This is a multicenter, prospective, observational study ,the aim of this study is to find factors affecting selection of double-chamber leadless pacemaker in patients with atrioventricular block and ambulatory atrioventricular synchronous pacing status over time using a leadless ventricular pacemaker.

Traditional pacemakers consist of a pulse generator and leads. Infections of the pulse generator pocket and lead-related complications are unavoidable issues in the application oftraditional pacemakers.Leadless pacemakers have emerged to address complications associated with the pacemaker pocket and leads in specific patients.The initial design of leadless pacemakers focused on single-chamber (right ventricular)sensing and pacing,However, patients with sinus rhythm may experience pacemakersyndrome symptoms due to atrioventricular desynchrony. Furthermore, a high proportion of atrioventricular dyssynchronous ventricular pacing might increase hospitalization rates for atrial fibrillation and heart failure.Recent developments in leadless dual-chamber pacemakersutilize a built-in triaxial accelerometer.This study aims to investigate factors considered by patients with atrioventricular block and clinical pacemaker implanting physicians when make sure the use of Micra AV. 2). It also seeks to evaluate the atrioventricular synchrony of Micra AV pacing in patients during both exercise and rest, while analyzing factors that influence the AV synchrony.For all screened patients, a questionnaire is required to be finished with data including age, gender, occupation, educational level, clinical history, comorbidities, previous infections, history of implanted electronic devices, economic status, and medical insurance conditions. At same time, all physicians are asked to complete a questionnaire for analyzing the factors influencing the decision of device option.An ambulatory electrocardiogram will be performed at 3 months, 6 months, and 1 year follow-up after device implantation. Data regarding the proportion of atrioventricular Research Protocol Template (Observational Study)_V1.0_2023.10.04 7/10 synchrony, atrial sensing atrial contraction mechanical wave (A4) threshold, ventricular pacing threshold, sensing, and impedance will be tested and collected. Postoperative exercise related symptoms and adverse events will be routinely tracked.

Inclusion Criteria:

1. Patients diagnosed with atrioventricular conduction block, meeting the indications for dual-chamber leadless pacemakers as per the "Chinese Expert Consensus on Clinical Application of Leadless Pacemakers (2022)".
2. Age ≥18 years.
3. Expected lifespan ≥1 year.
4. Consent to sign an informed consent form and cooperate in the collection of baseline data and subsequent follow-ups

Exclusion Criteria:

1. Patients anticipated to have a high ventricular pacing proportion (>40%) and with left ventricular ejection fraction less than 50%.
2. Patients with persistent atrial fibrillation and a high expected ventricular pacing proportion.
3. Post-tricuspid valve mechanical valve replacement surgery.
4. Patients with inferior vena cava pathway anomalies, precluding passage of the leadless pacemaker's delivery sheath.
5. Patients with an expected lifespan of less than 1 year. 6 Patients who are pregnant, planning pregnancy, or undergoing cardiac transplantation.

Patients diagnosed with atrioventricular conduction block, meeting the indications for dual-chamber leadless pacemakers as per the "Chinese Expert Consensus on Clinical Application of Leadless Pacemakers (2022)".All patients should sign written informed consent for agreement of the implantation procedure.