Surg Endosc (1993) 7:356-359 Surgical Endoscopy

© Sprioger-Verlag New York Inc. 1993

Biliary lithotripsy as an adjunct to laparoscopic common bile duct stone extraction

Brendan Carroll, Mudjianto Chandra, Thanasis Papaioannou, Leon Daykhovsky, Warren Grundfest, and Edward Phillips

Department of Surgery and Laser Research Center, Cedars-Sinai Medical Center, 8635 W Third Street, Suite 795 W, Los Angeles, CA 90048, USA

Summary. We investigated various energy sources and delivery systems suitable for fragmentation of common duct calculi by a laparoscopic technique. We evaluated electrohydraulic lithotripsy (EHL) us- ing !.9-Fr probe delivering 80 W and laser lithotripsy using a 200-tzm fiber delivering 30-70 mJ/pulse at 5-20 Hz. In vitro biliary stone fragmentation analysis suggested that the laser lithotripsy produced a more controllable fragmentation than EHL. Initial attempts to employ EHL techniques in animal models resulted in common bile duct injury or inadequate fragmenta- tion of stones. In contrast, biliary lithotripsy was accomplished in pigs using the pulsed-dye laser at 10 Hz and 60 mJ/pulse. Histologic evaluation revealed no evidence of ductal injury related to laser stone fragmentation. Subsequently, laser common duct lithotripsy was used in two human subjects. One patient had a 1.8-cm impacted ampullary stone and one patient had a 3-cm intrahepatic stone. In both cases, the stones were removed laparoscopically after laser fragmentation. Our experience suggests that the laser lithotripsy may facilitate laparoscopic common duct stone extraction procedures.

Key words: Biliary lithotripsy - Laparoscopy - Com- mon duct - Exploration - Pulsed-dye laser - EHL

Laparoscopic transcystic common bile duct stone extraction has proven successful in 80-90% of cases [1]. In this technique, common duct stones are with- drawn retrograde through the cystic duct using a flexible fiberoptic endoscope and a wire basket. The technique allows removal of common duct stones

Offprint requests to: B. Carroll

during laparoscopic cholecystectomy and spares the patient the need for a laparotomy, choledochotomy/ T-tube, or postoperative endoscopic sphincterotomy. This technique initially had been limited to smaller calculi which could easily be withdrawn retrograde through the cystic duct. However, with dilating bal- lons, the cystic duct can be enlarged to allow extrac- tion of stones up to 1 cm in size. Stones greater than 1 cm are rarely extractable through the cystic duct even with balloon dilatation. Patients with large or impacted common bile duct stones are therefore subjected to choledochotomy or postoperative sphinc- terotomy procedures. Choledochotomy, either open or laparoscopic, requires a prolonged convalescence due to the T-tube. ERCP is associated with pancreati- tis and treatment failures under these circumstances. Other techniques such as percutaneous chemical dissolution therapy and extracorporal shock-wave li- thotripsy have not gained wide acceptance. Electro- hydrolic and laser lithotripsy present two other alter- natives in the treatment of stone disease of the common bile duct. Stone disintegration during EHL is brought about by a series of shock waves produced at the tip of a two-electrode probe. These electrodes are coaxially arranged. When sufficient potential dif- ference is applied between the two electrodes, an electrical arc is produced at the distal part of the probe. This arc generates a cavitation bubble and associated shock waves that eventually fragment the stone. During laser irradiation, light absorption by the stone surface forms p l a s m a - a highly ionized gas. Consequent plasma expansion generates intense shock waves which cause shear stress in the stone, leading to fragmentation. The goal of this study is to identify and evaluate the optimal method of biliary stone fragmentation to facilitate laparoscopic transcystic duct stone extraction. We have evaluated EHL and pulsed-dye laser lithotripsy in vitro and in vivo for fragmentation ability, safety, and applicabil- ity to laparoscopic use.

Materials and methods

The EHL unit used is model AEH-2 (Circon ACMI, Stanford, CT). The laser lithotripter used is a pulsed-dye laser model MDL-1 (Can- dela Corp., Wayland, MA) operating at 504 nm.

In vitro study

One hundred sixty gallstones were collected after surgery and stored in saline solution. The stones were of mixed chemical composition, size, and color, mimicking the calculi found in a broad patient popula- tion. The gallstones were held with a wire basket and placed in a cylindrical container filled with saline. Laser irradiation was per- formed with a 200-~m core fiber at 30, 50, and 70 m J/pulse (fiber output). The laser repetition rate was set at 5, 10, 15, and 20 Hz. The EHL was operated at 80 W with 0.05-s discharge duration for 1-2 s per stone. A 1.9-Fr EHL probe was employed. The laser fiber and the EHL probe were kept in contact with the stones during fragmentation. Following laser fragmentation, the contents of the cylindrical container were filtered and the stone fragments were sorted by passing them through sieves of various sizes. Three groups with fragments of different sizes were considered: group A (size less than 1.2 ram), group B (size between 1.2 and 2.4 mm), and group C (size larger than 2.4 ram). The total weight for each group of stones was recorded and expressed as the percentage of the initial weight of each stone. Higher percentage of weight in group A than in group B or C was considered indicative of efficient fragmentation.

Table 1. Laser fragmentation results

En- Group

ergy A (%) B (%) C (%) (mJ) < 1.2 mm 1.2-2.4 mm > 2.4 mm

30 42 23 35 50 52 25 23 70 52 32 17

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In vivo study

Twenty farmer pigs (40-50 kg) were used for the in vivo experimenta- tion. The pigs were initially anesthetized with ketamine 20 mg/kg and acepromazine 0.5 mg/kg and anesthesia was maintained with enflurane. Midline laparotomy was performed, and the common bile duct was exposed. Ligatures were then placed 3 cm apart on the proximal portion of the common bile duct. This stabilized the com- mon duct in an open position and permitted access for each device. Stones were implanted in the common bile duct of 10 of these animals. In five, laser lithotripsy was performed (60 mJ/pulse, 10 Hz), while EHL was performed (80 W, 0.05 s) in the other five animals. The 10 remaining animals were used for histological studies to evaluate tissue effects of both modalities. The laser fiber (n = 5) and the EHL probe (n = 5) were applied directly to the common duct either at right angle or parallel to its axis. This simulated the in vivo situation of a worst-case and a best-case scenario found during laparoscopic transcystic common bile duct exploration. The treated tissue was excised and placed in 10% formalin. Histologic evaluation was per- formed after standard hematoxylin eosin staining. Three groups of samples were considered: control, right angle, and parallel. The pathologist carefully examined all histologic sections for evidence of perforation and damage to mucosa.

Results

In vitro study

Both modal i t ies ( laser and E H L ) were able to f r agment bi l iary s tones . Us ing e lec t rohydrau l i c l i thotr ipsy, 75% of all 80 s tones were f r agmen ted wi th in 20-40 dis- charges . The f ragment size ranged f rom 1.0 m m to 5.0 mm. R e d u c e d f ragment eff iciency was no ted with each pulse d ischarge due to de te ror ia t ion of the probes . Table 1 shows the resul ts of the laser f r agmenta t ion . The n u m b e r s ind ica te pe rcen tage of the total s tone weight for each f r agmen ta t i on group. Lase r l i thotr ipsy pe r fo rmed at 30 mJ/pulse c rea ted f ragments a lmos t e v e n l y d i s t r ibu ted at sizes of < 1 . 2 mm, 1.2-1.4 mm,

Fig. 1. Normal ductal mucosa in control group. H&E stain; original magnification 40 ×

and > 2 . 4 mm. At 50 mJ and at 70 mJ/pulse , more than 50% of the initial s tone weight was f r a g m e n t e d in p ieces smal ler than 1.2 mm. This suggests a more effect ive f r agmen ta t ion process at h igher pu lse energies . No sig- nif icant repe t i t ion rate d e p e n d e n c e of the f r agmen ta - t ion eff iciency was o b s e r v e d for all (5 -20 Hz) repe t i t ion rates used in this s tudy.

In vivo study

Dur ing laser i r rad ia t ion at 15 and 20 Hz, the qual i ty of the endoscop ic image was reduced . This was caused by an excess vo lume of pu lve r i zed s tone par t ic les . Op- era t ion at 5 or 10 Hz resu l ted in be t t e r image qual i ty . Therefore , in v ivo e x p e r i m e n t a t i o n was pe r f o rmed at 60 mJ/pulse and 10 Hz p rov id ing a good c o m p r o m i s e with respec t to energy ou tpu t (opt imal range ; 50 - 70 mJ/pulse) as well as a good con t ro l ove r the v isua l field. Good v i sua l i za t ion was also o b t a i n e d dur ing E H L .

Histology

In Figs. 1-3, the h is to logy of the E H L appl ica t ions is shown. F igure 1 shows n o r m a l duc ta l m u c o s a (control) , while Fig. 2 d e m o n s t r a t e s d e n u d a t i o n of the duc ta l m u c o s a for " p a r a l l e l " appl ica t ion . Pe r fo ra t ion of the m u c o s a for " p e r p e n d i c u l a r " app l i ca t ion is s h o w n in Fig. 3. F igure 4 shows the his tological resul t s o f the

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Fig. 2. Denudation of the ductal mucosa. Parallel application of EHL probe at 80 W, 0.05. H&E stain; original magnification 100 x

Fig. 3. Perforation of the ductal mucosa. Right-angle application of EHL probe. H&E stain; original magnification 100 ×

laser application. Control mucosa is uneffected (top). Low laser repetit ion rate (10 Hz, 60 mJ/pulse) shows minimal denudation (middle). High repetition rate (20 Hz, 60 m J/pulse) shows mucosal hemorrhage with- out perforat ion (bottom).

Case report

Case report #1

An 85-year-old Caucasian female was admitted with upper abdominal pains. Alkaline phosphatase was 1,400, SGOT 39, SGPT 48, and bilirubin 1. I. Amylase and WBC were normal. Ultrasound revealed a dilated common bile duct with an ampullary stone measuring 1.8 cm in diameter. Laparoscopy was performed and a cystic duct cholangiogram confirmed the 1.8-cm im- pacted ampullary stone. Laser lithotripsy of the im- pacted stone was performed via a transcystic duct tech- nique. Under direct visualization, 60 mJ/pulse energy at I0 Hz was delivered to the stone through the working channel of a 3.3-ram endoscope via a 200-/xm fiber.

Fig. 4. Top: Normal ductal mucosa in control group. Middle: Minimal denudation of ductal mucosa seen with pulse-dye laser at 60 mJ/ pulse and low repetition rate (10 Hz). Bottom: Mucosal hemorrhage seen with pulse-dye laser at 60 m J/pulse and high repetition rate (20 Hz). H&E stain; original magnification 160 x

The stone was fragmented and extraction of stone frag- ments was performed using a three-wire basket. Com- pletion cholangiography and transcystic duct choledo- choscopy were normal. The cystic duct was ligated. The operative time was 125 rain. The patient was discharged on the third postoperat ive day in good condition after normalization of liver function tests.

Case report #2

A 31-year-old female was transferred from another hos- pital after an ERCP revealed marked dilation of the common duct and multiple intrahepatic stones measur- ing up to 3 cm in diameter. The patient had fever to 100°F, alkaline phosphatase was 146, bilirubin 3.2, SGOT 112, SGPT 262. Amylase was normal. The WBC count was 11.6. Laparoscopy was performed and cholangiograms confirmed the presence of multiple in- trahepatic calculi measuring up to 3 cm. Laparoscopic choledochotomy and flexible choledoscopy were per- formed. The impacted intrahepatic stones were frag- mented using pulsed-dye laser introduced through the working channel of the choledoscope. Stones and de-

bris were removed from the common duct using wire baskets and pulsed saline lavage. A large T-tube was sewn in place and completion cholangiography via the T-tube revealed no defects. The operative time was 5 h. The patient was dicharged on the fourth postopera- tive day in good condition after normalization of her liver function tests.

Discussion

This study demonstrates that biliary stones can be safely and effectively fragmented during laparoscopic surgery using the pulsed-dye laser. Tissue absorption of light at 504 nm is minimal, which accounts for the lack of tissue effects noted during laser lithotripsy [2] as demonstrated by our histological findings. While the laser energy does not cause significant tissue effect, the laser fiber may cause mucosal abrasion or perforation. Although the fiber would create only 200-/xm hole, care must be taken to advance the fiber only under direct vision. In previous animal studies, gross and micro- scopic evaluation of common bile ducts 7 days after biliary laser lithotripsy showed no difference from con- trols [4]. Focal mucosal denudation and mild inflam- matory changes were thought to be due to mechanical trauma only and not laser-induced trauma. Prior animal experiments have shown that, during EHL, perforation of the common bile duct occurred in one-third of the test subjects [5]. Additional studies confirmed the sus- picion that the perforations can be caused by the frag- ments of the exploding stone [5, 6]. A prerequisite for EHL use in the common duct, therefore, has been that stones must be firmly lodged within a wire basket. However, basket manipulation is often difficult or im- possible in patients with huge or impacted common duct stones, making this prerequisite somewhat im- practical. Our study has confirmed prior results indicat- ing that when an EHL probe is in contact with or close to the bile duct wall, the electrical discharge itself can cause perforation even at minimal energy settings [7]. Application of the EHL probe parallel to the common duct caused denudation of mucosa, and direct applica- tion of the probe at right angles to the duct caused full- thickness perforation. High-speed photography [3] has also revealed large-size (greater than 3 mm) cavitation bubbles associated with EHL. This may also account for some of the histological damage observed in our study. After completion of the in vitro and in vivo studies, it was elected to apply laser lithotripsy in two

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human cases. Successful biliary stone fragmentation was accomplished in both patients using the pulsed- dye laser. Following fragmentation all fragments were removed using laparoscopic techniques.

Conclusion

We have performed both in vitro and in vivo laser and electrohydrolic lithotripsy. Our results suggest that pulsed-dye laser lithotripsy is safer than the EHL. We have found that EHL in its present form is too difficult to control for safe laparoscopic use in the common duct. There is significant risk of ductal injury both from exploding stone fragments and electrical discharge in proximity to the duct wall. These risks are especially difficult to minimize due to the constraints of the manip- ulation of the probe. In contrast, pulsed-dye laser litho- tripsy produced a more controllable fragmentation process - - one that is highly applicable to laparoscopic common bile duct exploration. This technique has been successfully used in two patients. The risk of ductal injury is low when the laser is used within specified parameters. Further studies are warranted prior to widespread application of laparoscopically delivered laser biliary lithotripsy.

Acknowledgments. The authors thank M. Fishbein, M.D., and Eric Partlow.

References

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2. Dretler SP, et al (1988) Laser lithotripsy: A review of 20 years of research and clinical application. Lasers Surg Med 8:341-356

3. Sterenborg HJ, de Reijke TM, Wiersma J, Erckens RC, Jogsma FH (1991) High-speed photographic evaluation of endoscopic li- thotripsy devices. Urol Res 19(6): 381-385

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5. Koch H, Roesh WD, Walz V (1980) Endoscopic lithotripsy in the common bile duct. Gastrointest Endosc 26(1): 16-18

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7. Tanaka M, Yoshimoto H, Ikeda S (1985) Two approaches for electrohydraulic lithotripsy in the common bile duct. Surgery 98(2): 313-318