His Bundle Pacing
When targeting the bundle of His either the C315His or the deflectable
C304-HIS delivery catheters are typically used. The S10 and C304-L69 can
also be used. There are two general methods for locating the His, sense
mapping and pace mapping. With either technique the lead is advanced
nearly to the end of delivery catheter without exposing the fixation
helix. When sense mapping, bipolar recordings from the lead are used to
locate the His deflection. Alternatively, if femoral access is in place
a standard multipolar catheter can be used to identify the location of
the His bundle. In our experience, pace mapping allows for more
efficient identification of the His bundle location. With this technique
the catheter is directed to the septal right ventricle just beyond the
tricuspid annulus and unipolar pacing from the lead tip at moderate
output (5V for 0.5ms) is performed. The catheter can then be manipulated
back to the tricuspid annulus until selective His capture (short stim to
QRS interval with QRS complex identical to conducted QRS, Figure 3) is
observed. The lead helix is then advanced just out of the catheter and
with 4-5 turns, affixed at this site. Obviously, a combination of these
techniques can be used as well.