Braided hemostasis shaft for improved torsional response

A medical insertion device, comprising:

• a handle including an actuator;
• and
• an elongated shaft extending between a proximal end coupled to the handle to a distal end, the shaft having flexibility sufficient for insertion through a working channel of an endoscope along a tortuous path, the shaft including and being coupled to the actuator so that actuation of the actuator rotates the shaft about a longitudinal axis thereof,
• wherein the shaft includes a coil extending from the proximal end of the shaft to the distal end of the shaft and having a channel extending longitudinally therethrough, the coil defining valleys between adjacent turns of the coil forming the shaft and peaks centered over the turns of the coil,
• wherein the shaft further includes a braided portion extending around a portion of the coil, the braided portion including a plurality of lines wound together such that first and second ones of the lines intersect at crossings to enclose a predetermined angle therebetween, the angle being at least 25 degrees and less than 50 degrees, and
• wherein each of the first and second ones of the lines includes at least one filament, a diameter of the filaments of the first one of the lines being different from a diameter of the filaments of the second one of the lines, a braid pattern of the braided portion being selected so that a first portion of the crossings are positioned within the valleys of the coil, while a second portion of the crossings are positioned at the peaks of the coil.