Effect of Balloon Catheter Dilatation of the Ureter on Upper Tract Dynamics and Ureteral Wall in Swine*

Abstract

Ten male pigs underwent balloon dilatation of the right ureter to three times its normal caliber during either infusion of IN saline (0.5,2, or 4 ml/min) or induced diuresis to a urine flow rate of 4 ml/min with the bladder open. There was no significant difference between the resting pelvic pressure (P_pvs) and the P_pvs on either the control and the dilated side immediately after dilatation except at a flow rate of 4 ml/min on the dilated side. Also, on the dilated side, the resting P_pvs was normal at 1 week, but there was a statistically significant increase in P_pvs (P = 0.02; Student's t test) when the system was challenged with a saline infusion. At 6 weeks, this obstructive change had disappeared except at a flow rate of 4 ml/min. Histologic and ultrastructural findings were confirmatory, with extensive damage 1 week postdilatation and nearly complete repair by 6 weeks. The results point to the importance of ureteral sten ting after dilatation and imply that patients should delay increasing their fluid intake for approximately 6 weeks. The results also suggest that the dilated ureter heals both by ingrowth of muscle fibers from the edge of the ruptured area and by regeneration by pluripotent fibroblasts.