Extracorporeal lithotripsy. Update on technology.

The development of shock-wave lithotripsy was a serendipitous event. Fortunately, the significance of this accidental discovery was not overlooked by the engineers at Dornier and their medical counterparts. There are many components that make up a lithotripter, but the heart of the lithotripter is its energy source. These machines often are categorized by the type of shock-wave generator used, and each type of generator has its own advantages and disadvantages. Unfortunately, no quantitative value of a shock-wave generator can be correlated to its qualitative effect. Interestingly, each type of energy source delivers its shock-wave energy with such distinctiveness that even the crater pattern it leaves in a stone is unique. New technology and ideas have transformed lithotripters in form and function so that they bear little resemblance to the original HM-1 prototype. Ongoing research is attempting to improve ESWL in several different ways, and advances in shock-wave generation, shock-wave measurement, and stone localization should result in even more efficient lithotripsy. The application of the time-reversal process to lithotripsy ultimately may enable lithotripters to track stones and electronically steer shock waves toward the target. Advances like these herald a time when ESWL, fortunately or unfortunately, will become automated completely.