The aim of this study is to evaluate mechanical and electrical cardiac dyssynchrony in patients with pacemakers and the right ventricular electrode implanted in His Bundle area.

Permanent His Bundle Pacing (HBP) is a well-known method of cardiac pacing which is increasingly used in everyday practice. After lead implantation in His Bundle area (HBA) capture of various tissues can be achieved: A. right ventricular myocardium near to HBP; B. cardiac conduction system selectively or nonselectively (with concomitant regional myocardium activation). The different excitability and refractory periods decide which tissue, myocardium or/and the conduction system is effectively paced. A lot of clinical trials revealed the advantage of HBP over apical ventricular pacing (AVP). HBP improves clinical (NYHA, quality of life, hospitalization rate) and echocardiographic (left ventricular dimension and ejection fraction) indicators of heart failure.

We are going to compare mechanical and electrical synchrony during the various type of myocardium activation: HBP (nsHBP or sHBP), RV pacing near HBA and native heart rhythm (if possible) in each patient recruited to the study. Adequate pacemaker programming will allow achieving different activations as shown above. The mechanical synchrony will be estimated by transthoracic echocardiography and the electrical one by the detailed analysis of ECG.

Inclusion Criteria:

• all adult patients after implantation of pacemaker system with pacing lead successfully captured His Bundle (selectively or/and nonselectively)

Exclusion Criteria:

• not willing or incapable to give written informed consent;
• previous implanted cardiac electronic device (pacemaker, implantable cardioverter-defibrillator, cardiac resynchronization therapy device)

Patients with bradyarrhythmia and indications for de novo permanent pacemaker implantation. The decision for pacing lead placement in His Bundle is left for physician discretion. Patients after pacemaker system implantation with His Bundle successfully pacing are to be asked to participate in the study. After having written informed consent obtained patients are to be scheduled for ventricular synchrony evaluation with ECHO and ECG after 3-6 months after implant (mid-term) and after 12 months (long-term).