Fragmentation of gallstones by extracorporeal shock waves

Histomorphologic evaluation of extracorporeal shock wave therapy of the fourth metatarsal bone and the origin of the suspensory ligament in horses without lameness

OBJECTIVE

To determine via histologic examination and scintigraphy the effect of focused extracorporeal shock wave therapy (ESWT) on normal bone and the bone-ligament interface in horses.

ANIMALS

6 horses without lameness.

PROCEDURE

Origins of the suspensory ligament at the metacarpus (35-mm probe depth) and fourth metatarsal bone (5-mm probe depth) were treated twice (days 0 and 16) with 2,000 shocks (energy flux density, 0.15 mJ/mm2). One forelimb and 1 hind limb were randomly treated, and the contralateral limbs served as nontreated controls. Bone scans were performed on days -1 (before ESWT), 3, 16, and 19. Histomorphologic studies of control and treated tissues were performed on day 30.

RESULTS

ESWT significantly increased the number of osteoblasts but caused no damage to associated soft tissue structures and did not induce cortical microfractures. A significant correlation between osteoblast numbers and radiopharmaceutical uptake was noticed on lateral views of the hind limb on days 3 and 16 and on caudal views of the forelimb on day 3.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that ESWT has the potential to increase osteoblast numbers in horses. The correlation between increased osteoblast numbers and radio-pharmaceutical uptake 3 days and 16 days after the first ESWT suggested that stimulation of osteogenesis occurred soon after ESWT. No damage to bone or the bone-ligament interface should occur at the settings used in this study, and ESWT can therefore be administered safely in horses.

Extracorporeal shock wave lithotripsy for the treatment of pancreatic duct stones

The purpose of endoscopic therapy in chronic pancreatitis is to decompress the main pancreatic duct and to remove the obstacles that impede the ductal flow of pancreatic juice. The availability of extracorporeal shock wave lithotripsy (ESWL) has improved the results of endoscopic drainage of the main pancreatic duct and has also expanded the indications of endoscopic therapy for chronic pancreatitis. This article briefly reviews ESWL for pancreatic duct stones in patients with chronic pancreatitis, including our experience with ESWL. ESWL is an effective and safe procedure for endoscopically unremovable main pancreatic duct stones, and, in selected patients, ESWL alone may be effective.

A ten-year prospective study on gallbladder stone recurrence after successful extracorporeal shock-wave lithotripsy

OBJECTIVE

The risk of recurrence has limited the acceptability of conservative therapies of gallbladder stones. The aim of the present study was to determine the long-term rate of stone recurrence and its risk factors after successful extracorporeal shock-wave lithotripsy (ESWL).

MATERIAL AND METHODS

The study comprised a prospective ultrasound follow-up at yearly intervals or whenever biliary pain was reported. A total of 192 consecutive patients (primary single stones, n=159; primary 2 or 3 stones, n=33) were followed for up to 11.2 years after becoming stone-free and after termination of adjuvant treatment with ursodeoxycholic acid (UDCA).

RESULTS

Eighty-four patients developed recurrent stones after a median of 2.6 years (maximum?=?8.8 years). The 108 patients without recurrence were followed for a median of 6.7 years (maximum=11.2 years). By actuarial analysis, the cumulative recurrence rates for these 192 stone-free patients were 27%+/-3%, 41%+/-4% and 54%+/-4% (observed +/-SE) at 3, 5 and 10 years, respectively. Cox's regression analysis was used to identify the presence of slight calcification in the primary stone(s) as a protective feature against recurrence (p=0.03).

CONCLUSIONS

1) The risk of recurrence continues to increase over time, and although it rises less steeply after 5 years, it does not reach a plateau until at least 10 years. 2) Having had slightly calcified stone(s) seems to be associated with a reduced risk of recurrence and might signal a "burnt out" lithogenic process. 3) The long-term results are unsatisfactory and ESWL of gallbladder stones should be offered only in special cases.

Endoscopic gallbladder stent placement for treatment of symptomatic cholelithiasis in patients with end-stage liver disease

OBJECTIVES

Symptomatic cholelithiasis is a common disease in the general population with an increased prevalence in patients with cirrhosis. While cholecystectomy is the procedure of choice for the treatment of symptomatic cholelithiasis, cirrhotics have an increased risk of complications associated with this therapy. We have found that placement of an endoscopic gallbladder stent is an alternative, less invasive treatment for cirrhotic patients with symptomatic gallbladder disease and describe our experience here.

METHODS

A retrospective medical record review of 23 patients with cirrhosis who underwent endoscopic retrograde cholangiography with gallbladder stent placement for symptomatic gallbladder disease from July 1994 to August 2004.

RESULTS

Indications for stent placement included recurrent biliary colic (56.5%), acute calculous cholecystitis (39%), acalculous cholecystitis (8.6%), and gallstone pancreatitis (8.6%). All patients experienced resolution of their symptoms following stent placement. Twenty patients (87%) were asymptomatic from 5 days to 3 years post-procedure until transplantation, death, or end of study period. Nine patients (39%) underwent liver transplantation, 5 days to 34 months after the procedure. Eleven patients are well, with ten patients awaiting liver transplantation. Three patients developed late complications and were treated successfully with antibiotics.

CONCLUSION

Endoscopic stenting of the gallbladder may be a potential treatment for symptomatic gallbladder disease in patients with cirrhosis awaiting liver transplantation, considered to be high-risk for cholecystectomy.

Gallstone disease: Symptoms, diagnosis and endoscopic management of common bile duct stones

Bile duct stones (BDS) are often suspected on history and clinical examination alone but symptoms may be variable ranging from asymptomatic to complications such as biliary colic, pancreatitis, jaundice or cholangitis. The majority of BDS can be diagnosed by transabdominal ultrasound, computed tomography, endoscopic ultrasound or magnetic resonance cholangiography prior to endoscopic or laparoscopic removal. Approximately 90% of BDS can be removed following endoscopic retrograde cholangiography (ERC)+sphincterotomy. Most of the remaining stones can be removed using mechanical lithotripsy. Patients with uncorrected coagulopathies may be treated with ERC+pneumatic dilatation of the sphincter of Oddi. Shockwave lithotripsy (intraductal and extracorporeal) and laser lithotripsy have also been used to fragment large bile duct stones prior to endoscopic removal. The role of medical therapy in treatment of BDS is currently uncertain. This review focuses on the clinical presentation, investigation and current management of BDS.

Ten years experience with piezoelectric extracorporeal shockwave lithotripsy of gallbladder stones

BACKGROUND

A critical review of the experience with extracorporeal shockwave lithotripsy (ESWL) of gallbladder stones is needed to clarify whether this method should continue to be applied to patients.

METHODS

Patients with symptomatic gallbladder stones were treated by piezoelectric ESWL according to a prospective protocol between 1988 and 1997. ESWL treatment was limited to a maximum of three (solitary stones <20 mm diameter) to five sessions (larger solitary or multiple stones) and 3000 pulses per session. Univariate and multivariate analyses of pretreatment and treatment variables were performed to investigate their impact on fragmentation efficacy and stone clearance. A tree-based analysis was used to identify prognostically homogenous subgroups of individuals with maximum benefit from ESWL.

RESULTS

Four hundred and eight patients, 76% female and 24% male, with a mean age of 46 (SD, 13) years, were selected for evaluation. Cox regression analysis identified three pretreatment variables with significant prognostic impact: (1) number of gallstones >1 (relative risk, 2.6 (95% CI, 1.9-3.5)), (2) size of stones >17 mm (1.7 (1.4-2.2)), and (3) computed tomography (CT) density of stones >55 Hounsfield units (H) (1.4 (1.1-1.8)). According to tree-based analysis, the stone clearance rate after 1 year was 85% (95% CI, 75-91%) for solitary stones <16 mm, 79% (70-86%) for solitary stones > or =16 mm with a CT density <84 H, 45% (32-55%) for solitary stones > or =16 mm with a CT density > or =84 H, and 42% (30-51%) for multiple stones. Five years after stone clearance, recurrence occurred in 43% of patients (95% CI, 39-47%).

CONCLUSIONS

ESWL treatment showed an acceptable stone clearance in the case of small solitary gallbladder stones (<16 mm) or larger solitary stones with a CT density <84 H, but a very low success rate in the case of multiple stones. The poor long-term success, however, is an important argument against the use of ESWL of gallbladder stones.

Extracorporeal shock wave lithotripsy of gallstones: 20th anniversary of the first treatment

Twenty years ago, in January 1985, extracorporeal shock wave lithotripsy (ESWL) was first applied successfully in a patient with gallbladder stones. In the following years, the conditions which influence the success rate of ESWL have been extensively investigated. It was shown that the characteristics of the stones, gallbladder emptying and the degree of stone fragmentation are the most important factors which determine the clearance of all fragments from the gallbladder after ESWL. Severe side effects, such as biliary pancreatitis and liver haematoma, were found to be rare and no deaths related to the procedure have been reported. One or more episodes of biliary pain were observed in about one third of patients within the first 3-4 months after ESWL. Follow-up studies after successful treatment, however, have shown that stone recurrence is considerable, limiting the use of ESWL as a non-invasive therapeutic option. Stone recurrence varies between different subgroups of patients indicating that gallbladder motor function and other less well defined factors may be of importance. The recurrence of stones after ESWL is one of the reasons why laparoscopic cholecystectomy has become the standard treatment of symptomatic gallbladder stones today. ESWL has kept its role only in the treatment of bile duct stones resistant to endoscopic extraction. Unless stone recurrence can be decreased by better patient selection and/or other measures to prevent gallstone recurrence, ESWL of gallbladder stones has little chance of surviving.

Antibacterial effects of extracorporeal shock waves

Despite considerable knowledge about effects of extracorporeal shock-wave therapy (ESWT) on eukaryotic tissues, only little data are available concerning their effect on prokaryotic microorganisms. The objective of the present study was to determine the bactericidal activity as a function of energy flux density and shock-wave impulse number. Standardised suspensions of Staphylococcus aureus ATCC 25923 were exposed to different impulse numbers of shock waves with an energy flux density (ED) up to 0.96 mJ mm(-2) (2 Hz). Subsequently, viable bacteria were quantified by culture and compared with an untreated control. After applying 4000 impulses, a significant bactericidal effect was observed with a threshold ED of 0.59 mJ mm(-2) (p < 0.05). A threshold impulse number of more than 1000 impulses was necessary to reduce bacterial growth (p < 0.05). Further elevation of energy and impulse number exponentially increased bacterial killing. ESWT proved to exert significant antibacterial effect in an energy-dependent manner. Certain types of difficult-to-treat infections could offer new applications for ESWT.

Extracorporeal shockwave lithotripsy of gallstones in cystic duct remnants and Mirizzi syndrome

BACKGROUND

Although the efficacy of extracorporeal shockwave lithotripsy for treatment of bile duct calculi is established, there are few studies of the value of extracorporeal shockwave lithotripsy for cystic duct remnant stones and for Mirizzi syndrome.

METHODS

Patients who required extracorporeal shockwave lithotripsy for cystic duct stones were identified in a cohort of 239 patients with bile duct stones treated by extracorporeal shockwave lithotripsy between January 1989 and December 2001 at a single institution. The medical records of these patients were reviewed. Follow-up information was obtained by telephone contact.

OBSERVATIONS

Six women (age range 19-85 years) underwent extracorporeal shockwave lithotripsy for cystic duct stones after failure of endoscopic treatment measures. Three of the patients presented with retained cystic duct remnant calculi (one also had Mirizzi syndrome type I), and 3 presented with Mirizzi syndrome type I. The stones were fragmented successfully by extracorporeal shockwave lithotripsy in all patients; the fragments were extracted endoscopically in 5 patients. Endoscopy plus extracorporeal shockwave lithotripsy was definitive treatment for all patients except one who subsequently underwent cholecystectomy.

CONCLUSIONS

Gallstones in a cystic duct remnant and in Mirizzi syndrome can be successfully treated by extracorporeal shockwave lithotripsy in conjunction with endoscopic measures. Extracorporeal shockwave lithotripsy is especially useful when surgery is contraindicated.

Approach to idiopathic recurrent pancreatitis

Acute pancreatitis is caused by acute or chronic alcohol intake or choledocholithiasis in approximately 80% of cases. In the absence of alcohol abuse or gallstones, a variety of established and putative factors must be considered, any of which can cause a single or recurrent attacks of acute pancreatitis. When the underlying cause eludes detection following an initial thorough search and leads to a second attack, the term idiopathic acute recurrent pancreatitis (IARP) is applied. This article discusses IARP and its work-up.

Application of shock waves as a treatment modality in the vicinity of the brain and skull

OBJECT

Shock waves have not previously been used as a treatment modality for lesions in the brain and skull because of the lack of a suitable shock wave source and concerns about safety. Therefore, the authors have performed experiments aimed at developing both a new, compact shock wave generator with a holmium:yttrium-aluminum-garnet (Ho:YAG) laser and a safe method for exposing the surface of the brain to these shock waves.

METHODS

Twenty male Sprague-Dawley rats were used in this study. In 10 rats, a single shock wave was delivered directly to the brain, whereas the protective effect of inserting a 0.7-mm-thick expanded polytetrafluoroethylene (ePTFE) dural substitute between the dura mater and skull before applying the shock wave was investigated in the other 10 rats. Visualizations on shadowgraphy along with pressure measurements were obtained to confirm that the shock wave generator was capable of conveying waves in a limited volume without harmful effects to the target. The attenuation rates of shock waves administered through a 0.7-mm-thick ePTFE dural substitute and a surgical cottonoid were measured to determine which of these materials was suitable for avoiding propagation of the shock wave beyond the target.

CONCLUSIONS

Using the shock wave generator with the Ho:YAG laser, a localized shock wave (with a maximum overpressure of 50 bar) can be generated from a small device (external diameter 15 mm, weight 20 g). The placement of a 0.7-mm-thick ePTFE dural substitute over the dura mater reduces the overpressure of the shock wave by 96% and eliminates damage to surrounding tissue in the rat brain. These findings indicate possibilities for applying shock waves in various neurosurgical treatments such as cranioplasty, local drug delivery, embolysis, and pain management.

Extracorporeal shockwave lithotripsy in the management of salivary calculi

BACKGROUND

The aim was to investigate the results of extracorporeal shockwave lithotripsy in the management of salivary calculi using a dedicated sialolithotriptor.

METHODS

Some 122 salivary calculi (84 submandibular and 38 parotid) were treated in an experimental study using a sialolithotriptor.

RESULTS

Complete success was achieved in 40 procedures (33 per cent), 27 of 84 submandibular and 13 of 38 parotid calculi. A further 43 patients (35 per cent) were rendered asymptomatic although some stone debris remained in the duct (26 submandibular and 17 parotid). Failure (retention of stone debris and continued symptoms) occurred in 39 patients (32 per cent), 30 submandibular and eight parotid glands. The chance of failure increased with the size of the calculus and increasing duration of symptoms.

CONCLUSION

Extracorporeal shockwave lithotripsy provides a useful option for the management of salivary calculi, particularly for stones less than 7 mm in diameter.

Quality of life after cholecystectomy and after successful lithotripsy for gallbladder stones: a matched-pairs comparison

BACKGROUND

There are few data on the quality of life of patients after successful extra-corporeal shock-wave lithotripsy of gallbladder stones and how it compares with the quality of life of patients who underwent cholecystectomy.

DESIGN

Prospective case-control study.

PATIENTS AND METHODS

Eighteen consecutive patients who had been rendered stone free in 1992 in our unit and who have not shown recurrence until now were selected. For comparison, 18 individually matched (sex, age, body mass index and number of gallbladder stones) controls were selected among the patients who underwent unsuccessful extra-corporeal shock-wave lithotripsy at the same time, eventually undergoing cholecystectomy. Between January and April 2000, all 36 patients answered a validated questionnaire on quality of life focusing on digestive complaints: the Gastro Intestinal Quality of Life Index (GIQLI).

RESULTS

The overall GIQLI scores for both groups were good: a median of 128 points (out of a maximum of 144 points) for the extra-corporeal shock-wave lithotripsy group versus a median of 124 points for the cholecystectomy group. The slight advantage of the extra-corporeal shock-wave lithotripsy group was not significant (P = 0.33, paired sign-test). However, the extra-corporeal shock-wave lithotripsy group scored significantly better in the eight questions regarding dyspeptic complaints (P = 0.01, paired sign-test), mainly in the items regarding nausea and need for dietary restriction. There were no significant differences in the questions regarding symptoms of gastro-oesophageal reflux disease, bowel complaints or general well-being.

CONCLUSIONS

The quality of life after either cholecystectomy or extra-corporeal shock-wave lithotripsy is good overall, but cholecystectomy might be associated with a higher rate of dyspeptic complaints than a gallbladder preserving treatment like extra-corporeal shock-wave lithotripsy.

Economics of surgery

The time has come to subject surgery to the same rigours of economic assessment that other health-care sectors are already receiving--namely, the comparative assessment of costs and benefits. The surgical management of gallstones provides a good example of the role of economics in surgery. Gallstone disease is common and patients are usually referred to a surgeon, but the threshold for intervention is not agreed and varies widely, with considerable implications for resources. Gallstone removal has been subject to much innovation over the past 10 years, yet economic assessment of laparoscopic and "mini" cholecystectomy and of gallstone lithotripsy is rare, despite the fact that operation rates have increased by up to 50% in some countries. For surgery to compete with other interventions, economic assessment of new surgical techniques will be increasingly important. This assessment should be based on well-conducted clinical trials in which interventions are provided in a routine service setting, and in which benefits are assessed among other things on the basis of the patient's perceived quality of life. Economic assessment often needs data beyond those collected in a clinical trial, however pragmatic the trial design, so modelling will often be required, incorporating a range of sources of evidence. Finally, evidence alone will not be enough to promote cost-effective practices. The take-up of surgical techniques will always be affected by the way hospitals and surgeons are remunerated. Affecting practice requires a realistic system of reimbursement that reflects evidence on cost effectiveness.

Endoscopic management of biliary tract disease

New investigations, evaluation of controversial issues, and advances in technology continue to shape the endoscopic management of biliary disorders. This article discusses recent literature related to the diagnosis and therapy of biliary tract disease. Specifically, the diagnosis and management of choledocholithiasis, complications of biliary endoscopy and potential preventive measures, roles for endosonography in the evaluation of biliary disease, and endoscopic therapy of postoperative liver transplantation complications are reviewed. Recent advances in biliary stents and the use of cholangioscopy in biliary disorders are also assessed.

Correlations between the duration of pain and the success of shock wave therapy

Patients who have had successful treatment for either chronic heel pain (plantar fasciitis) or humeral epicondylitis subsequently were evaluated for a comparable problem in the contralateral heel or elbow. Patients who had experienced symptoms in the contralateral heel or elbow for a shorter period were less likely to have a positive result from shock wave therapy than those patients who had received treatments for more chronic symptoms.

Long-term evaluation of extracorporeal shock-wave lithotripsy for cholesterol gallstones

BACKGROUND

Extracorporeal shock-wave lithotripsy (ESWL) is a treatment that preserves the gallbladder. Problems after ESWL treatment include stone recurrence and the development of biliary symptoms.

METHODS

Two hundred and sixty-two patients with cholesterol-type gallstones, the best indication for ESWL treatment, and 42 control patients with cholesterol-type gallstones who received no treatment entered this study. We evaluated the factors associated with recurrence of gallstones after stone clearance and the development of biliary symptoms after ESWL treatment.

RESULTS

The 3-, 5- and 7-year cumulative probabilities of gallstone recurrence were 20.6, 27.1 and 33.1%, respectively, with the recurrence probability significantly lower in patients with good gallbladder contractility. In patients with recurrence, ursodeoxycholic acid (UDCA) treatment was effective. In 69 patients with residual gallstones, the 3-, 5- and 7-year cumulative risks of biliary symptoms were 17.3, 24.9 and 30.5%, respectively. With residual gallstones, the risk of biliary symptoms developing was significantly lower in patients with a < or = 3 mm fragment size at the end of ESWL treatment and in those treated consistently with UDCA for 6 months or more after treatment with ESWL. The risk of biliary symptoms was significantly lower in ESWL-treated patients with residual stones who had a < or = 3 mm fragment size after treatment compared to those of control patients.

CONCLUSIONS

Ursodeoxycholic acid was effective in clearing stones in patients with gallstone recurrence. In patients with residual stones, the fragmentation of stones to < or = 3 mm and UDCA administration effectively reduced the risk of subsequent biliary symptoms.

Extracorporeal shock wave lithotripsy for clearance of bile duct stones resistant to endoscopic extraction

BACKGROUND

Endoscopic extraction of bile duct stones after sphincterotomy has a success rate of up to 95%. Failures occur in patients with extremely large stones, intrahepatic stones, and bile duct strictures. This study examined the efficacy and the safety of extracorporeal shock-wave lithotripsy in a large cohort of patients in whom routine endoscopic measures including mechanical lithotripsy had failed to extract bile duct stones.

METHODS

Out of 1587 consecutive patients, endoscopic stone extraction including mechanical lithotripsy was unsuccessful in 313 (20%). These 313 patients (64% women, median age, 73 years) underwent high-energy extracorporeal shock-wave lithotripsy. Stone targeting was performed fluoroscopically (99%) or by ultrasonography (1%).

RESULTS

Complete clearance of bile duct calculi was achieved in 281 (90%) patients. In 80% of the patients, the fragments were extracted endoscopically after shock-wave therapy; spontaneous passage was observed in 10%. For patients with complete clearance compared with those without there were no differences with regard to size or number of the stones, intrahepatic or extrahepatic stone location, presence or absence of bile duct strictures, or type of lithotripter. Cholangitis (n = 4) and acute cholecystitis (n = 1) were the rare adverse effects.

CONCLUSIONS

In patients with bile duct calculi that are difficult to extract endoscopically, high-energy extracorporeal shock-wave lithotripsy is a safe and effective therapy regardless of stone size, stone location, or the presence of bile duct stricture.

Prospective evaluation of morphology, function, and quality of life after extracorporeal shockwave lithotripsy and endoscopic treatment of chronic calcific pancreatitis

OBJECTIVE

Therapeutic endoscopy may be effective in selected patients with chronic calcific pancreatitis (CCP). We prospectively evaluated the early outcome of extracorporeal shockwave lithotripsy (ESWL) in combination with interventional endoscopy, using broad inclusion criteria.

METHODS

A total of 48 consecutive patients (35 male, 13 female) were recruited for ESWL and endoscopic therapy of symptomatic CCP. Symptoms, quality of life, pancreatic morphology and function were assessed before and after.

RESULTS

Multiple stones (n = 43), strictures (n = 34), and pancreas divisum (n = 11) were found. A median of 13 ESWL sessions (range 2-74) with a median of 22,100 shockwaves (1,700-150,900) were required. Endoscopic pancreatic sphincterotomy (n = 48), stricture dilation (n = 12), and/or stenting (n = 27) were performed. After therapy, drainage of the pancreatic duct system was achieved in 36, complete stone clearance in 21 patients. Follow-up (n = 38) at 7 months (range 5-9) showed a significant decrease in pancreatic duct diameter (p < 0.001) and pain score (p < 0.0001) whereas complete pain relief was observed in 45% of cases. Several quality of life scores improved significantly. Weight gain occurred in 68% of patients. Normalization of fasting blood glucose and HbA1c levels were observed in four patients, without modifying their treatment. Improvement in pain score correlated with weight gain and decrease in pancreatic duct diameter. Nonalcoholic etiology was associated with a better chance for improvement in pain score and decrease in pancreatic duct diameter. The presence of strictures did not deteriorate the clinical outcome.

CONCLUSIONS

Besides pain relief, ESWL in combination with interventional endoscopy resulted in pancreatic ductal decompression, weight gain, and improvement in quality of life in a considerable number of patients with advanced CCP.

Factors affecting gallstone recurrence after successful extracorporeal shock wave lithotripsy

Ninety-six patients treated successively for symptomatic cholelithiasis with extracorporeal shock wave lithotripsy (ESWL) and oral bile acid therapy consisting of ursodeoxycholic acid in daily dosages of 600 mg were prospectively followed for gallstone recurrence for a median of 13 months. Ultrasonography was performed to detect stone recurrence at 3, 6, and 12 months, and then yearly after the termination of therapy. Recurrent stones were found in 17 patients (18%). The cumulative probability of gallstone recurrence was 15.8% at 12 months, 26.1% at 24 months, and 30.7% at 36 months. The probability of stone recurrence over the entire period of observation was not dependent on stone number, whereas the median interval to detection of recurrence was significantly shorter in the patients with multiple stones (2 months) than in those with solitary stones (8 months) (p < 0.05). The rate of impaired gallbladder contractility was higher in patients with recurrence (8/15, 53.3%) when compared with those with no recurrence (15/72, 20.8%) (p < 0.01). Neither age, gender, or stone characteristics predicted stone recurrence. Only one patient with a recurrence reported biliary pain. Of the 15 patients with recurrent stones who opted for further nonsurgical treatment, complete stone disappearance was achieved in 10. Impaired gallbladder function may predict gallstone recurrence after ESWL.

Extracorporeal shock wave lithotripsy of gallstones revisited: current status and future promises

The improvement and refinement of extracorporeal shock wave lithotripsy (ESWL) has made this non-invasive treatment modality not only more effective, but also applicable to a larger population of gallstone patients. It can be performed safely on an outpatient basis. Advances in lithotripsy technology have made it possible to fragment stones into very small, sand-like particles (pulverization), which clear the gall-bladder faster than large fragments. Recent studies provide evidence that adjuvant bile acids may not be necessary in most cases in which pulverization is achieved. Good gall-bladder emptying appears both to promote the clearance of gallstones after ESWL and to decrease their recurrence. Although generally found to be more expensive than surgery if bile acids are used, ESWL should be cost-effective, as bile acids may not be necessary in all patients. Elderly patients with radiolucent, solitary and less than 30 mm gallstones can particularly benefit from lithotripsy.

Modeling of an electrohydraulic lithotripter with the KZK equation

The acoustic pressure field of an electrohydraulic extracorporeal shock wave lithotripter is modeled with a nonlinear parabolic wave equation (the KZK equation). The model accounts for diffraction, nonlinearity, and thermoviscous absorption. A numerical algorithm for solving the KZK equation in the time domain is used to model sound propagation from the mouth of the ellipsoidal reflector of the lithotripter. Propagation within the reflector is modeled with geometrical acoustics. It is shown that nonlinear distortion within the ellipsoidal reflector can play an important role for certain parameters. Calculated waveforms are compared with waveforms measured in a clinical lithotripter and good agreement is found. It is shown that the spatial location of the maximum negative pressure occurs pre-focally which suggests that the strongest cavitation activity will also be in front of the focus. Propagation of shock waves from a lithotripter with a pressure release reflector is considered and because of nonlinear propagation the focal waveform is not the inverse of the rigid reflector. Results from propagation through tissue are presented; waveforms are similar to those predicted in water except that the higher absorption in the tissue decreases the peak amplitude and lengthens the rise time of the shock.

The management of sialolithiasis in 2 children through use of extracorporeal shock wave lithotripsy

The management of salivary calculi in children may prove difficult for a number of reasons. Traditional investigations require ionizing radiation and in cases of sialography may be poorly tolerated. Similarly, any surgical treatment is likely to require general anesthesia and, in a number of cases, removal of the affected gland, which is associated with attendant risks. As an alternative, ultrasound and extracorporeal shock wave lithotripsy therapy offers low morbidity and outpatient procedures that are well tolerated, as illustrated by these 2 cases.

The effect of ESWL of renal calculi on pancreatic function

Fifteen patients were treated by ESWL for renal calculi. The sagittal size of the head, neck and tail of the pancreas, and serum amylase, insulin, c-peptide and 24-hour urine amylase levels were estimated pre and post-treatment. Serum glucose, serum amylase and urinary levels remained within normal limits. Serum levels of insulin, c-peptide and the size of the gland increased but this was not statistically significant. There may be some danger to the pancreas during ESWL as there are some morphological changes even though there are no evident peptide changes. Caution should be taken if patients have a history of pancreatitis.

Application of extracorporeal shock wave lithotripter (ECSWL) in orthopedics. I. Foundations and overview

In this paper we have reviewed the feasibility of using a shock wave lithotripter to loosen the interface between the bone and acrylic bone cement for revision arthroplasty. We have reviewed the physics of shock wave and its applications in medicine, especially its interaction with tissues. The calculations show that the energy is greatly reduced at the interface both in the soft tissue-bone interface and cement-bone interface. On the other hand, a tensile and compressive pressure can be operated at the cement-bone interface that can cause the interface to break if the pressure exceeds the tensile strength of the cement-bone interface. Subsequent papers will deal with in vitro and in vivo application of the shock wave in the treatment of the cement from the intramedullary canal.

Gallstones

Gallstone disease is a common clinical problem that poses particular difficulties for our aging and increasingly obese population. Exciting new research suggests an infectious cause for most cholesterol stones. The keys to managing patients with gallstone disease are recognition of the wide spectrum of clinical disease resulting from gallstones and a flexible, multidisciplinary approach to diagnosis and treatment. The biliary tract has been a proving ground in the development of minimally invasive technology.

Nonsurgical management of gallstone disease

Cholelithiasis is a common disease in the United States associated with significant morbidity. Surgical treatment with cholecystectomy has been increasing with a significant cost to the health care system. Surgical management is not without risk. Cholecystectomy has also been associated with a significant morbidity and mortality in elderly patients. Cholecystectomies are often performed unnecessarily in gallstone patients for nonspecific symptoms. Many patients with nonspecific pain, which may have a psychogenic component, continue to experience similar pain after cholecystectomy. There are problems in determining the symptom status of patients. Patients who believe surgery will relieve symptoms may maximize their symptoms, whereas patients who are reluctant to undergo surgery may minimize their symptoms. Although cholecystectomy is the mainstay of gallstone treatment, bile acid therapy and, if available, ESWL and topical dissolution are nonsurgical treatment alternatives in selected patients. In selected cases, in particular in the elderly and in other patients at increased risk from surgery, nonsurgical management offers lower morbidity and mortality than does operative treatment. The decision for surgical versus nonsurgical management should be based on both objective selection criteria and patient choice.

Sonochemically induced radicals generated by pulsed high-energy ultrasound in vitro and in vivo

The aim of this study was to evaluate the role of radicals as a mechanism of tissue damage induced by pulsed high-energy ultrasound. Transient cavitation has proved to be an important mechanism for the generation of reactive radical species during pulsed high-energy ultrasound applications. The amount of radicals studied in in vitro experiments using a chemical dosimeter based on iodine release is proportional to the number of pulses. Sonications of the R3327-AT1 subline of the Dunning prostate rat tumor transplanted in the thigh of Copenhagen rats were performed applying 500 and 2000 pulses at a pulse repetition frequency of 1 Hz. Tumor growth after treatment was compared with sham-treated controls. We were able to assess a significant growth delay, but could not find a significant difference between the two groups treated. In conclusion, radical formation does not seem to be the major mechanism for tissue necrosis induced by pulsed high-energy ultrasound.

[Changes in and acceptance of surgical and noninvasive therapy procedures in cholecystolithiasis]

BACKGROUND

The treatment of cholecystolithiasis has changed fundamentally in recent years due to the development of non-surgical techniques (extracorporeal shockwave lithotripsy [ESWL], oral litholysis) and the implementation of laparoscopic cholecystectomy.

PATIENTS AND RESULTS

Retrospective analysis of 2270 patients (1649 women, 621 men; age: 47.2 +/- 14 years) presenting with gallstone disorders in a university medical outpatients department between 1988 and 1992 in order to be instructed as to the most suitable therapy method bear witness to the rapid change in therapeutic procedure. Laparoscopic removal of the gallbladder has virtually supplanted conventional cholecystectomy, and within 5 years the proportionate role of ESWL has declined from 21 to 12%. Over the years, the proportion of patients requiring no therapeutic intervention remained constant (at about 20%). The therapeutic recommendations of the "experts" were implemented in almost 80% of cases. The majority of patients were satisfied with the chosen therapeutic approach (surgery: 93.0%, ESWL: 77.6%), although 44% of ESWL-patients and 36% of surgically managed patients reported complaints which persisted even after completion of therapy. Despite unsuccessful ESWL (residual fragments or recurrent stones) 58/95 (61%) of interviewed patients would again give preference to this non-invasive modality in the event of a renewed therapeutic decision.

CONCLUSION

Only a few years after its introduction, laparoscopic cholecystectomy has asserted itself as the predominant treatment option. But as far as acceptance and preference by the patient are concerned extracorporeal shockwave lithotripsy--as a non-invasive treatment modality--also enjoys high popularity and can be recommended as an alternative to surgery in suitable patients chosen according to the currently established stringent selection criteria.

Extracorporeal shock-wave lithotripsy for bile duct calculi

BACKGROUND

Bile duct calculi (BDC) can be cleared or treated with modern endoscopic techniques in most patients. However, large stones, bile duct strictures, or unusual anatomy may make endoscopic clearance difficult. The purpose of the present study was to determine the efficacy of extracorporeal shock-wave lithotripsy (ESWL) in treating patients with complicated BDC.

METHODS

Between 1989 and January 1995, 16 patients with BDC were treated at our institution with ESWL using a Dornier HM-3 lithotropter. The average age of patients was 62 years (range 32 to 88). Endoscopic retrograde cholangiopancreatography (ERCP) with sphincterotomy and attempted stone extraction (100%), nasobiliary drainage (83%), and biliary stents (6%) were used prior to ESWL. Eleven patients (61 %) had solitary stones, ranging in diameter from 0.5 to 2.6 cm, whereas 7 patients had multiple stones, ranging in diameter from 0.5 to 5.0 cm. The indications for ESWL were stone impaction (56%), stone size (38%), and bile duct stricture (6%).

RESULTS

The 16 patients received 27 ESWL treatments (mean = 2101 shock at 21 kV); with 4 patients (22%) requiring multiple treatments. Stone fragmentation was achieved in 94% of patients. All patients had ERCP performed post-ESWL, and only 2 (13%) patients required immediate operations. At discharge, 94% of patients were stone-free. Minor complications (eg, pain, hematuria) were common. With an average follow-up of 3 years, only 1 patient (6%) has required retreatment for BDC. Hepatic transplantation was required in an additional patient.

CONCLUSIONS

In this cohort of patients with both major medical comorbidities and/or technical contraindications to standard methods of endoscopic and surgical clearance of BDC, we found that ESWL facilitated stone clearance in 94% of patients with minimal morbidity and no mortality. In our opinion, ESWL should be used more frequently in the treatment of these complex patients.

Plastic and metal stents for postoperative benign bile duct strictures: the best and the worst

BACKGROUND

Endoscopic treatment of postoperative benign bile duct strictures (BBDS) is technically challenging, and the long-term outcome after stricture dilation remains poorly defined.

METHODS

Forty-eight cases of postoperative BBDS with attempted endoscopic treatment (either transient plastic stenting or definitive metal stent insertion) were reviewed.

RESULTS

Endoscopic stricture dilation succeeded in 47 of 48 cases (98%). No procedure-related mortality was observed; 16 (33%) procedure-related or stent-associated complications were observed during treatment. Endoscopic treatment was interrupted in five patients. Stricture relapse occurred in 6 of 6 (100%) and 7 of 36 (19%) patients after metal stent insertion and plastic stent removal, respectively (p < 0.001) (mean follow-up periods 50+/-12 and 44+/-34 months, respectively). After plastic stent removal, stricture relapses were more frequent among patients with strictures related to liver transplantation as opposed to other surgical procedures (p < 0.05); these recurrent strictures were successfully treated by repeated insertion of plastic stents on a temporary basis. At the end of follow-up, all but one patient treated with plastic stents had normal serum alkaline phosphatase values.

CONCLUSION

Metal stents proved to be inadequate for treating postoperative BBDS. Temporary insertion of a plastic stent (possibly repeated) provided long-term results equal or superior to those reported for surgical biliary drainage. Repeated insertion of plastic stents was more frequently indicated for strictures related to liver transplantation compared with other surgical procedures.

Use of extracorporeal shock waves in the treatment of pseudarthrosis, tendinopathy and other orthopedic diseases

PURPOSE

The use of shock waves in orthopedic diseases was reviewed with special regard to the clinical applications.

MATERIALS AND METHODS

Findings in the literature and results from our own studies were analyzed and summarized.

RESULTS

Extracorporeal shock waves induced osteoneogenesis in animal models with intact and fractured bones. Based on these findings shock waves were used for the treatment of pseudarthrosis in humans. Most patients had at least 1 unsuccessful operation before shock wave therapy. Complete reunion was noted in 62 to 91% of cases and shock waves are recommended by some as the first choice of treatment for hypertrophic pseudarthrosis. After failed nonoperative therapy shock waves were used for the treatment of patients with various diseases as secondary treatment. The success rate for treatment of tendinopathies, such as tennis elbow, periarthritis humeroscapularis or calcaneal spur, was approximately 80%. For calcific tendinitis shock wave therapy seems to be superior to all other minimal or noninvasive techniques without compromising a potential later operation.

CONCLUSIONS

Shock waves have changed medical therapy substantially. Accounting for the epidemiology of the treated diseases, this new change may equal or even surpass the impact of extracorporeal shock wave lithotripsy.

Ultrastructure of cholesterol gallstones as observed by electron microscopy after freeze-fracturing

The ultrastructure of cholesterol gallstones (mixed type) was studied in detail for the first time under the transmission electron microscope after freeze-fracturing. Gallstones consisted essentially of cholesterol crystals, some impurities, and fluid. In accord with the theoretical 3.4 nm bilayered structure of cholesterol crystals, 3-4 nm periodicity of crystal layering was observed. However, gallstone cholesterol crystals were not perfect and often showed structural defects. Between crystals, complete edge-to-surface, edge-to-edge and surface-to-surface adhesions, and overall block-like aggregations were found. These may represent the structural basis for the stability of cholesterol crystal aggregation. The easy breakdown of cholesterol gallstones by extracorporeal shock wave lithotripsy is discussed in relation to their ultrastructure.

Management of giant common bile duct stones in high-risk patients using a combined transhepatic and endoscopic approach

BACKGROUND

Endoscopic sphincterotomy (EST) for removing common bile duct stones is regarded as the safest and most successful method, particularly in patients with a high surgical risk. However, giant immobile stones still continue to present a therapeutic problem.

METHODS

In our 12 patients, when endoscopic sphincterotomy and lithotomy proved to be unsuccessful a transhepatic choledochoscopic lithotomy was attempted.

RESULTS

The stones were fragmented using choledochoscopic electrohydraulic lithotripsy and then were completely removed through both the transhepatic route and an EST opening in all 12 patients. The number of sessions required for these choledochoscopic procedures combined with EST was fewer than that required for only a transhepatic approach (2.5 +/- 1.3 versus 3.2 +/- 1.2), which thus resulted in a shorter hospital stay. Minor complications occurred in three patients with bleeding (two from the bile duct, one from the EST opening) and in two with postprocedure chills and fever.

CONCLUSIONS

A combined lithotomy through duodenoscopic and choledochoscopic approaches is considered to be an efficient method for removing giant biliary calculi in patients who are not successfully treated by an ordinary duodenoscopic lithotomy.

ESWL experience in the therapy of difficult bile duct stones

In recent years, alternatives to surgery for difficult bile duct stones have been developed. Routine endoscopy fails in about 10% of patients. To verify the role of extracorporeal shock wave lithotripsy in residual CBD stones, we treated 32 patients by HM4 or MPL 9000 Dornier lithotripters. Ten (34.4%) patients needed two extracorporeal shock wave lithotripsy sessions, and 3 (10.3%) patients three. Complete clearance was achieved in 29 patients (90.6%) after one or more sessions either by endoscopic (20 pts) or percutaneous (9 pts) extraction of the debris; of the remaining 3 patients, in 2 a bilioduodenal stent was placed and in 1 electrohydraulic lithotripsy was performed. Eighteen and seven-tenths percent transient mild hemobilia, 12.5% microhematuria, and no mortality were observed. It is possible to state that in site- or size-related difficult biliary stones, extracorporeal shock wave lithotripsy is a rapid, safe, and highly effective treatment as an additional nonoperative option to resolve the failure of routine endoscopic measures.

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.

Extracorporeal shockwave lithotripsy of common bile duct stones without preliminary endoscopic sphincterotomy

BACKGROUND

Endoscopic sphincterotomy (EST) is now a standard procedure for common bile duct stones. It is less invasive than surgical treatment and is well established, but complications such as bleeding and perforation occasionally occur. We have been investigating the safest and most useful method of preserving the papilla of Vater. In the present study we evaluated the effectiveness and safety of extracorporeal shock wave lithotripsy (ESWL) for common bile duct stones without preliminary EST.

METHODS

From May 1992 to May 1995 ESWL was performed on 52 patients with common bile duct stones at our hospital. In all 52 patients a nasobiliary tube was inserted endoscopically, without preliminary EST, and ESWL was performed.

RESULTS

Fragmentation and subsequent complete clearance of stones was achieved in 35 patients (67.3%), and no additional treatment was necessary. In 17 patients (25.0%) fragmentation was not achieved, so EST and endoscopic extraction were performed, and the stones were cleared completely. None of the patients had major complications with clinical sequelae. We compared the completely cleared group and the failed group, to assess the influence of various factors. Our findings indicated that smaller, 'floating' stones responded more favorably to ESWL. When the largest stone was < 15 mm in diameter and the stone index (diameter of common bile duct/diameter of stone) was > 1.0, the success rate was very high 25 of 27 = 92.6%).

CONCLUSIONS

This treatment offers several advantages because it is less invasive, has few complications, and can preserve the papilla of Vater. This method is especially suitable for patients with smaller, floating stones.

Why laparoscopic cholecystectomy today?

Traditional open cholecystectomy became the "gold standard" of surgical treatment for symptomatic gallstone disease during the last century. In spite of its good results, clinicians have been trying to establish effective nonsurgical methods of eliminating gallstones. Although oral, percutaneous, or retrograde litholysis can be used effectively for cholesterol stones, these represent only 10% of all gallstones. Moreover, intracorporeal lithotripsy is an invasive method, and while extracorporeal shock wave lithotripsy is a promising procedure, even after careful selection, only 70%-80% of the patients become stone-free within 1 year. In fact, none of the methods which leave the gallbladder intact are free of complications, and they are followed by 50% stone recurrence within 5 years. Since 1987, laparoscopic cholecystectomy has become the procedure of choice as it is safe and only minimally invasive. We believe that the laparoscopic technique is a promising way to the surgery of the future.

Gallstone recurrence after successful dissolution therapy

After successful dissolution therapy of cholesterol gallbladder stones bile again becomes supersaturated and recurrent gallstones may develop. Three different postdissolution treatments [500 mg ursodeoxycholic acid (UDCA) per day (N = 14, group I), 100 mg aspirin per day (N = 14, group II) and diet (N = 15, group III) versus a control group (no treatment, N = 15, group IV) aimed at preventing recurrence of gallstones were investigated in a prospective, randomized study in 58 gallstone patients (33 female, 25 male) after complete stone clearance. Bile samples (prior to dissolution therapy and at stone recurrence) were investigated for biliary cholesterol (C), phospholipids (PL), total bile acid concentration (BA), cholesterol saturation index (CSI), total lipid concentration (TLC), total biliary protein concentration (TP), and nucleation time (NT). In group IV multiple gallstones tended to recur more often than solitary stones (66.7% vs 16.7%) whereas in groups I-III only solitary stones recurred. Recurrent gallbladder stones were detectable in 10 patients (eight patients in group IV and one each in groups I and II, respectively) within one year after dissolution and in two patients (one each in groups III and IV, respectively) after 15 months. Furthermore, the probability of stone recurrence was significantly higher in untreated patients as compared to treated patients. In nine (group IV) of 12 patients with recurrent stones NT, C, CSI, PL, BA, TLC, TP, and bile acid spectrum remained nearly unchanged as compared to their pretreatment values, whereas in three (groups I-III) of 12 cases a decrease in C, CSI, and TP was observed during therapy. However, in each of these three patients, initial and after-treatment TP was significantly higher and NT shorter as compared to groups I-IV. Furthermore, in these cases (N = 3) NT was prolonged, whereas no significant changes were found in PL, BA, TLC, and bile acid spectrum. Recurrence of gallstones, which seems to occur more likely in patients with multiple stones as compared to solitary stones, will happen in the early stage after stone clearance, again causing biliary pain. UDCA, aspirin or diet will reduce the probability for recurrent stones after complete gallstone dissolution.

Clinical evaluation of extracorporeal shock wave lithotripsy for salivary stones

The treatment of sialolithiasis is discussed in this report. Generally, stones within the distal salivary duct are easily removed by transoral ductotomy, although proximal stones are usually treated by excision of the salivary gland and its duct. Since 1980, extracorporeal shock wave lithotripsy (ESWL) has been in clinical use for the treatment of renal and gallbladder stones. We used this technique as a treatment for sialolithiasis. We undertook ESWL on 14 submandibular gland stone patients and 1 parotid gland stone patient, clinical symptoms such as pain and swelling disappeared without excision of the affected salivary gland. Stones larger than 10 mm seem to have a tendency to form Steinstrassen. Although computed tomography findings correlate with success in breaking up gallstones, they did not predict success for salivary stones. We conclude that sialolithiasis is treated successfully without adverse effects by ESWL in selected patients.

The influence of high-energy shock waves on the development of metastases

The hypothesis that exposure of a solid tumor to high-energy shock waves (HESW) could lead to an increase of metastases was investigated in an animal model. The highly metastatic AT-6 Dunning R3327 rat prostate cancer subline was implanted in the hind limb of a Fisher-Copenhagen rat and was exposed to 6000 shock waves delivered by an experimental lithotripter, or sham-treated, as soon as the tumor had reached a volume of 175-225 mm3. The tumor-bearing leg was amputated 24 h later and the number of metastases was examined 12 weeks thereafter at autopsy. Metastases were seen in 82% of the animals exposed to HESW and in 25% of the sham-treated animals. There was no significant difference in weight of the lungs that contained metastases, between sham and treated animals. These results were confirmed in a second experiment. We conclude that the metastatic spread of tumors with a high metastatic potential may be enhanced by shock-wave exposure.

Bile acids in health and disease

Over the last quarter of a century Danish research on bile acids has comprised studies of their physical and chemical properties, their physiology, pathophysiology, metabolism, and kinetics, and their clinical applicability. In the beginning of the period a major contribution was made to the understanding of the factors involved in the solubility of cholesterol in bile. The growing international understanding of the potential importance of the bile acids in health and disease gave raise to a substantial Danish contribution in the 1970s and 1980s in parallel with international achievements. Emphasis was on the possible clinical implications of bile acids. Studies on physiology and pathophysiology were in focus. Patients who have had an intestinal bypass operation for obesity served as a model for obtaining new knowledge on various aspects of the properties of the bile acids. Also the analytical methods were improved. Important physiological research on the mechanisms of hepatic bile flow was conducted. An intestinal perfusion model served as a tool providing information on absorption kinetics and on transmucosal water and electrolyte movements. The gallstone disease, liver diseases, inflammatory bowel disease, fat malabsorption, and other intestinal disorders were studied. The 'idiopathic ileopathy' as a cause for bile acid malabsorption causing diarrhoea was established as a new disorder. Thus, in the time period concerned, substantial Danish contributions emerged on major and minor topics of the bile acid field.

Dissolution of human cholesterol gallstones in bile salt/lecithin mixtures: effect of bile salt hydrophobicity and various pHs

BACKGROUND

Unconjugated bile salts currently available for gallstone dissolution are poorly effective. We evaluated in vitro the litholytic potency of taurine-amidated bile salts against human cholesterol gallstones.

METHODS

Seventy radiolucent gallstones with similar size and composition (cholesterol content, 70.1 +/- 0.9%) from a single patient were incubated in model biles composed of 100 mM of either taurochenodeoxycholate (TCDC), taurocholate (TC), taurohyodeoxycholate (THDC) or tauroursodeoxycholate (TUDC) and of 45 mM egg yolk lecithin in saline buffered with tris/HCl (at pHs 7 and 8) or phosphate (at pHs 4 and 6). Biles (total lipids, 10 g/dl; cholesterol saturation, 99%) were incubated at 37 degrees C for 40 days. Gallstones were periodically weighed and returned to the dissolution vials, and the biliary cholesterol concentration was monitored.

RESULTS

Model biles remained optically clear during the initial 48 h of incubation. Then, biles containing THDC and TUDC, but not those with TC and TCDC, became progressively turbid until, after several days, a white precipitate surrounded the residual stone. Abundant liquid crytalline droplets were observed at polarizing microscopy in biles containing TUDC and THDC. Gallstone dissolution was closely related to cholesterol solubilization and decreased in the order TCDC > THDC > or = TC > TUDC, being highest at pH 8. At the physiologic pH of 7 THDC was more litholythic than TC.

CONCLUSIONS

In vitro, the litholytic potency of bile salts on cholesterol gallstones primarily depends on their hydrophobicity. THDC is a new potential gallstone-dissolving agent, deserving in vivo studies.