Newer devices, drugs simplify stone disease treatment

May 15, 2007

A new generation of devices and medical therapies is simplifying the treatment of kidney stone disease and allowing urologists to be more effective at treating stone disease.

"With the recent shift away from shockwave lithotripsy, there is an increase in endoscopic procedures for the treatment of stone disease," said David M. Albala, MD, professor of urology at Duke University Medical Center, Durham, NC. "Flexible endoscopes and Holmium laser lithotripsy are two technologies that have really changed the way renal and ureteral stones are treated in 2007."

The new generation of ureteroscopes is smaller and more flexible. The 7.5F ureteroscopes have dual deflection and are more durable than they have been in the past, according to Dr. Albala. New instruments with smaller 1.9F nitinol baskets reduce the amount of lost deflection of the ureteroscope, allowing greater access to the lower part of the kidney. These scopes can be passed up the ureter, and, when used in combination with the Holmium laser, can fragment stones effectively to render patients stone-free.

The disadvantages of this laser are that the drilling action on stones can be time consuming for hard, large calculi, and there is greater chance of mucosal injury on the ureteral wall if the surgeon is not careful with this device.

Ureteral access sheaths represent another major innovation. The sheaths allow the scope to pass through without damaging the walls of the ureter.

"These access sheaths gently dilate the ureter," Dr. Albala said. "The sheath protects the ureteral wall, minimizing potential trauma or complications. You also get better stone-free rates when you use the sheath in comparison to [rates in] patients who don't have the sheath at the time of stone removal."

At Duke, a retrospective analysis of 256 ureteroscopic cases for the management of renal calculi was done to evaluate the effect of ureteral access sheaths on stone-free rates. The stone-free rate in the ureteral access sheath group was 79% compared to 67% in the non-sheath group. The study also found that the sheaths facilitated ureteroscopic access, lowered intrarenal pressures, and reduced overall costs (Urology 2005; 66:252-5).

Another helpful device is the stone cone, nitinol and stainless wires that are configured into an expandable tapered cone. This device was developed by Stephen Dretler, MD, of Massachusetts General Hospital, Boston.

"It is passed above the stone in the ureter, and the laser is then used to break up the stone," Dr. Albala explained. "After the stone is broken up into smaller pieces, you can pull the stone cone down, and the fragments are pulled out as it unravels. This device prevents stone migration, which can be a common problem during laser lithotripsy. It has been a nice addition to the armamentarium of tools that we already have."

For stones that don't pass spontaneously or for patients who prefer medical intervention, there are a number of medical therapies that can facilitate the process. The standard treatments are alpha-blockers for distal ureteral stones and nifedipine (Adalat, Afeditab CR, Procardia) for upper ureteral stones.