Ultrasonic Lithotripsy in the Ureter

In vitro comparisons of retropulsion and fragmentation efficacy of 2 cordless, handheld pneumatic and electromechanical lithotripsy devices

OBJECTIVE

To compare, in vitro, probe velocity/displacement, retropulsion, and fragmentation capacity of the cordless electromechanical (LithoBreaker) (hard vs soft probe guide) and pneumatic (StoneBreaker).

MATERIALS AND METHODS

Probe velocities/displacements were measured using high-speed resolution camera (100.000 frames/s). The lithotripsy probes were projected through a 7.5F ureteroscope against a nonfrangible led ball placed in a 15F horizontally mounted silicone tube immersed in water bath as an in vitro ureter model. Retropulsion is considered as displacement distance of led ball. Fragmentation efficiency was quantified as number of shots required to break Bego-stone phantoms (hard [15:3] and soft [15:6], average size 7.5 × 5.5 mm) placed on metal mesh into <3-mm fragments. Mean and standard deviation of repetitive measurements were statistically analyzed.

RESULTS

StoneBreaker yielded higher probe velocity (22 ± 1.9 m/s) compared with LithoBreaker with hard (14.2 ± 0.5 m/s) and soft (11.5 ± 0.5 m/s) probe. Maximum probe displacement for StoneBreaker was 1.04 mm vs 0.9 mm and 1.1 mm (hard vs soft LithoBreaker-probe, respectively). Retropulsion using 1-mm probes showed no statistical differences. Using harder 2-mm probe decreased Lithobreaker retropulsion significantly compared with Stonebreaker. The amount of shots (1-mm probe) to fragment soft Bego stones was significantly higher for LithoBreaker with soft (mean 31.5 ± 11.31) and hard (mean 21.5 ± 5.29) probe guide vs StoneBreaker (mean 11.2 ± 2.65). Fragmentation efficiency for hard Bego stones showed similar statistically significant outcome. Comparison of the 2 probe guides showed higher velocity linked to harder-probe that improved LithoBreaker fragmentation performance and reduce propulsion.

CONCLUSION

Both examined lithotripters are effective in cracking stone phantoms with relatively low pulse number. They produce comparable retropulsions. Fragmentation improved substantially using LithoBreaker with hard probe guide. More tests are required to assess differences in stone clearance time.

Tissue effects of intracorporeal lithotripsy techniques during percutaneous nephrolithotomy: comparison of pneumatic and ultrasonic lithotripters on rat bladder

The objectives of this study were to determine the tissue effects of ultrasonic and pneumatic lithotripsy on the rat urothelium. The rats were divided into three groups. Groups I and II consisted of ten rats each that underwent intracorporeal lithotripsy (pneumatic and ultrasonic lithotripsy, respectively). Group III contained ten control rats and no lithotripsy method was used, they served as references for absence of injury. The light microscopy findings were evaluated as follows: squamous metaplasia, papillary projection, inflammation, increased stratification, and stone formation. In five (71.4%) animals of group II, bladders were edematous and hemorrhagic, macroscopically. Histologically, the bladder wall was normal in four rats of group I and in one of group II. There was a significant increase in inflammation (31.5%), squamous metaplasia (85.7%), papillary projection (71.4%), increased stratification (71.4%), and microscopic or macroscopic stone formation (85.7%) in the bladder wall of group II rats in comparison with group I and control group. In the rat model, we noted that ultrasonic devices have a potential risk for tissue injury. In turn, this was associated with a markedly increased deposition of CaOx stones in the kidney. When confronted with harder stones, pneumatic lithotripsy can be more effective while also minimizing tissue injury.

Comparison of percutaneous nephrolithotomy using pneumatic lithotripsy (lithoclast®) alone or in combination with ultrasonic lithotripsy

PURPOSE

Percutaneous nephrolithotomy (PCNL) is the procedure of choice for treating large renal stones. Pneumatic lithotripsy (Lithoclast®) is effective regardless of the stones' composition, and ultrasonic lithotripsy allows the aspiration of small debris during lithotripsy. We investigated the efficacy and safety of PCNL via Lithoclast® alone or combined with ultrasonic lithotripsy.

MATERIALS AND METHODS

Thirty-five (group A) and 39 (group B) patients underwent Lithoclast® PCNL and combination therapy, respectively, from May 2001 to March 2010, and the two groups were compared in terms of stone size, location, and composition; operative time; average number of treatments; hospital days; hemoglobin loss; ancillary procedures; rate of device failure; and initial and total stone-free rates.

RESULTS

The two groups did not differ significantly in preoperative stone size, location, or composition; the average number of treatments; or the initial and overall stone-free rates. However, combination therapy was associated with a significantly lower operative time (181±50 vs. 221±65 min, respectively, p=0.004), number of hospital days (11.6±3.8 vs. 14.2±4.4 days, respectively, p=0.009), and average hemoglobin loss (1.12±0.61 vs. 1.39±1.02 g/dl, respectively, p=0.013). Transfusions were required in 6 patients (4 and 2 in each group, respectively), but there were no significant complications related to percutaneous access. There were 2 (5.7%) mechanical failures (Lithoclast® probe fracture) in the group A and 5 (12.8%) in the group B (2 cases of suction tube obstruction, 3 cases of overheating).

CONCLUSIONS

The combination of ultrasonic lithotripter and Lithoclast® is more effective than Lithoclast® alone because it significantly decreases operative time, hemoglobin loss, and the hospital stay. This may reflect the superior power of Lithoclast® and the ability to aspirate the debris during ultrasonic lithotripsy.

The evolution and progress of ureteroscopy

Technology and refinements in urology have prospered with the bonding of engineers and surgeons. The introduction of fiberoptics and the development of the ureteroscope opened the doors to the field of ureteroscopy. Advances in rigid and flexible ureteroscopy with irrigating and working channels have expanded the capability of the urologist to diagnose and treat most abnormalities of the upper tracts in adult and pediatric populations. Instrument development has easily paralleled the growth and development of the ureteroscope and has improved success, patient safety, and comfort with the incorporation of access sheaths, nitinol materials, and Ho:YAG laser technology. Owing to their minimal morbidity and high success rate, ureteroscopic evaluation and therapeutic interventions in the upper tract represent the gold standard of management. Albert Einstein said, "There are only two ways to live your life. One is as though nothing is a miracle. The other is as though everything is a miracle." Contemporary ureteroscopy is a historical miracle that has opened a vista of endless limits in upper tract endoscopy (Fig. 4, Box 1).

In Vitro Comparison of 4 Ultrasound Lithotripsy Devices

PURPOSE

Endoscopic lithotripsy is still the method of choice for a number of stones, especially large renal stones. Various disintegration techniques exist. Ultrasound is widely used because it is the only method that allows disintegration and active suction of stone debris at the same time. We evaluated 4 ultrasound lithotriptors in vitro.

MATERIALS AND METHODS

We used a newly developed experimental setup and compared 4 ultrasound devices, namely the 27085 K (Karl Storz Endoscopy, Tuttlingen, Germany), 2167.01 (Wolf, Knittlingen, Germany), USL 2000 (Circon Corp., Santa Barbara, California) and an ultrasound prototype lithotriptor (EMS, Nyon, Switzerland). RESULTS All ultrasound lithotriptors achieved stone disintegration, which depended on the pressure used to apply ultrasound. Newer devices with modified technology provided better disintegration.

CONCLUSIONS

All ultrasound devices are effective for lithotripsy. Changes in the ultrasound setup and integration of modern technical knowledge into ultrasound devices increase efficacy.

In vitro comparison of two ballistic systems for endoscopic stone disintegration

Endoscopic stone disintegration can be performed with various lithotripsy techniques. We compared two ballistic systems in vitro: the Swiss Lithoclast and the Combilith (Olympus). Measurements of the probe movement; i.e., maximum velocity and displacement, were performed using an optical high-speed technique based on a frame transfer camera. The Lithoclast and Combilith both achieve excellent probe velocities. However, the Lithoclast achieves equal velocity with less probe displacement.

Investigation of the tissue effects of a new device for intracorporeal lithotripsy--the Swiss Lithoclast

Currently three modalities are available for intracorporeal stone fragmentation--electrohydraulic, ultrasound and laser lithotripsy. A new device, the Swiss Lithoclast, has been developed by the Departments of Medical Electronics and Urology at the University of Lausanne, Switzerland. This device has been used clinically in several countries for the treatment of stones throughout the human urinary tract. While no adverse outcomes have been reported, the potential tissue effects of the device have not been thoroughly investigated in an animal model. The objective of the present study is to evaluate the possible acute and long-term tissue effects of this instrument on the pig urinary tract. In all acute animals, visible mucosal lesions were seen at the site of probe firing in the bladders and ureters. Histologic examination demonstrated the effects of acute trauma with edema, hemorrhage and mucosal denudation. No significant long-term tissue effects were noted either pathologically or on radiographs in the 3- and 6-week animals. This study confirms our clinical impression that the Swiss Lithoclast effectively fragments urinary calculi and is associated with a large margin of safety.

In situ echoguided extracorporeal shock wave lithotripsy of ureteric stones with the Dornier MPL 9000: a multicentric study group

OBJECTIVE

To study the efficacy of the Dornier MPL 9000 lithotripter with a real time ultrasound transducer in the localization and treatment of upper and prevesical ureteric stones.

PATIENTS AND METHODS

Two-hundred and eighty-five patients with pre-vesical ureteric stones and 247 patients with upper ureteric stones underwent extracorporeal shock wave lithotripsy (ESWL) using ultrasound targeting, under no regional or general anaesthesia.

RESULTS

At follow-up after 3 months 97% of patients with pre-vesical stones and 96% with upper ureteric stones were stone free. Ninety-nine patients were treated more than once. The average number of sessions of ESWL for all patients was 1.19 (1.17 for patients with prevesical stones and 1.22 for those with upper ureteric stones). Ureteric stenting was employed in 6% of cases. The infrequent use of ureteric stenting did not reduce ESWL efficacy, nor increase either the complication or the retreatment rates. In many cases upper urinary tract dilatation was provoked by administering intravenous fluid and a diuretic.

CONCLUSION

In situ echoguided ESWL is a simple, safe and effective technique for treating ureteric stones which can be detected on ultrasound.

"In situ" echo-guided extracorporeal shock wave lithotripsy of ureteral stones. Methods and results with Dornier MPL 9000

In 285 patients with prevesical ureteral stone and 247 with upper ureteral stone, extracorporeal shock wave lithotripsy (ESWL) was performed with the Dornier MPL 9000 ultrasonographic targeting device. All these stones were treated "in situ" and without regional or general anaesthesia. At 3-month follow-up 96.8% of the patients treated for prevesical stone and 95.5% of those with upper ureteral stone were stone-free. ESWL was repeated once or twice in 99 cases; the average number of sessions was 1.2 for all patients (similar for prevesical and upper ureteral stones). Sparse use of ureteral stenting (6.2% of cases) did not seem to reduce the efficacy of ESWL or increase complications or need for retreatment. Intravenous fentanyl analgesia was given to 40.9% of the patients and intravenous infusion of a furosemide solution was employed in many cases to give adequate dilation of the urinary tract. In situ echo-guided ureteral ESWL is simple, safe and efficacious and can be the technique of choice for sonographically detectable ureteral stone.

An evaluation of 646 stone patients treated on the HM4 extracorporeal shock wave lithotriptor

Extracorporeal shock wave lithotripsy (ESWL) has become the preferred treatment modality for the majority of urinary tract calculi. This form of treatment boasts excellent patient acceptance and has significantly reduced the need for surgical intervention. An evaluation of our first 646 patients undergoing 722 ESWL treatments at Walter Reed Army Medical Center revealed an overall stone-free rate at 1 and 3 months of 52% and 79%, respectively. The exact location of each stone within the kidney and ureter further determined the stone-free rates at 1 and 3 months. Stone-free rates at 3 months ranged from 89% for renal pelvic stones to 64% for lower pole caliceal stones. Upper third ureteral stones treated in situ without stenting resulted in a 74% stone-free rate at 3 months. This rate increased to 85% when these patients were stented and treated in situ. Although statistically insignificant, when the upper third ureteral stones were manipulated into and treated in the renal pelvis (31% of our patient population) the 3-month stone-free rate increased to 87%. Attempts were made to stent all ureteral stones before treatment. The stone-free rate at 3 months was 86% for mid third ureteral stones and 81% for lower third ureteral stones. The overall retreatment rate was 11.8% with a complication rate of 7.6% and a 6.3% post-ESWL intervention rate (open or percutaneous surgery, stent or percutaneous nephrostomy placement).