Endocardial/Shallow Lead Fixation
For endocardial fixation of lumenless leads the delivery catheter is
directed to the desired chamber with the tip pointing toward the
targeted tissue. The lead is then advanced through the catheter and out
to make contact with the tissue, once contact is established the lead is
rotated clockwise to secure the fixation helix. The Medtronic 3830 lead
has a significantly smaller diameter and tip surface area than most
leads, which means that for a given amount of forward force applied the
tissue, pressure exerted is higher. With this in mind caution should be
taken to not extend the lead out of the delivery catheter if it is
firmly pressed against tissue, rather the delivery catheter should be
back from the endocardial surface within the targeted chamber and the
lead, with its flexible body, advanced to the tissue. The considerable
flexibility of the lead prevents significant forward force from being
applied to the tissue and reduces the risk of cardiac perforation. When
endocardial fixation is desired such as in the right atrial appendage, 4
to 5 clockwise rotations are sufficient to achieve tissue
anchoring[10]. Over-torquing the lead may well result in penetration
into and through the endocardium. The lead should be rotated with
careful attention to the header of the lead, observing the labels to
count the rotations, as the number of rotations cannot be assessed
fluoroscopically. Fixation can be assessed by introducing and
withdrawing lead slack while observing the stability of the lead tip
under fluoroscopy. Implantation related injury current should also be
present on the bipolar electrogram, See figure 2. If injury current is
not observed after initial placement, we suggest applying 1-2 more
clockwise rotations to the lead and reassessing; if there is still no
injury observed we will typically move the lead to a different position.
Once fixation is confirmed the delivery catheter is slit and the lead
can be anchored to the fascia.
When placing the lead in the right atrial appendage, endocardial or
shallow fixation is desired. Here we typically utilize the pre-formed J
shaped delivery catheter (C315J), which is directed to the mid right
atrium. We then apply clockwise torque to direct the curvature
anteriorly. The lead is advanced from the catheter superiorly to the
right atrial appendage when tissue contact is observed (either the lead
flexes slightly or the delivery catheter is pushed posteriorly). The
lead should not be advanced any further and should be affixed with 3-4
clockwise rotations. If the lead achieves tissue contact before the body
of the lead is out of the catheter, then the delivery catheter is likely
too high in the atrium directly opposed to tissue and should be
advanced. We do not recommend placemen of this lead on the atrial free
wall.