US Patent 8992506 Microcatheter

A microcatheter comprises a coil formed over an inner liner. The coil is covered with a series of outer jacket segments that decrease in durometer relative to proximally adjacent segments. Preferably, these segments have angled ends that allow each segment to be inserted and bonded into the segment prior to it. The outer jacket ultimately terminates at a distal of the microcatheter with the segment having the lowest durometer.