A deflectable introducer sheath assembly comprising: a tubular sheath member having a proximal end portion including a proximal end, a distal end portion terminating in a distal tip, and an internal sheath lumen extending through the proximal and distal end portions of the sheath member; a handle assembly coupled to the proximal end portion of the sheath member, the handle assembly including an outer housing, a control knob axially rotatable relative to the outer housing, a drive shaft within the outer housing and rotatable with the control knob relative to the outer housing, a shuttle assembly disposed about and operably engaged with the drive shaft such that rotation of the control knob and drive shaft relative to the outer housing causes axial translation of the shuttle assembly relative to the drive shaft within the outer housing, an inner housing within the outer housing enclosing the shuttle assembly, and a pulley assembly located proximal to the drive shaft and the shuttle assembly within the inner housing, the pulley assembly including: a pulley support member having a first side and an opposite second side; a first pulley shaft extending laterally from the first side of the pulley support member; a first pulley wheel mounted on the first pulley shaft; a second pulley shaft extending laterally from the second side of the pulley support member; and a second pulley wheel mounted on the second pulley shaft; a first pull wire having a distal end portion connected to the sheath member proximate the distal tip thereof, and a proximal end portion extending into the handle assembly, the proximal end portion of the first pull wire extending around and supported by the first pulley wheel and operably coupled to the shuttle assembly; and a second pull wire having a distal end portion connected to the sheath member proximate the distal tip thereof, and a proximal end portion extending into the handle assembly, the proximal end portion of the second pull wire extending around and supported by the second pulley wheel and operably coupled to the shuttle assembly, wherein axial rotation of the control knob in a first direction of rotation causes the shuttle assembly to translate proximally relative to the sheath member and thereby apply tension to the distal end portion of the first pull wire to deflect the distal end portion of the sheath member in a first direction of deflection, and wherein axial rotation of the control knob in a second direction of rotation opposite the first direction of rotation causes the shuttle assembly to translate distally relative to the sheath member and thereby apply tension to the distal end portion of the second pull wire to deflect the distal end portion of the sheath member in a second direction of deflection to provide bi-directional deflectability in the sheath member. a tubular sheath member having a proximal end portion including a proximal end, a distal end portion terminating in a distal tip, and an internal sheath lumen extending through the proximal and distal end portions of the sheath member; a handle assembly coupled to the proximal end portion of the sheath member, the handle assembly including an outer housing, a control knob axially rotatable relative to the outer housing, a drive shaft within the outer housing and rotatable with the control knob relative to the outer housing, a shuttle assembly disposed about and operably engaged with the drive shaft such that rotation of the control knob and drive shaft relative to the outer housing causes axial translation of the shuttle assembly relative to the drive shaft within the outer housing, an inner housing within the outer housing enclosing the shuttle assembly, and a pulley assembly located proximal to the drive shaft and the shuttle assembly within the inner housing, the pulley assembly including: a pulley support member having a first side and an opposite second side; a first pulley shaft extending laterally from the first side of the pulley support member; a first pulley wheel mounted on the first pulley shaft; a second pulley shaft extending laterally from the second side of the pulley support member; and a second pulley wheel mounted on the second pulley shaft; a first pull wire having a distal end portion connected to the sheath member proximate the distal tip thereof, and a proximal end portion extending into the handle assembly, the proximal end portion of the first pull wire extending around and supported by the first pulley wheel and operably coupled to the shuttle assembly; and a second pull wire having a distal end portion connected to the sheath member proximate the distal tip thereof, and a proximal end portion extending into the handle assembly, the proximal end portion of the second pull wire extending around and supported by the second pulley wheel and operably coupled to the shuttle assembly, wherein axial rotation of the control knob in a first direction of rotation causes the shuttle assembly to translate proximally relative to the sheath member and thereby apply tension to the distal end portion of the first pull wire to deflect the distal end portion of the sheath member in a first direction of deflection, and wherein axial rotation of the control knob in a second direction of rotation opposite the first direction of rotation causes the shuttle assembly to translate distally relative to the sheath member and thereby apply tension to the distal end portion of the second pull wire to deflect the distal end portion of the sheath member in a second direction of deflection to provide bi-directional deflectability in the sheath member.