A catheter assembly comprises a catheter shaft having a proximal region a distal region and a rotational seal therebetween. The rotational seal comprises a first component fixedly engaged to the proximal region and a second component fixedly engaged to the distal region. The components engaged in an overlapping arrangement. The rotational seal is actuatable between a non-activated and activated states. In the non-activated state the first component and the second component are separated by a gap which provides for the distal region of the catheter shaft to be rotatable relative to the proximal region. In the activated state at least a portion of the first component and the second component being sealingly engaged together such that distal region is made static relative to the proximal region.