Michael Ferrandino, MD

Various aspects of shock wave lithotripsy (SWL) were the focus of several abstracts presented at the World Congress of Endourology & SWL here. Data from one U.S. group seemed to suggest, however, that SWL's "gold standard" offers better stone fragmentation and clearance than at least one newer device. 

Separately, researchers reported beneficial effects of using an escalating voltage SWL strategy. 

A comparison study from Washington University School of Medicine in St. Louis retrospectively evaluated 129 consecutive patients who had undergone SWL with either the unmodified Dornier HM3 (Dornier MedTech America, Kennesaw, GA) or the Modulith SLX-F2 (Karl Storz, Kennesaw, GA). Seventy-one patients were treated with the HM3 and 58 with the Modulith SLX-F2. Patients were classified as either stone free/having asymptomatic fragments ≤2 mm or as having asymptomatic residual fragments ≤4 mm, based on kidney, ureter, or bladder (KUB) x-ray or computed tomography imaging at 6 weeks and at 3 months after treatment with SWL. 

The auxiliary procedure rate was 11% for the HM3 group versus 25% for the SLX-F2 group (

=.09), whereas 5.8% of those treated with the HM3 required re-treatment compared to 3.8% for those treated with the Storz device (

The investigators concluded that the "gold standard" HM3 demonstrates better stone fragmentation and clearance compared to the SLX-F2 and that "success" should be better defined. 

A study from the Columbia University Medical Center, New York, examined both the stone-free rate and the renoprotective effects of voltage escalation on 40 patients with similar age, sex distribution, and stone size (median, 8 mm) who were undergoing SWL. Patients were divided into two groups. Those in a dose escalation protocol were subjected to 500 shocks at 14 kV, 1,000 shocks at 15 kV, and 1,000 shocks at 16 kV; those randomized to undergo a fixed strategy received 2,500 shocks at 16 kV. 

Stone-free rate (defined as <2-mm fragments) was assessed by KUB x-ray. Renal injury was evaluated by measurement of beta-2 microglobulin and microalbumin before treatment, immediately after treatment, and 1 week after treatment. 

At 3 months, 89% of the patients in the voltage escalation group were stone-free compared to 48% in the fixed voltage group (

<.05) at 3 months, reported lead author Mantu Gupta, MD, director of the New York-Presbyterian Hospital Kidney Stone Center and director of endourology at Columbia.  

No significant differences were noted in markers of renal parenchymal injury in the immediate postoperative period; however, urinary microalbumin measured at 1 week post-SWL approached statistical significance (

"Dose escalation demonstrates better stone fragmentation and potentially provides protection from renal parenchymal damage due to shock wave lithotripsy," Dr. Gupta explained. 

Articles

Various aspects of shock wave lithotripsy (SWL) were the focus of several abstracts presented at the World Congress of Endourology & SWL here. Data from one U.S. group seemed to suggest, however, that SWL's "gold standard" offers better stone fragmentation and clearance than at least one newer device.

'Gold standard' lithotripter wins clearance comparison

The World Congress of Endourology & SWL proved to be a fertile platform for technological advancements in ureteroscopy. Three studies in this area were particularly noteworthy. 

Thirteen patients underwent ureteroscopic stone fragmentation combined with administration of the BackStop polymer. Twelve were stone free after one sitting, and in only one patient did the stone migrate through the gel. The polymer was effectively irrigated out of the ureter at the end of all procedures, leaving no residual occlusion. The surgeons rated the visibility as good but said the polymer can be difficult to see. 

Dr. Rane and colleagues are trial investigators for Pluromed. 

Another advance that has become an integral part of endourology is the application of robotic technology, and Cleveland Clinic urologists have begun exploring the incorporation of robotics into ureteroscopy. Co-author Monish Aron, MD, a clinical faculty member in advanced laparoscopic urology, presented Cleveland Clinic's initial clinical experience with flexible robotic ureteroscopic laser lithotripsy (Hansen Medical, Mountain View, CA). This abstract was awarded Best Overall Paper at the World Congress. 

The device is based on a flexible robotic catheter system originally designed for robotic cardiac catheterization. A total of 18 patients, mostly with lower pole renal calculi, were enrolled and underwent robotic ureteroscopy. Patients had a mean stone size of 11.9 mm, and total mean operative time was 91 minutes (of which 41 minutes was robotic console time). The surgical team rated stone localization as 8.3, maneuverability as 8.5, and stone fragmentation as 9.2 on a visual analog scale of 1 to 10, with 10 being best. At 3 months follow-up, 89% of patients were stone free based on intravenous urogram. 

"Some of the advantages may be the ease of maneuverability, the stability of the platform, and surgeon ergonomics," said Dr. Aron, who worked on the study with Inderbir Gill, MD, and colleagues.  

"One of the biggest advantages is the ability for the surgeon to minimize fluoroscopic exposure. Certainly, the major question is the cost." 

Co-authors Mihir Desai, MD, and Dr. Gill are consultants and stockholders with Hansen Medical.

  A collaborative effort from the University of Michigan, Ann Arbor, and the University of British Columbia, Vancouver investigated the treatment of chronic flank pain associated with papillary calcifications by laser endopapillotomy. They performed a retrospective review of patients who underwent ureteroscopic intervention and reported on the success rates and durability of laser ablation. 

The cohort consisted of patients without free collecting system stones and who had a non-colicky, chronic backache with the only radiographic finding being papillary calcification. A total of 62 patients were identified, 61% of whom had multiple procedures, for a total of 164 ureteroscopies. Although only 48 patients had adequate follow-up, 84% of those treated reported significantly less pain. 

The report documented a durable response of 26 months, with 60% of patients in remission for greater than 1 year. The authors conclude that laser endopapillotomy is an effective and safe treatment for chronic flank pain associated with calcified papillae. 

The World Congress of Endourology & SWL proved to be a fertile platform for technological advancements in ureteroscopy. Three studies in this area were particularly noteworthy.

Author | Michael Ferrandino, MD

Articles

'Gold standard' lithotripter wins clearance comparison

New polymer, robotics head advances in ureteroscopy