors with recirculation zones shown near the entry and exit of 92% stenotic sections The CFD models of blood flow through renal artery with increasing size of stenoses are then sequentially solved in the similar fashion. The trends for increasing velocity, increasing pressure drops, increasing fluid shear stress near wall and increasing pressure coefficients are observed, they are listed in TABLE 2. Table 2: CFD results of investigated parameters for blood flow % Stenosis Pressure diff. (N/m2 ) % Press. rise ∆P Pressure in mm Hg (120 mm baseline) Max. Velocity (mm/s) Shear Stress MPa 0 125 0 120 367 3.85 23 132 6 127 409 3.95 44 153 19 143 480 4.80 61 203 39 167 587 6.74 71 261 52 183 690 8.94 75 285 56 188 735 9.08 80 361 65 199 819 13.30 83 460 73 208 975 14.77 86 534 77 212 1114 16.26 92 725 83 219 1360 20.24 The distribution of blood pressure loss (∆P) is shown in Fig. 7 (a). It shows there is a loss of about 124.5 N/m2 (0.94 mm of Hg) between the entry and exit of the artery for 0 % stenosis (healthy artery model) case. This means that if there is gauge pressure of 15892.2 N/m2 (120 mm of Hg) at outlet, the gauge pressure at the inlet would be 160017.055 N/m2 (120.94 mm of Hg). The distribution of pressure loss for 92% stenotic renal artery is shown in Fig. 7 (b). It shows that there is a pressure difference of about 725.194 N/m2 (5.47 mm of Hg) between the entry and exit of the 92 % stenotic renal artery, which is almost 83 % higher than the ∆P in case of healthy artery. The values of ∆P obtained from CFD analysis for increasing stenosis and corresponding % ∆P rise to healthy artery case are listed in TABLE 2.
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 5, September - October (2013) © IAEME 17 (a) (b) Figure 7 (a): The distribution of pressure loss (∆P), for blood flow, within the section of modeled artery without blockage (0% stenosis) — this value of pressure loss (∆P) is used as reference; (b) The distribution of pressure loss (∆P), for blood flow, within the section of modeled artery with 92% stenosis; compared to ∆P of healthy section (124 N/mm2 ), ∆P in this case is about (725N/mm2); therefore, change in ∆P (from 0% to 92%) is about 83% Maximum blood shear stress of 20.24 MPa is found at the stenotic wall in 92 % stenotic artery whereas the shear stress was found merely to be about 5 MPa for 0 % Stenosis. Shear stresses in both cases are shown in Fig. 8 (a and b). (a) (b) Figure 8: (a) Maximum fluid shear stress of 20.4 MPa in blood flow near the stenotic vessel wall in 92% stenosis; the maximum shear stress in blood flow, as expected, is more than that of water; (b) Maximum fluid shear stress of 3.9 MPa, in blood flow near the stenotic vessel wall in 0% stenosis, is concentrated at the artery wall near entry; this is the favorable location for plaque deposition. If 120 mm of mercury column (systolic blood pressure) is considered as standard baseline reference in non-stenotic renal artery, the incremental blood pressure rise is found because of the presence of increasing extent of stenoses. And hence to obtain the values of corresponding secondary hypertension in column number 4 of TABLE 2. The respective % increase in ∆P (converting to mmHg), is simply added to 120 mm of Hg baseline pressure. Referring TABLE 2, Pressure difference (∆P) increases and therefore, if pressure at outlet is maintained constant, the pressure at inlet rises. TABLE 3, CFD study also revealed that there is loss of blood flow to kidney due to stenotic renal artery. Further, it is found that the increasing extent of stenoses reduces the downstream blood flow to kidney.
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 6340(Print), ISSN 0976 – 6359(Online) Table 3: CFD results indicating reduction in Blood flow to Kidney due to RAS % stenosis Area (mm2 ) 0 50.24 23 38.46 44 28.26 61 19.62 71 14.51 75 12.56 80 10.04 83 8.54 86 7.06 92 4.15 4. QUANTIFICATION TOOL TO RELATE RAS & RVH Considering the first determined flow of 18438.08 (mm and possibly 100 % blood flow to kidney (T of increasing stenosis section. Mapping the CFD results of reduced blood flow to kidney, shown in TABLE 3, by standard curve fitting techniques, mathematical mod Quadratic Polynomial Fit: y=a+bx+cx mathematic model of blood pressure rise based on varied extents of stenotic arterial sections now can be expanded by interpolation. Model thus developed can be shown as a simple graph as shown in Fig. 9. Similarly, a typical and convenient graph can also be presented as shown in how much less flow would be available for kidney for a specific extent o be very much helpful in determining the shrinkage to kidney and possible atrophy. Fig 9: A ready utility tool to diagnose probable Renal Artery Stenosis based on measured Blood International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 6359(Online) Volume 4, Issue 5, September - October 18 CFD results indicating reduction in Blood flow to Kidney due to RAS Max velocity (mm/s) Flow to Kidney (mm3 /s) % Reduction in flow % Blood flow finally available to kidney 367 18438 0 409 15732 15 480 13564 26 587 11519 38 690 10015 46 735 9231 50 819 8226 55 975 8334 55 1114 7870 57 1360 5647 69 QUANTIFICATION TOOL TO RELATE RAS & RVH Considering the first determined flow of 18438.08 (mm3 /s), for healthy section, as reference % blood flow to kidney (TABLE 3); the % reduction can be easily computed for rest of increasing stenosis section. Mapping the CFD results of reduced blood flow to kidney, shown in , by standard curve fitting techniques, mathematical model is researched to fit the data. Quadratic Polynomial Fit: y=a+bx+cx2 , appreciably maps the data and is found suitable. Expanded of blood pressure rise based on varied extents of stenotic arterial sections now can interpolation. Model thus developed can be shown as a simple graph as shown in Fig. Similarly, a typical and convenient graph can also be presented as shown in Fig how much less flow would be available for kidney for a specific extent of stenosis. These results could be very much helpful in determining the shrinkage to kidney and possible atrophy. A ready utility tool to diagnose probable Renal Artery Stenosis based on measured Blood Pressure International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – (2013) © IAEME CFD results indicating reduction in Blood flow to Kidney due to RAS % Blood flow finally available to kidney 100 85 74 62 54 50 45 45 43 31 /s), for healthy section, as reference ); the % reduction can be easily computed for rest of increasing stenosis section. Mapping the CFD results of reduced blood flow to kidney, shown in el is researched to fit the data. , appreciably maps the data and is found suitable. Expanded of blood pressure rise based on varied extents of stenotic arterial sections now can interpolation. Model thus developed can be shown as a simple graph as shown in Fig. Fig 10 to understand These results could A ready utility tool to diagnose probable Renal Artery Stenosis based on measured Blood
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 6340(Print), ISSN 0976 – 6359(Online) Fig 10: A derived quantification tool to determine probable reduction in blood flow To read and understand Fig. about 64% blood pressure (Secondary Hypertension 198 mm of Hg), about 55 % reduction of blood flow to kidney. It can be seen in receives only 45% of otherwise normal blood supp supplied to kidney. Therefore even without using any pressure measuring deice or flow measuring devices, a couple of simple and handy charts as given in Fig. 9 and Fig. 10 can be used as as a primary diagnostic tool. Some of research reviewed and a few medical experts when consulted and accepted the utility of the presented mathematical models. 5. CONCLUSION The CFD study of blood flow through stenotic models of RAS provides easy information to doctors dealing with patients of high BP. It is sort of handy clini general medical practitioners to diagnose RAS. The information could be used in the tabular or graphical form to conjecture the likelihood of RAS based on measured blood pressure of the patient. REFERENCES [1] G. Coen, S. Calabria, and S. Lai, Atherosclerotic ischemic renal, Diagnosis and prevalence in a hypertensive and/or uremic elderly population, [2] M.B. Harding, L.R. Smith, and S.I. Himmelstein, Renal artery stenosis: prevalence and associated risk factors in patients undergoing routine cardiac catheterization, vol.2, pp. 1608–16, 1992. [3] J.H. Rundback, D. Sacks, and K.C. Kent, Guidelines for the reporting of renal artery revascularization in clinical trials, [4] P.S. Watson, P. Hadjipetrou, S.V. Cox, T.C. Piemonte, and A.C. Eisenhauer, Effect o artery stenting on renal function and size in patients with atherosclerotic renovascular disease, Circulation, vol. 102, pp. 1671 International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 6359(Online) Volume 4, Issue 5, September - October 19 on tool to determine probable reduction in blood flow known percentage of RAS. Fig. 9 and Fig. 10, consider example of 80 % RAS, there is rise of about 64% blood pressure (Secondary Hypertension 198 mm of Hg), as seen in Fig. 9 duction of blood flow to kidney. It can be seen in Fig. 10. This demonstrates receives only 45% of otherwise normal blood supply i.e. instead of 1 LPM only 250 ml of blood is even without using any pressure measuring deice or flow measuring devices, a couple of simple and handy charts as given in Fig. 9 and Fig. 10 can be used as as a primary diagnostic tool. Some of research reviewed and a few medical experts when consulted and accepted the utility of the presented mathematical models. The CFD study of blood flow through stenotic models of RAS provides easy information to doctors dealing with patients of high BP. It is sort of handy clinical information to the general medical practitioners to diagnose RAS. The information could be used in the tabular or graphical form to conjecture the likelihood of RAS based on measured blood pressure of the patient. S. Lai, Atherosclerotic ischemic renal, Diagnosis and prevalence in a hypertensive and/or uremic elderly population, BMC Nephrology, vol.4, pp. 20 M.B. Harding, L.R. Smith, and S.I. Himmelstein, Renal artery stenosis: prevalence and associated risk factors in patients undergoing routine cardiac catheterization, J Am Soc Nephrol J.H. Rundback, D. Sacks, and K.C. Kent, Guidelines for the reporting of renal artery revascularization in clinical trials, J Vasc Interv Radiol., vol.14, pp. S477–92, 2003. P.S. Watson, P. Hadjipetrou, S.V. Cox, T.C. Piemonte, and A.C. Eisenhauer, Effect o artery stenting on renal function and size in patients with atherosclerotic renovascular disease, 1671-1677, 2000. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – (2013) © IAEME on tool to determine probable reduction in blood flow Kidney based on , consider example of 80 % RAS, there is rise of 9 and also there is 10. This demonstrates kidney ly i.e. instead of 1 LPM only 250 ml of blood is even without using any pressure measuring deice or flow measuring devices, a couple of simple and handy charts as given in Fig. 9 and Fig. 10 can be used as as a primary diagnostic tool. Some of research reviewed and a few medical experts when consulted have confirmed The CFD study of blood flow through stenotic models of RAS provides easy-to-use cal information to the general medical practitioners to diagnose RAS. The information could be used in the tabular or graphical form to conjecture the likelihood of RAS based on measured blood pressure of the patient. S. Lai, Atherosclerotic ischemic renal, Diagnosis and prevalence in a 20-26, 2003. M.B. Harding, L.R. Smith, and S.I. Himmelstein, Renal artery stenosis: prevalence and J Am Soc Nephrol, J.H. Rundback, D. Sacks, and K.C. Kent, Guidelines for the reporting of renal artery 92, 2003. P.S. Watson, P. Hadjipetrou, S.V. Cox, T.C. Piemonte, and A.C. Eisenhauer, Effect of, renal artery stenting on renal function and size in patients with atherosclerotic renovascular disease,
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 5, September - October (2013) © IAEME 20 [5] J. R. Cebral, P. J. Yim, Rainald Lohner, O. Soro and P. L. Choyke, Blood flow modeling in carotid arteries with computational fluid dynamics and MR Imaging. Academic Radiology, vol. 9 (11), pp. 1286-1299, 2002. [6] R. G. Woolfson, Renal artery stenosis: Diagnosis and management. Indian journal of heart, vol. 54, pp. 261-265, 2003. [7] V. Dehlaghi, M.T. Shadpoor, and S. Najarian, Analysis of wall shear stress in stented coronary artery using 3D computational fluid dynamics modeling, Journal of materials processing technology, vol. 197, pp. 174-181, 2008. [8] K. Hassani, M. Navidbakhsh and M. Rostami, Modeling of the aorta artery aneurysms and renal artery stenosis using cardiovascular electronic systemModeling of AAA and RAS, Biomedical Engineering online, pp. 6-22, 2007. [9] S.F. Henry, Simulation of flow through model stented arteries, In: Proceedings of the ASME BED Bioengineering Conference, vol. 50, pp. 329–330, 2001. [10] O.R. Bude, R.A. and Forauer RA, Is it necessary to study accessory arteries when screening the renal arteries for renovascular hypertension? Journal of radiology, vol. 226 (2), pp. 411-416, 2003. [11] A. Valencia, and M. Villnueva, Unsteady flow and mass transfer in models of stenotic arteries considering fluid structure interaction, International communication in heat and mass transfer, vol. 33, pp. 966-975, 2006. [12] V.V. Shukla, P. M. Padole, Dr. S. Deshpande, Dr. H. M. Mardikar, “Secondary Hypertension manifests Renal artery Stenosis and weakened kidney”, Journal of Mechanics in Medicine and Biology.Vol 11,Issue 1, PP 73-100, 2011. [13] Dr.Muhanned Alfarras, “Early Detection of Adult Valve Disease–Mitral Stenosis using the Elman Artificial Neural Network”, International Journal of Computer Engineering & Technology (IJCET), Volume 3, Issue 3, 2012, pp. 255 - 264, ISSN Print: 0976 – 6367, ISSN Online: 0976 – 6375. [14] Atul Pradhan, Vidushi Kapoor, Sanjay Kumar, Prateek Tandon and Priyanka Kumari, “Analytical Techniques used for Disease Diagnosis–Invasive and Non-Invasive Tools”, International Journal of Advanced Research in Engineering & Technology (IJARET), Volume 4, Issue 1, 2013, pp. 9 - 27, ISSN Print: 0976-6480, ISSN Online: 0976-6499. [15] Rajneesh Kakar, Kanwaljeet Kaur and K. C. Gupta, “Viscoelastic Modeling of Aortic Excessive Enlargement of an Artery”, International Journal of Mechanical Engineering & Technology (IJMET), Volume 4, Issue 2, 2013, pp. 479 - 493, ISSN Print: 0976 – 6340, ISSN Online: 0976 – 6359.