[Characteristics of the hydrodynamic situation in the urinary tract in vesico-ureteral reflux based on an analysis of a general type of equation of the linear transport model].

Upper urinary tract urodynamics are described through a linear deterministic chamber model. An analysis of possible urodynamic variants in vesico-ureteral reflux (VUR), using a mathematical model, has suggested that hydrodynamic situation in the refluxing ureter will be dependent on vesical and ureteral activity where ureterovesical incompetence and VUR are of similar grades. Where ureteral anatomy and function remain fairly intact, urinary regurgitation under high pressure shall be accompanied by the development of a considerable intraureteral hypertension. Besides, VUR-associated urodynamic disorder must have an obstructive component whose markedness will depend on the extent of arterial motor impairment, intravesical hypertension or a combination of the two. Urodynamic and radioisotopic studies have completely confirmed the theoretical postulations. In second- or third-degree VUR, for example, the highest intraureteral pressure developed in children with uninhibited bladder, while in fourth-degree VUR the bladder showed no response to gradual intravesical pressure rise. Urodynamic disturbance was already shown to have a functional/obstructive component in those cases of second-degree VUR where the bladder was uninhibited and be free of it in cases of normal bladder reflex and third-degree VUR.