New generation shock wave lithotripsy

Improving the lens design and performance of a contemporary electromagnetic shock wave lithotripter

The efficiency of shock wave lithotripsy (SWL), a noninvasive first-line therapy for millions of nephrolithiasis patients, has not improved substantially in the past two decades, especially in regard to stone clearance. Here, we report a new acoustic lens design for a contemporary electromagnetic (EM) shock wave lithotripter, based on recently acquired knowledge of the key lithotripter field characteristics that correlate with efficient and safe SWL. The new lens design addresses concomitantly three fundamental drawbacks in EM lithotripters, namely, narrow focal width, nonidealized pulse profile, and significant misalignment in acoustic focus and cavitation activities with the target stone at high output settings. Key design features and performance of the new lens were evaluated using model calculations and experimental measurements against the original lens under comparable acoustic pulse energy (E+) of 40 mJ. The -6-dB focal width of the new lens was enhanced from 7.4 to 11 mm at this energy level, and peak pressure (41 MPa) and maximum cavitation activity were both realigned to be within 5 mm of the lithotripter focus. Stone comminution produced by the new lens was either statistically improved or similar to that of the original lens under various in vitro test conditions and was significantly improved in vivo in a swine model (89% vs. 54%, P = 0.01), and tissue injury was minimal using a clinical treatment protocol. The general principle and associated techniques described in this work can be applied to design improvement of all EM lithotripters.

Rapid Communication: First Clinical Experience with Doli S 220F-XP Extracorporeal Lithotripter for Urinary Lithiasis

PURPOSE

To assess the initial results of the Dornier Doli S 220F-XP extracorporeal lithotripter for the management of solitary urinary calculi.

PATIENTS AND METHODS

We prospectively examined the outcome of shockwave lithotripsy (SWL) in the first 140 patients with solitary renal and ureteral lithiasis treated by one urologist with the new power Doli S lithotripter. Ninety-one patients (group A) had renal stones, and 49 patients (group B) had ureteral stones. Data were collected with respect to stone size, location, and fragmentation.

RESULTS

In group A, clinical success was documented in 77 patients (84%) at 1 month after lithotripsy. Three months after lithotripsy, 69 patients (75.2%) were stone free and 8 (8.8%) had fragments <4 mm. In group B, 41 patients (83%) achieved clinical success 1 month after lithotripsy. Thirty-eight patients (77%) were stone free 3 months after treatment, and 3 (6%) had fragments <4 mm. Seven patients (7%) in group A and three patients (6%) in group B required re-treatment. The overall efficiency quotient was 67%. No patient developed a perinephric hematoma. Ninety-four percent of the patients reported mild pain during lithotripsy. The majority (91%) mentioned that they were satisfied with this treatment modality for urinary lithiasis (mean visual analog scale satisfaction score 8).

CONCLUSIONS

The Doli S 220 F-XP is a safe and effective device for managing calculi throughout the urinary tract.

Can prilocaine infiltration alone be the most minimally invasive approach in terms of anesthesia during extracorporeal shock wave lithotripsy?

OBJECTIVES

To evaluate the analgesic effect and utility of prilocaine infiltration alone for minimal morbidity during extracorporeal shock wave lithotripsy.

METHODS

A total of 114 patients with kidney stones, aged 18 to 69 years, were randomly separated into two groups. The 58 patients in group 1 received intramuscular diclophenac 30 minutes before extracorporeal shock wave lithotripsy, and the 56 patients in group 2 received prilocaine infiltration into the 30 cm2 area below the 12th rib right before the session. A visual analog scale (0 to 100 mm) was used to evaluate pain.

RESULTS

The visual analog scale scores for group 2 were statistically lower at 1, 10, and 20 minutes compared with the scores for group 1 (P = 0.006, P = 0.005, and P = 0.006, respectively). However, no difference was detected at the end of the procedure. The requirement for additional analgesic was less in group 2 (P = 0.007).

CONCLUSIONS

Prilocaine infiltration alone can be used for analgesic purposes efficiently and safely during extracorporeal shock wave lithotripsy with minimal morbidity.

Single-Center Experience Using Three Shockwave Lithotripters with Different Generator Designs in Management of Urinary Calculi

PURPOSE

We retrospectively reviewed the treatment outcomes of extracorporeal shockwave lithotripsy (SWL) in a single center using either the Wolf Piezolith 2300 (a piezoelectric lithotripter), the Dornier MPL9000 (an electrohydraulic lithotripter), or the Dornier Compact Delta (an electromagnetic lithotripter) from January 1992 to June 2002.

PATIENTS AND METHODS

A series of 3123 (1449 Piezolith 2300, 780 MPL9000, and 894 Compact Delta) solitary radiopaque urinary stones of < or =15 mm receiving primary SWL were identified. "Stone free" was defined as the absence of evidence of stone on plain radiography. Treatment outcomes were assessed by the stone-free rate 3 months after one treatment session, the retreatment rate, the auxiliary procedure rate, the complication rate, and the effectiveness quotient (EQ). In order to have a better assessment of the efficacy of individual lithotripters, multiple logistic regression was performed to control various factors affecting treatment outcomes, including lithotripter-type, patients' sex and age, history of previous SWL, the stone characteristics (side, site, and size), and the presence of a stent or nephrostomy tube.

RESULTS

There were significant differences in the stone site distribution and mean stone size among the three groups. The overall EQ for the Piezolith 2300, MPL9000, and Compact Delta were 0.345, 0.303, and 0.257, respectively. However, using the multiple logistic regression model, the adjusted odds ratio (AOR) of a patient being stone-free after 3 month for the Piezolith 2300 and MPL9000 (using the Compact Delta as the referent category) were 1.38 (95% CI 1.15, 1.65) and 1.72 (95% CI 1.39, 2.11), respectively. Patients treated using the MPL9000 had significantly less re-treatment (AOR = 0.57; 95% CI 0.48, 0.69) than the other groups. No significant difference in the auxiliary procedure rate and complication rate for the three machines was observed.

CONCLUSION

Based on multivariate analysis results, the Dornier MPL9000 had the best treatment outcomes in terms of stone-free rate and re-treatment rate among the three lithotripters.

Extracorporeal shock wave lithotripsy with a transportable electrohydraulic lithotripter: experience with >300 patients

OBJECTIVE

To review a multicentre experience of using a transportable lithotripter (STS-T, Medstone, Inc, Aliso Viejo, CA. USA) for treating patients with urolithiasis in all parts of the urinary tract.

PATIENTS AND METHODS

In all, 326 patients with a total of 370 stones were treated as outpatients with the STS-T lithotripter. All patients received a single shock wave lithotripsy treatment and were followed after 4-6 weeks in the outpatient clinic, the primary endpoint being to determine the efficacy (as defined by the stone-free rate). Secondary objectives included establishing a database of patient demographic information, stone characteristics, stone location, procedural endpoints, and complication rates.

RESULTS

In all there were 370 procedures, with a mean of 2394 shocks administered at an energy level of 24 kV. The mean treatment time was 51 min, excluding anaesthesia-induction time. The mean stone aggregate size was 8.2 mm; 62% of the stones were in the kidney while 38% were in various locations in the ureter. Of the treated stones, 90% had definite or probable evidence of fragmentation. The overall stone-free rate after one treatment with the STS-T was 52.8%. Of patients with residual fragments, most (61%) had fragments of <4 mm in aggregate diameter. The overall complication rate was 3.8%, the most common complication being postoperative pain.

CONCLUSION

The Medstone STS-T lithotripter was an effective device for treating urolithiasis in all parts of the urinary tract. This system had a high margin of safety, as shown by the low complication rate. With no apparent sacrifice of efficacy compared to first-generation or fixed (not transportable) second-generation devices, the Medstone STS-T represents an important advance in the development of a truly transportable lithotripter.

A comparative review of extracorporeal shock wave generation

Shock waves are specific sound waves produced by shock-wave generators; the generators currently available have different physical properties and represent different technical solutions. The measurement of shock-wave pressure is necessary in laboratory settings to define the physical characteristics of a given shock-wave source. Under clinical conditions other variables, e.g. the stone-free rate or the percentage of complications, are used to describe the efficacy and safety of a lithotripter.

Re-auditing a regional lithotripsy service

OBJECTIVE

To assess, in a repeat audit of a regional lithotripsy service, whether changes implemented after a regional audit in 1994 (which showed disappointing results from shock wave lithotripsy, attributable to both poor patient selection and an inadequate fixed-site lithotripter) have had any effect.

PATIENTS AND METHODS

A data-collection sheet was devised to gather information on the site, size and number of stones treated, together with information on the lithotripsy treatment and outcome. Patients selected for the audit were the first 50 new patients treated with lithotripsy at each centre in 1999. As only one hospital has a fixed-site lithotripsy machine, the results of mobile lithotripsy were grouped by machine for analysis.

RESULTS

There was an overall improvement in patient selection from the previous audits. Few stones of > 16 mm or < 4 mm were treated. Two units treated more ureteric stones, thought to reflect first the influence of a fixed-site lithotripter, and second a willingness to insert a ureteric stent and await the next mobile lithotripter visit. The stone free rates were all disappointingly low (16.7-26.7%) but the results improved when fragments of < 4 mm were included as "successful" giving an "overall success rate" of 45.9-66.7%. The unit with a fixed-site lithotripter appeared to perform better (two-thirds successful) than the mobile machines (Modulith SLX, 51%; Modulith SLK, 46%). One centre visited by both mobile machines had a success rate of 65% but a high rate of auxiliary procedures (35% vs 16-19% vs the fixed-site).

CONCLUSION

Although these results show some improvement in patient selection for our regional lithotripsy service, stone-free and success rates are poorer than those reported elsewhere. This may reflect the modern lithotripsy machines that allow day-case treatment with minimal analgesia, and confirms reports by other authors who encourage a re-examination of success rates of shock wave lithotripsy.

Urolithiasis in the low birth weight infant: the role and efficacy of extracorporeal shock wave lithotripsy

PURPOSE

Nephrolithiasis in preterm infants rarely requires surgical management. When it persists despite conservative therapy, treatment options are not clearly defined. We report a single institutional experience with extracorporeal shock wave lithotripsy (ESWL)* for the treatment of these small infants.

MATERIALS AND METHODS

We treated 8 infants (mean age 13 months) with a history of prematurity and 9 persistent stones with a Dornier HM3 lithotriptor between 1996 and 1999. Mean weight was 7,700 gm. Of the infants 7 had been treated with furosemide for bronchopulmonary dysplasia and 1 presented with multiple anatomical abnormalities. Gantry modification with a wooden platform and polystyrene foam positioning was used for lung and visceral protection. Ureteral stents were placed in 5 patients before ESWL. Renal ultrasonography was performed before, and 2 and a mean of 8 weeks after ESWL. Stone risk factors in our population were investigated through a multispecialty approach.

RESULTS

Average stone burden was 47.9 mm.2. A total of 9 sessions of ESWL were required for complete fragmentation of the 9 renal stones. A mean total of 2,100 shocks at a mean 16.1 kV. were administered. One patient with bilateral stones was treated in 2 separate sessions after a 4-week interval. No repeat ESWL sessions or other surgical interventions were required in any patient. Renal ultrasonography demonstrated no post-ESWL morphological changes. Practices leading to a higher incidence of neonatal nephrolithiasis at our institution were also identified.

CONCLUSIONS

ESWL is effective treatment for nephrolithiasis in small infants. Short-term safety has been established but continued long-term functional followup is essential. Multifactorial etiologies of nephrolithiasis must be identified and modified promptly in the care of preterm infants.

Urolithiasis in the low birth weight infant: the role and efficacy of extracorporeal shock wave lithotripsy

PURPOSE

Nephrolithiasis in preterm infants rarely requires surgical management. When it persists despite conservative therapy, treatment options are not clearly defined. We report a single institutional experience with extracorporeal shock wave lithotripsy (ESWL)* for the treatment of these small infants.

MATERIALS AND METHODS

We treated 8 infants (mean age 13 months) with a history of prematurity and 9 persistent stones with a Dornier HM3 lithotriptor between 1996 and 1999. Mean weight was 7,700 gm. Of the infants 7 had been treated with furosemide for bronchopulmonary dysplasia and 1 presented with multiple anatomical abnormalities. Gantry modification with a wooden platform and polystyrene foam positioning was used for lung and visceral protection. Ureteral stents were placed in 5 patients before ESWL. Renal ultrasonography was performed before, and 2 and a mean of 8 weeks after ESWL. Stone risk factors in our population were investigated through a multispecialty approach.

RESULTS

Average stone burden was 47.9 mm.2. A total of 9 sessions of ESWL were required for complete fragmentation of the 9 renal stones. A mean total of 2,100 shocks at a mean 16.1 kV. were administered. One patient with bilateral stones was treated in 2 separate sessions after a 4-week interval. No repeat ESWL sessions or other surgical interventions were required in any patient. Renal ultrasonography demonstrated no post-ESWL morphological changes. Practices leading to a higher incidence of neonatal nephrolithiasis at our institution were also identified.

CONCLUSIONS

ESWL is effective treatment for nephrolithiasis in small infants. Short-term safety has been established but continued long-term functional followup is essential. Multifactorial etiologies of nephrolithiasis must be identified and modified promptly in the care of preterm infants.

Generation of very high pressure pulses at the surface of a sandwiched piezoelectric material

New clinical concepts in lithotripsy demand small shock heads. Reducing the size of piezoelectric shock heads will only be possible if the pressure generated at the surface of each transducer can be increased so that the total pressure at the focus remains very high. We propose for the first time to increase the pressure without increasing the transducer voltage by using sandwiched transducers, which are a combination of several stacked transducers. When excited at appropriate time intervals, the pressure waves generated by each one reinforce when they reach the load. This new technique has been successfully tested. A pressure of 2.5 MPa was generated with two stacked, 5 mm-thick 1-3 piezocomposite transducers operating at an excitation voltage of 8 kV. No transducer damage was detected after 10(6) shocks, which corresponds approximately to the treatment of 500 patients.

Extracorporeal lithotripsy. Update on technology

The development of shock-wave lithotripsy was a serendipitous event. Fortunately, the significance of this accidental discovery was not overlooked by the engineers at Dornier and their medical counterparts. There are many components that make up a lithotripter, but the heart of the lithotripter is its energy source. These machines often are categorized by the type of shock-wave generator used, and each type of generator has its own advantages and disadvantages. Unfortunately, no quantitative value of a shock-wave generator can be correlated to its qualitative effect. Interestingly, each type of energy source delivers its shock-wave energy with such distinctiveness that even the crater pattern it leaves in a stone is unique. New technology and ideas have transformed lithotripters in form and function so that they bear little resemblance to the original HM-1 prototype. Ongoing research is attempting to improve ESWL in several different ways, and advances in shock-wave generation, shock-wave measurement, and stone localization should result in even more efficient lithotripsy. The application of the time-reversal process to lithotripsy ultimately may enable lithotripters to track stones and electronically steer shock waves toward the target. Advances like these herald a time when ESWL, fortunately or unfortunately, will become automated completely.

Extracorporeal shock wave lithotripsy. Development, instrumentation, and current status

In this article, the author briefly reviews the early development of the lithotriptor, provides a detailed review of lithotriptors that are currently available, and gives an overview of the present extracorporeal shock wave lithotripsy indications and techniques. The author also presents a brief overview of the results that are produced by various lithotriptors.

A piezocomposite shock wave generator with electronic focusing capability: application for producing cavitation-induced lesions in rabbit liver

In this work, a piezocomposite shock wave generator with electronic focusing capability is presented. The system is composed of a bidimensional array and its electronic hardware. The array is composed of 274 independent piezocomposite transducers arranged in a spherical shell of 280 mm in diameter and focused at 190 mm from its surface. The electronic hardware includes 274 x 6.6 kV distinct impulse generators. For the purpose of performing the electronic steering of shock waves, the delay time of each channel can be adjusted from 100 ns to 100 microseconds in steps of 100 ns. In order to enhance the effect of cavitation at the focus for the purpose of tissue destruction, the pressure-time waveform starts with a half cycle of negative pressure with a peak amplitude of about -150 x 10(5) Pa, followed by a very steep shock front with a positive peak pressure > 1000 x 10(5) Pa and a rise time of about 10 ns. Using this generator, the cavitation-induced lesions in rabbit liver were studied. To obtain a predefined lesion volume, two methods of scanning were used: mechanical and electronic. Comparison of the lesions obtained by these two methods shows that they have identical macroscopic and histological characteristics, which justify the feasibility of electronic beam steering of shock waves in tissue destruction applications.

Safety and effectiveness of Lithostar shock tube C in the treatment of urinary calculi

Over 14 years of clinical use of extracorporeal shockwave lithotripsy (SWL), great technical modifications resulted in the development of many second-generation lipthotripters. The Siemens Lithostar machine, with its standard shockwave tube, was introduced in 1986. The objective of this study was to assess the safety and effectiveness of the newly proposed Lithostar shock tube C in the treatment of urinary calculi. Between July 1992 and August 1993, 319 patients (214 males and 105 females, average 49.7 years) with 433 renal or ureteral stones or both were treated at five centers in Canada and the United States. Most of the stones (72%) were located in the kidneys, while 28% were located in the ureters. Most (81%) of the treated sides (side = kidney and ureter) presented with single stones, 11% presented with two stones, and 8% presented with three or more stones. The average stone burden was 13.6 mm. The average duration of treatment for the whole population of patients was 39.3 minutes using an average number of shockwaves of 3633 in a minimum and maximum energy setting of 0.11 and 3.82, respectively. The majority of treatments (92%) were performed without anesthesia. Fragmentation was achieved in 93.5% of treatments, with a 3-month stone-free rate of 62.5% and a success rate (stone free or fragment < 5 mm) of 72%. Auxiliary procedures were necessary in conjunction with 108 treatments, and most of them were in form of catheter/stent placement. Treatment applied on a separate occasion to different stones but in the same collecting system (either a kidney or a ureter) were considered retreatments.(ABSTRACT TRUNCATED AT 250 WORDS)

Pediatric low energy lithotripsy with the Lithostar

Between November 1988 and July 1993, 238 renal stones and 208 ureteral stones were treated in 446 pediatric patients using 26 mobile and 2 fixed base Siemens Lithostar lithotriptors. The stones were treated by a group of 245 urologists using the modified Puigvert technique and the standard shock tube. The success rate for renal stones (asymptomatic fragments less than 4 mm.) was 76.6%, stone-free rate was 67.9%, retreatment rate was 14.1% and ancillary procedures were performed in 36.3%. The stone-free rate for ureteral stones was 91.1%, retreatment rate was 3.5% and ancillary procedures were performed in 17.7%. Anesthesia was required in 31% of the renal and 21% of the ureteral procedures. Sepsis in a 6-year-old child after treatment of a ureteral stone was the only major complication. Low energy lithotripsy with the Lithostar in our series of pediatric patients was safe and effective.

Electronic beam steering of shock waves

Shock-wave generators are now currently used for the treatment of renal stones. In all these generators the focal zone is determined by their geometrical parameters. We propose, for the first time, a piezocomposite shock-wave generator with electronic focusing. The system is composed of a two-dimensional array and its electronic hardware. The array is composed of 121 independent piezocomposite transducers arranged in a spherical shell 20 cm in diameter and focused at 190 mm. The electronic hardware includes 121 x 6 kV-impulse generators. The interdelay of each channel can be adjusted between 10 ns to 100 microseconds by steps of 10 ns. The results show: the use of composite material is possible for the generation of high amplitude pressure waves; the pressure-voltage relationship is linear up to a pressure of about 28 x 10(5) Pa at the transducer front face; the material can be used for a long period of time; i.e., after one million shocks, no decrease in sensitivity, no alteration in its electrical behaviour and no time wave form distortion were observed. Electronic focusing is efficient in an ellipsoidal region of about 4 cm in diameter and 6 cm in length. The pressure in the focal zone is about 600 x 10(5) Pa.

Piezolith extracorporeal shockwave lithotripsy: the Hotel-Dieu de France experience

A total of 1500 patients underwent treatment with the Wolf Piezolith 2300 extracorporeal shockwave lithotripter for renal, ureteral, and bladder stones. Follow-up data were available at 3 months for 1435 patients. At that time, the overall stone-free rate was 82.7%: 82.4% for patients with renal stones, 81.0% for those with ureteral stones, and 100% for those with bladder stones. The overall success rate was 92.3%: 93.8% for patients with renal stones, 87.1% for those with ureteral stones, and 100% for those with bladder stones. The auxiliary treatment rate was 14.9%, and the retreatment rate was 53%. The effectiveness quotient was 49.2%. The Wolf Piezolith 2300 is an effective treatment for most stones smaller than 30 mm.

Effects of stents on lithotripsy of ureteral calculi: treatment results with 18,825 calculi using the Lithostar lithotriptor

Between November 14, 1988 and August 1, 1993, 18,825 ureteral calculi were treated in the United States using 25 different mobile and 2 fixed base Siemens Lithostar lithotriptors. Lithotripsy was performed by 1,012 urologists using the modified Puigvert technique. The overall stone-free rate was 83.8% with a retreatment rate of 10.8%. The stone-free rate varied from 85.8% with stones of 10 mm. or smaller to 67.9% for stones larger than 20 mm. A ureteral stent or catheter was placed before lithotripsy in 19.3% of all treatments and 80.7% had in situ treatment without instrumentation. For calculi of any size, the use of ureteral stents or catheters had no effect on treatment outcome at any ureteral location.

Effects of extracorporeal shock-wave lithotripsy on referred hyperalgesia from renal/ureteral calculosis

In patients suffering from colics due to calculosis of one upper urinary tract the evolution in time of referred parietal hyperalgesia after stone fragment elimination promoted by extracorporeal shock wave lithotripsy (ESWL) was studied. Before ESWL, all patients presented clinical evidence (positivity to dermographism and Head's procedure, pinch palpation, digital pressure and Giordano's manoeuver) and instrumental signs (significant lowering of pain threshold to electrical tissue stimulation) of cutaneous, subcutaneous and muscular tissue hyperalgesia in the lumbar region of the affected side. After ESWL, hyperalgesia decreased in the three tissues, as shown by progressive change in the clinical tests and an increase in pain threshold to electrical stimulation in relation to the extent of stone fragment expulsion. In the stone-free condition, hyperalgesia had disappeared in the skin but remained to a mild and moderate extent in the subcutaneous tissue and muscle respectively. It is concluded that the persistence in time of referred hyperalgesia is only in part linked to the continuing presence and activity of the stone in the urinary tract. To a certain extent, the phenomenon seems to become independent of the primary focus, possibly as a result of plastic neuronal changes in the central nervous system which, triggered by afferent visceral inputs, are maintained even after their removal.

Low energy lithotripsy with the Lithostar: treatment results with 19,962 renal and ureteral calculi

Between November 1988 and January 1992, 19,962 renal and ureteral calculi were treated in the United States using 18 different mobile and 2 fixed base Lithostar lithotriptors. Lithotripsy was performed on 11,516 renal and 8,446 ureteral calculi by 750 urologists using the same technique. The success rate (asymptomatic with stone fragments of 4 mm. or less) for renal stones was 87.9%, the stone-free rate was 68.9% and the retreatment rate was 16.5%. Auxiliary procedures were performed in 32.2% of the renal calculi. The success rate for ureteral calculi was 89.5%, the stone-free rate was 83.5% and the retreatment rate was 10.7%. Auxiliary procedures were performed in 25.5% of the ureteral calculi. The overall success rate was 88.4% stone-free rate 75.5%, retreatment rate 14.0% and auxiliary procedure rate 29.4%. Anesthesia personnel were used in 1.9% of the cases. Low energy extracorporeal shock wave lithotripsy was found to be safe and effective.

Extracorporeal shock-wave lithotripsy with Lithostar lithotriptor

Initial experience of extracorporeal shock-wave lithotripsy (ESWL) using the Lithostar lithotriptor is reported; 193 patients underwent 248 treatments for 210 stones. A total of 139 renal calculi (126 patients) and 71 ureteral stones (67 patients) were analyzed. Treatments were performed without anesthesia in 65 calculi (27.6%), with intravenous sedation in 91 (42.5%), and under epidural anesthesia in 34 calculi (29.9%). A three-month follow-up showed a success rate of 88.0 percent for renal calculi and 95.5 percent for ureteral calculi treated in situ. Renal stone fragmentation was achieved with a mean of 4,890 shocks at 17.4 kV and ureteral calculi were fragmented with a mean number of 4,798 shocks at a mean of 18.3 kV. Auxiliary procedures after ESWL were required in 2 patients with renal stones and in 1 with ureteral calculi. A comparison between stone size and number of shock waves required to achieve stone fragmentation revealed a linear relationship. Hospitalization was not necessary in 84.4 percent of renal calculi and 89.6 percent of ureteral calculi. Retreatments were necessary in 22 (15.8%) of the renal calculi (18 had 2 sessions, 3 had 3 sessions, and 1 had 4 sessions). Of the ureteral calculi, 8 (11.3%) underwent retreatment (6 had 2 sessions, 1 had 3 sessions, and 1 had 4 sessions). The low morbidity with a large number of patients treated on an outpatient basis, minimizing the need for anesthesia, demonstrated a favorable initial successful experience with the Lithostar.

Efficacy of second generation lithotriptors: a multicenter comparative study of 2,206 extracorporeal shock wave lithotripsy treatments with the Siemens Lithostar, Dornier HM4, Wolf Piezolith 2300, Direx Tripter X-1 and Breakstone lithotriptors

Extracorporeal shock wave lithotripsy (ESWL) has become the treatment of choice for urinary calculi. The good results of the first generation Dornier HM3 lithotriptor stimulated the development of second generation machines. A multicenter trial is presented involving the Siemens Lithostar, Dornier HM4, Wolf Piezolith 2300, Direx Tripter X-1 and Breakstone lithotriptor to compare the therapeutic efficacy of second generation machines. Treatment results were best for calculi less than 2 cm. in diameter. Although the second generation lithotriptors are comparable to each other, none of the machines provided a success rate comparable to that of the first generation unmodified Dornier HM3 lithotriptor. The 5 machines differed mainly in types of stones treated in relation to imaging system, use of anesthesia, use of auxiliary procedures and hospitalization but overall success rates were similar. We conclude that second generation ESWL is less effective than first generation ESWL.

Cenni storici: History

Between the 60s and the 80s, research was carried out on the generation of shock waves as well as experimentation to evaluate their effectiveness in the disintegration of kidney stones at the Grosshaden Urology Clinic in Munich where in 1980 the first patient was treated with success. Lithotriptors were later progressively perfected.

Lithostar extracorporeal shock wave lithotripsy: the first 1,000 patients. Toronto Lithotripsy Associates

To our knowledge this study of our first consecutive 1,000 patients treated with the Siemens Lithostar device is the largest prospective series reported to date. Treatment results were determined at 3, 12 and 24 months after completion of therapy. The results at 3 months are presented. Complete followup data were available on 801 patients: 674 with renal and 127 with ureteral calculi. Results were analyzed according to stone size, location and number. The average number of shocks per treatment was 3,804 and the retreatment rate was 18.6%. At 3 months the stone-free rate was determined by a plain film of the kidneys, ureters and bladder and plain tomograms for renal calculi, and by an excretory urogram for ureteral calculi. The stone-free rate was 52% for renal and 76% for ureteral calculi. The overall stone-free rate for all calculi was 55.7%. Success rate, defined as stone-free or asymptomatic residual fragments measuring 4 mm. or less, was 72% for renal and 83% for ureteral calculi. The overall success rate for all calculi was 73.9%.

Laser lithotripsy of the difficult ureteral calculus: results in 122 patients

We studied 122 patients with ureteral calculi who could not be treated by extracorporeal shock wave lithotripsy (ESWL) because the stones could not be localized or focused for treatment, the patient had failed prior ESWL, the stones were impacted and in situ ESWL was likely to fail or the stones were proximal to a ureteral stricture. These patients underwent laser lithotripsy using the Candela pulsed dye laser. In 107 patients (88%) the calculi were completely fragmented with the laser alone, while 10 (8%) needed another procedure (ESWL in 8 and stone fragment extraction by basket in 2), and 5 (4%) had failed laser therapy and needed some other form of treatment (ESWL in 4 and percutaneous antegrade extraction in 1). At 3 months 116 of 122 patients (95%) were stone-free. There were 2 immediate complications (ureteral perforations) and 1 late complication (ureteral stricture). Laser lithotripsy is a safe and effective method of intracorporeal fragmentation, even of the difficult ureteral calculus, and it is a useful adjunct to ESWL.

Potential for inter-observer and intra-observer variability in x-ray review to establish stone-free rates after lithotripsy

The potential for variability among observers interpreting diagnostic tests is well known but has not been well established for radiological imaging of urolithiasis. We measured the inter-observer and intra-observer variability in the reporting of plain abdominal films and tomograms from patients who had undergone extracorporeal shock wave lithotripsy (ESWL). Unlabeled copies of the plain abdominal films and tomograms for 58 patients were individually submitted to 3 different radiologists. Selected films from 25 patients were resubmitted to the same radiologists. We found differences among radiologists reporting plain abdominal films alone 52% of the time and even by the same radiologist rereading the films 24% of the time. Tomograms alone decreased the uncertainty but differences still occurred among radiologists 24% of the time and with themselves 16% of the time. When plain abdominal films and tomograms were read together there were differences among radiologists 28% of the time and with themselves 7% of the time but these were usually minor. We concluded from this study that the plain abdominal film alone was frequently difficult to interpret, resulting in uncertainty about the presence or absence of residual stone fragments. Tomograms alone or a plain abdominal film plus tomograms is superior to a plain abdominal film alone. Finally, radiological assessment with all modalities probably overestimates stone-free rates after ESWL even without consideration of the potential for reporting variability among observers.

Surgical aspects of urolithiasis in children

Operative management of renal calculi has changed radically in the last decade. New operative techniques, the use of intra-operative ultrasound and Doppler sonography have even made possible the removal of complete staghorn calculi in short and kidney-preserving procedures. The introduction of percutaneous nephrolithotomy and stone extraction using a specially designed ureteroscope and, above all, the clinical application of extracorporeal shock wave lithotripsy have made stone surgery less invasive and have provided a higher rate of preservation of kidney function.

Extracorporeal shock wave lithotripsy of urinary calculi: experience in treatment of 3,278 patients using the Siemens Lithostar and Lithostar Plus

Between March 1986 and June 1989, 3,278 patients with upper urinary tract calculi were treated at our medical center with the Lithostar lithotriptor. The stones were located in the calices in 41.9% of the cases, renal pelvis in 25.7% and ureter in 32.4%. Perirenal hematoma was noted in 0.5% of the patients but this resolved spontaneously within a few days. Auxiliary procedures were performed in 37.3% of the cases, including Double-J stent and ureteral catheter in 26.8%, ureterorenoscopy in 2.1%, percutaneous nephrostomy in 1.6%, Zeiss loop in 4.3% and percutaneous nephrolithotripsy in 3.5%. Of the treatments 83.1% were performed without general or regional anesthesia. Followup after 3 months showed a 63.8% rate free of stone. The Lithostar upgraded with the overhead lithotripsy module is called Lithostar Plus. A total of 25 patients with upper urinary stones underwent treatment with the overhead module. Initial experience revealed fragmentation of stones after the first session in 20 patients, while a second session was necessary in 5. Analgesic sedation was used in 4 patients in whom a Double-J stent was inserted.

Endoscopic manipulation of ureteral calculi in children by rigid operative ureterorenoscopy

To date, rigid operative ureterorenoscopy with ultrasound lithotripsy for the treatment of ureteral calculi has been performed only in adults or older children. The size of the instrument with the working channel for the ultrasound probe has been considered unsuitable for delicate anatomical structures, such as those of children younger than 4 years. We performed 8 ureterorenoscopic examinations in 7 patients (3 boys) 3 to 8 years old and have demonstrated that the 11.5F ureteroscope can be inserted without difficulty into the ureteral meatus of a 3-year-old boy. Introduction of the instrument is facilitated by the use of the Perez-Castro irrigation pump. This procedure does not lead to any urethral or ureteral damage, nor is vesicoureteral reflux shown on a postoperative cystogram. This technique allows extracorporeal shock wave lithotripsy to be extended also to small children, offering the possibility of easy and successful management of any residual steinstrasse.

Extracorporeal lithotripsy and combined surgical procedures in the treatment of renoureteral stone disease: our experience with 2,955 patients

From May, 1985 to August, 1987, a total of 2,955 patients with renoureteral stone disease presented at our institution and were treated either by extracorporeal lithotripsy alone or combined with percutaneous nephrolithotomy, ureteroscopy, or open surgery. Seventy-three percent of patients were stone-free at the 3 month follow-up date while 22% presented with negative urine culture and small (less than 5 mm) asymptomatic fragments deemed susceptible to spontaneous discharge. The rate of major complications was extremely low (sepsis, 0.03% and major renal bleeding, 1.55%). The application of this multimodal therapeutic strategy allowed successful treatment in almost every case of renoureteral lithiasis with minor iatrogenic damage to the renal parenchyma.

Small caliceal stones: what is the best method of treatment?

In a retrospective analysis classical radial nephrolithotomy, percutaneous nephrolithotomy and extracorporeal shock wave lithotripsy for symptomatic small nonobstructive caliceal stones were compared to evaluate morbidity. Size (less than 1 cm.) and location of the stone (caliceal and nonobstructive) did not explain the severity of the symptoms nor would they have been an indication for an operation. In 8 patients treated by an open operation, 16 treated percutaneously and 6 who underwent extracorporeal shock wave lithotripsy the procedure time, success rate, complication rate and length of hospitalization were analyzed. Followup consisted of ultrasound and/or a plain film of the kidneys, ureters and bladder 1 day and 3 months postoperatively. A nephrotomogram was included in group 3 patients. Of 30 patients 3 had persistent stone fragments for more than 3 months: 2 underwent percutaneous nephrolithotomy and 1 was treated by extracorporeal shock wave lithotripsy. A total of 28 patients (93.3 per cent) achieved complete or significant relief of pain. In the percutaneous group both patients with persistent fragments were symptomatic in contrast with the extracorporeal shock wave lithotripsy group, in which 1 patient presented with stone fragments but was free of pain. The group treated percutaneously had a shorter procedure time (60 minutes) and the shock wave group had a shorter hospitalization. On the other hand, the open operation group had a better success rate as well as relief of pain. These observations showed that small, nonobstructive caliceal stones can be responsible for persistent, severe flank pain. Since extracorporeal shock wave lithotripsy is an effective noninvasive procedure that does not require routine anesthesia and hospitalization, with prompt return of the patient to normal life, it must be considered the method of choice in these particular patients.

Current state and future developments of noninvasive treatment of human urinary stones with extracorporeal shock wave lithotripsy

Extracorporeal shock wave lithotripsy has now been in clinical use for 8 years and it has replaced other treatment techniques for the majority of surgical calculi in the upper urinary tract. For the first time it provides a completely noninvasive method for the treatment of renal and ureteral stones. The current range of its indications includes approximately 70 per cent of nonselected urinary stone patients. An additional 25 per cent of the patients with more complex stones in the upper urinary tract can receive treatment with the lithotriptor combined with endourological procedures. More recent additions to the range of clinical routine applications with the original lithotriptor have been its use on common bile duct stones combined with endosurgical or radiological manipulations. With a modified kidney lithotriptor gallstones have been treated successfully, which has led to the development of a multipurpose device for biliary and urinary stones.

Urinary extracorporeal shock wave lithotripsy: equipment, techniques, and overview

Second generation urinary lithotriptors are characterized by extensive technical alterations and significant equipment improvement in the functional, logistical, and medical aspects of shock wave lithotripsy (SWL). These newer devices feature a water bath-free environment, a reduced anesthesia requirement, improved imaging, functional uses in addition to lithotripsy, or combinations thereof. Shock wave generation by spark gap, electromagnetic, piezoelectric and microexplosive techniques are related to their peak energy, frequency, and total energy capabilities which impacts on both anesthesia needs and the length and number of treatment sessions required to pulverize calculi. A master table summarizes the types of SW energy, coupling, imaging systems, patient transport, functional features, cost, and treatment effectiveness of 12 worldwide lithotriptors in various stages of investigative and clinical trials as monitored by the Food and Drug Administration (FDA) of America.

A prototype device for nonimmersion shock wave lithotripsy using ultrasonography for calculus localization

Extracorporeal shock wave lithotripsy has revolutionized the clinical treatment of renal calculi. A device was constructed with a spark gap for shock wave generation and a water-filled ellipsoidal reflector to focus the shock wave energy. A membrane coupled the device to the pig and an ultrasonic transducer was used for stone visualization. Initial in vitro experiments and in vivo studies using dwarf pigs demonstrated fragmentation of calculi.