Electrohydraulic lithotripsy (EHL) was the first form of contact lithotripsy developed. EHL can fragment urinary calculi of all compositions but it has the narrowest margin of safety. Injuries to structures surrounding a stone occur when the probe discharges too close to the tissues.
Electrohydraulic lithotripsy, the first technique used for intracorporeal stone fragmentation, utilizes a probe containing two electrodes separated by an area of insulation. While electric current is passed between two electrodes, a spark is created which vaporizes the water or other surrounding fluids at the end of the probe. This spark gap creates a cavitation bubble, which rapidly expands, creating a shock wave. Once the cavitation bubble collapses a secondary pressure wave is created which is then transmitted to the adjacent stone. At the stone-water interface, the difference in acoustic impedance causes energy to be released, resulting in stone fragmentation. This process is exactly similar to shock wave lithotripsy in generating a spark gap, however, the difference in EHL is that the shock wave is not focused, so the stone must be placed where the shock wave is generated (the "F1" point).
Advantages of EHL
Disadvantages of EHL
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