Estimation of Mound Height in Endoscopic Treatment of VUR

Estimation of megabucks Height in Endoscopic manipulation of VURA Numerical Study to Precise the Estimation of the Good Mound Height in Endoscopic preaching of VURAuthor(s)Mehdi Shirazi1, Zahra Jahanabadi2, Zeinab Hooshyar5, Zahra Mortazavinia4, Alireza Mehdizadeh3, Mojtaba Taherisadr6AbstractPurpose it seems that in that location is no de bounded and standard mightiness to ascertain the technique and record of shooter in severalise to growing the victory sum up of endoscopic VUR interference. In this study, we introduced a novel manner to quantitatively jell the human human relationship amid virtually indexes in order to determine optimal twirler bloom promise to standardize the scene technique in this kind-hearted of word.Material and method The of import purpose of this study is to construct a finite fragment seeming of internal ureter and injected atomic reactor which aims to numeric every(prenominal)y go down the relationship between indexes which admit influence in VUR endoscopic interposition. utilize linearization software and numerically simulation data the relationship between strong indexes has been derived.Result By linearization of the effective parameters of assorted finite component part models, the relationship between effective parameters in filling phase is derived as H=0.7456D+ 0.02174L +0.01846. This equation depicts commensurate injected mickle vizor as a manoeuver of midland diameter and internal space, H=f(L,D). cultivation Using numerical simulation, we introduced the novel formula to foreshadow the tip of injected good deal in endoscopic VUR treatment. As a vector sum of this study, in order to step-up the triumph rate of this treatment, the ratio of mountain upside to internal ureter diameter should be approximately 74% (3/4).Keywords Mound height, Endoscopic treatment, Vesico ureteral ebb, Finite element modelIntroductionVesico ureteral ebbing (VUR) is a major disorder of puerilit y declared by retreat weewee flow from the bladder toward the kidney, predisposing affected roles to UTI and nephritic scarring and in long term leading to renal insufficiency and hypertension1. afoot(predicate) treatment options include close observation with urinary chemoprophylaxis, token(prenominal)ly encroaching(a) endoscopic subureteral injection of bulking agents and open or laparoscopic reimplantation2. The prophylactic antibiotic ascend is proper for uncomplicated wane (grade I-III without planetary houseificant renal scarring or find infection)3. This type of treatment doesnt cure VUR and has some problems such(prenominal) as patient noncompliance and increased antibiotic resistance4.Surgical reimplantation of the ureter is an invasive method5 and already used for patients with high grade reflux, children with breakthrough UTI and children with reflux and developed renal scarring6. Endoscopic subureteral injection of bulking agents was introduced by Matouscheck as an evolution in treatment of reflux with a high winner rate and minimal invasion6, 7. The way used as a bulking existent should be biocompatible, nonantigenic, nonmigratory and non-toxic with minimal local inflammation8. Multiple techniques on injection have been described. These methods include subureteral needle placement8, intraureteral needle placement9, 10 or some combinations of these. During new-fashioned years, several studies have been through with(p) to determine success or failure of endoscopic treatment, and various injection techniques have been introduced. Puri et al., described release appearance as the main sign of success of injection11. The proper shape was demonstrated by adequate coaptation of the ureteral hatchway and by its location in the bladder below the ureteral opening and/or along the waldeyers sheat12, 13.Despite all the studies carried out to determine the success or failure of endoscopic treatment, such as description of volcano appearance, i njection technique in combination with hydrodistention, increasing injected volume, use of intraoperative cystogram with a simulated riddance phase, at that place is no clear and standard index to ascertain the technique and volume of injection in order to increase the success rate. In this study, we introduced a novel method to numerically define the relationship between some indexes in order to determine optimum atomic pile height promise to standardize the injection technique.Materials MethodIn this study, a computational simulation was proposed to simulate the intramural ureter and injected mound which aims to numerically define the relationship between indexes which have influence in retrograde urine flow from intramural ureter.Geometry of the numerical modelFig. 1 illustrates delineated representation of the functional habitus of the ureterovesical junction and urinary anti reflux mechanism as the accumulation of urine within the bladder leave lead to the tight result of the portion of the ureter in between, thus preventing the regardant(postnominal) return of urine to the kidneys, urinary anti reflux mechanism. In Fig. 1, P, D, H and L are intravesical contract, intramural ureter diameter, injected mound height, and intramural ureter duration, respectively. Section A in Figure 1 depicts the cross section of the intramural ureter with injected mound. The geometrical data of intramural ureter and ureterovesical junction were apply as per Table 1.Materials Properties and sharpness ConditionsMaterial properties for the intramural ureter wall were assumed to be linear elastic, isotropic, incompressible, and consistent with Youngs modulus of 10 Kpa 18. The injected mound was modeled as a rigid volume as shown in Fig.3. The boundary conditions for the wall were (1) the throne surface of intramural wall was fixed at the connection to the inhering bladder wall. (2) The upper wall was assumed to be free such that the deformation would occur due to the intravesical atmospheric wring and contri stille to the tight period of the portion of the ureter in between.Solution MethodThe ANSYS 11 software was industrious to simulate the intramural ureter with injected mound in voiding phase. The intravesical pressure was use on the upper portion of the intramural wall. The upper bound of intravesical pressure was considered to be 160 CmH2 O to encompass both male and female person intravesical voiding pressures15, see Table 1. The 8-Node structural solid mesh has been utilized in finite element model to have adequate adoption with this geometry and material behavior.3 ResultsFig. 2 illustrates the total deformation of the intramural ureter with injected mound in voiding phase. As shown, the intramural ureter has been closed due to the intravesical pressure. Fig. 3 shows the deformed and undeformed intramuralwall in re perplex and voiding phase. As shown, in voiding position the injected mound height is high enough for the intramura l ureter to be closed due to the intravesical pressure and prevents retrograde urine flow.In the first attempt, keeping the intramural ureter length constant, by ever-changing intravesical pressure and internal diameter, the adequate injected mound height leading to tight closure of intramural ureter was obtained.By linearization of the effective parameters of about 30 different finite element models, the primary relationship between injected mound height, intravesical pressure and internal diameter of intramural ureter was defined as bellow, H=f(D,P)H=-0.0000003219P+0.7864D+0.000233(4) concord to this relationship, it has been inferred that intravesical pressure coefficient is minute in comparison with coefficient of other effective parameters and it shows that changing the intravesical pressure plays an in real role in adequate injected mound height.In order to investigate the more effective indexes on injected mound height, the intramural length has been considered as one of vari able parameters in finite element modeling. Varying internal diameter, intramural length and linearization of obtained data, the relationship between parameters was derived asH=0.7456D+ 0.02174L +0.01846(5)This equation depicts optimum mound height as a function of internal diameter and intramural length, H=f(L,D).4DiscussionEndoscopic treatment of VUR was introduced more than 25 years ago and since then many different substances and injection techniques have been used with different results13. Choosing endoscopic treatment is reasonable, as it has many advantages, such as technical simplicity, greater acceptance of patients and parents and significant decrease in post- operation complications7. By improving the injection techniques the rate of endoscopic treatment has significantly increased as compared with open ureteral reimplantation2. During the recent years, many studies have been done to increase the ability to identify factors predicting success with the endoscopic subureter al injection19. At 2003, Puri et al.11 described volcano appearance as the main sign of success of injection. The proper shape was demonstrated byadequate coaptation of the ureteral orifice and by its location in the bladder below the ureteral orifice and/or along the waldeyers sheat12.In different studies conducted by Lavelle et al.12 and Yucel et al. 20, it was institute that a subjectively proper mound appearance was highly prognosticative of injection success, but it should be noned that the morphology and location of the mound are not perfectly predictive of injection success or failure, as the mound seems perfectly adequate in some injections but the injection is not successful also, the imperfect mound morphology does not necessarily imply injection failure12. Moreover, Ellworth PI et al. showed no correlation between the presence of a mound on post-injection ultrasound and the success of injection19. round research agrees that an intraureteral injection technique in combi nation with hydrodistention results in high success rates but this is controversial9,10,20,21. The effect of injected volume on increasing the success rate is also controversial. Mathew D et al. showed that increasing the injection material volume will improve the success of subureteric injection22 but other centers have shown that higher injection material volume doesnt necessarily increase the treatment success rate21. So the effect of the injected volume in sleeper with improved success rate remain unclear12.To determine the treatment success or failure, Tarry WF et al. described the utility of an intraoperative cystogram with a simulated voiding phase, but they demonstrated that an introperative cystogram can only detect de novo contralateral reflux but is not a proper method to predict the final success of injection6. Despite all the mentioned studies, still there is no definite and standard index to ascertain the technique and volume of injection, and also there is no quant itative index for determining the proper mound size and shape. So, we have conducted a study aiming to define an optimum injection mound by finite element modeling.In this study, we introduced a novel method to numerically define the relationship between some indexes in order to determine optimum mound height promise to standardize the injection technique in VUR treatment. It should be noted that due to every patient individual properties of intramural, it is not logical to consider similar injected mound height for all VUR treatment cases. Thus, it is needed to state the adequate injected mound height based on individual indexes of each case. The Intravesical pressure, intramural ureter diameter and length are some of these effective indexes. By specifying the relationship between all of these effective factors, the adequate and optimum injected mound height can be determined which can contribute to more success in treatment of VUR. In addition, it can help to save the needed inje cted mound height and make this injection method more economical.The results of this study show that the intravesical pressure has an insignificant effect on the required injected mound height. However, intramural length plays an important role on it in comparison with Intravesical Pressure. Moreover, the ratio of mound height to intramural ureter diameter is approximately 0.74 (3/4), which is drawn that in order to have successful VUR treatment, it is needed that about 74% of intramural ureter diameter be filled with the injected mound.It should be mentioned that in Department of urogenital medicine of Shiraz University for the first time, an innovative method, introduced by Taheri et al.23, is used to measure the injected mound height to assure the adequate injected mound height. In this method by adjusting camera, laparoscopy electron lens and imaging screen, it would be possible to measure the injected mound height as a ratio of projected picture on the screen.This study has se rved some point of accumulation. The realistic cross section of intramural ureter has star shape. However, because of some limitation in finite element modeling, the circular one considered. Furthermore, we considered computational simulation only in voiding phase, although VUR may occur in resting phase.ConclusionIn this study using numerical simulation, we introduced the novel formula to predict the height of injected mound in endoscopic VUR treatment. As a result of this study, in order to increase the success rate of this tevhnique, the ratio of mound height to intramural ureter diameter should be approximately 74% (3/4). Moreover, clinical study has been conducted to ascertain the accuracy of this obtained height.Fig. 1Diagrammatic representation of the functional anatomy of the ureterovesical junctionFig. 2Intramural ureter displacement in voiding phaseFig. 3Deformed and undeformed intramural urine wallReferencesLenaghan, D., et al., The natural history of reflux and longterm effects of reflux on the kidney. J Urol, 1976.115(6) p. 728-30.Cerwinka, W.H., et al., Radiologic features of implants later endoscopic treatment of vesicoureteral reflux in children. AJR Am J Roentgenol, 2010. 195(1) p. 234-40.Harper, L., et al., Postoperative cystography and endoscopic treatment of lowgrade vesicoureteral reflux. J Laparoendosc Adv Surg Tech A, 2008. 18(3) p. 461-463.Hsieh, M.H., et al., Treatment of Pediatric Vesicoureteral Reflux Using Endoscopic jibe of Hyaluronic Acid/Dextranomer mousse Intermediate-term Experience by a Single Surgeon.j urology, 2010. 76(1) p. 199-203.Elder, J.S., et al., Pediatric Vesicoureteral Reflux Guidelines table Summary Report on the focus of Primary Vesicoureteral Reflux in Children. j urology, 1997. 157(5) p. 1846-1851.Perlmutter, A.E., et al., Utility of an intraoperative cystogram with a simulated voiding phase after endoscopic treatment of vesicoureteral reflux. W V Med J, 2008. 104(4) p. 22-4.Rivilla, F., Endoscopic treatme nt of vesicoureteral reflux in a paediatric surgery ambulatory unit. Vol. 7. 2011.132-5.Bae, Y.D., et al., Endoscopic Subureteral blastoff for the Treatment of Vesicoureteral Reflux in Children Polydimethylsiloxane (Macroplastique) versus Dextranomer/Hyaluronic Acid Copolymer (Deflux). Korean J Urol, 2010. 51(2) p. 128-131.Gupta, A. and W. Snodgrass, Intra-Orifice Versus Hydrodistention implantation Technique in Dextranomer/Hyaluronic Acid Injection for Vesicoureteral Reflux. J urology, 2008. 180(4) p. 1589-1593.Kirsch, A.J., et al., The modified sting procedure to correct vesicoureteral reflux improved results with submucosal implantation within the intramural ureter. J urology, 2004. 171(6 Pt 1) p. 2413-2416.Puri, P., et al., Treatment of Vesicoureteral Reflux by Endoscopic Injection of Dextranomer/Hyaluronic Acid Copolymer Preliminary Results. J urology, 2003. 170(4) p. 1541-1544.Routh, J.C. and Y. Reinberg, Predicting Success in the Endoscopic Management of Pediatric Vesicoure teral Reflux. Uro, 2010. 76(1) p. 195-198.Lavelle, M.T., M.J. Conlin, and S.J. Skoog, Subureteral injection of Deflux for correction of reflux Analysis of factors predicting success. Uro, 2005. 65(3) p. 564-567.Yeung CK, G.M., Duffy PG, Ransley PG., Nat