Shock wave lithotripsy in the year 2012

Abstract

The introduction of new lithotripters increased problems of shock wave application. Recent studies concerning mechanisms of stone disintegration, shock wave focussing, coupling and application have appeared that may address some of these problems. Moreover, manufacturers have introduced new devices with significant modifications.The theory of dynamic squeezing offers new insight in stone fragmentation. Manufacturers have modified sources to either enlarge focal zone or offer different focal sizes. Efficacy of ESWL can be increased by lowering the pulse rate to 60-80 SW/min and by ramping the SW energy. With the water cushion, quality of coupling has become a critical factor depending on amount, viscosity and temperature of coupling gel. Fluoroscopy time can be reduced by automated localization or the use of optical and acoustic tracking systems.The trend of more pre-ESWL auxiliary measures has stopped due to increased use of alternative endourological procedures. The rate of ureteral stones is still high (18-41%), representing a stable figure. Re-treatment rate varies considerably from 6% to 49% between the different devices. Electro-hydraulic systems offer lower re-ESWL rates (6-21%) compared to electromagnetic (11-49%) and piezoelectric (20-45%). Three-month stone-free rates vary between 64% and 89%. However, it has been also shown that the experience of the operator with the device plays an important role on the outcome. The best EQmodreported was 0.69 using an electromagnetic device at a very experienced centre, whereas it usually ranges between 0.49 and 0.60. This means that maximally 50-60% of the patients can be treated successfully by a single in situ session of ESWL. The existing literature does not support the dogma that the Dornier HM3 is still by far the best device in the world.