Ultrasound Guided Leadless Pacemaker Implantation

The leadless pacemaker is a novel pacing technology that has emerged in recent years. Compared with conventional lead pacemakers, its design avoids many complications associated with leads and pacemaker pockets, including lead fracture, pocket infection, and venous access stenosis. Because of its small size and the absence of a pacemaker pocket or pacing lead, the leadless pacemaker is particularly suitable for patients with contraindications to conventional pacemaker implantation, including patients undergoing hemodialysis, patients with recurrent pocket infection, and patients without suitable vascular access. Currently, leadless pacemaker implantation is performed primarily under fluoroscopic guidance. Fluoroscopy provides real-time intraoperative anatomical localization information but places high demands on the operator's technical skills and the precise intraoperative positioning of the pacemaker. However, procedures performed under fluoroscopic guidance require dedicated procedure rooms and radiation-generating equipment. Such large-scale equipment is expensive, and it requires special protective measures that make the surrounding walls, doors and windows meet the protection standards, so as not to cause harm to the surrounding environment and personnel. When procedures are performed under fluoroscopic guidance in dedicated catheterization laboratories, both operators and patients are exposed to potential health risks, and fluoroscopy-guided procedures are contraindicated in some pregnant women. In addition, X-ray imaging remains two-dimensional, and visualization may be inadequate in some patients because of individual anatomical variation, potentially increasing procedural difficulty. Therefore, exploring a radiation-free, real-time, and accurate guidance method has become a key approach to improving the success rate and safety of leadless pacemaker implantation.

Inclusion Criteria: 1. Age ≥ 18 years, regardless of sex; 2. Patients with indications for permanent pacemaker implantation who are expected to have a low ventricular pacing burden, or patients who are expected to have a high ventricular pacing burden (≥40%) but have normal cardiac function, including complete or intermittent high-grade atrioventricular block, intermittent sinus arrest, and persistent sinus bradycardia (meeting the indications for implantation specified in the Chinese expert consensus on leadless pacemaker (2022)), particularly those with the following conditions: renal insufficiency, contraindications to X-ray radiation exposure, or potential adverse consequences from X-ray radiation exposure, as these patients are most likely to directly benefit from the ultrasound-guided procedure; 3. Patients who have signed informed consent form. Exclusion Criteria: 1. Those with significant chest wall deformity (e.g., severe pectus carinatum or barrel chest) or severe obesity affecting transthoracic echocardiography image quality; 2. Those with severe anatomical abnormalities of the right heart (e.g., an excessively small right ventricle, severe tricuspid regurgitation, Ebstein anomaly, or arrhythmogenic right ventricular cardiomyopathy); 3. Those with presence of any lead from an existing pacemaker, implantable cardioverter-defibrillator (ICD), or cardiac resynchronization therapy (CRT) device; 4. Those with presence of a mechanical tricuspid valve prosthesis, inferior vena cava filter, or left ventricular assist device (LVAD); 5. Those with known intolerance to nickel-titanium alloy (nitinol); 6. Those with concurrent active infection (e.g., bacteremia or infective endocarditis) or uncontrolled systemic infection; 7. Those with life expectancy \< 1 year; 8. Those who have recently undergone another interventional cardiac procedure that may interfere with the study results; 9. Those who are unable to complete study follow-up, such as cognitive impairment or extremely poor adherence.