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.