Dynamics of the ureterovesical junction; effectiveness of its ureteral peristalsis in high pressure pig bladders.

In pigs, the effectiveness of ureteral peristaltic fluid discharge from the ureterovesical junction at high intravesical pressures was evaluated by ureterovesical perfusion pressure (UVPP) measurements and continuous endoscopic observation of the ureteral orifice during cystometry. Basal UVPPs either remained low, or were elevated but then intermittently could be reduced to near pre-bladder-filling levels at the end of the peristaltic pressure waves during which fluid was discharged from the ureteral orifice. Reductions of elevated basal UVPP correlated with the volumes of the associated discharged fluid boluses and with the perfusion times until such decreased basal UVPP again reached the elevated level it had before the peristaltic pressure waves. Even an elevated juxtavesical basal ureteral pressure which was already well below high intravesical pressure could be further reduced to near normal level after a ureteral peristaltic contraction which was accompanied by fluid discharge from the ureteral orifice. The clinical implications of these findings are discussed.