A balloon assist device is disclosed which includes an inner body and a balloon bonded to the inner body. The inner body extends along an axis from a proximal end to a distal end and the cross-section of the inner body partially encloses the axis. The balloon assist device also includes an inflation tube in sealed communication with the volume enclosed by the inner body and the sheath. The balloon assist device may also include a pusher for sliding the balloon assist device along the catheter. The pusher may extend parallel to the axis from the proximal end of the balloon assist device in a proximal direction. The inflation tube may also be used as a pusher. The inner body of the balloon assist device may be a split cylinder extending along the axis from the proximal end to the distal end.
