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PubMed2000

Laser lithotripsy and cyanide.

BACKGROUND AND PURPOSE: Holmium:YAG lithotripsy of uric acid calculi produces cyanide. The laser and stone parameters required to produce cyanide are poorly defined. In this study, we tested the hypotheses that cyanide production: (1) varies with holmium:YAG power settings; (2) varies among holmium:YAG, pulsed-dye, and alexandrite lasers; and (3) occurs during holmium:YAG lithotripsy of all purine calculi. MATERIALS AND METHODS: Holmium:YAG lithotripsy of uric acid calculi was done using various optical fiber diameters (272-940 microm) and pulse energies (0.5-1.5 J) for constant irradiation (0.25 kJ). Fragmentation and cyanide were quantified. Cyanide values were divided by fragmentation values, and fragment sizes were characterized. To test the second hypothesis, uric acid calculi were irradiated with Ho:YAG, pulsed-dye, and alexandrite lasers. Fragmentation and cyanide were measured, and cyanide per fragmentation was calculated. Fragment sizes were characterized. Finally, Ho:YAG lithotripsy (0.25 kJ) of purine and nonpurine calculi was done, and cyanide production was measured. RESULTS: Fragmentation increased as pulse energy increased for the 550- and 940-microm optical fibers (P < 0.05). Cyanide increased as pulse energy increased for all optical fibers (P < 0.002). Cyanide per fragmentation increased as pulse energy increased for the 272-microm optical fiber (P = 0.03). Fragment size increased as pulse energy increased for the 272-microm, 550-microm, and 940-microm optical fibers (P < 0.001). The mean cyanide production from 0.25 kJ of optical energy was Ho:YAG laser 106 microg, pulsed-dye 55 microm, and alexandrite 1 microg (P < 0.001). The mean cyanide normalized for fragmentation (microg/mg) was 1.18, 0.85, and 0.02, respectively (P < 0.001). The mean fragment size was 0.6, 1.1, and 1.9 mm, respectively (P < 0.001). After 0.25 kJ, the mean amount of cyanide produced was monosodium urate stones 85 microg, uric acid 78 microg, xanthine 17 microg, ammonium acid urate 16 microg, calcium phosphate 8 microg, cystine 7 microg, and struvite 4 microg (P < 0.001). CONCLUSIONS: Cyanide production varies with Ho:YAG pulse energy. To minimize cyanide and fragment size, Ho:YAG lasertripsy is best done at a pulse energy < or = 1.0 J. Cyanide production from laser lithotripsy of uric acid calculi varies among Ho:YAG, pulsed-dye, and alexandrite lasers and is related to pulse duration. Cyanide is produced by Ho:YAG lasertripsy of all purine calculi.

Cyanides↗
PubMed1994

Endoscopic pulsed-dye laser lithotripsy: 159 consecutive cases.

The application of the coumarin-based pulsed-dye laser has allowed the endoscopist to employ more delicate instruments with smaller working channels in treating urinary and biliary calculi. We have previously reported our first 100 patients treated with this laser. In 159 consecutive patients, 176 renal, ureteral, bladder, urethral, and biliary calculi with an average size of 1.6 cm were treated with the pulsed-dye laser in antegrade or retrograde fashion using rigid (6.9F-11.5F) or flexible (8.5-10.5F) endoscopes. The laser fibers ranged from 200 to 550 microns and the energy from 60 to 200 mJ. In some cases, the laser was used as an adjunct to percutaneous nephrolithotomy for staghorn calculi, to fragment bladder calculi without anesthesia, to free encrusted ureteral catheters, or as a lithotrite in the biliary tree. Only 4 stones (2.5%) could not be fragmented. There were no complications directly attributable to the use of laser energy. The pulsed-dye laser is safe and efficacious as an endoscopic lithotrite.

Anesthesia↗
PubMed1992

[Laser lithotripsy in gastroenterology].

Almost 90% of all stones in the bile duct can be removed after sphincterotomy and additional mechanical or electrohydraulic lithotripsy. However, a small number of very large or very hard or impacted stones remain, which cannot be removed by conventional endoscopic methods. Intracorporeal laser-induced lithotripsy is a new, promising method to improve stone clearance rate in the common bile duct and--in special cases--also of the pancreatic duct system. Laser-induced lithotripsy especially in combination with a stone tissue detection system is a safe and effective method which can be performed either under direct endoscopic vision or--in selected cases--under X-ray control alone.

Cholelithiasis↗
PubMed1991

Pulsed dye laser lithotripsy--currently applied to urologic and biliary calculi.

The flash lamp excitation of coumarin dye to produce light energy of the specific wavelength of 504 nm is the basis for the new wave of pulsed dye lasers. Numerous urological applications have been developed. Treatment of ureteral and renal calculi has proven to be an atraumatic and effective treatment modality. Most recently, this technology has been applied to the endoscopic treatment of biliary calculi. The authors review the most recent treatment techniques in both biliary and urinary stone disease.

Cholelithiasis↗
PubMed2001

A perspective on laser lithotripsy: the fragmentation processes.

This paper describes in simple terms the physics of laser-calculus interactions and introduces a method with which physicians can understand or evaluate the application of any new laser technique for use in lithotripsy or other medical fields. Tissue optical properties and laser parameters govern the mechanism(s) of fragmentation of urinary or biliary calculi. Laser pulse energies for clinical lithotripsy range from Q0 = 20 mJ to 2 J for short-pulsed lasers to long-pulsed lasers, respectively. Lasers with short pulse durations (i.e., less than a few microseconds) fragment calculi by means of shockwaves following optical breakdown and plasma expansion of ionized water or calculus compositions or by cavitation collapse, thus manifesting a photoacoustical effect. Laser-tissue interactions involving dominant photomechanical or photoacoustical effects are usually stress confined. Long-pulsed lasers (i.e., >100 microsec), on the other hand, generate minimal acoustic waves, and calculi are fragmented by temperatures beyond the thresholds for vaporization of calculus constituents, melting, or chemical decomposition.

Humans↗
PubMed1999

Holmium:YAG laser lithotripsy: A dominant photothermal ablative mechanism with chemical decomposition of urinary calculi.

BACKGROUND AND OBJECTIVE: Evidence is presented that the fragmentation process of long-pulse Holmium:YAG (Ho:YAG) lithotripsy is governed by photothermal decomposition of the calculi rather than photomechanical or photoacoustical mechanisms as is widely thought. The clinical Ho:YAG laser lithotriptor (2.12 microm, 250 micros) operates in the free-running mode, producing pulse durations much longer than the time required for a sound wave to propagate beyond the optical penetration depth of this wavelength in water. Hence, it is unlikely that shock waves are produced during bubble formation. In addition, the vapor bubble induced by this laser is not spherical. Thus the magnitude of the pressure wave produced at cavitation collapse does not contribute significantly to lithotripsy. STUDY DESIGN/MATERIALS AND METHODS: A fast-flash photography setup was used to capture the dynamics of urinary calculus fragmentation at various delay times following the onset of the Ho:YAG laser pulse. These images were concurrently correlated with pressure measurements obtained with a piezoelectric polyvinylidene-fluoride needle-hydrophone. Stone mass-loss measurements for ablation of urinary calculi (1) in air (dehydrated and hydrated) and in water, and (2) at pre-cooled and at room temperatures were compared. Chemical and composition analyses were performed on the ablation products of several types of Ho:YAG laser irradiated urinary calculi, including calcium oxalate monohydrate (COM), calcium hydrogen phosphate dihydrate (CHPD), magnesium ammonium phosphate hexahydrate (MAPH), cystine, and uric acid calculi. RESULTS: When the optical fiber was placed perpendicularly in contact with the surface of the target, fast-flash photography provided visual evidence that ablation occurred approximately 50 micros after the initiation of the Ho:YAG laser pulse (250-350 micros duration; 375-400 mJ per pulse), long before the collapse of the cavitation bubble. The measured peak acoustical pressure upon cavitation collapse was negligible (< 2 bars), indicating that photomechanical forces were not responsible for the observed fragmentation process. When the fiber was placed in parallel to the calculus surface, the pressure peaks occurring at the collapse of the cavitation were on the order of 20 bars, but no fragmentation occurred. Regardless of fiber orientation, no shock waves were recorded at the beginning of bubble formation. Ablation of COM calculi (a total of 150 J; 0.5 J per pulse at an 8-Hz repetition rate) revealed different Ho:YAG efficiencies for dehydrated calculus, hydrated calculus, and submerged calculus. COM and cystine calculi, pre-cooled at -80 degrees C and then placed in water, yielded lower mass-loss during ablation (20 J, 1.0 J per pulse) compared to the mass-loss of calculi at room temperature. Chemical analyses of the ablated calculi revealed products resulting from thermal decomposition. Calcium carbonate was found in samples composed of COM calculi; calcium pyrophosphate was found in CHPD samples; free sulfur and cysteine were discovered in samples composed of cystine samples; and cyanide was found in samples of uric acid calculi. CONCLUSION: These experimental results provide convincing evidence that long-pulse Ho:YAG laser lithotripsy causes chemical decomposition of urinary calculi as a consequence of a dominant photothermal mechanism.

Holmium↗
PubMed1990

Percutaneous pulsed-dye laser lithotripsy of gallbladder stones in swine.

Human gallstones were surgically implanted in the gallbladders of 14 pigs. Nine to 16 days later a sheath was successfully placed percutaneously into the gallbladders of 13 animals using ultrasound and fluoroscopy. Two methods were used to guide laser fragmentation: (1) fluoroscopy and a steerable double lumen catheter (two animals), and (2) a flexible endoscope (11 animals). Laser treatment was done in 12 animals with a flashlamp-pumped pulsed-dye laser. A mean of 3600 pulses/animal were delivered using a wavelength of 504 nm and a maximum energy of 60 mJ/pulse. No fragmentation occurred in two animals, partial fragmentation occurred in six, and complete fragmentation occurred in four. Endoscopic guidance was superior to fluoroscopic guidance. Complications (sheath dislodgment, gallbladder perforation, bleeding) occurred in eight of 14 animals. Pulsed-dye laser fragmentation of gallbladder stones is feasible using endoscopic guidance. The use of this technique through an acute percutaneous tract may be associated with complications.

Animals↗
PubMedDate not supplied

Peroral tunable-dye laser lithotripsy of intrahepatic stones in oriental cholangitis.

This case report details the use of a pulsed tunable-dye laser lithotripter in the endoscopic management of recurrent intrahepatic stones in a patient with Oriental cholangitis. A 42-year-old Chinese man had a cholecystectomy and choledochoduodenostomy in 1980. Subsequently he had three episodes of recurrent cholangitis which responded to medical treatment. The patient presented in April 1989 with a fourth attack of cholangitis. Endoscopic retrograde cholangiopancreatography (ERCP) and ultrasound demonstrated a large mass of stones in the right intrahepatic ductal system. A flexible upper gastrointestinal endoscope was passed into the right hepatic duct via the choledochoduodenostomy. The stones were fragmented with a tunable-dye laser and the residual fragments were removed endoscopically.

Adult↗
PubMed1995

[Laser lithotripsy of the upper urinary tract].

Approximately 10% of all stone patients require an endoscopic stone treatment. With the advent of laserlithotripters a new technology became available, featuring extremely thin (200 microns) and flexible lithotripsy probes. As a consequence, miniscopes have been developed for endoscopic stone manipulation in the ureter. These miniscopes greatly facilitate ureteroscopy and expectantly will reduce complications associated with this procedure. The success rates of laserlithotripsy are in the 90% range, the only serious drawback are the high purchase costs of the laser. Independent from these new possibilities for intracorporeal lithotripsy, extracorporeal shockwave lithotripsy (ESWL) remains the first therapy of choice for ureteral calculi.

Adult↗
PubMed2002

Expanding role of ureteroscopy and laser lithotripsy for treatment of proximal ureteral and intrarenal calculi.

PURPOSE OF REVIEW: Ureteroscopy has assumed an expanded and important role in the treatment of proximal ureteral and intrarenal calculi with the development of new endoscopes, more effective grasping devices, and the holmium laser lithotriptor. RECENT FINDINGS: The success rate for treating proximal ureteral stones with small rigid and flexible ureteroscopes and the holmium laser is well over 90%. Lower pole renal calculi can also be treated with a success rate of approximately 80%, which surpasses that of shock wave lithotripsy. Selected stones that are over 2 cm in diameter, along with branched stones, can also be treated successfully with ureteroscopy. SUMMARY: Ureteroscopy is the most successful technique for the treatment of ureteral calculi (success rates >90%) and is an optional treatment for many renal calculi.

Humans↗
PubMed2001

Retrograde ureteropyeloscopic holmium laser lithotripsy for large renal calculi.

OBJECTIVE: To assess the efficacy and safety of the retrograde ureteropyeloscopic holmium laser for treating renal stones that are too large to treat with extracorporeal shock wave lithotripsy (ESWL). PATIENTS AND METHODS: Thirty patients (22 men and eight women, mean age 43 years, range 18-62) with a renal stone burden of > 2 cm were selected for laser treatment. The stones were in the renal pelvis in 16 patients, lower calyx in five, middle calyx in two, upper calyx in one and multiple pelvic and calyceal in six. Lithotripsy was undertaken using a holmium laser through 550 microm and 200 microm laser fibres passed through a semi-rigid fibre-optic long ureteroscope or the actively deflectable flexible ureteropyeloscope, respectively. Success was defined as total fragmentation of the stone to < 2 mm in diameter and/or clear imaging on renal ultrasonography and plain films within the 3-month follow-up. Patients in whom the treatment failed received either alternative therapy or complementary ESWL. RESULTS: Endoscopic access and complete stone fragmentation was achieved in 23 of the 30 patients (77%). The treatment failed in seven patients because of poor visualization, the initial presence of stones in, or migration of their large fragments to, an inaccessible calyx. There were no major intraoperative complications. Minor complications after treatment included haematuria that persisted for 2 days in one patient and high-grade fever in two patients; all were treated conservatively. CONCLUSION: Large renal calculi that are not amenable to ESWL monotherapy can be safely and effectively treated with a retrograde endoscopic technique that seems to compete well with the more invasive percutaneous or open surgical manoeuvres.

Adolescent↗
PubMed1993

Five years experience in experimental laser lithotripsy.

In the first part of our experience approximately 300 stones of different composition have been treated in vitro with three different laser sources: Nd-YAG laser (1,064 nm), dye laser (504 nm) and alexandrite laser (755 nm). Calcium oxalate monohydrate and brushite stones appeared to be the most resistant to lithotripsy. Highest fragmentation rates were obtained for calcium oxalate dihydrate stones followed by struvite, uric acid and hydroxyapatite stones. The Nd-YAG laser did not appear to be ideal for lithotripsy since early damage to the fiber tip was observed when this source was used. Both the dye and the alexandrite lasers were almost always effective in fragmenting the various types of stones. We subsequently treated some cystine stones while immersed in water or in solutions of carmine indigo (2%), methylene blue (5%), rifamycin (0.6 and 6%) and rifampicin (0.8 and 0.3%) with the dye or the alexandrite laser. The spectra of these solutions, previously analyzed with the spectrophotometer, showed that rifamycin and rifampicin absorbed large amounts of light radiation at the wave length of the dye laser (504 nm). Successful fragmentation occurred only when the dye laser was used to treat stones immersed in the more concentrated solutions of these two substances. The quantity of fragmented material after treating a 10-cm3 cystine stone previously immersed in the more concentrated solutions of rifamycin and rifampicin (30 and 10 mm3, respectively) confirmed previous results.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗
PubMed2000

Pulse dye laser lithotripsy for large biliary tract stones.

From 1997 to 1998 the first series of 21 patients with large biliary tract stones (1.5-4.0 cm with average 2.5 cm in diameter) who underwent endoscopic stone extraction by using combination of ERCP and EST with automatic stone-tissue detection pulse dye laser was carried out. Male = 8, Female = 13, average age = 57.5 years (32-83) most of the stones were primary stones (71.4%). Laser fibers were controlled by balloon catheter with fluoroscope (blind technique) in 16 cases and by mother-babyscope system in 5 cases. The result in successful fragmentation of stones was 87.5 per cent with the blind technique and 100 per cent with the mother-babyscope technique. Temporary stents were used in the patients who had severe cholangitis and those who required more than one session of lithotripsy (19%). Complications consisted of controllable cholangitis in 2 cases (9.5%) and there was no mortality. We conclude that stone-tissue detection lithotripsy is very safe and effective in patients with large biliary tract stones and high surgical risk especially via the direct mother-babyscope system.

Adult↗
PubMed2004

Percutaneous pneumatic and laser lithotripsy as a possible therapeutic strategy for bilateral large calculi in a horseshoe kidney.

This report concerns a case of bilateral large calculi in a horseshoe kidney. Three sessions of percutaneous nephrolithotripsy for the calculi successfully disintegrated and removed the fragments without any complications. For complete stone removal we used pneumatic and laser lithotriptors which were passed, respectively, through a rigid nephroscope and a flexible pyeloscope. It is emphasized that the selection of the most suitable lithotriptor by taking their various features into account is important in endoscopic surgery for calculi which are likely to recur such as stones accompanied by infection or for anatomically anomalous kidneys such as horseshoe kidneys.

Female↗