**5.3 Lead fixation**

Lead instability is another problem for HBP, which increases the probability of lead dislocation in the post-operational period despite the active lead fixation type [4, 8, 23, 27]. According to the data from Geisinger Institute, 4.2% of patients required lead correction after performing HBP [7].

#### **5.4 Summary**

Summing up data of HBP in patients with indications for CRT, it becomes possible to conclude that HBP leads to adequate cardiac resynchronization in 70–92% of cases, resulting in shortening of QRS complex compared to BVP and decreasing required time for the procedure.

Even though the solid theoretical background and practical applicability among experienced physicians, HBP cannot fully replace conventional BVP nowadays. HBP limitations include higher pacing thresholds, lower R-wave amplitude, and probable difficulties with ventricular signal sensing. On the other hand, there is also a possibility of hypersensitivity to far-field P-waves signals. Lead instability in continuous pacing is another point of concern, along with long-term effects of HBP because of potentially damaging influence on the distal structures of the His–Purkinje system.

Data from upcoming randomized clinical trials may remove the ambiguity in HBP [30, 32]. There is also a need for direct comparison of HBP to RV pacing and conventional multifocal BVP. Additional research may answer further questions regarding HBP complications and mechanisms of non-selective HBP. Could nonselective HBP be treated as an alternative to selective HBP? And what problems may arise during lead extraction?

Much work remains to be done with conducting thoroughly planned randomized clinical trials that will evaluate the potential of HBP in cardiac pacing.
