Active fixation cardiac lead
An active fixation cardiac electrode lead having a fixation helix movably placed in a housing at the electrode lead's distal end so as to be extended out of the housing's distal end and retraced into an inner space enclosed by the housing. The housing has a wall and a protrusion formed in the wall that protrudes into the inner space into interspaces between windings of the fixation helix. The protrusion causes an axial movement of the helix when the helix is rotated around its longitudinal axis. The protrusion is an integral part of the housing's wall which is bent or embossed to form the protrusion.
1. An active fixation cardiac electrode lead comprising:
an electrode lead;
a housing coupled with said electrode lead;
a fixation helix comprising windings movably placed in said housing at a distal end of said electrode lead so as to be extended out of said distal end of said housing and retraced into an inner space enclosed by said housing;
said housing having a wall and a protrusion fixed to said wall wherein said protrusion protrudes toward a centerline of said housing into said inner space wherein said protrusion further protrudes into interspaces between said windings of said fixation helix so as to cause an axial movement of said fixation helix with respect to said housing when said fixation helix is rotated around a longitudinal axis of said fixation helix defined by said centerline and wherein said housing does not rotate and wherein said housing remains unaffected by said axial movement of said helix;
said protrusion being an integral part of said wall of said housing; and,
wherein said protrusion in said inner space enclosed by said housing is situated radially inward toward said centerline with respect to an indentation on an outside of said wall wherein said indentation is also an integral part of said wall and is inward toward said centerline of said housing and not outward with respect to said wall of said housing.
2. The electrode lead according to claim 1 wherein said wall comprises a plurality of protrusions.
3. The electrode lead according to claim 2 , wherein said plurality of protrusions are arranged opposing each other with respect to a central, longitudinal axis of said housing of said electrode lead.
4. The electrode lead according to claim 2 wherein each protrusion selected from said plurality of protrusions is a section of a helical path around an inner wall of said housing forming a helical thread at an inner wall side of said housing matching a pitch of windings of said fixation helix and cover an angle of rotation of less than 120°.
5. The electrode lead according to claim 1 , wherein said protrusion is formed by a groove-like depression covering an angle of more than 180° around a central, longitudinal axis of said housing of said electrode lead, said groove-like depression stamped from an outside of said housing along a helical path around said housing forming a helical thread at an inner wall side of said housing matching a pitch of windings of said fixation helix.
6. The electrode lead according to claim 1 , wherein a single protrusion is formed by a bend-in a distal wall portion of said housing.
7. The electrode lead according to claim 6 , wherein said bend-in wall portion is defined by two axial slits cut into said housing parallel to a longitudinal axis starting from a distal edge of said housing.
8. The electrode lead according to claim 1 , wherein said housing is made of a ductile material.
9. The electrode lead according to claim 8 , wherein said ductile material is a metal.