Therapeutic applications of ultrasound

Therapeutic applications of ultrasound predate its use in imaging. A range of biological effects can be induced by ultrasound, depending on the exposure levels used. At low levels, beneficial, reversible cellular effects may be produced, whereas at high intensities instantaneous cell death is sought. Therapy ultrasound can therefore be broadly divided into "low power" and "high power" applications. The "low power" group includes physiotherapy, fracture repair, sonophoresis, sonoporation and gene therapy, whereas the most common use of "high power" ultrasound in medicine is probably now high intensity focused ultrasound. Therapeutic effect through the intensity spectrum is obtained by both thermal and non-thermal interaction mechanisms. At low intensities, acoustic streaming is likely to be significant, but at higher levels, heating and acoustic cavitation will predominate. While useful therapeutic effects are now being demonstrated clinically, the mechanisms by which they occur are often not well understood.

Endoscopic management of common bile duct stones: European Society of Gastrointestinal Endoscopy (ESGE) guideline

ESGE recommends offering stone extraction to all patients with common bile duct stones, symptomatic or not, who are fit enough to tolerate the intervention.Strong recommendation, low quality evidence.ESGE recommends liver function tests and abdominal ultrasonography as the initial diagnostic steps for suspected common bile duct stones. Combining these tests defines the probability of having common bile duct stones.Strong recommendation, moderate quality evidence.ESGE recommends endoscopic ultrasonography or magnetic resonance cholangiopancreatography to diagnose common bile duct stones in patients with persistent clinical suspicion but insufficient evidence of stones on abdominal ultrasonography.Strong recommendation, moderate quality evidence.ESGE recommends the following timing for biliary drainage, preferably endoscopic, in patients with acute cholangitis, classified according to the 2018 revision of the Tokyo Guidelines:- severe, as soon as possible and within 12 hours for patients with septic shock- moderate, within 48 - 72 hours- mild, elective.Strong recommendation, low quality evidence.ESGE recommends endoscopic placement of a temporary biliary plastic stent in patients with irretrievable biliary stones that warrant biliary drainage.Strong recommendation, moderate quality of evidence.ESGE recommends limited sphincterotomy combined with endoscopic papillary large-balloon dilation as the first-line approach to remove difficult common bile duct stones. Strong recommendation, high quality evidence.ESGE recommends the use of cholangioscopy-assisted intraluminal lithotripsy (electrohydraulic or laser) as an effective and safe treatment of difficult bile duct stones.Strong recommendation, moderate quality evidence.ESGE recommends performing a laparoscopic cholecystectomy within 2 weeks from ERCP for patients treated for choledocholithiasis to reduce the conversion rate and the risk of recurrent biliary events. Strong recommendation, moderate quality evidence.

Histotripsy methods in mechanical disintegration of tissue: towards clinical applications

In high intensity focused ultrasound (HIFU) therapy, an ultrasound beam is focused within the body to locally affect the targeted site without damaging intervening tissues. The most common HIFU regime is thermal ablation. Recently there has been increasing interest in generating purely mechanical lesions in tissue (histotripsy). This paper provides an overview of several studies on the development of histotripsy methods toward clinical applications. Two histotripsy approaches and examples of their applications are presented. In one approach, sequences of high-amplitude, short (microsecond-long), focused ultrasound pulses periodically produce dense, energetic bubble clouds that mechanically disintegrate tissue. In an alternative approach, longer (millisecond-long) pulses with shock fronts generate boiling bubbles and the interaction of shock fronts with the resulting vapour cavity causes tissue disintegration. Recent preclinical studies on histotripsy are reviewed for treating benign prostatic hyperplasia (BPH), liver and kidney tumours, kidney stone fragmentation, enhancing anti-tumour immune response, and tissue decellularisation for regenerative medicine applications. Potential clinical advantages of the histotripsy methods are discussed. Histotripsy methods can be used to mechanically ablate a wide variety of tissues, whilst selectivity sparing structures such as large vessels. Both ultrasound and MR imaging can be used for targeting and monitoring the treatment in real time. Although the two approaches utilise different mechanisms for tissue disintegration, both have many of the same advantages and offer a promising alternative method of non-invasive surgery.

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.

Acoustic cavitation generated by an extracorporeal shockwave lithotripter

Evidence is presented of acoustic cavitation generated by a Dornier extracorporeal shockwave lithotripter. Using x-ray film, thin aluminum sheets, and relatively thick metal plates as targets, evidence of liquid jet impacts associated with cavitation bubble collapse was observed. The jet impact was violent enough to puncture thin foils and deform metal plates. Furthermore, numerous jet impacts were generated over a volume of greater than 200 cm3. It is likely that such violent cavitation will also occur in tissue, and observed biological effects (e.g. renal calculus disintegration and tissue trauma) may be related to cavitation damage.

Shock wave technology and application: an update

CONTEXT

The introduction of new lithotripters has increased problems associated with shock wave application. Recent studies concerning mechanisms of stone disintegration, shock wave focusing, coupling, and application have appeared that may address some of these problems.

OBJECTIVE

To present a consensus with respect to the physics and techniques used by urologists, physicists, and representatives of European lithotripter companies.

EVIDENCE ACQUISITION

We reviewed recent literature (PubMed, Embase, Medline) that focused on the physics of shock waves, theories of stone disintegration, and studies on optimising shock wave application. In addition, we used relevant information from a consensus meeting of the German Society of Shock Wave Lithotripsy.

EVIDENCE SYNTHESIS

Besides established mechanisms describing initial fragmentation (tear and shear forces, spallation, cavitation, quasi-static squeezing), the model of dynamic squeezing offers new insight in stone comminution. Manufacturers have modified sources to either enlarge the focal zone or offer different focal sizes. The efficacy of extracorporeal shock wave lithotripsy (ESWL) can be increased by lowering the pulse rate to 60-80 shock waves/min and by ramping the shock wave energy. With the water cushion, the quality of coupling has become a critical factor that depends on the amount, viscosity, and temperature of the gel. Fluoroscopy time can be reduced by automated localisation or the use of optical and acoustic tracking systems. There is a trend towards larger focal zones and lower shock wave pressures.

CONCLUSIONS

New theories for stone disintegration favour the use of shock wave sources with larger focal zones. Use of slower pulse rates, ramping strategies, and adequate coupling of the shock wave head can significantly increase the efficacy and safety of ESWL.

Histotripsy beyond the intrinsic cavitation threshold using very short ultrasound pulses: microtripsy

Histotripsy produces tissue fractionation through dense energetic bubble clouds generated by short, high-pressure, ultrasound pulses. Conventional histotripsy treatments have used longer pulses from 3 to 10 cycles, wherein the lesion-producing bubble cloud generation depends on the pressure-release scattering of very high peak positive shock fronts from previously initiated, sparsely distributed bubbles (the shock-scattering mechanism). In our recent work, the peak negative pressure (P-) for generation of dense bubble clouds directly by a single negative half cycle, the intrinsic threshold, was measured. In this paper, the dense bubble clouds and resulting lesions (in red blood cell phantoms and canine tissues) generated by these supra-intrinsic threshold pulses were studied. A 32-element, PZT-8, 500-kHz therapy transducer was used to generate very short (<2 cycles) histotripsy pulses at a pulse repetition frequency (PRF) of 1 Hz and P- from 24.5 to 80.7 MPa. The results showed that the spatial extent of the histotripsy-induced lesions increased as the applied P- increased, and the sizes of these lesions corresponded well to the estimates of the focal regions above the intrinsic cavitation threshold, at least in the lower pressure regime (P- = 26 to 35 MPa). The average sizes for the smallest reproducible lesions were approximately 0.9 × 1.7 mm (lateral × axial), significantly smaller than the -6-dB beamwidth of the transducer (1.8 × 4.0 mm). These results suggest that, using the intrinsic threshold mechanism, well-confined and microscopic lesions can be precisely generated and their spatial extent can be estimated based on the fraction of the focal region exceeding the intrinsic cavitation threshold. Because the supra-threshold portion of the negative half cycle can be precisely controlled, lesions considerably less than a wavelength are easily produced, hence the term microtripsy.

Optimal therapy for the distal ureteral stone: extracorporeal shock wave lithotripsy versus ureteroscopy

Extracorporeal shock wave lithotripsy (ESWL not equal to) is the optimal therapy for renal calculi less than 2 cm. in diameter and for proximal ureteral calculi. Controversy continues over the initial approach to distal ureteral calculi (that is below the bony pelvis): in situ ESWL versus ureteroscopy. Since February 1990, 76 distal ureteral calculi were treated at our institution using either in situ ESWL (Dornier HM3 ESWL with a Stryker frame modification in 27 patients or Siemen's Lithostar electromagnetic ESWL in 22) or ureteroscopy (27 patients). Patient age and stone size were similar among the groups. All ESWL treatments were performed with the patient under intravenous sedation and on an outpatient basis. Stone-free rates were 96% for the HM3 device, 84% for the Lithostar and 100% for ureteroscopy. Retreatment was required in 3 Lithostar cases (14%) and 1 HM3 case (4%). When compared to ESWL ureteroscopy for distal ureteral stones was more time-consuming, entailed routine placement of a ureteral stent, often required general anesthesia, more often led to hospitalization and doubled the convalescence period. From a cost standpoint, ESWL on an HM3 unit was a few hundred dollars more expensive than ureteroscopy. In summary, we believe that in situ ESWL provides optimal first line therapy for distal ureteral calculi, while ureteroscopy is better reserved as a salvage procedure should ESWL fail.

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.

Painless piezoelectric extracorporeal lithotripsy

A total of 693 stones in 438 renoureteral units from 426 patients 4 months to 84 years old was treated with a mobile piezoelectric lithotriptor using ultrasound stone localization. Of the units 37 per cent had solitary stones smaller than 1.5 cm. in diameter, (group 1), 32 per cent had multiple stones up to this size (group 2), 21 per cent had stones 1.6 to 2.5 cm. in diameter (group 3) and 10 per cent had calculi larger than 2.5 cm. in diameter (group 4). No sedation or analgesics were necessary in 96.2 per cent of the treatments. Of all stones 97.2 per cent were disintegrated, with 39 per cent of the units requiring repeat treatments usually on an outpatient basis. Of the patients 82 per cent had transient hematuria, 6 per cent had fever and 28 per cent temporarily took some type of analgesics within the first 3 months after treatment. Nine per cent of the patients required postoperative ancillary interventions. After 3 months 92 per cent of the renoureteral units in group 1, 73 per cent in group 2, 74 per cent in group 3 and 50 per cent in group 4 were free of stones. Piezoelectric extracorporeal lithotripsy proved to be as efficient as spark-gap lithotripsy, yet it was essentially painless. Ultrasound localization permits treatment of all renal stones but it restricts lithotripsy of ureteral stones to the most proximal and distal fourths of the ureter.

Mechanical lithotripsy of bile duct stones in 209 patients--effect of technical advances

Between 1982 and 1987, mechanical lithotripsy of common bile duct (CBD) stones was performed in 209 patients (mean age +/- SD: 72 +/- 10 years), using self-constructed lithotripters and baskets with breaking strengths of approximately 50 and 100 kg between 1982 and 1986, and stronger and bigger baskets with breaking strengths of approximately 125 kg since 1987. Patients with single (49.3%) and multiple stones (50.7%) were distributed about equally. Stone size ranged between 4 and 80 mm (mean longitudinal diameter 18 +/- 9 mm, mean transversal diameter 13 +/- 3 mm), with a majority of the patients (61.2%) having stones of between 10 and 19 mm, and about one-third (32.1%) of the patients with stones greater than or equal to 20 (20-80) mm. The overall success rate of mechanical lithotripsy in all 209 patients treated between 1982 and 1987 was 87.6% including 79.1% for CBD stones greater than or equal to 20 mm and 67.6% for stones greater than or equal to 25 mm. The introduction of baskets with breaking strengths of approximately 125 kg in 1987 considerably increased the success rate of mechanical lithotripsy, especially for "large and giant" CBD stones, to 92.3% (greater than or equal to 20 mm) and 85.7% (greater than or equal to 25 mm), respectively.

A survey of the acoustic output of commercial extracorporeal shock wave lithotripters

A survey of the pressures and intensities generated by different commercial extracorporeal shock wave (ESWL) lithotripters is reported. The lithotripters included in the survey are the Dornier HM3, Wolf Piezolith 2200 and 2300, Siemens Lithostar, Technomed Sonolith 2000 and 3000, and EDAP LT-01. Measurements were made using a polyvinylidene difluoride (PVdF) membrane hydrophone in water. The zero crossing frequency of one complete cycle of the focused pulse from ESWL equipment is in the range 0.1 to 1 MHz. Spatial-peak temporal-peak positive and negative pressures up to 114 MPa and 10 MPa, respectively, have been measured and the rise times of the positive pressure half cycle at maximum output settings are 30 ns or less. The mean spatial-peak temporal-average intensity of the lithotripters is 5.0 x 10(2) W m-2 when operated at a pulse repetition frequency of 1 Hz. The spatial-peak pulse-average intensity ranges from 6.6 x 10(7) to 1.24 x 10(9) W m-2. The estimated acoustic energy in a single pulse (at the focus) at the maximum output setting of the lithotripters varies from 2.0 x 10(-3) J to about 9.0 x 10(-2) J. The beam area in the focal plane varies by a factor of 100 on different lithotripters and the temporal-peak pressure at the position of the skin at the entry point of the beam by a factor of 30. Measurement problems associated with hydrophone damage and the uncertainties in the hydrophone calibration at high pressures are discussed and an estimate of the total uncertainty in the absolute measurements of the spatial-peak temporal-peak positive pressure is given as +/- 36%.

Ureteropyeloscopic treatment of ureteral and intrarenal calculi

Endoscopic lithotripsy is an essential part of the armamentarium at any complete stone treatment center. It is first-line therapy for complicated upper urinary tract calculi and for patients who fail primary extracorporeal shock wave lithotripsy. In the presented series, ureteroscopy is defined as a safe and particularly effective treatment for upper urinary tract calculi. Endoscope miniaturization, the Holmium laser, and refined surgical technique have positive results. Complications are less frequent today, even with in the most complex large stone burdens being addressed in a retrograde ureteroscopic way.

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.

New approaches to nonlinear diffractive field propagation

In many domains of acoustic field propagation, such as medical ultrasound imaging, lithotripsy shock treatment, and underwater sonar, a realistic calculation of beam patterns requires treatment of the effects of diffraction from finite sources. Also, the mechanisms of loss and nonlinear effects within the medium are typically nonnegligible. The combination of diffraction, attenuation, and nonlinear effects has been treated by a number of formulations and numerical techniques. A novel model that incrementally propagates the field of baffled planar sources with substeps that account for the physics of diffraction, attenuation, and nonlinearity is presented. The model accounts for the effect of refraction and reflection (but not multiple reflections) in the case of propagation through multiple, parallel layers of fluid medium. An implementation of the model for axis symmetric sources has been developed. In one substep of the implementation, a new discrete Hankel transform is used with spatial transform techniques to propagate the field over a short distance with diffraction and attenuation. In the other substep, the temporal frequency domain solution to Burgers' equation is implemented to account for the nonlinear accretion and depletion of harmonics. This approach yields a computationally efficient procedure for calculating beam patterns from a baffled planar, axially symmetric source under conditions ranging from quasilinear through shock. The model is not restricted by the usual parabolic wave approximation and the field's directionality is explicitly accounted for at each point. Useage of a harmonic-limiting scheme allows the model to propagate some previously intractable high-intensity nonlinear fields. Results of the model are shown to be in excellent agreement with measurements performed on the nonlinear field of an unfocused 2.25-MHz piston source, even in the near field where the established parabolic wave approximation model fails. Next, the model is used to compare the water path and in situ fields of a medical ultrasound device. Finally, the model is used to calculate the spatial heating rate associated with a nonlinear field and to simulate the phenomenon of saturation-induced beam broadening.

Effect of overpressure and pulse repetition frequency on cavitation in shock wave lithotripsy

Cavitation appears to contribute to tissue injury in lithotripsy. Reports have shown that increasing pulse repetition frequency [(PRF) 0.5-100 Hz] increases tissue damage and increasing static pressure (1-3 bar) reduces cell damage without decreasing stone comminution. Our hypothesis is that overpressure or slow PRF causes unstabilized bubbles produced by one shock pulse to dissolve before they nucleate cavitation by subsequent shock pulses. The effects of PRF and overpressure on bubble dynamics and lifetimes were studied experimentally with passive cavitation detection, high-speed photography, and B-mode ultrasound and theoretically. Overpressure significantly reduced calculated (100-2 s) and measured (55-0.5 s) bubble lifetimes. At 1.5 bar static pressure, a dense bubble cluster was measured with clinically high PRF (2-3 Hz) and a sparse cluster with clinically low PRF (0.5-1 Hz), indicating bubble lifetimes of 0.5-1 s, consistent with calculations. In contrast to cavitation in water, high-speed photography showed that overpressure did not suppress cavitation of bubbles stabilized on a cracked surface. These results suggest that a judicious use of overpressure and PRF in lithotripsy could reduce cavitation damage of tissue while maintaining cavitation comminution of stones.

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.

Long-term results of extracorporeal shock wave lithotripsy in children

Extracorporeal shock wave lithotripsy was performed for treatment of calculi of the upper urinary tract in 73 children. All patients were treated with the standard HM3 Dornier lithotriptor. A total of 138 calculi in 86 renal units was treated, requiring 111 extracorporeal shock wave lithotripsy sessions. After therapy no serious complications were encountered. Six months after treatment 79 per cent of the patients were free of stones and 17 per cent had small residual fragments (less than 3 mm.), while extracorporeal shock wave lithotripsy was considered to be unsuccessful in 3 children, although disintegration could be obtained in all patients. During a median followup of 24 months (range 13 to 40 months) growth of residual fragments was noted in 33 per cent of the patients and the recurrence rate was 10 per cent.

Biological effects of shock waves: in vivo effect of high energy pulses on rabbit bone

Extracorporeal shock waves have recently been introduced to treat pseudarthrosis and aseptic bone necrosis. Only little information exists up to now about the morphological effects of shock waves on normal bone. To study both their acute effect on bone and their long-term effect on its remodelling, 1500 shock waves generated with a Dornier XL1 experimental electrohydraulic lithotripter were applied at 27.5 kV to 19 rabbits divided into five groups. Changes were evaluated after 6, 11, 41, 59 and 85 days. The discharges were focused to the right femur 1 cm above the knee joint. Bone remodelling was assessed in four groups by four-colour fluorescent labelling with labels administered sequentially over 8-day periods during the first month after shock-wave application. Radiographs were taken at dissection to detect fractures. As a result, shock waves were found to induce periosteal detachment with subperiosteal haemorrhages and to press marrow contents out of the medullary cavity. In the medullary cavity, diffuse haemorrhages, haematomas and foci of fractured and displaced bony trabeculae were found. The bone cortex and the knee joint were normal. Radiographs showed lucencies in the marrow but no fractures. During the weeks following shock-wave application, there was intense apposition of new cortical bone resulting in considerable cortical thickening while trabecular remodelling in the medullary cavity was only minor. The displacement of bony trabeculae and marrow contents point to the action of cavitation as the major mechanism of shockwave damage to bone.

Extracorporeal shockwave lithotripsy of 2000 urinary calculi with the modulith SL-20: success and failure according to size and location of stones

PURPOSE

We analyzed the successes and failures of SWL in the treatment of 2016 urinary calculi stratified according to size and position in the urinary tract.

METHODS

All the patients were treated with a Modulith SL-20 (Storz Medical).

RESULTS

The overall stone-free rate, regardless of the size and position of the stone, was 87.4%. The rate was different for kidney and ureteral stones. The stone-free rate observed for the different positions of the calculi within the kidney was upper calix 89.2%, middle calix 90.5% lower calix 84.8%, and renal pelvis 86.0%. For staghorn calculi, the stone-free rate was 60.0%. The stone-free rate for the different positions of calculi within the ureter was: upper ureter 84.3%, iliac ureter 82.4%, and pelvic ureter 91.0%. For calculi >24 mm, the retreatment rate increased, and the success rate dropped sharply.

CONCLUSION

Extracorporal shockwave lithotripsy should be the first therapeutic option for urinary calculi of <24 mm regardless of their position in the urinary tract.

Application of extracorporeal shock wave on bone: preliminary report

BACKGROUND

We have studied the effect of extracorporeal shock waves (ESW) on bone. ESW emitted by the new powerful generator provides three to six times greater energy than a common lithotriptor. Because the ESW causes fracture of rabbit femurs and induces new bone formation, we have called this treatment as ESWIB (ESW-induced bone formation). The purpose of this study is to confirm the effect of ESWIB on a canine model, which is more similar to clinical cases, and to apply ESWIB on nonunion of clinical cases.

METHODS

In our basic research, ESWIB was applied on six canine femurs as follows: group I with 100, 500, 1,000 shots and group II with 100, 500, 1,000 shots. A femur was extracted immediately after ESWIB in group I and 2 months after ESWIB in group II. Blood tests, including blood cell counts and blood chemistry studies, were performed before and after ESWIB in group II. In our clinical research, we applied ESWIB to six patients of delayed or nonunion of the fracture. The sites of the ESWIB application were three tibiae, one radius, one femur, and one humerus. Average age of the patients, the period from the previous surgery, and the period until fusion was achieved were 38.6 years, 14.0 months, and 4.3 months, respectively.

RESULTS

In our basic research, group I, 500 or more shots caused periosteum detachment. In addition, small fractures of the inner surface of the cortex were observed. However, gross fracture with displacement was not observed. In group II, 500 or more shots caused callus formation beneath the detached periosteum. Subcutaneous hemorrhage was seen in all dogs, and the degree of bleeding was directly proportional to the number of the shots. The blood was absorbed within a week. The level of serum creatine kinase was significantly high 2 days after ESWIB, but it recovered in a week. In our clinical research, four of the patients achieved union without any complications except mild subcutaneous bleeding.

CONCLUSIONS

We predict that ESWIB will be one of the tactics for treatment of the delayed union or nonunion of the fracture in the future.

Single-operator duodenoscope-assisted cholangioscopy is an effective alternative in the management of choledocholithiasis not removed by conventional methods, including mechanical lithotripsy

BACKGROUND AND STUDY AIMS

The widespread use of cholangioscopy in the management of difficult choledocholithiasis has been limited by the need for two expert operators. This report describes the use of a technique of single-operator duodenoscope-assisted cholangioscopy (SODAC) in the successful management of 75 patients with choledocholithiasis.

PATIENTS AND METHODS

The single-operator technique, allowing simultaneous control of both the duodenoscope and cholangioscope, was prospectively studied between June 1999 and June 2001 in the diagnosis and treatment of choledocholithiasis.

RESULTS

A total of 109 SODAC procedures were conducted in 75 patients to manage choledocholithiasis. The indications were: firstly, SODAC-guided electrohydraulic lithotripsy (EHL) of stones in which conventional methods, including mechanical lithotripsy, had not been successful (52 SODAC procedures in 26 patients); and secondly, direct visualization of the biliary tree after cholangiography to assess the presence of stones (57 SODAC procedures in 49 patients). The locations and numbers of the stones, but not their size, were predictive of the number of SODAC-guided lithotripsy sessions required. All of the patients were free of stones at the end of the study period, and no complications were recorded.

CONCLUSIONS

Single-operator SODAC-guided electrohydraulic lithotripsy was effective in the treatment of difficult cases of choledocholithiasis in which conventional methods had previously failed. The technique may allow increased use of cholangioscopy in the management of choledocholithiasis.

Outcome of simple use of mechanical lithotripsy of difficult common bile duct stones

AIM

The usual bile duct stone may be removed by means of Dormia basket or balloon catheter, and results are quite good. However, the degree of difficulty is increased when stones are larger. Studies on the subject reported many cases where mechanical lithotripsy is combined with a second technique, e.g. electrohydraulic lithotripsy (EHL), where stones are crushed using baby-mother scope electric shock. The extracorporeal shock-wave lithotripsy (ESWL) or laser lithotripsy also yields an excellent success rate of greater than 90%. However, the equipment for these techniques are very expensive; hence we opted for the simple mechanical lithotripsy and evaluated its performance.

METHODS

During the period from August 1996 to December 2002, Mackay Memorial Hospital treated 304 patients suffering from difficult bile duct stones (stone >1.5 cm or stones that could not be removed by the ordinary Dormia basket or balloon catheter). These patients underwent endoscopic papillotomy (EPT) procedure, and stones were removed by means of the Olympus BML-4Q lithotripsy. A follow-up was conducted on the post-treatment conditions and complications of the patients.

RESULTS

Out of the 304 patients, bile duct stones were successfully removed from 272 patients, a success rate of about 90%. The procedure failed in 32 patients, for whom surgery was needed. Out of the 272 successfully treated patients, 8 developed cholangitis, 21 developed pancreatitis, and 10 patients had delayed bleeding, and no patient died. Among these 272 successful removal cases, successful bile duct stone removal was achieved after the first lithotripsy in 211 patients, whereas 61 patients underwent multiple sessions of lithotripsy. As for the 61 patients that underwent multiple sessions of mechanical lithotripsy, 6 (9.8%) had post-procedure cholangitis, 12 (19.6%) had pancreatitis, and 9 patients (14.7%) had delayed bleeding. Compared with the 211 patients undergoing a single session of mechanical lithotripsy, 3 (1.4%) had cholangitis, 1 (0.4%) had delayed bleeding, and 7 patients (3.3%) had pancreatitis. Statistical deviation was present in post-procedure cholangitis, delayed bleeding, and pancreatitis of both groups.

CONCLUSION

Mechanical bile stone lithotripsy on difficult bile duct stones could produce around 90% successful rate. Moreover, complications are minimal. This finding further confirms the significance of mechanical lithotripsy in the treatment of patients with difficult bile duct stones.

Diameters of the main excretory ducts of the adult human submandibular and parotid gland: a histologic study

In assessing new minimally invasive diagnostic techniques (duct endoscopy) and therapy (lithotripsy), it is of importance to know the true dimensions of the excretory ducts. Twenty-five ducts of the parotid gland and 20 ducts of the submandibular gland were examined histologically at different points of their anatomic course, and their in vivo diameters were evaluated with the use of a previously determined formalin-induced shrinking-factor. The mean diameter of Stensen's duct at four different points along its length ranged between 1.4 mm and 0.5 mm, with a maximum of 2.3 mm and a minimum of 0.1 mm, depending on the site. A narrowing at the middle of the duct was striking. In all preparations examined, the minimum width of the excretory duct was located at the ostium. In Wharton's duct the narrowest duct diameter was also identified at the ostium. The mean values for the duct diameters ranged between 1.5 mm and 0.5 mm. The largest duct diameter reached 2.2 mm; the smallest one, 0.2 mm. For diagnostic and therapeutic purposes, endoscopes, balloon catheters, and stone-extraction-baskets probably should, despite the extensibility of the duct, conform as much as possible to the physiologic duct widths. A diameter of 1.2 mm should be aimed at as an upper limit for these instruments. Our findings also suggest that, in the case of salivary stone lithotripsy, the best results will be achieved when the maximum size of stone fragments does not exceed 1.2 mm.

Shockwave lithotripsy of salivary duct stones

Surgical extirpation of the affected gland has been necessary for cases of sialolithiasis in which the stone cannot be removed by dilatation or dissection of the salivary duct. The ability of the piezoelectric lithotripter to deliver shockwaves to a small focus makes extracorporeal shockwave lithotripsy of salivary gland stones potentially safe. Its safety and efficacy have been assessed in 51 patients with symptomatic solitary salivary stones that could not be removed by conservative measures. The stones had a median diameter of 8 (range 4-18) mm and were located in the submandibular gland in 69% of patients and in the parotid gland in 31%. A total of 72 shockwave treatment sessions (maximum 3 per patient) were given under continuous sonographic monitoring. In 45 patients (88%) complete fragmentation (fragments less than or equal to 3 mm) of the concrements was achieved. No patient needed anaesthesia, sedatives, or analgesics. The only untoward effects were localised petechial haemorrhages after 10 (13%) out of 72 treatments and transient swelling of the gland immediately after delivery of shockwave in 2/72 (3%) sessions. 20 weeks after the first session 90% (46/51) of patients were free of discomfort, and 53% (27/51) were stone free. Stone-clearance rate was higher among patients with stones in the parotid gland (81%) than among those with stones of the submandibular gland (40%). Auxiliary measures such as dilatation or dissection of the salivary duct were required only in patients with stones in the submandibular gland (20%). No long-term damage to the treated salivary gland or to adjacent tissue structures was noted during the median follow-up of 9 (1-24) months. Extracorporeal piezoelectric shockwave therapy seems likely to be safe, comfortable, and effective minimally-invasive, non-surgical treatment for salivary stones.