This is a prospective clinical observation and registration study. The investigator aimed to evaluate the efficacy and safety of cardiac denervation ablation as a treatment strategy for severe sinus bradycardia.

Severe sinus bradycardia (SSB) is a common clinical condition that can lead to symptoms such as dizziness, fainting, and even cardiac arrest, posing a serious threat to patients' health and life. The causes of SSB vary: in elderly patients, SSB is often caused by ischemia and degenerative changes in the sinoatrial node, while in younger patients, it is often due to abnormal elevation of vagal nerve tone resulting in slowed heart rate and weakened myocardial contractility. Although implanting a pacemaker can effectively alleviate SSB bradycardia, the incidence of pacemaker electrode-related complications (such as electrode displacement, insulation layer rupture, lead infection, and fracture) is not low. Moreover, the impact of pacemaker implantation on patients' quality of life and the economic burden of regular pacemaker battery replacement impose significant psychological and financial burdens on patients, especially young patients. Clearly, for young SSB patients, if the abnormally elevated vagal nerve tone can be continuously reduced, it would be more effective in treating bradycardia and avoiding pacemaker implantation, which has significant social and economic value.

The investigators has pioneered the technique of cardiac denervation ablation, which can modulate the autonomic nervous tone of the heart and is used to treat autonomic nervous system-related diseases. In a preliminary exploratory study involving 6 SSB patients, investigators found that cardiac denervation ablation for SSB can reduce vagal nerve tone, increase sinus heart rate, and effectively alleviate bradycardia symptoms, thus avoiding the need for pacemaker implantation.

Therefore, based on the preliminary work, this project aims to conduct a prospective observational study and establish a registry. SSB patients who meet the indications for pacemaker implantation will be selected to evaluate the efficacy and safety of cardiac denervation ablation for SSB, its impact on quality of life, and the effectiveness of avoiding pacemaker implantation. The project will establish standardized surgical strategies and protocols for cardiac denervation ablation for SSB, summarize experiences, and lay the foundation for the clinical promotion and guideline revision of catheter ablation for SSB.

Inclusion Criteria:

1. Sinus bradycardia and pacemaker implantation indication: long interval with mean heart rate <45 bpm or 3s recorded within 6 months before inclusion;
2. Negative atropine test: sinus heart rate> 90bpm after atropine injection
3. SSB related symptoms: dizziness, palpitations, fatigue, amaurosis, syncope, etc.
4. Age ≥18 and <60 years old;
5. The patient has agreed to participate in this trial and has signed the informed consent form.

Exclusion Criteria:

1. Previous history of atrial arrhythmia ablation or surgical procedure;
2. Structural heart disease, chronic liver and kidney dysfunction, diabetes mellitus, neurological diseases.;
3. Drug-related SSB;
4. presence of left atrial thrombus;
5. Pregnant women.

SSB patients undergoing cardiac denervation ablation