title: The electromechanical impactor: a new device for intracorporeal stone fragmentation.
abstract: The Electromechanical Impactor was conceived as a safe and effective device for intracorporeal stone fragmentation. It is a 3 French EHL electrode enclosed within a stainless steel sheath. The interior is irrigated with saline. Discharge of the system causes an EHL spark which vaporizes saline and produces a cavitation bubble and subsequent shock wave. The shock wave propels a conical titanium tip forward for a distance of 2.7 mm with an impact pressure of 900 bar. Bench and animal testing has proven its effectiveness for stone fragmentation and safety for use within the ureter. The mean lifetime of each probe is approximately 700 pulses. It is used under direct vision through the straight operating port of a rigid or semi-rigid 9.5 French ureteroscope. Clinical studies at the Massachusetts General Hospital (reported herein) and the Mayo Clinic demonstrate approximately 90% efficacy. It is especially effective on cystine, calcium oxalate dihydrate, struvite and mixed calcium oxalate monohydrate calculi. Shiny-smooth black calcium oxalate monohydrate calculi will fragment but are more resistant. There has been no evidence of ureteral wall injury. The EMI is currently 5 French and is used both safely and effectively under direct vision of fragment ureteral calculi. Larger sizes are designed for percutaneous use and for bladder stone fragmentation.
authors.affiliation: Harvard Medical School, Boston.
authors.forename: S P
authors.initials: SP
authors.lastname: Dretler
mesh_terms: D004566:Electrodes; D004867:Equipment Design; D004869:Equipment Safety; D005069:Evaluation Studies as Topic; D006801:Humans; D008096:Lithotripsy / Q000295:instrumentation*; D014514:Ureteral Calculi / Q000628:therapy