The artherosclerotic artery has been tested for its response to impact strength. The intima has very little impact strength and an external blow delivered by a dull blade held against the vessel severs the intima without injuring the other coats. The impact strength of the intima was measured. From these measurements, an instrument has been devised which imparts an impact of proper strength. This instrument is used in vascular surgery to transect the intima at either end in the operation of endarterectomy. The device has been successfully used in more than 150 operations. Since the intima is not detached on sectioning, the distal intima is not sutured to outer walls of the vessel. No complications have arisen by omitting the suture of the intima to the outer vessel wall.