Effects Of Alpha-Blocker On Ureteral Dynamics With And Without A Ureteral Stone: An In Vivo Porcine Study

Main Category: Urology / Nephrology
Article Date: 20 Jun 2008 - 1:00 PDT

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ORLANDO, FL (UroToday.com) - Medical expulsive therapy for ureteral calculi has been established in several randomized controlled clinical trials. However, the exact mechanism of action and the extent of their influence on renal pelvic and ureteral dynamics has not been elucidated.

In a novel model, Das and colleagues from Saint Louis, Missouri studied the effects of an oral alpha blocker (alfuzosin HCL) on ureteral peristalsis, intrapelvic pressure (IPP) and stone movement. Twenty four domestic pigs were randomized to 4 groups (6 animals in each group). Group 1: Controls with normal ureter, Group 2: animals with ureteral stone and no -blocker therapy, Group 3: animals treated with an alpha blocker but had no ureteral stone, and Group 4: animals that were given an alpha blocker and had a ureteral stone. Ureteral peristalsis was studied by a magneto-resistive sensor and EMG electrodes deployed on the extraluminal ureteral surface through a lumbotomy incision under GA. The IPP was measured by a pressure transducer in the renal pelvis. Alfuzosin, 10mg, was given orally 2 days before the experiment and serum drug level was measured after 48 hours. Ureteral dynamics including urine output was recorded before and 6 hours after placement of a 6mm radio-opaque stone in the proximal ureter. Stone movement was monitored using digital fluoroscopy.

Their results showed that mean peristaltic rate before and after stone placement was 9(8-15) and 14(7 - 19)/10 min. respectively, in those without alpha blocker therapy. The peristalsis rate in pigs with -blocker therapy with and without ureteral stone was 11(5 - 24) and 7(5- 14)/10 min. respectively (p=0.1). Following stone placement, there was a mean increase in IPP in all the animal groups with or without alpha blocker therapy (p=0.03). There was no significant difference in stone movement (mean 3cm) in any of the 4 groups during the observation period of 6 hours. They concluded that in the group without a ureteral stone, there was decrease in IPP and a minimal decrease in peristalsis following alpha blocker therapy. However, with a stone in the ureter there was an increase in IPP and peristalsis rate in both animal groups with or without alpha blocker therapy.

This porcine in vivo model of alfuzosin alpha blocker therapy on the ureter with a stone shows a novel model to determine the efficacy of alpha blocker therapy. Unfortunately, the lack of any significant difference between the stone and no stone groups may be because of the short duration of observation.

Presented by Ramakrishna Venkatesh, MD, et al., at the Annual Meeting of the American Urological Association (AUA) - May 17 - 22, 2008. Orange County Convention Center - Orlando, Florida, USA.

Reported by UroToday.com Contributing Editor Michael K. Louie, MD

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