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NCT Number: NCT07458724

Radiation-free Anatomical Direct Imaging Approach for No-fluoroscopy Cardiac Electrode Implantation

Permanent pacemaker implantation is traditionally performed under fluoroscopic (X-ray) guidance. Although effective, fluoroscopy exposes patients and medical staff to ionizing radiation. Transthoracic echocardiography (TTE) is a non-invasive ultrasound imaging technique that allows real-time visualization of cardiac structures without radiation exposure. However, its role in guiding permanent pacemaker implantation has not been systematically evaluated.

This study aims to assess the feasibility and safety of performing permanent pacemaker implantation under sole TTE guidance. In the first phase, eligible patients will undergo pacemaker implantation guided only by transthoracic echocardiography. In the second phase, outcomes of patients treated with TTE guidance will be compared with matched patients undergoing conventional fluoroscopy-guided implantation. The study will evaluate procedural success, lead positioning accuracy, electrical performance, complication rates, and elimination of radiation exposure. The overall goal is to determine whether a radiation-free imaging strategy can safely replace conventional fluoroscopic guidance in selected patients requiring pacemaker implantation.

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Key information

Conditions

Arrhythmia Arrhythmias, Cardiac Cardiovascular Diseases Heart Diseases Pathologic Processes Pathological Conditions, Signs and Symptoms

Age range

18 year–80 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

National Clinical Research Center for Cardiovascular Diseases, Fuwai Hospital, Chinese Academy of Medical Sciences

Beijing, 100037, China

About this study

Fluoroscopy-guided permanent pacemaker implantation has been the standard imaging strategy for decades. While fluoroscopy provides reliable projection-based visualization of lead advancement, it exposes patients and medical personnel to ionizing radiation and does not allow direct visualization of myocardial tissue contact or early structural complications. Increasing awareness of cumulative radiation exposure has led to the exploration of alternative imaging strategies in structural and electrophysiological interventions.

Transthoracic echocardiography (TTE) provides real-time, radiation-free visualization of cardiac chambers, septal structures, valvular anatomy, and the pericardial space. TTE has been successfully applied in selected structural heart procedures; however, its use in guiding permanent pacemaker implantation has not been systematically studied. The principal challenges of TTE-guided pacing include limited visualization of the entire lead shaft, difficulty in assessing three-dimensional orientation, and uncertainty regarding fixation mechanics. With procedural refinements and structured imaging protocols, these limitations may be overcome.

This study is designed to evaluate a radiation-free implantation strategy using sole transthoracic echocardiographic guidance. The first component prospectively assesses procedural feasibility and safety in consecutively enrolled patients. The second component compares outcomes of the TTE-guided cohort with a matched cohort undergoing conventional fluoroscopy-guided implantation. The same prospectively enrolled TTE cohort will serve both feasibility assessment and comparative analysis.

The central hypothesis is that TTE-guided pacemaker implantation can achieve high procedural success and acceptable electrical performance while eliminating radiation exposure and maintaining safety comparable to conventional fluoroscopic guidance. By leveraging direct septal visualization and continuous structural monitoring, this approach may provide mechanistic advantages in lead positioning accuracy and complication detection.

If validated, this strategy could represent an important step toward fully radiation-free electrophysiological and structural cardiac interventions.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Age ≥ 18 years
  • Indication for permanent pacemaker implantation according to current ESC or ACC/AHA guidelines
  • Adequate transthoracic echocardiographic acoustic window allowing visualization of right atrium, right ventricle, and interventricular septum
  • Ability to provide written informed consent

Exclusion criteria

  • Inadequate transthoracic acoustic window precluding reliable visualization of right-sided cardiac structures
  • Severe tricuspid regurgitation (moderate-to-severe or greater)
  • Left ventricular ejection fraction <35% without indication for cardiac resynchronization therapy
  • Documented malignant ventricular arrhythmia requiring implantable cardioverter-defibrillator as primary indication
  • Intrinsic heart rate <40 beats per minute with hemodynamic instability requiring emergent pacing
  • Active systemic infection
  • Pregnancy
  • Life expectancy less than 12 months due to non-cardiac comorbidities

Treatment and study plan

Permanent Pacemaker Implantation

Procedure

Permanent pacemaker implantation performed under sole transthoracic echocardiographic (TTE) guidance without the use of fluoroscopy. Venous access, lead advancement, positioning, and fixation are guided by real-time transthoracic imaging. Ventricular leads are positioned at the interventricular septum under direct echocardiographic visualization. In dual-chamber systems, atrial leads are positioned at the atrial septum due to limitations in visualizing the right atrial appendage under transthoracic imaging. Lead position, septal contact, and potential procedural complications (e.g., pericardial effusion, valvular interference) are continuously assessed using multi-plane echocardiographic views. Fluoroscopy is reserved only for bailout situations if adequate lead positioning cannot be achieved under TTE guidance.

Primary outcomes

  1. Procedural Feasibility and Success Rate

    Time frame: From initiation of vascular access to hospital discharge, assessed up to 5 days after the index procedure.

    Feasibility phase: Successful completion of permanent pacemaker implantation under sole transthoracic echocardiographic (TTE) guidance without fluoroscopic conversion and with acceptable acute electrical parameters (capture threshold ≤1.5 V at 0.4 ms, stable sensing amplitude, and lead impedance within manufacturer-recommended range).

    Comparative phase: Successful device implantation without major procedural complications and with acceptable acute electrical parameters.

Secondary outcomes

  1. Total Procedure Time

    Time frame: During the index procedure (single-day assessment at Day 0).

    Total procedure time measured from skin preparation to wound dressing completion.

  2. Lead Positioning Time

    Time frame: During the index procedure (single-day assessment at Day 0).

    Time required to achieve stable ventricular septal lead positioning and atrial septal lead positioning under imaging guidance.

  3. Radiation Exposure

    Time frame: During the index procedure (single-day assessment at Day 0).

    Total fluoroscopy time (minutes) and cumulative radiation dose (mGy). For the TTE-guided group, fluoroscopy time is expected to be zero unless bailout conversion is required.

  4. Acute Electrical Performance

    Time frame: Immediately post-implantation (Day 0, within 24 hours after device placement).

    Atrial and ventricular pacing thresholds, sensing amplitude, and lead impedance measured at implantation.

  5. Electrical Stability at 3 Months

    Time frame: Assessed at 3 months (±14 days) after implantation.

    Maintenance of acceptable pacing thresholds and absence of lead dislodgement.

  6. Major Procedural Complications

    Time frame: From the date of the index procedure until the first occurrence of a major procedural complication or completion of 12-month follow-up, whichever occurs first.

    Composite of cardiac perforation, pericardial tamponade, pneumothorax, major vascular injury, pocket hematoma requiring intervention, device infection, or procedure-related mortality.

  7. Structural Cardiac Impact

    Time frame: Assessed at discharge (≤5 days), 3 months (±14 days), 6 months (±30 days), and 12 months (±30 days) after implantation.

    New pericardial effusion or significant progression of tricuspid regurgitation assessed by transthoracic echocardiography.

Sponsors and collaborators

Lead sponsor

Chinese Academy of Medical Sciences, Fuwai Hospital

Other

Registry information

Official study title

Feasibility and Safety of Transthoracic Echocardiography-Guided Permanent Pacemaker Implantation Without Fluoroscopy

Acronym: RADIANCE

Important dates

Study start
2024
Primary completion
2025
Study completion
2026
First posted
Mar 9, 2026
Registry last updated
Mar 9, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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