Second prize: In-vivo physiological impact of alpha blockade on the porcine ureter with distal ureteral obstruction.

PURPOSE

Alpha blockade has been well described clinically for expulsion of distal ureteral stone. However, the in-vivo effects of α-blockade on ureteral dynamics during stone passage are not clear. We studied the effects of oral alfuzosin on ureteral pressure and peristalsis in a distally obstructed porcine ureter.

METHODS

Twenty-four female domestic swine (75-82 kg) were incorporated into the study. The study was powered to detect a 30% difference in distal ureteral pressure, with a secondary endpoint of frequency of ureteral peristalsis. The animals were divided into four equal groups: a control group without α-blockade or ureteral obstruction, a group with α-blockade and no ureteral obstruction, a cohort without α-blockade but with distal ureteral obstruction, and a group with α-blockade and distal obstruction. Peristalsis was measured by a magnetic sensor and ureteral pressure through a 5F ureteral balloon catheter. Observations were recorded for 10-minute intervals every hour for 5 consecutive hours.

RESULTS

There was increase in ureteral pressure and peristaltic rate with distal ureteral obstruction (p < 0.01). Alpha blockade did not produce significant changes in the above parameters with or without ureteral obstruction compared with the nonmedicated groups. We observed a 0.2 mm Hg lower increase in change of ureteral pressure during peristalsis compared with resting ureteral pressure (delta pressure) in the treated obstructed model (95% confidence interval: -0.55 -0.10; p = 0.06).

CONCLUSIONS

In the porcine model, alfuzosin appears to decrease the delta pressure in the distal ureter during obstruction; however, statistical significance was not reached. Further investigation into the in-vivo physiology of medical expulsive therapy is warranted.