A transvenous implantable medical device adapted for implantation in a body,
and
which is particularly adapted for use in a vessel such as the coronary sinus or
cardiac great vein. The implantable medical device may take the form of a lead
or catheter, and includes an extendable distal fixation member such as a helix.
In one embodiment, the fixation member is a helix constructed of a shape memory
metal or other super-elastic material. Upon deployment, the helix assumes a predetermined
helix shape larger than the diameter of the lead body diameter. The helix functions
to wedge or fix the lead within the vessel in a manner that does not impede the
flow of blood through the vessel. The helix may be retracted for ease of repositioning
and/or removal. In one embodiment of the invention, the fixation member may be
advanced using a stiffening member such as a stylet. In another embodiment, the
helix is coupled to a coiled conductor such that rotation of the conductor extends
or retracts the helix. According to yet another aspect of the invention, a helix
lumen including a flexible fluid-tight seal may be utilized to house the helix
when it is in the retracted position.
