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. 2017 Nov 18;8(1):117-125.
doi: 10.1007/s13534-017-0053-0. eCollection 2018 Feb.

A computational model of ureteral peristalsis and an investigation into ureteral reflux

G Hosseini  1 , C Ji  2 , D Xu  2 , M A Rezaienia  1 , E Avital  1 , A Munjiza  3 , J J R Williams  4 , J S A Green  5
Affiliations

A computational model of ureteral peristalsis and an investigation into ureteral reflux

G Hosseini et al. Biomed Eng Lett. .

Abstract

The aim of this study is to create a computational model of the human ureteral system that accurately replicates the peristaltic movement of the ureter for a variety of physiological and pathological functions. The objectives of this research are met using our in-house fluid-structural dynamics code (CgLes-Y code). A realistic peristaltic motion of the ureter is modelled using a novel piecewise linear force model. The urodynamic responses are investigated under two conditions of a healthy and a depressed contraction force. A ureteral pressure during the contraction shows a very good agreement with corresponding clinical data. The results also show a dependency of the wall shear stresses on the contraction velocity and it confirms the presence of a high shear stress at the proximal part of the ureter. Additionally, it is shown that an inefficient lumen contraction can increase the possibility of a continuous reflux during the propagation of peristalsis.

Keywords: CFD; PUJ; Reflux; Ureter; VUJ; VUR.

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Conflict of interest statement

None.All scans showing the whole ureter with normal anatomy were anonymised and chosen at random from a larger educational set.

Figures

Fig. 1
Fig. 1
a Cropped 3D model of the right ureter and bladder, b the combined fluid and solid domains of the ureter
Fig. 2
Fig. 2
The non-linear stress–strain relationship of the ureteral wall data, extracted from Yin and Fung [2] and an exponential function matched to this data and implemented in the structural code
Fig. 3
Fig. 3
The piecewise linear function evaluated at t for different sections in the ureter
Fig. 4
Fig. 4
The IAP algorithm
Fig. 5
Fig. 5
Comparison between the two simulations in the absence (a) and in the presence (b) of the IAP
Fig. 6
Fig. 6
Contractions A and B which mimic pacemaker activities in the proximal and distal part of the ureter, Z is the distance along the ureter
Fig. 7
Fig. 7
a The pressure time evolution using the PLFM in comparison with the experimental data extracted from the study by Kiil [20]. b The deformation of a cross-section over the same period of contraction time, where R is the radial displacement of the cross-section in cm
Fig. 8
Fig. 8
Longitudinal distribution (cm) of wall shear stress (Barye) that was computed with a pressure difference of 0.6 cm H2O (healthy condition)
Fig. 9
Fig. 9
The average velocities of urine in the ureter using the model (t = 0.5, 1.25, 2.0 s) in the healthy condition
Fig. 10
Fig. 10
The urine velocity vectors behind the moving Contraction A at t = 0.5 s
Fig. 11
Fig. 11
Instantaneous velocity profiles in Contractions A and B for the simulation of the unhealthy condition
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References

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