Transjugular Approach for Implantation of Active Fixation Leadless Pacemakers

Inclusion Criteria: 1. Aged 18 to 85 years, regardless of gender. 2. Symptomatic bradyarrhythmia meeting the ventricular pacing indications recommended by the 2023 ACC/AHA/HRS Guideline for the Evaluation and Management of Bradyarrhythmias, the 2020 Chinese Expert Consensus on the Evaluation and Management of Patients with Bradycardia and Conduction Disorders, and the 2022 Chinese Expert Consensus on the Clinical Application of Leadless Pacemakers, including any of the following conditions: * Third-degree or advanced atrioventricular (AV) block; * Second-degree type II AV block, alternating bundle branch block, or bifascicular/trifascicular block with intermittent advanced/third-degree AV block; * Adult congenital complete AV block; persistent irreversible advanced/third-degree AV block following myocardial infarction or cardiac surgery; * Symptomatic bradycardia (e.g., dizziness, presyncope, syncope, fatigue, decreased exercise tolerance) or sick sinus syndrome (including chronotropic incompetence and tachy-brady syndrome); * Drug-induced persistent symptomatic bradycardia with no alternative treatment options; * Atrial fibrillation with slow ventricular response requiring long-term ventricular pacing; * New-onset persistent complete left bundle branch block after TAVR, or new-onset advanced AV block after hypertrophic cardiomyopathy ablation; * Neuromuscular disease, infiltrative cardiomyopathy, or adult congenital heart disease with progressive AV/branch conduction abnormalities and bradycardia-related symptoms; * High infection risk populations (e.g., recurrent pacing system infection, diabetes mellitus, long-term corticosteroid use, end-stage renal disease on dialysis) or patients with abnormal conventional pacing access or at extremely high risk of conventional pacing lead complications. 3. Anatomical feasibility and vascular access assessment: * Preoperative imaging confirms suitable right internal jugular vein access to accommodate the delivery sheath, without thrombosis, severe stenosis, or anatomical malformations; * Right ventricular anatomy is suitable with adequate trabeculation to support active fixation of the leadless pacemaker, without severe structural abnormalities; * Priority for enrollment: patients with limited femoral or inferior vena cava access (e.g., iliac/inferior vena cava stenosis, thrombosis, prior venous surgery, obesity precluding femoral access). 4. New York Heart Association (NYHA) functional class ≤ III, and expected survival \> 1 year. 5. Able to cooperate with preoperative evaluation, intraoperative procedure, and 3-month follow-up. 6. Voluntarily signs written informed consent and agrees to complete all scheduled observations per the study protocol. Exclusion Criteria: 1. Anatomical malformations, severe stenosis, occlusion, or thrombosis of the internal jugular vein or superior vena cava that preclude transjugular access for the procedure. 2. Abnormal right ventricular anatomy, including but not limited to right ventricular hypoplasia, severe right ventricular dilation, or severe right ventricular myocardial fibrosis, preventing safe implantation of an active-fixation leadless ventricular pacemaker. 3. Severe tricuspid regurgitation, or status post-mechanical tricuspid valve replacement, significantly affecting pacemaker implantation, device fixation, or function. 4. NYHA functional class IV, or refractory heart failure, cardiogenic shock, rendering the patient unable to tolerate the procedure and perioperative management. 5. Severe hepatic or renal impairment (eGFR \< 30 mL/min/1.73m², severe liver dysfunction), coagulopathy, or active bleeding disorders constituting clear surgical contraindications. 6. Confirmed allergy or severe intolerance to leadless pacemaker materials, intraoperative contrast media, or anesthetic agents. 7. Prior implantation of other cardiovascular implantable electronic devices (e.g., pacemaker, ICD, CRT) or retained intracardiac leads/devices that would interfere with the current implantation or device function. 8. Advanced malignancy, severe active infection, active autoimmune disease, or other serious systemic conditions with an expected survival \< 12 months, precluding completion of the 3-month follow-up. 9. Pregnant or lactating women, or women planning pregnancy during the follow-up period. 10. Psychiatric disorders, cognitive impairment, or inability to cooperate with preoperative evaluation, intraoperative procedure, or regular postoperative follow-up due to personal or geographic reasons. 11. Concurrent participation in another cardiovascular device clinical trial that may interfere with the outcome assessment of this study. 12. Any other condition deemed by the investigator to make the participant unsuitable for enrollment.