A flexible tubular drive shaft for a medical device comprising: an elongated tubular body having an opening extending along a longitudinal axis from a proximal end and a distal end. The elongated tubular body includes a proximal portion having a first rigid section and a first flexible section; a middle portion having a second rigid section; and a distal portion having a second flexible section. The first rigid section is configured to couple the tubular drive shaft to a torque input apparatus to transfer torque to the distal end of the tubular body. The first flexible section is configured to minimize torsion of the tubular body between the first rigid section and the second rigid section, and the second flexible section is configured to increase flexibility of the distal portion of the tubular body.