Effect of modification of shock-wave delivery on stone fragmentation

Shock-wave lithotripsy has been the mainstay of urinary-stone treatment over the past 20 years, with three generations of lithotripters now in the market place. Little improvement, however, has been made in the overall efficiency, since the original Dornier HM3 lithotripter. Over the past 5 years much progress has been made in the basic research of shock-wave lithotripsy, with better understanding of the mechanisms involved in stone fragmentation. This progress has led to new modifications in the way shock-wave pulse is generated and delivered.

Clinical studies, reflecting improved understanding of basic mechanisms of stone comminution, are being published. Two recent prospective clinical trials have shown the higher efficiency of slow-rate compared with fast-rate shock-wave lithotripsy. A very practical solution requiring no hardware upgrade albeit at longer procedure times. Other promising developments include the use of twin-head technology, with either simultaneous or sequential shock waves. In addition, chemolytic pretreatment and dose-escalation techniques have shown early encouraging results. This review provides an update of the latest shock-wave technology and delivery strategies.

Long-term studies, to document anticipated improved safety with slow shock-wave rate, are needed. Future in-vivo and clinical studies of twin-head technology and dose-escalation strategy of shock-wave lithotripsy may initiate new lithotripter designs that will lead to improved stone-free rates, while simultaneously reducing associated renal trauma.