Use of a prototype 3F electrohydraulic electrode with ureteroscopy for treatment of ureteral calculous disease

Influence of Ureteral Stone Components on the Outcomes of Electrohydraulic Lithotripsy

Purpose

We evaluated the influence of urinary stone components on the outcomes of ureteroscopic removal of stones (URS) by electrohydraulic lithotripsy (EHL) in patients with distal ureteral stones.

Materials and Methods

Patients with a single distal ureteral stone with a stone size of 0.5 to 2.0 cm that was completely removed by use of EHL were included in the study. Operating time was defined as the time interval between ureteroscope insertion and complete removal of ureteral stones. Ureteral stones were classified into 5 categories on the basis of their main component (that accounting for 50% or more of the stone content) as follows: calcium oxalate monohydrate (COM), calcium oxalate dihydrate, carbonate apatite (CAP), uric acid (UA), and struvite (ST).

Results

A total of 193 patients (131 males and 62 females) underwent EHL. The mean operating time was 25.1±8.2 minutes and the mean stone size was 1.15±0.44 cm. Calcium oxalate stones accounted for 64.8% of all ureteral stones, followed by UA (19.7%), CAP (8.3%), and ST (7.2%) stones. The mean operating time was significantly longer in the UA group (28.6±8.3 minutes) than in the COM group (24.0±7.8 minutes, p=0.04). In multivariate analyses, the stone size was negatively associated with the odds ratio (OR) for successful fragmentation. UA as a main component (OR, 0.42; 95% confidence interval, 0.20 to 0.89; p=0.023) was also found to be significantly important as a negative predictive factor of successful fragmentation after adjustment for stone size.

Conclusions

The results of the present study suggest that successful fragmentation by URS with EHL could be associated with the proportion of the UA component.

Holmium Laser Percutaneous Nephrolithotomy Using a Unique Suction Device

BACKGROUND AND PURPOSE

Most percutaneous nephrolithotomies are performed with electrohydraulic, ballistic, or ultrasonic lithotripsy, with holmium laser use reserved for ureteroscopy or ureterorenoscopy. We evaluated the feasibility of holmium laser use in percutaneous nephrolithotomy with the assistance of a unique suction device.

PATIENTS AND METHODS

The charts of 71 consecutive patients undergoing 90 percutaneous procedures were reviewed. A unique suction device and the holmium laser were used in nearly half the patients. The average stone burden was 3.25 cm. Use of holmium laser, energy settings, stone burden, operative time, complications, and stone-free rate were evaluated.

RESULTS

The average operative time was 167 minutes with a complication rate of 14%. A stone-free rate of 83% was achieved with the laser.

CONCLUSIONS

With the assistance of a unique suction device, the holmium laser can, in the appropriate situation, be an efficient and successful lithotrite with percutaneous nephrolithotomy.

Surgical management of urolithiasis

The surgical management of urinary calculus disease has changed dramatically in the past two decades. Minimally invasive options have made open stone surgery nearly obsolete. The development of shock wave lithotripsy, percutaneous nephrostolithotomy techniques and intracorporeal lithotripsy devices has conferred unprecedented management tools for upper tract stones. Moreover, transfusion rates, hospital costs, and convalescence periods have been markedly reduced when compared to open surgery. Likewise, the advent of fiberoptic technology has resulted in miniaturization of ureteroscopes making access to the entire collecting system possible from either a retrograde or antegrade approach. With experience, successful stone retrieval has occurred in upwards of 90% of cases, again with minimal complications. The subspecialty of Endourology has emerged over the past 20 years and significantly changed the management of urinary tract calculi within this short period of time. Further advancements in shock wave and laser technology, training modules and the development of more durable endoscopes may prove beneficial in providing even better stone treatments with a reduction in morbidity.

Update on contact lithotripsy

Despite the development of extracorporeal shockwave lithotripsy, endoscopic stone removal, with or without intracorporeal lithotripsy, is still an effective minimally invasive alternative for special indications. There is no defined all-purpose lithotripsy procedure for contact lithotripsy. The choice of the lithotripsy procedure for endoscopic stone disintegration depends on a number of different factors, the main one being stone localization. Small calibre, flexible probes (electrohydraulic, pneumatic, laser) are especially appropriate for ureterorenoscopy, but the speed of stone disintegration is a limiting factor. In contrast, large calibre rigid probes (ultrasound) are clearly more effective, but are unsuitable in size for flexible ureterorenoscopy. This indicates that the type and size of the endoscope decisively influences the choice of devices for endoscopic stone disintegration. Additional inhibiting factors are the flexibility or the rigidity of the instrument and the diameter of the working channel. It must be noted that total costs are not only calculated on the purchase of the equipment, but must also cover disposable materials.

Long-term follow-up after treatment of Mirizzi syndrome by peroral cholangioscopy

BACKGROUND

The standard treatment for Mirizzi syndrome is surgical, although endoscopic and percutaneous management have also been described. The aim of this study was to evaluate the usefulness of shock wave lithotripsy combined with peroral cholangioscopy and its long-term outcome in patients with Mirizzi syndrome.

METHODS

The records of 25 patients with Mirizzi syndrome who underwent endoscopic treatment between April 1990 and November 1998 were retrospectively reviewed. Shock wave lithotripsy was performed under direct vision with a "mother-baby" endoscope system in 2 patients with type I and 23 with type II Mirizzi syndrome (12 men and 13 women, mean age 60 years). Follow-up data were obtained from clinical records or through telephone interviews.

RESULTS

In the two patients with type I, the cholangioscopic approach failed and both patients underwent open cholecystectomy. The 23 patients with type II were all successfully treated with shock wave lithotripsy alone. The cholangioscopic approach was unsuccessful in the treatment of residual gallbladder stones. Follow-up data were obtained in all but one patient (mean 43.6 months, range 4 to 103 months). Of the 23 patients with type II, 12 with no gallbladder stones had remained asymptomatic during the follow-up period. Of the 6 patients with type II with large residual gallbladder stones, 4 had acute cholangitis due to stone migration 6, 9, 28, and 34 months after endoscopic treatment. Two patients died during the follow-up period, one of non-biliary causes and the other of coexistent gallbladder carcinoma.

CONCLUSIONS

Endoscopic treatment of Mirizzi syndrome using peroral cholangioscopy is a safe and effective alternative to surgery, especially in patients with the type II syndrome. A favorable long-term outcome depends on the absence of large residual gallbladder stones.

Intracorporeal lithotripsy. Update on technology

The number and variety of devices currently available for endoscopic lithotripsy reflect the reality that no single device is ideal in all situations. Although the search for the universal lithotriptor continues, the urologist must consider several factors if faced with the decision of which device to purchase. Perhaps foremost among these factors is the clinical situation with which one commonly deals. For example, although the smaller, flexible probes such as EHL or laser demonstrate considerable utility if used ureteroscopically, the larger stone burden associated with today's percutaneous nephrolithotripsy population often is treated more efficiently with one of the mechanical devices employing a larger, rigid probe, such as ultrasound or the Lithoclast. Similarly, the type and size of endoscopic equipment at one's disposal have a significant impact on which device to purchase or use. There are physical constraints affecting which device may or may not be used, rigid versus flexible endoscope, working channel caliber, and offset versus end-on-port. The skill and experience of the surgeon is also a factor of obvious importance, particularly if one is using a modality with a relatively narrow margin of safety such as EHL. Likewise, the training and experience of nursing personnel is a factor, especially regarding the use of lasers, which require certified personnel who are well versed in laser safety. Finally, in today's environment one must carefully evaluate cost in terms of not only initial capital outlay but also ongoing charges for disposable and maintenance items. Thus, the decision of which device to purchase is complex and requires careful evaluation of all of the previously noted variables. Likewise, if one is fortunate enough to have more than one device available, the decision of which lithotriptor to employ requires a similar decision based on sound surgical judgment.

Treatment of lower ureteral stones: extracorporeal shockwave lithotripsy or intracorporeal lithotripsy?

OBJECTIVE

In this study, 1121 patients with lower ureteral stones were evaluated to compare the effectiveness of extracorporeal shockwave lithotripsy (SWL) and ureteroscopy with three different lithotripsy modalities.

METHODS

Of these patients, 726 were treated with SWL, whereas 430 underwent ureteroscopy, with pneumatic lithotripsy (PL), ultrasonic lithotripsy (USL), and electrohydraulic lithotripsy (EHL) performed in 125 (29.0%), 276 (64.2%), and 29 (6.8%) patients, respectively. Thirty-five patients underwent both types of treatment because of unsuccessful SWL therapy.

RESULTS

In the SWL group, the stone-free rate was 42.2% and the fragmentation rate was 59.5%. These values were 96.8% and 98.4% for PL, 89.4% and 90.5% for USL, 93.1% and 96.5% for EHL, respectively.

CONCLUSIONS

These data show that SWL was less effective than ureteroscopic lithotripsy (p < 0.001). The PL modality had the highest stone-free and fragmentation rate, and EHL had the highest complication rate (43.5%). Ureteroscopic lithotripsy is the most effective treatment choice in lower ureteral stones no matter which kind of energy is used, and PL is the most effective and least morbid approach.

Pneumatic v electrokinetic lithotripsy in treatment of ureteral stones

Recently, a new device (Combilith) for electrokinetic lithotripsy (EKL) has become available which is very similar to the well-known device for pneumatic (ballistic) lithotripsy (Swiss Lithoclast). The Lithoclast uses air pressure to push a projectile within the handpiece against the end of a metal probe, which is thereby accelerated and thrown like a jackhammer against the stone. In principle, the same stroking movement of a small metal probe is provided by EKL; the difference is that instead of a projectile, a magnetic core within the handpiece is accelerated by the electromagnetic principle. This paper compares the clinical efficacy and the features of the two devices. Testing the devices on a stone model, taking into account stone propulsion, the systems turned out to equally effective regarding stone disintegration. However, stone displacement was more pronounced with the Lithoclast applied on easily breaking stones. In a second experiment, an optoelectronic movement-measuring apparatus (Zimmer camera) was employed to measure the range and velocity of the movement of the probe tip without any contact. The linear acceleration velocity ranged from 5 to a maximum of 12.5 m/sec with both systems, but the maximum height of the stroke was 2.5 mm with the Lithoclast and 1 mm with EKL. After the initial break-up of soft stones, further impact of the probe tip against the stone resulted merely in propulsion; thus, the greater probe stroke height is the cause of the stone displacement. In a clinical trial, 22 ureteral stones were treated with the Lithoclast and 35 with the EKL. The two devices were equally effective in terms of stone disintegration and safety margin. Fixation using a Dormia basket was necessary in 12 cases (8 Lithoclast, 4 EKL). Although a difference in probe stroke height was noted when comparing pneumatic and electrokinetic lithotripsy, there were no clinically significant differences in the efficacy of stone fragmentation or stone-free rates. At the current time, EKL is less costly.

Laboratory and clinical assessment of pneumatically driven intracorporeal lithotripsy

A pneumatically driven intracorporeal lithotripter (the Swiss Lithoclast) has recently been approved for use in the United States. We compared its performance in vitro with ultrasonic, electrohydraulic and laser lithotripsy devices using a standard plaster-of-Paris stone phantom. The probe sizes and output settings were identical to those used during clinical treatment. The fragmentation efficiency index (measured as the lithotripsy time needed to reduce the stone phantom to particles <2 mm divided by the initial stone weight) ranged from 5.0 to 8.5 min/g of stone mass, with this value increasing from pneumatic to electrohydraulic to laser and to ultrasonic lithotripsy. We also performed an objective study in a swine model, which showed no adverse consequence of pneumatic lithotripsy. Finally, we evaluated our initial 41 patients who had undergone pneumatic stone fragmentation. We treated 8 patients having 11 renal calculi, 30 patients having 37 ureteral calculi, and 3 patients having 6 bladder calculi employing pneumatic probes ranging in size from 0.8 to 2.0 mm. Stone fragmentation was successful in a single session in 95% of the ureteral calculi and 100% of both renal and bladder calculi. Stone analysis in 23 patients revealed 17 (74%) calcium oxalate monohydrate and 1 (4%) cystine calculi. Our clinical and laboratory assessment of this newly developed pneumatic lithotripsy device further validates its efficacy in fragmenting stone of all compositions and its overall safety associated with clinical application.

Safety and efficacy of the Alexandrite laser for the treatment of renal and ureteral calculi

OBJECTIVES

To assess the safety and efficacy of the Alexandrite laser for intracorporeal lithotripsy of renal and ureteral stones in conjunction with ureterorenoscopy or percutaneous nephrostolithotomy.

METHODS

We retrospectively analyzed the records of 137 patients with 169 calculi in 143 renoureteral units who were treated with the Alexandrite laser via a retrograde (91.5%) or antegrade (8.5%) endoscopic approach.

RESULTS

Adequate intraoperative fragmentation of the stone was observed in 88.8% of the cases. No intraoperative complications were attributable to the laser. At a mean follow-up of 34 days, the overall stone-free rate was 74.4%. The stone-free rate for ureteral stones (n = 115) was 80%, whereas the stone-free rate for renal stones (n = 22) was only 44%. In the best subgroup of ureteral stones (10 mm or less in the distal ureter), the stone-free rate was 97.4%.

CONCLUSIONS

The Alexandrite laser is a safe modality for intracorporeal lithotripsy and is highly effective for ureteral stones less than 10 mm in size.

Treatment of Ureteral Stones: Intracorporeal Or Extracorporeal Lithotripsy?

Over the last 15 years the treatment of ureteral stones has been considerably revolutionised thanks to new, less invasive technologies compared to traditional surgery. The urologist is, however, faced with a dilemma: whether to cure the patient with easy-to-perform extracorporeal lithotripsy (ESWL) without anesthesia in Day Surgery, but which often requires more than one session to clear the stones completely, or to carry out ureteroscopy and intracorporeal lithotripsy, which resolves most cases in just one treatment but is more invasive in that it requires general anesthesia and hospitalisation. The authors present their experience and compare the two methods.

Electrohydraulic lithotripsy: an effective and economical modality of endoscopic ureteric lithotripsy

BACKGROUND

Electrohydraulic lithotripsy (EHL) has been available for endoscopic treatment of urinary calculi since 1960, but the large probe size and concerns regarding safety had previously restricted its use to the treatment of bladder calculi. However, recent refinements have made it particularly suitable for the treatment of ureteric calculi.

METHODS

The authors report their initial experience using EHL in conjunction with mini-ureteroscopy in the treatment of 94 ureteric calculi in 89 patients. The size of the calculi ranged from 3 to 19 mm in diameter, with a mean of 8.2 mm. The mean operating time was 29 min, ranging from 10 to 120 min.

RESULTS

A complete fragmentation rate of 91.5% of the calculi was achieved. There were no major complications and a low incidence of minor complications: haematuria (2.2%), urinary tract infection (3.4%) and postoperative ureteric colic (2.2%). There were four cases of minor ureteric perforations (4.5%); all were successfully treated using conservative measures.

CONCLUSIONS

It is concluded that EHL is a safe and effective method of treating ureteric calculi.

Intracorporeal lithotripsy. Instrumentation and development

This article describes the history of intracorporeal lithotripsy and the impact of previous techniques on modern devices. Technical and clinical specifics for several historical and current intracorporeal lithotripsy methods are described.

Percutaneous transhepatic endoscopic electrohydraulic lithotripsy of biliary tract calculi after orthotopic liver transplantation

The development of biliary tract calculi after orthotopic liver transplantation presents a unique clinical problem. Previously described techniques for removing biliary stones by shock wave lithotripsy, litholytic therapy with oral bile acids, and endoscopic mechanical extraction may be ineffective or contraindicated in liver transplant patients. For this reason, percutaneous transhepatic electrohydraulic lithotripsy (EHL) was performed using an 11 French flexible ureteroscope in two pediatric patients who developed biliary tract calculi following orthotopic liver transplant. There were no complications and postoperative follow-up over 4 years has been uneventful. To our knowledge, these represent the first reported cases of percutaneous transhepatic endoscopic EHL to fragment biliary tract stones in a transplanted liver, which for us has been a safe and effective therapeutic option.

First temporal and spatial quantification of single-shot electrohydraulic lithotripsy in vitro

Single electrohydraulic lithotripsy (EHL) discharges from a human ureter were analyzed with a mechanical high-speed motion analysis camera. We found a cavitation bubble, at 650 mJ, 4-11 mm in size, with a lifetime of 400-500 microseconds. Varying sizes and lifetimes were found using single-shot analysis, as well as in different shot-sequences. This supports similar observations by recent investigations of cavitation bubble size with high-shutter-speed videofilm, which have depicted events at shutter speeds of 4000/s, i.e., an approximate exposure time of 250 microseconds. Due to the occurrence of high-voltage interference from the EHL high-voltage generator, no other technical electronic event timing equipment has so far been available capable of mechanical high-speed film motion analysis, while at the same time avoiding high-voltage interference.

Electrohydraulic versus pneumatic disintegration in the treatment of ureteral stones: a randomized, prospective trial

The efficacy and safety of electrohydraulic versus pneumatic lithotripsy in the treatment of ureteral stones were evaluated in a prospective, randomized study. A total of 72 patients with stones not capable of passing spontaneously and unsuitable for extracorporeal shock wave lithotripsy was randomized to either method (34 to electrohydraulic lithotripsy and 38 to pneumatic lithotripsy). While both techniques were equivalent in efficacy (85.3% for electrohydraulic and 89.5% for pneumatic lithotripsy), the perforation rates were significantly different (17.6 versus 2.6%, respectively). Although the long-term results revealed no significant differences, pneumatic lithotripsy, as the markedly safer and easier to handle technique, is currently the method of choice at our stone center for ureteral calculi requiring treatment but not suitable for extracorporeal shock wave lithotripsy.

Ureteral and bladder lesions after ballistic, ultrasonic, electrohydraulic, or laser lithotripsy

Four techniques of intracorporeal lithotripsy are now available: ballistic, ultrasonic, electrohydraulic, and laser. Their therapeutic efficacies have generally been evaluated and compared, but very few data have been available on their relative risks of iatrogenic trauma to the urothelial wall. We conducted a comparative analysis of this risk by testing the pig ureteral and bladder wall with the EMS Lithoclast, Olympus ultrasonic lithotripter, Walz Lithotron EL 23, and Versa Pulse Ho:YAG Coherent Laser. We measured the number of shockwaves or the energy required to perforate the ureter and bladder by delivering shocks perpendicular to the walls. Ureteral perforation was impossible with the 1.0-mm Lithoclast transducer and the 1.5-mm ultrasound transducer. Perforation was induced after 250 shocks with the 0.8-mm Lithoclast transducer, after 110 shocks with the 3F electrohydraulic electrode, and after 0.02 kJ with the laser. Bladder perforation was impossible with the 2.0-mm Lithoclast device and the 3.4-mm ultrasound transducer but was induced after 0.04 kJ had been delivered with the laser. We evaluated the iatrogenic risk under normal conditions of use by delivering the shocks tangentially to the ureteral wall and perpendicular to the bladder wall. We sacrificed animals on days 0, 1, and 6. The immediate histologic lesions induced by the Lithoclast and the ultrasound lithotripter were similar, consisting of a moderate reduction of the epithelial layers or intraepithelial detachments. Electrohydraulic shocks induced almost complete abrasion of the urothelium, and the laser induced extensive lesions of partial or complete necrosis of the urothelial wall.(ABSTRACT TRUNCATED AT 250 WORDS)

New tip design and shock wave pattern of electrohydraulic probes for endoureteral lithotripsy

A new tip design of a 3.3F electrohydraulic probe for endoureteral lithotripsy was evaluated in comparison to a regular probe. The peak pressure, as well as the slope of the shock front, depend solely on the voltage. Increasing the capacity leads merely to broader pulses. A laser-like short high-pressure pulse has a greater impact on stone disintegration than a corresponding broader low-pressure pulse of the same energy. Using the regular probe, only positive pressures were obtained. Pressure distribution around the regular tip was approximately spherical, whereas the modified probe tip "beamed" the shock wave to a great extent. In addition, a negative-pressure half-cycle was added to the initial positive peak pressure, which resulted in a higher maximal pressure amplitude. The directed shock wave had a greater depth of penetration into a model stone. Thus, the ability of the new probe to destroy harder stones especially should be greater. The trauma to the ureter was reduced when touching the wall tangentially. No difference in the effect of the two probes was seen when placing the probe directly on the mucosa.

Impact of voltage and capacity on the electrical and acoustic output of intracorporeal electrohydraulic lithotripsy

The electrical and acoustic output created by the spark discharge for electrohydraulic lithotripsy at the tip of a 3.3-F probe was evaluated. Spark generation was achieved by variable combinations of voltage and capacity. The effective electrical output was determined by means of a high-voltage probe, a current coil and a digital oscilloscope. Peak pressures, rise times and pulse width of the shock waves were recorded using a polyvinylidene difluoride needle hydrophone in 0.9% NaCl solution at a distance of 10 mm. The effective electrical output is lower than the calculated output, due to inductivities, capacities and resistances of the cables and plugs. The life of the probes is markedly shorter when a combination of high voltage and low capacity is used than with low voltage and high capacity corresponding to the same energy. The peak pressure and the slope of the shock front depend solely on the voltage, while the pulse width is correlated with the capacity. The pulse intensity integral of the shock wave is likely to be the best equivalent to the applied energy.

Endoscopic laser lithotripsy of large bile duct stones

Experimental work has established that the Candela (Candela Laser Corporation, Wayland, MA) flashlamp excited dye laser (wavelength, 504 nm) is a highly effective method for fragmenting biliary stones and has minimal potential for injuring the bile duct wall. This technique was evaluated in 25 complex patients whose stones, usually because of large size, did not respond to standard nonoperative treatment. The laser imaging was applied through a quartz fiber and aimed either under direct vision with choledochoscopes passed percutaneously or through a special "mother" duodenoscope or under fluoroscopic guidance at standard duodenoscopy. Laser treatment resulted in some fragmentation of stones in 23 cases. Subsequently, it proved that it was possible to clear the bile duct of stones in 20 patients, 12 of them receiving successful treatment during the same endoscopic procedure. There were no significant complications. This endoscopic technique seems to be a useful new alternative to surgery in patients with large and difficult bile duct stones.

Electrohydraulic lithotripsy of renal and ureteral calculi

Electrohydraulic lithotripsy was used to manage 45 upper tract calculi (23 renal and 22 ureteral stones) in 40 patients. Electrohydraulic lithotripsy successfully fragmented 91% of the calculi. All ureteral fragments cleared; in 2 patients with renal calculi solitary 4 mm. stone fragments remained. There were no intraoperative or long-term complications directly related to the use of electrohydraulic lithotripsy in the upper urinary tract. We conclude that intrarenal and intraureteral electrohydraulic lithotripsy is a safe, effective, inexpensive means to perform intracorporeal lithotripsy.

The role of open stone surgery since extracorporeal shock wave lithotripsy

Of 893 stone procedures 37 (4.1 per cent) performed during the first 19 months after extracorporeal shock wave lithotripsy was instituted at our medical center were open operations. Procedures included ureterolithotomy in 23 patients (with simultaneous pyelolithotomy in 1), anatrophic nephrolithotomy in 8, pyelolithotomy in 3 (with concomitant pyeloplasty in 2), partial nephrectomy in 2 and nephrolithotomy with a bowel segment inlay in 1. The most common reasons for electing an open operation were unsuccessful endoscopic stone manipulation, presence of anatomical obstruction in the intrarenal collecting system or ureter, morbid obesity and underlying medical problems precluding lengthy repeated endourological procedures. Over-all surgical results were excellent. Our study indicates that patients who presently require an open stone operation have complex calculous disease associated with a variety of anatomical and physiological problems. Despite this finding good results may be attained.