Abstract
Many researchers and urologists are presently studying different designs of ureteral stents to advance the feature of their surgeries and the succeeding recovery of the patient. With the aim of help during this design procedure, several computational models have been established to simulate the performance of various biological tissues and deliver an accurate computational environment to estimate the stents. As a result of the high difficulty of the complicated issues, they generally introduce interpretations to create these simulations a smaller amount computationally trying. A DJ stent (double J) is used to improve the blocking of urine in the upper urinary tract while there is ureteral stenosis, which causes the disturbance of normal urine flow and affects renal or kidney failure. The intention of employing a DJ stent is to confirm enough urine flow in the ureter, but the DJ stent performs as a foreign body in the urinary tract and sometimes acts as a difficulty in achieving satisfactory urine flow.
TopIntroduction
At the time of normal urination, urine flows or streams from the kidney to the urinary bladder via ureter in normal fit persons for two causes: (a) the peristaltic movement or peristalsis, and (b) a physical event (Matloubiech et al., 2020). Several usual pathologies which can block or obstruct the ureters are urinary stones or renal stones, infections, tumorous tissues, or inflammations (Park et al., 2020). These difficulties can decrease or even make problems with the normal urination and cause more severe malfunctions or pathologies and threats for patients (Modi et al., 2019). To resolve these difficulties, two dissimilar treatments are generally performed, for example, (a) nephrostomy which provisionally helps to open the urinary tract portion by an external flexible thin tube or catheter, and (b) ureteral stenting technique which attachments a flexible thin tube named stent into the ureter that helps the drain urine from the kidney. Both methods accomplish repairing the urine flow, reducing intra-pelvic stress, and avoiding kidney failure. In the processes while a stent is applied in obstructed ureters, a continuing loss of muscle tone happens due to this ureter stent (Kinn et al., 2002) (Demzik et al., 2021) and the ureter does not create the peristaltic function anymore. Hereafter, stented ureters are merely affected by the pressure gradient.
Figure 1.
Refine the 3D model from MRI/CT image
At present, all these conducts are experienced and improvedbyapplying the investigational models that permit mimicking exact precisely the physiological performance under dissimilarboundary circumstances. For urologic investigation, a pig is assumed as the perfect model, because its features (kidney and urethral anatomy and physiology) related to humans (Leonhäuser et al., 2019). Though, a number of studies are complicated or impracticable to be conducted with experimentaltests for dissimilarcauses: dimensionlimitations, ethical concerns, instrumental constraints, etc. Therefore, FEM (finite element models) and another computational software representation have been initiated as a model analysis of the urine flow and for supporting in the design and improvement of innovative ureteral stents (Beysens et al., 2018) (Al et al., 2020) (Oliver et al., 2018). Figure 1 shows flow chart of the procedure of refine the 3D model making. Various experiments have conducted to achieve the biomechanical characteristics of the urethral wall (Taguchi et al., 2018). Different ex-vivo examinations have performedby Yin et al., 1971to find the stress-strainresults of a ureter and describe its biomechanical performs. Afterward, in-vivo characteristics were executed by Sokolis et al., 2012, and presenting the anisotropic performance of ureters that demonstrated with a four-factor Fung-type strain energy function. Figure 2 shows the (a) CT image of urinary system, and the 3D model of (b) front, (c) side view of urinary system. Furthermore, Rassoli et al., 2014 presented important data of human ureter stress-strain results fixed with a four-constraint Fung-type representation and five- constraint polynomial models.
Figure 2.
(a) CT scan image of urinary system, and 3D model (b) Front view (d) Side view
Key Terms in this Chapter
CFD: Computation fluid dynamics (CFD) models effort to simulate the collaboration of gases and liquids where the surfaces are described by boundary situations.
Kidney Stone: Rigid bonds/deposits formed by salts and minerals inside kidneys, it is also known as renal calculi. Excess body weight, improper diet, various medical disorders, and certain medications and supplements are among the several reasons of kidney stones.
Hematuria: Blood in urine is known as a hematuria. The causes of hematuria include inflammation of the kidney, bladder, urethra, kidney or bladder cancer, polycystic kidney disease, and or prostate infection etc.
UTI: An infection of the urinary tract system, also known urinary tract infection. UTI can involve kidneys which is known as pyelonephritis, urethra which is known as urethritis, bladder which is known as cystitis.
DJ Stent: Ureteral DJ or double-J stents are normally used to release ureteral blockade and commonly as a routine part of the Ureteroscopic processes by urologist surgeons. The placement of DJ stent has the possible side effects for instanceurinary tract infection (UTI), flank pain due to backward urine flow.
Urology: A clinical and surgical specialty which deals with the treatment of situations concerning the urinary tract of male and female, and the reproductive organs of male.