Fundamental mechanisms and pitfalls of scissors-type ultrasonically activated devices

In an ultrasonically activated device, electric energy is transformed to mechanical vibration, which is transmitted to the device's tip. By clamping the vessel between the tissue pad and vibrating blade, frictional heat is generated. This heat, significantly milder than that in electrocautery technique, is ideal for sealing the vessel. The ultrasonic vibration eventually divides the vessel. In the experimental studies, the cut end of medium-sized vessels divided by a scissor type ultrasonically activated device (USAD) withstood high intravascular pressure. However, our clinical experiences with the USADs suggest there are pitfalls including: - giving excessive tension to the vessel, - incomplete clamping of the vessel, - contacting the adjacent vessel with the back side of the active blade tip, - contacting the adjacent vessel with the blade tip. Some devices are described to prevent these pitfalls. (C) 2000 Editions scientifiques et medicales Elsevier SAS.