Since Chaussy et al.
] reported the application of ESWL with an HM-3 lithotriptor manufactured by Dornier Co., Ltd. in clinical practice in the 1980 s, various models of ESWL equipment have been developed and improved. Shock wave generators have been developed, starting with the underwater spark gap type, followed by the electromagnetic conversion type and the piezoelectric element type. ESWL is now the first-line treatment for upper urinary tract stones.
Our hospital introduced the Sonolith vision (manufactured by EDAP) on March 1, 2004. This model belongs to third generation ESWL equipment. It uses electrical conduction electrodes as the shock wave generator, which generates shock waves in a highly electrical-conductive fluid. It provides accurate electrical discharge with high reproducibility, thus producing stable and constant energy. The use of a hydrophone pressure detector allows real-time display of the effective pressure of shock waves on a monitor. The generator is a shallow oval shape, and the output power can be adjusted to 100 different levels. The diameter of the shock-wave head is as large as 22 cm, and the consumptive electrodes can be used in four to five patients. This equipment has a focal depth of 130 mm and a focal size of 3 × 28 mm. The focal point is adjusted using an X-ray C-arm.
In 226 Japanese cases with renal or ureteral stones who were treated with ESWL in our hospital, the stone-free rate was 85.4% and the efficacy rate was 88.9%, showing similar results to those obtained by other researchers [2
]. (Table ).
With regard to lower ureteral stones, Hochreiter et al.
] treated distal ureteral stones with the HM-3 lithotriptor manufactured by Dornier in 518 patients, and reported a stone-free rate of 97.3% and efficacy rate of 99.4%. Park et al.
], however, reported that the stone-free rate was 55.6% for lower ureteral stones of 10 mm or larger. Pardalidis et al.
] also reported that treatment was not so effective, with a stone-free rate of 84.6%. Ghalayini et al.
] compared laser TUL with ESWL, and reported that laser TUL was significantly more effective than ESWL, with a stone-free rate of 97.5% vs. 81.5% three months after operation. Wu et al.
] compared holmium yttrium-aluminum-garnet (YAG) laser TUL with ESWL in patients with upper ureteral stones, and reported that there was no significant difference in the treatment effect on stones 10 mm or smaller, with a stone-free rate of 91.1% for TUL vs. 85.3% for ESWL, while there was a significant difference in the treatment effect on stones 10 mm or larger, with a stone-free rate of 76.8% for TUL vs. 35.2% for ESWL. They stated that laser TUL was superior to ESWL for the treatment of stones 10 mm or larger. In our study, however, all subjects with stones 10 mm or larger achieved a stone-free status. This may be attributable to our new measures: we usually place patients in the contralateral prone position to potentiate the treatment effect on lower ureteral stones, in accordance with the report by Köse et al.
], and before ultrasonography we also apply jelly in a thin layer to the skin surface and to the area on the treatment table around the spot in contact with the skin to avoid exposure to air, thereby reducing minute air bubbles generated from the skin surface and minimizing attenuation of shock waves. ESWL seems to be an effective first-line treatment also in subjects who have lower ureteral stones 10 mm or larger but do not wish to undergo TUL, but it is sometimes difficult to treat stones greater than 10 mm by ESWL monotherapy. So, it is necessary to perform ESWL and TUL combination therapy. In contrast, these subjects with X-ray-negative stones underwent intravenous pyelography (IVP) and ureteral catheter insertion in combination with ESWL. These patients of ours had a stone-free status with only ESWL therapy.
Madbouly et al.
] recently reported that the treatment effect of ESWL with the Lithostar Multiline performed under general anesthesia was significantly greater when shock waves were delivered at a slow rate (60/min) than at a rapid rate (120/min), with an efficacy rate of 98.7% vs. 90.0%. Pace et al.
] and Peterson et al.
] also reported similar results. Thus, ESWL treatment should be performed at a slow rate in the future.
Complications of ESWL include renal subcapsular hematoma, the incidence of which has been reported to be between 0.078% and 0.6% [1
], and has also been reported to increase up to 32% as a result of performance of postoperative routine CT and MRI [17
]. Risk factors for renal subcapsular hematoma are reported to be 1) hypertension, 2) coagulopathy, and 3) previous ESWL therapy [18
]. In our study, renal subcapsular hematoma occurred in one subject. This subject had a history of hypertension, which may have caused this complication.