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

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

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.

Study Overview

• Status: Completed
• Conditions: Arrhythmia
• Intervention / Treatment: Procedure: Permanent Pacemaker Implantation

Detailed Description

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.

• Study Type: Interventional
• Enrollment (Actual): 31
• Phase: Not Applicable

Contacts and Locations

Study Locations

• China
  • Beijing, China, 100037
    • National Clinical Research Center for Cardiovascular Diseases, Fuwai Hospital, Chinese Academy of Medical Sciences

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

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

Exclusion Criteria:

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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

Experimental: TTE-guided arm; Transthoracic Echocardiography-Guided Pacemaker Implantation

Procedure: Permanent Pacemaker Implantation; 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.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Procedural Feasibility and Success Rate	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.	From initiation of vascular access to hospital discharge, assessed up to 5 days after the index procedure.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Total Procedure Time	Total procedure time measured from skin preparation to wound dressing completion.	During the index procedure (single-day assessment at Day 0).
Lead Positioning Time	Time required to achieve stable ventricular septal lead positioning and atrial septal lead positioning under imaging guidance.	During the index procedure (single-day assessment at Day 0).
Radiation Exposure	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.	During the index procedure (single-day assessment at Day 0).
Acute Electrical Performance	Atrial and ventricular pacing thresholds, sensing amplitude, and lead impedance measured at implantation.	Immediately post-implantation (Day 0, within 24 hours after device placement).
Electrical Stability at 3 Months	Maintenance of acceptable pacing thresholds and absence of lead dislodgement.	Assessed at 3 months (±14 days) after implantation.
Major Procedural Complications	Composite of cardiac perforation, pericardial tamponade, pneumothorax, major vascular injury, pocket hematoma requiring intervention, device infection, or procedure-related mortality.	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.
Structural Cardiac Impact	New pericardial effusion or significant progression of tricuspid regurgitation assessed by transthoracic echocardiography.	Assessed at discharge (≤5 days), 3 months (±14 days), 6 months (±30 days), and 12 months (±30 days) after implantation.

Collaborators and Investigators

• Sponsor: Chinese Academy of Medical Sciences, Fuwai Hospital
• Investigators: Study Chair: Xiangbin Pan, MD, PhD, National Center for Cardiovascular Disease, China & Fuwai Hospital

Study record dates

Study Major Dates

• Study Start (Actual): September 1, 2024
• Primary Completion (Actual): September 1, 2025
• Study Completion (Actual): February 1, 2026

Study Registration Dates

• First Submitted: February 25, 2026
• First Submitted That Met QC Criteria: March 4, 2026
• First Posted (Actual): March 9, 2026

Study Record Updates

• Last Update Posted (Actual): March 9, 2026
• Last Update Submitted That Met QC Criteria: March 4, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Keywords: arrhythmia
• Additional Relevant MeSH Terms: Cardiovascular Diseases; Pathologic Processes; Heart Diseases; Pathological Conditions, Signs and Symptoms; Arrhythmias, Cardiac
• Other Study ID Numbers: 2025-2617; BRWEP2024W014030105 (Other Grant/Funding Number: Beijing Research Ward Excellence Program, BRWEP)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Individual participant data (IPD) will not be shared due to institutional data protection policies and the relatively small sample size, which may increase the risk of participant re-identification. De-identified aggregate data will be reported in peer-reviewed publications.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: Yes
• product manufactured in and exported from the U.S.: Yes