Upgrade procedure
The 4.1F 3830 (SelectSecure, Medtronic, Minneapolis, MN) pacing lead was
delivered using the C315HIS (Medtronic, Minneapolis, MN) sheath. His
bundle electrograms were mapped in a unipolar configuration and recorded
on the recording system (Prucka Cardiolab, GE Healthcare, Waukesha, WI).
To locate the optimal site for the His bundle lead, the sheathes and
leads were delivered to the ventricular end for the distal HBP/LBBP, and
the pacing rate was decreased to 30 bpm for an escape rhythm. If no his
electrogram was observed, pace mapping was conducted to identify a site
with evidence for His bundle capture. His bundle pacing was acceptable
when capture threshold was lower than 2.0V/1.0ms.For the patients with
third-degree atrioventricular block (III°AVB) or ventricular pacing
dependent, right ventricular backup pacing was retained if threshold of
his bundle pacing is higher than 2.0v/0.5ms. LBBP would be further
performed when HBP failed.