British Journal of Urology (1992),70,594599 01992 British Journal of Urology
Extracorporeal Shock Wave Lithotripsy of Ureteric Stones with the Modulith SL 20
I
J. RASSWE1LER.T. 0. HENKEL,A. D. JOYCE, K. U. KOHRMANN, MARTINA MANNING and P. ALKEN Departments of Urology, Mannheim Hospital, Heidelberg, Germany, and King's College Hospital, 1ondon
Summary-A series of 138 patients with ureteric calculi was treated by in sit0 extracorporeal shock wave lithotripsy (ESWL) during the clinical introduction of the Modulith SL 20. This machine representsa newly developed lithotriptor with an electromagnetic cylinder as shock wave source and a dual localisation system consisting of in-line ultrasound and an integrated fluoroscope C-arm. During the first 2 months, 12 patients (phase 1) were treated under ultrasound localisation alone; during the next 5 months, 37 patients (phase 2) were treated using dual imaging modalities with reduced peak pressure (max. 18 kV=800 bar); during the final 7 months, 89 patients (phase 3) were treated under ultrasonic and fluoroscopic localisation combined with an increased maximal shock wave pressure (20 kV= 1024 bar). The introduction of fluoroscopic targeting (phases 2 and 3) resulted in satisfactory localisation of calculi in the mid-ureter, previously limited by use of only coaxial ultrasound. The extension of stone localisation to the whole length of the ureter was associated with a marked decrease in treatment time, reflecting the easy handling of the dual localisation system. The rise in generator voltage (phase 3) improved the disintegration rate from 81% (phase 2) to 85%, whereas the number of impulses remained unchanged. However, the rate of auxiliary procedures following ESWL (adjuvant and curative) was reduced from 33% (phase 2) to 24.5%. Thus the Modulith SL 20 in its final design enables in situ ESWL to be the treatment of choice for all ureteric calculi, rendering special positioning techniques or multiple treatment unnecessary.
Previous reports have advocated in situ ESWL as the treatment of choice in the management of ureteric calculi (Rassweiler et al., 1986a and b; Graff et al., 1988). This concept i s based on the principle of minimal morbidity and invasiveness. In the past, the success of this method has been limited by difficulties in stone localisation, particularly for calculi in the mid-ureter (Cole and Shuttleworth, 1988). The necessity for additional procedures, including ureteroscopy and retrograde stone mobilisation, to achieve stone clearance also underlinedthe shortcomings of the first and second generation lithotriptors (Simon et al., 1990). In an
Accepted for publication 1 1 February 1992
earlier series, retrograde mobilisation was possible in 80% of cases at the most, resulting in further invasive, curative measures such as retrograde or antegrade ureteroscopy (Alken et al., 1985 ; M i l l e r et al., 1985). Not only are these adjuvant manoeuvres more invasive-they also carry the risk of septicaemia and ureteric stenosis. Other factors, including total obstruction, stone size and duration of impaction, have been implicated in the failure of in situ ureteric ESWL (Rassweiler et al., 1986a and b). Storz Medical A G (Kreuzlingen, Switzerland) and the Department of Urology, Klinikum Mannheim (Clinical Faculty of the University of Heidelberg, Germany) have developed a new lithotriptor, the Storz Modulith SL 20, aimed at overcoming these limitations (Table 1) (Rassweiler
594
ESWL WITH THE MODULITH SL 20
Table 1 Criteria for a Third GenerationLithotriptor 1.
X-ray and ultrasonic stone localisation for ESWL of urinary and biliary calculi.
11.
Wide energy range of shock wave source for effective disintegration of difficult stones.
111.
Large aperture focusing system for treatment under minimal analgesia.
IV.
Fluoroscopic table allowing multifunctionaluse of the lithotriptor.
V.
Low cost and maintenance.
et al., 1990a). This advanced lithotriptor has enabled us to re-evaluate the question of in situ
ESWL for all ureteric calculi and, in particular, to determine whether the combination of imaging techniques and higher shock wave energy will improve on our previous experience. Materials and Methods Technical data In the Modulith SL 20 the shock wave source consists of an electromagnetic cylinder containing an in-line ultrasound scanner. The shock front is focused by a parabolic metal reflector with a diameter of 30 cm. The focal size is 6 x 28 mm (at 15 kV). Fluoroscopic localisation is provided by the integrated C-arm (Table 2).
Table 2 Modulith-Shock
Wave Generator
Shock wave source
Electromagnetic cylinder
Range Focusing Aperture (cm) Focal size (mm) Focal depth (cm)
12-20 kV (19G1200 bar) Paraboloid reflector 30 6x28 2-15
Stone localisation Ultrasonic localisation was employed for upper and pre-vesical ureteric calculi with the patient in either the supine-oblique (upper third) or the prone-flat position. Fluoroscopic localisation was primarily used for all other ureteric stones with the patient in either the supine-flat (upper third) or prone-flat (mid and distal ureter) position. The patient is manoeuvred
595 under the integrated C-arm and then centred in the virtual focus (FJ. He/she is then manually manoeuvred back on to the shock wave source and the water cushion is carefully coupled without moving the patient (Fig. 1). In approximately 20% of these cases the stone can be visualised by an in-line ultrasound and thus monitored during treatment. In the remainder, fluoroscopy is carried out after 400 shocks and then after 500-1000 impulses, depending on the stability of the patient’s position. It must be emphasised that this stability is ensured by the integrated “acoustic cradle” consisting of an impedance-adapted foil (Fig. 2). Patients and indications Between August 1989 and December 1990, 138 patients with ureteric calculi were treated by 1 of 3 therapeutic protocols (phase 1, 2 or 3). Allocation depended on the time of presentation during the study and in situ ESWL was performed regardless of stone size or duration of obstruction. Phase 1. This 2-month study involved the first 12 patients treated on the prototype Modulith SL 10, incorporating coaxial ultrasound as the only means of stone localisation. The maximum generator voltage was 18 kV, corresponding to a peak pressure of 800 bar (PVDF-hydrophone, Imotec). Phase 2. The next stage of the study, which lasted for 5 months, involved 37 patients treated on the upgraded Modulith SL 20. This incorporated the dual imaging modalities of coaxial ultrasound and fluoroscopic stone localisation. The concept was to provide a total imaging system with respect to all ureteric calculi. The maximum generator voltage in this series remained the same (18 kV). Phase 3. The final 7 months of the study involved 89 patients treated on the Modulith SL 20, which was subject to further modification. The shock wave energy was increased to 20 kV (corresponding to a peak pressure of 1024 bar), with the aim of improving disintegration without causing additional pain. Statistically, there was no significant difference between the various treatment groups with respect to stone distribution, stone size or duration of obstruction (Table 3). In all 3 phases the patients were treated with a standard regimen of analgesia: 3.5-7.5 mg piritramide (Dipidolor@)intravenously plus 5-10 mg midazolam (Dormicum@)if necessary.
596
BRITISH JOURNAL OF UROLOGY
Fig. 1 Storz Modulith SL 20. Fluoroscopic stone localisation. Shift from real focus (in-line ultrasound) into virtual focus F,. After fluoroscopic stone localisation,mechanical return to treatment position and careful coupling with flat position of the water cushion.
Table 3 Ureteric Stone Distribution
Table 4 Auxiliary Procedures
Phase
1
2
3
Curative
Adjuvant
No.ofpatients No. of stones
12 12
37 37
89 91
Loop extraction Ureteroscopy Laser lithotripsy
Retrograde mobilisation Percutaneous nephrostomy Stent
Site: Upper(%) Middle(%) Lower(%)
67 -
50 7 43
56 16
33
28
anaesthesia may become necessary, particularly in male patients. Adjuvant intervention, either before or after ESWL, involved minor procedures to prevent or resolve the complications of in situ treatment. These were performed either without or Successful in situ ESWL was defined as complete under mild anaesthesia. This study had 2 aims with respect to the Storz disintegration of the calculus in 1 or 2 sessions Modulith SL 20. without the need for auxiliary measures due to incomplete fragmentation. Auxiliary measures 1. Does the combination of a combined targeting were categorised as curative or adjuvant (Table 4). system lead to satisfactory stone localisation of all ureteric calculi? Curative procedures were defined as measures undertaken to achieve stone clearance after incom- 2. Does increasing the shock wave energy (kV) improve the efficacy of the lithotriptor with a plete fragmentation (mainly ureteroscopic stone consequent reduction in invasive auxiliary proextraction). Ureterorenoscopy (URS) is often percedures to achieve stone clearance? formed under analgesic sedation, but general Size: < I cm(%) > 1 cmck)
67 33
75 25
66 34
597
ESWL WITH THE MODULITH SL 20
Table 6 Results of Treatment after 5 Months Phase
2
3
Disintegration rate rk) Retreatment rate (%) Stone-free (%) Remnants < 5 mm (%) Remnants > 5 mm (%)
81 6 82 11 7
85 14 90 2.5 7.5
Table 7 Auxiliary Procedures
Fig. 2 Stable position of the patient during shifting by means
of the “acousticcradle”.
Results
In all, 138 patients were treated by in situ ESWL with a stone distribution listed in Table 3. The absence of stones in the mid-ureter in the phase 1 study reflects the limitations of localisation using coaxial ultrasound alone. The introduction of a fluoroscopic targeting system for phases 2 and 3 resulted in satisfactory localisation of calculi in the mid-ureter,previously described as “nowhere land” (Eisenberger et al., 1985; Chaussy, 1988). Thus, a dual imaging system combining X-ray and ultrasound provided suitable access to the whole of the ureter and achieved the first aim of the study. Treatment data for the 3 phases of the study are listed in Tables 5 and 6. There was no significant difference with respect to the number of shock waves for each phase, but there was a marked decrease in treatment time. The initial time difference between phases 1 and 2 reflects our learning curve with the Modulith, but the further reduction in treatment time in phase 3 coincided with an increase in shock wave energy (kV) and reflects the easy handling of the combined localisation system. Table 5 Ureteric Stones: ESWL Data Phase No. of treatments/patients No. of shock waves Generator voltage (kV) Mean treatment time (min)
1
2
3
1.16 2423 17.7
1.06 2875 17.7 59
1.15 2895 19.3 38
80
Phase
21%)
Curative Loop extraction Ureteroscopy PCNL*
8 10 1
Adjuvant Before : Retrograde mobilisation Stent PCNL After: Stent URS
-
Total
39t
3 11 3 14
3(%1 6 9 -
2.5 7 3 5 4.5 31$
* PCNL: percutaneous nephrolithotomy. t 11% of patients underwent pre- and post-ESWL
auxiliary measures. $ 6% of patients underwent pre- and post-ESWL auxiliary measures.
Consequently, the increase in generator voltage was seen to improve the disintegration rate of ureteric calculi in phase 3 (81 to 85%). The success of this higher disintegration level reduced the complicationrate for in situ ESWL, as demonstrated by the reduced number of curative and adjuvant interventional procedures performed after ESWL in phase 3 (24.5 us 33%) (Table 7). Curative measures were mainly URS and the post-ESWL adjuvant measures comprised placement of an indwelling stent in the vast majority of cases. It should be noted that 11% of patients in phase 2 and 6% of patients in phase 3 underwent additional auxiliary procedures before and after ESWL. The cost of this reduction in post-ESWL adjuvant measures is reflected in the higher retreatment rate in phase 3 (14 us 6%). Despite the department’s acquisition of a pulsed dye laser, the rate of curative procedures remained unchanged. These results confirm that a combination of targeting systems with a high shock wave energy increases both the disintegration rate and improves the overall success rate of in situ ureteric ESWL.
598 Discussion Previous experience with in situ ESWL for ureteric calculi was associated with disappointing initial success rates of 60 to 62% (Alken et al., 1985; Miller et al., 1985). Improved focusing and positioning techniques increased the success rate to 75% with the Dornier HM3 (Rassweiler et al., 1986a and b; Graff et al., 1988). Retrograde mobilisation, whenever possible, resulted in a 95% disintegration rate and this method became routine in several centres (Alken et al., 1985; Lingeman et al., 1986). Experimental work by Muller et al. (1986) implicated some important factors in the failure of in situ ESWL. It was proposed that the main cause of failure was the lack of a suitable interphase between the calculus and urine to allow expansion of fragments. Other important difficulties with in situ treatment involved localisation of the ureteric calculus and attenuation of shock wave energy on stone impaction (Rassweiler et al., 1986a and b). The stones in the various treatment groups in the present study did not differ with respect to these criteria (Table 3). The development of the Modulith was undertaken with the following characteristics in mind : (1) Fluoroscopic and ultrasonic localisation to permit ESWL of all urinary and biliary calculi; (2) wide energy range of shock wave source for effective disintegration of difficult stones ; (3) large aperture focusing system to permit treatment under intravenous analgesia; (4) multifunctional use of the lithotriptor table; (5) low cost and maintenance (Rassweilerel al., 1990a). Such characteristics may define a so-called “third generation lithotriptor” (Table 1). In vitro measurements and in vivo animal trials, using the prototype Modulith, demonstrated that the wide range of energy source and the generator voltage was safe for clinical lithotripsy (Rassweiler et al., 1988, 1990a). The preliminary results were promising in the treatment of urinary and biliary calculi (Henkel et al., unpublished data). Ultrasonic stone localisation systems, as used in most of the second generation lithotriptors, limit the overall success rate of in situ treatment of ureteric calculi to 42% (Rassweiler et al., 1990b; Schmidt et al., 1990). These are generally calculi in the upper third of a dilated ureter or situated in the distal intramural portion. Fluoroscopic localisation, in contrast, localises more than 80% of ureteric calculi, but there is still the area over the iliac ureter. Previously, this was also considered “nowhere land” for in situ ESWL (Eisenberger et al., 1985; Chaussy, 1988). The combination of a dual
BRITISH JOURNAL OF UROLOGY
targeting system in phase 2 of this study, with ESWL in the prone position for calculi over the sacroiliac joint (Miller and Hautmann, 1987; Jenkins and Gillenwater, 1988), demonstrates that all ureteric calculi are now suitable for in situ ESWL. For the treatment of mid or distal ureteric stones it should be noted that, unlike the Dornier HM3, no special positioning technique (Rassweiler et al., 1986a and b; Miller and Hautmann, 1987; Cole and Shuttleworth, 1988; Jenkins and Gillenwater, 1988; Miller et al., 1988) is necessary on the Modulith SL 20. I n situ treatment of ureteric calculi is usually performed in the upper range of shock wave energy to achieve satisfactory disintegration. Any attenuation of the shock wave (in order to reduce pain) decreases the disintegration rate and increases the number of retreatment or auxiliary procedures required to achieve complete stone clearance. Neisius et a1 (1991) reported that all of their ureteric calculi had to be treated twice on the Piezolith 2500, which is also fitted with a dual localisation system. Increasing the generator voltage, as in phase 3 of the present study, could theoretically render the treatment unacceptable under intravenous analgesia because of increased pain. Our results show that a shock wave energy of 20 kV (corresponding to a rise in peak pressure from 800 to 1024 bar) improved the disintegration rate with no adverse effect on the patient’s perception of pain. Presumably this is a result of the wide aperture focusing system on the Modulith. Thus there is no significant change in the focal zone and focal depth after increasing the maximum generator voltage. The rise in generator voltage has also reduced the number of post-ESWL adjuvant procedures, which indicates improved fragmentation. Although this involved an increase of 8% in the retreatment rate, it is a small price to pay considering the fact that further intervention, especially in the male, often requires general anaesthesia and carries a risk of further morbidity (Carter et al., 1986; Coptcoat et al., 1987; Miller et al., 1988). However, it must be noted that the introduction of miniscopes as well as lasertripsy has minimised these risks (Watson et al., 1987; Rassweiler et al., 1991). For this reason, we performed most of our remaining “curative” ureteroscopies in phase 3 (Table 7) with the patient under analgesic sedation, using a new dye laser with a stone-detection device (Rassweiler et al., 1992). The results of this study confirm the efficacy of the dual localisation concept of the Modulith SL 20 for the treatment of all ureteric calculi. The rise in
599
ESWL WITH THE MODULITH SL 20
generator voltage further improves the success rate of in situ ESWL. Acknowledgement We thank Mrs M. Meyer for typing the manuscript. A. D. Joyce was a Research Fellow in this department during the data evaluation period.
References Alken, P., Hardemam, S., Wdbert, D. et d (1985). Extracorporeal shock wave lithotripsy (ESWL): alternativesand adjuvant procedures. World J . Urol., 3,48-52. Carter, S. St C., Cox, R. and Wickham, J. E. A. (1986). Complications associated with ureteroscopy. Br. J. Urol.,58, 625-628. Chaussy,C. (1988).ESWL: past, present and future. J. Endourol., 2.97-105. Cole, R. S. and Shuttleworth, K. E. D. (1988). Is extracorporeal shockwave lithotripsy suitable treatment for lower ureteric stones?Br. J. Urol., 62, 525-530. Coptcoat, M. J., Watson, G. and Wickham, J. E. A. (1987). Lasertripsy for ureteric stones : 100 clinical cases. J . Endourol., I, 119-122. Eisenberger, F., Fuchs, F., Miller, K. et d (1985). Non-invasive renal stone therapy with extracorporeal shockwave lithotripsy (ESWL). In Radiology Today, ed. Heuck, F. and Donner, M. Volume 3, pp 161-167. Berlin, New York, Heidelberg: Springer. Graff, J., Pastor, J., Funke, P. J. e t d (1988). ESWL for ureteric stones: a retrospective analysis of 417 cases. J. Urol., 138, 513-516. Jenkins, A. D. and Gillenwater, J. Y. (1988). Extracorporeal shockwave lithotripsy in the prone position: treatment of stones in the distal ureter or anomalous kidney. J . Urol., 139, 91 1-915. Lingeman, J. E., Sonda, L. P., Kahnoski, R. J. et d (1986). Ureteric stone management: emerging concepts. J. Urol., 135, 1172- 1174. Miller, K., Fuchs, G., Rassweiler, J. et d (1985). Treatment of ureteric stone disease: the role of ESWL and endourology. World J. Urol., 3, 53-57. Miller, K. and Hautmann, R. (1987). Treatment of distal ureteric calculi with ESWL: experience with more than 100 consecutive cases. World J . Urol., 5,259-265. Miller, K., Bachor, R. and Hautmann, R. (1988). Extracorporeal shock wave lithotripsy of stones in the prone position: technique, indications, results. J. Endourol., 2,113-115.
Miiller, S. C., Wdbert, D., Thiiroff, J. W. er d (1986). Extracorporeal shock wave lithotripsy of ureteric stones: clinical experience and experimental findings. J. Urol., 135, 101-122. Neisius, D.,Zwergel, Th.,Zwergel, U. et d (1991). Klinische Erfahrungen mit der piezoelektrischen Lithotripsie von Harnsteinen. Med. Tech. (Suppl.), 2,38 (abstract). Rassweiler, J., Hath, U., Bub, P. et d (1986). Extracorporeal shock wave lithotripsy for distal ureteric calculi. Endourol. News,4,15-17. Rassweiler, J., Henkel, T., Tschada, R. et d (1992). Interdisciplinary experience with the Lithognostkthe impact of optical, feedback-controlled stone detection in lasertripsy. J. Endourol., 6,233-237. Rassweiler, J., Kohrmam, U., Heine, G. et al. (1990a). Modulith SL 10/2kxperimental introduction and first clinical experience with a new interdisciplinary lithotripter. Eur. Urol., 18, 237-241. Rassweiler, J., Lutz, K., Gumpinger, R. et d (1986). Efficacy of in situ extracorporeal shock wave lithotripsy for upper ureteric calculi. Eur. Urol., 12, 377-386. Rassweiler, J., Schmidt, A., Gumpinger, R. et d (1990b). ESWL for ureteric calculi using the Dornier HM3, HM3 + and Wolf Piezolith 2200. J. Urol. (Paris), 96,149-155. Rassweiler, J., Westhauser, A., Bub, P. et d (1988). Second generation lithotripters : a comparative study. J. Endourol., 2, 192-203. Schmidt,A., Rassweiler,J., Gumpinger, R. et al. (1990). Minimally invasive treatmentofuretericcalculi using modern techniques. Br. J . Urol., 65,242-249. Simon, J., van den Bosshe, M. and Schulman, C. C. (1990). Shock wave treatment of ureteric stones in situ with secondgeneration lithotriptor. Eur. Urol., 17,200-202. Watson, G., Murray, S.,Dretler, S. P. et al. (1987). An assessment of the pulsed dye laser for fragmenting calculi in the pig ureter. J . Urol., 138, 199-202.
The Authors J . Rassweiler, MD, Chief Senior Registrar, Mannheim Hospital. T. 0. Henkel, MD, Registrar, Mannheim Hospital. A. D. Joyce, MD, Senior Registrar, King’s College Hospital. K. U. Kohrmann, MD, Registrar, Mannheim Hospital. Martha Manning, Medical Student, Mannheim Hospital. P. Alken, MD, Professor, Head of Department of Urology, Mannheim Hospital. Requests for reprints to: J. Rassweiler, Urologische Klinik, Klinikum Mannheim, Klinische Fakultat der Universitat Heidelberg, Theodor-Kutzer-Ufer, W-6800 Mannheim, Germany.
Extracorporeal Shock Wave Lithotripsy of Ureteric Stones with the Modulith SL 20
I
J. RASSWE1LER.T. 0. HENKEL,A. D. JOYCE, K. U. KOHRMANN, MARTINA MANNING and P. ALKEN Departments of Urology, Mannheim Hospital, Heidelberg, Germany, and King's College Hospital, 1ondon
Summary-A series of 138 patients with ureteric calculi was treated by in sit0 extracorporeal shock wave lithotripsy (ESWL) during the clinical introduction of the Modulith SL 20. This machine representsa newly developed lithotriptor with an electromagnetic cylinder as shock wave source and a dual localisation system consisting of in-line ultrasound and an integrated fluoroscope C-arm. During the first 2 months, 12 patients (phase 1) were treated under ultrasound localisation alone; during the next 5 months, 37 patients (phase 2) were treated using dual imaging modalities with reduced peak pressure (max. 18 kV=800 bar); during the final 7 months, 89 patients (phase 3) were treated under ultrasonic and fluoroscopic localisation combined with an increased maximal shock wave pressure (20 kV= 1024 bar). The introduction of fluoroscopic targeting (phases 2 and 3) resulted in satisfactory localisation of calculi in the mid-ureter, previously limited by use of only coaxial ultrasound. The extension of stone localisation to the whole length of the ureter was associated with a marked decrease in treatment time, reflecting the easy handling of the dual localisation system. The rise in generator voltage (phase 3) improved the disintegration rate from 81% (phase 2) to 85%, whereas the number of impulses remained unchanged. However, the rate of auxiliary procedures following ESWL (adjuvant and curative) was reduced from 33% (phase 2) to 24.5%. Thus the Modulith SL 20 in its final design enables in situ ESWL to be the treatment of choice for all ureteric calculi, rendering special positioning techniques or multiple treatment unnecessary.
Previous reports have advocated in situ ESWL as the treatment of choice in the management of ureteric calculi (Rassweiler et al., 1986a and b; Graff et al., 1988). This concept i s based on the principle of minimal morbidity and invasiveness. In the past, the success of this method has been limited by difficulties in stone localisation, particularly for calculi in the mid-ureter (Cole and Shuttleworth, 1988). The necessity for additional procedures, including ureteroscopy and retrograde stone mobilisation, to achieve stone clearance also underlinedthe shortcomings of the first and second generation lithotriptors (Simon et al., 1990). In an
Accepted for publication 1 1 February 1992
earlier series, retrograde mobilisation was possible in 80% of cases at the most, resulting in further invasive, curative measures such as retrograde or antegrade ureteroscopy (Alken et al., 1985 ; M i l l e r et al., 1985). Not only are these adjuvant manoeuvres more invasive-they also carry the risk of septicaemia and ureteric stenosis. Other factors, including total obstruction, stone size and duration of impaction, have been implicated in the failure of in situ ureteric ESWL (Rassweiler et al., 1986a and b). Storz Medical A G (Kreuzlingen, Switzerland) and the Department of Urology, Klinikum Mannheim (Clinical Faculty of the University of Heidelberg, Germany) have developed a new lithotriptor, the Storz Modulith SL 20, aimed at overcoming these limitations (Table 1) (Rassweiler
594
ESWL WITH THE MODULITH SL 20
Table 1 Criteria for a Third GenerationLithotriptor 1.
X-ray and ultrasonic stone localisation for ESWL of urinary and biliary calculi.
11.
Wide energy range of shock wave source for effective disintegration of difficult stones.
111.
Large aperture focusing system for treatment under minimal analgesia.
IV.
Fluoroscopic table allowing multifunctionaluse of the lithotriptor.
V.
Low cost and maintenance.
et al., 1990a). This advanced lithotriptor has enabled us to re-evaluate the question of in situ
ESWL for all ureteric calculi and, in particular, to determine whether the combination of imaging techniques and higher shock wave energy will improve on our previous experience. Materials and Methods Technical data In the Modulith SL 20 the shock wave source consists of an electromagnetic cylinder containing an in-line ultrasound scanner. The shock front is focused by a parabolic metal reflector with a diameter of 30 cm. The focal size is 6 x 28 mm (at 15 kV). Fluoroscopic localisation is provided by the integrated C-arm (Table 2).
Table 2 Modulith-Shock
Wave Generator
Shock wave source
Electromagnetic cylinder
Range Focusing Aperture (cm) Focal size (mm) Focal depth (cm)
12-20 kV (19G1200 bar) Paraboloid reflector 30 6x28 2-15
Stone localisation Ultrasonic localisation was employed for upper and pre-vesical ureteric calculi with the patient in either the supine-oblique (upper third) or the prone-flat position. Fluoroscopic localisation was primarily used for all other ureteric stones with the patient in either the supine-flat (upper third) or prone-flat (mid and distal ureter) position. The patient is manoeuvred
595 under the integrated C-arm and then centred in the virtual focus (FJ. He/she is then manually manoeuvred back on to the shock wave source and the water cushion is carefully coupled without moving the patient (Fig. 1). In approximately 20% of these cases the stone can be visualised by an in-line ultrasound and thus monitored during treatment. In the remainder, fluoroscopy is carried out after 400 shocks and then after 500-1000 impulses, depending on the stability of the patient’s position. It must be emphasised that this stability is ensured by the integrated “acoustic cradle” consisting of an impedance-adapted foil (Fig. 2). Patients and indications Between August 1989 and December 1990, 138 patients with ureteric calculi were treated by 1 of 3 therapeutic protocols (phase 1, 2 or 3). Allocation depended on the time of presentation during the study and in situ ESWL was performed regardless of stone size or duration of obstruction. Phase 1. This 2-month study involved the first 12 patients treated on the prototype Modulith SL 10, incorporating coaxial ultrasound as the only means of stone localisation. The maximum generator voltage was 18 kV, corresponding to a peak pressure of 800 bar (PVDF-hydrophone, Imotec). Phase 2. The next stage of the study, which lasted for 5 months, involved 37 patients treated on the upgraded Modulith SL 20. This incorporated the dual imaging modalities of coaxial ultrasound and fluoroscopic stone localisation. The concept was to provide a total imaging system with respect to all ureteric calculi. The maximum generator voltage in this series remained the same (18 kV). Phase 3. The final 7 months of the study involved 89 patients treated on the Modulith SL 20, which was subject to further modification. The shock wave energy was increased to 20 kV (corresponding to a peak pressure of 1024 bar), with the aim of improving disintegration without causing additional pain. Statistically, there was no significant difference between the various treatment groups with respect to stone distribution, stone size or duration of obstruction (Table 3). In all 3 phases the patients were treated with a standard regimen of analgesia: 3.5-7.5 mg piritramide (Dipidolor@)intravenously plus 5-10 mg midazolam (Dormicum@)if necessary.
596
BRITISH JOURNAL OF UROLOGY
Fig. 1 Storz Modulith SL 20. Fluoroscopic stone localisation. Shift from real focus (in-line ultrasound) into virtual focus F,. After fluoroscopic stone localisation,mechanical return to treatment position and careful coupling with flat position of the water cushion.
Table 3 Ureteric Stone Distribution
Table 4 Auxiliary Procedures
Phase
1
2
3
Curative
Adjuvant
No.ofpatients No. of stones
12 12
37 37
89 91
Loop extraction Ureteroscopy Laser lithotripsy
Retrograde mobilisation Percutaneous nephrostomy Stent
Site: Upper(%) Middle(%) Lower(%)
67 -
50 7 43
56 16
33
28
anaesthesia may become necessary, particularly in male patients. Adjuvant intervention, either before or after ESWL, involved minor procedures to prevent or resolve the complications of in situ treatment. These were performed either without or Successful in situ ESWL was defined as complete under mild anaesthesia. This study had 2 aims with respect to the Storz disintegration of the calculus in 1 or 2 sessions Modulith SL 20. without the need for auxiliary measures due to incomplete fragmentation. Auxiliary measures 1. Does the combination of a combined targeting were categorised as curative or adjuvant (Table 4). system lead to satisfactory stone localisation of all ureteric calculi? Curative procedures were defined as measures undertaken to achieve stone clearance after incom- 2. Does increasing the shock wave energy (kV) improve the efficacy of the lithotriptor with a plete fragmentation (mainly ureteroscopic stone consequent reduction in invasive auxiliary proextraction). Ureterorenoscopy (URS) is often percedures to achieve stone clearance? formed under analgesic sedation, but general Size: < I cm(%) > 1 cmck)
67 33
75 25
66 34
597
ESWL WITH THE MODULITH SL 20
Table 6 Results of Treatment after 5 Months Phase
2
3
Disintegration rate rk) Retreatment rate (%) Stone-free (%) Remnants < 5 mm (%) Remnants > 5 mm (%)
81 6 82 11 7
85 14 90 2.5 7.5
Table 7 Auxiliary Procedures
Fig. 2 Stable position of the patient during shifting by means
of the “acousticcradle”.
Results
In all, 138 patients were treated by in situ ESWL with a stone distribution listed in Table 3. The absence of stones in the mid-ureter in the phase 1 study reflects the limitations of localisation using coaxial ultrasound alone. The introduction of a fluoroscopic targeting system for phases 2 and 3 resulted in satisfactory localisation of calculi in the mid-ureter,previously described as “nowhere land” (Eisenberger et al., 1985; Chaussy, 1988). Thus, a dual imaging system combining X-ray and ultrasound provided suitable access to the whole of the ureter and achieved the first aim of the study. Treatment data for the 3 phases of the study are listed in Tables 5 and 6. There was no significant difference with respect to the number of shock waves for each phase, but there was a marked decrease in treatment time. The initial time difference between phases 1 and 2 reflects our learning curve with the Modulith, but the further reduction in treatment time in phase 3 coincided with an increase in shock wave energy (kV) and reflects the easy handling of the combined localisation system. Table 5 Ureteric Stones: ESWL Data Phase No. of treatments/patients No. of shock waves Generator voltage (kV) Mean treatment time (min)
1
2
3
1.16 2423 17.7
1.06 2875 17.7 59
1.15 2895 19.3 38
80
Phase
21%)
Curative Loop extraction Ureteroscopy PCNL*
8 10 1
Adjuvant Before : Retrograde mobilisation Stent PCNL After: Stent URS
-
Total
39t
3 11 3 14
3(%1 6 9 -
2.5 7 3 5 4.5 31$
* PCNL: percutaneous nephrolithotomy. t 11% of patients underwent pre- and post-ESWL
auxiliary measures. $ 6% of patients underwent pre- and post-ESWL auxiliary measures.
Consequently, the increase in generator voltage was seen to improve the disintegration rate of ureteric calculi in phase 3 (81 to 85%). The success of this higher disintegration level reduced the complicationrate for in situ ESWL, as demonstrated by the reduced number of curative and adjuvant interventional procedures performed after ESWL in phase 3 (24.5 us 33%) (Table 7). Curative measures were mainly URS and the post-ESWL adjuvant measures comprised placement of an indwelling stent in the vast majority of cases. It should be noted that 11% of patients in phase 2 and 6% of patients in phase 3 underwent additional auxiliary procedures before and after ESWL. The cost of this reduction in post-ESWL adjuvant measures is reflected in the higher retreatment rate in phase 3 (14 us 6%). Despite the department’s acquisition of a pulsed dye laser, the rate of curative procedures remained unchanged. These results confirm that a combination of targeting systems with a high shock wave energy increases both the disintegration rate and improves the overall success rate of in situ ureteric ESWL.
598 Discussion Previous experience with in situ ESWL for ureteric calculi was associated with disappointing initial success rates of 60 to 62% (Alken et al., 1985; Miller et al., 1985). Improved focusing and positioning techniques increased the success rate to 75% with the Dornier HM3 (Rassweiler et al., 1986a and b; Graff et al., 1988). Retrograde mobilisation, whenever possible, resulted in a 95% disintegration rate and this method became routine in several centres (Alken et al., 1985; Lingeman et al., 1986). Experimental work by Muller et al. (1986) implicated some important factors in the failure of in situ ESWL. It was proposed that the main cause of failure was the lack of a suitable interphase between the calculus and urine to allow expansion of fragments. Other important difficulties with in situ treatment involved localisation of the ureteric calculus and attenuation of shock wave energy on stone impaction (Rassweiler et al., 1986a and b). The stones in the various treatment groups in the present study did not differ with respect to these criteria (Table 3). The development of the Modulith was undertaken with the following characteristics in mind : (1) Fluoroscopic and ultrasonic localisation to permit ESWL of all urinary and biliary calculi; (2) wide energy range of shock wave source for effective disintegration of difficult stones ; (3) large aperture focusing system to permit treatment under intravenous analgesia; (4) multifunctional use of the lithotriptor table; (5) low cost and maintenance (Rassweilerel al., 1990a). Such characteristics may define a so-called “third generation lithotriptor” (Table 1). In vitro measurements and in vivo animal trials, using the prototype Modulith, demonstrated that the wide range of energy source and the generator voltage was safe for clinical lithotripsy (Rassweiler et al., 1988, 1990a). The preliminary results were promising in the treatment of urinary and biliary calculi (Henkel et al., unpublished data). Ultrasonic stone localisation systems, as used in most of the second generation lithotriptors, limit the overall success rate of in situ treatment of ureteric calculi to 42% (Rassweiler et al., 1990b; Schmidt et al., 1990). These are generally calculi in the upper third of a dilated ureter or situated in the distal intramural portion. Fluoroscopic localisation, in contrast, localises more than 80% of ureteric calculi, but there is still the area over the iliac ureter. Previously, this was also considered “nowhere land” for in situ ESWL (Eisenberger et al., 1985; Chaussy, 1988). The combination of a dual
BRITISH JOURNAL OF UROLOGY
targeting system in phase 2 of this study, with ESWL in the prone position for calculi over the sacroiliac joint (Miller and Hautmann, 1987; Jenkins and Gillenwater, 1988), demonstrates that all ureteric calculi are now suitable for in situ ESWL. For the treatment of mid or distal ureteric stones it should be noted that, unlike the Dornier HM3, no special positioning technique (Rassweiler et al., 1986a and b; Miller and Hautmann, 1987; Cole and Shuttleworth, 1988; Jenkins and Gillenwater, 1988; Miller et al., 1988) is necessary on the Modulith SL 20. I n situ treatment of ureteric calculi is usually performed in the upper range of shock wave energy to achieve satisfactory disintegration. Any attenuation of the shock wave (in order to reduce pain) decreases the disintegration rate and increases the number of retreatment or auxiliary procedures required to achieve complete stone clearance. Neisius et a1 (1991) reported that all of their ureteric calculi had to be treated twice on the Piezolith 2500, which is also fitted with a dual localisation system. Increasing the generator voltage, as in phase 3 of the present study, could theoretically render the treatment unacceptable under intravenous analgesia because of increased pain. Our results show that a shock wave energy of 20 kV (corresponding to a rise in peak pressure from 800 to 1024 bar) improved the disintegration rate with no adverse effect on the patient’s perception of pain. Presumably this is a result of the wide aperture focusing system on the Modulith. Thus there is no significant change in the focal zone and focal depth after increasing the maximum generator voltage. The rise in generator voltage has also reduced the number of post-ESWL adjuvant procedures, which indicates improved fragmentation. Although this involved an increase of 8% in the retreatment rate, it is a small price to pay considering the fact that further intervention, especially in the male, often requires general anaesthesia and carries a risk of further morbidity (Carter et al., 1986; Coptcoat et al., 1987; Miller et al., 1988). However, it must be noted that the introduction of miniscopes as well as lasertripsy has minimised these risks (Watson et al., 1987; Rassweiler et al., 1991). For this reason, we performed most of our remaining “curative” ureteroscopies in phase 3 (Table 7) with the patient under analgesic sedation, using a new dye laser with a stone-detection device (Rassweiler et al., 1992). The results of this study confirm the efficacy of the dual localisation concept of the Modulith SL 20 for the treatment of all ureteric calculi. The rise in
599
ESWL WITH THE MODULITH SL 20
generator voltage further improves the success rate of in situ ESWL. Acknowledgement We thank Mrs M. Meyer for typing the manuscript. A. D. Joyce was a Research Fellow in this department during the data evaluation period.
References Alken, P., Hardemam, S., Wdbert, D. et d (1985). Extracorporeal shock wave lithotripsy (ESWL): alternativesand adjuvant procedures. World J . Urol., 3,48-52. Carter, S. St C., Cox, R. and Wickham, J. E. A. (1986). Complications associated with ureteroscopy. Br. J. Urol.,58, 625-628. Chaussy,C. (1988).ESWL: past, present and future. J. Endourol., 2.97-105. Cole, R. S. and Shuttleworth, K. E. D. (1988). Is extracorporeal shockwave lithotripsy suitable treatment for lower ureteric stones?Br. J. Urol., 62, 525-530. Coptcoat, M. J., Watson, G. and Wickham, J. E. A. (1987). Lasertripsy for ureteric stones : 100 clinical cases. J . Endourol., I, 119-122. Eisenberger, F., Fuchs, F., Miller, K. et d (1985). Non-invasive renal stone therapy with extracorporeal shockwave lithotripsy (ESWL). In Radiology Today, ed. Heuck, F. and Donner, M. Volume 3, pp 161-167. Berlin, New York, Heidelberg: Springer. Graff, J., Pastor, J., Funke, P. J. e t d (1988). ESWL for ureteric stones: a retrospective analysis of 417 cases. J. Urol., 138, 513-516. Jenkins, A. D. and Gillenwater, J. Y. (1988). Extracorporeal shockwave lithotripsy in the prone position: treatment of stones in the distal ureter or anomalous kidney. J . Urol., 139, 91 1-915. Lingeman, J. E., Sonda, L. P., Kahnoski, R. J. et d (1986). Ureteric stone management: emerging concepts. J. Urol., 135, 1172- 1174. Miller, K., Fuchs, G., Rassweiler, J. et d (1985). Treatment of ureteric stone disease: the role of ESWL and endourology. World J. Urol., 3, 53-57. Miller, K. and Hautmann, R. (1987). Treatment of distal ureteric calculi with ESWL: experience with more than 100 consecutive cases. World J . Urol., 5,259-265. Miller, K., Bachor, R. and Hautmann, R. (1988). Extracorporeal shock wave lithotripsy of stones in the prone position: technique, indications, results. J. Endourol., 2,113-115.
Miiller, S. C., Wdbert, D., Thiiroff, J. W. er d (1986). Extracorporeal shock wave lithotripsy of ureteric stones: clinical experience and experimental findings. J. Urol., 135, 101-122. Neisius, D.,Zwergel, Th.,Zwergel, U. et d (1991). Klinische Erfahrungen mit der piezoelektrischen Lithotripsie von Harnsteinen. Med. Tech. (Suppl.), 2,38 (abstract). Rassweiler, J., Hath, U., Bub, P. et d (1986). Extracorporeal shock wave lithotripsy for distal ureteric calculi. Endourol. News,4,15-17. Rassweiler, J., Henkel, T., Tschada, R. et d (1992). Interdisciplinary experience with the Lithognostkthe impact of optical, feedback-controlled stone detection in lasertripsy. J. Endourol., 6,233-237. Rassweiler, J., Kohrmam, U., Heine, G. et al. (1990a). Modulith SL 10/2kxperimental introduction and first clinical experience with a new interdisciplinary lithotripter. Eur. Urol., 18, 237-241. Rassweiler, J., Lutz, K., Gumpinger, R. et d (1986). Efficacy of in situ extracorporeal shock wave lithotripsy for upper ureteric calculi. Eur. Urol., 12, 377-386. Rassweiler, J., Schmidt, A., Gumpinger, R. et d (1990b). ESWL for ureteric calculi using the Dornier HM3, HM3 + and Wolf Piezolith 2200. J. Urol. (Paris), 96,149-155. Rassweiler, J., Westhauser, A., Bub, P. et d (1988). Second generation lithotripters : a comparative study. J. Endourol., 2, 192-203. Schmidt,A., Rassweiler,J., Gumpinger, R. et al. (1990). Minimally invasive treatmentofuretericcalculi using modern techniques. Br. J . Urol., 65,242-249. Simon, J., van den Bosshe, M. and Schulman, C. C. (1990). Shock wave treatment of ureteric stones in situ with secondgeneration lithotriptor. Eur. Urol., 17,200-202. Watson, G., Murray, S.,Dretler, S. P. et al. (1987). An assessment of the pulsed dye laser for fragmenting calculi in the pig ureter. J . Urol., 138, 199-202.
The Authors J . Rassweiler, MD, Chief Senior Registrar, Mannheim Hospital. T. 0. Henkel, MD, Registrar, Mannheim Hospital. A. D. Joyce, MD, Senior Registrar, King’s College Hospital. K. U. Kohrmann, MD, Registrar, Mannheim Hospital. Martha Manning, Medical Student, Mannheim Hospital. P. Alken, MD, Professor, Head of Department of Urology, Mannheim Hospital. Requests for reprints to: J. Rassweiler, Urologische Klinik, Klinikum Mannheim, Klinische Fakultat der Universitat Heidelberg, Theodor-Kutzer-Ufer, W-6800 Mannheim, Germany.
