PacemakerNCT07094217
Fluoroless Conduction System Implant
An observational study of Pacemaker and Conduction System Pacing, run by Imperial College London.
Trial summary
Conduction system pacing is a new way of stimulating the heart using pacemaker wires. Traditional pacemakers stimulate the heart muscle which causes disordered heart beats: the walls of the heart move at different times. This wears down the heart over time. Read more about this study
- Who is it for?
- Ages 18 to 100 years
- Conditions the study is for
- Pacemaker, Conduction System Pacing
- How many people
- 75 participants
- Where
- No sites listed yet
- Study dates
- 30 Jul 2025to 30 Jul 2026
- Phase
- Observational
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 100 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Study population: The study population will consist of patients referred for a cardiac pacemaker at Imperial College Healthcare Trust.
Who may be able to join
- Patients with a ventricular pacing indication: high grade atrioventricular block and symptomatic trifasicular, bifasicular block or left bundle branch block LBBB for cardiac resynchronisation therapy
- Adults willing to take part (ages 18 - 100 years old)
- Able to give consent.
Who cannot join
- Unable to give consent
- Children age < 18 years and adults > 100 years old
- Pregnant patients • As per standard of care, female patients of child-bearing age will have a urine pregnancy test prior to their procedure.
Trial locations and contacts
No sites are listed yet. Contact the study team or a site near you to ask about taking part.
About this study
Conduction system pacing is a new way of stimulating the heart using pacemaker wires. Traditional pacemakers stimulate the heart muscle which causes disordered heart beats: the walls of the heart move at different times. This wears down the heart over time.
Conduction system pacemakers stimulate the heart's electrical system directly producing natural heart beats that are much less disordered. These pacemakers can be challenging to insert with different heart shapes, sizes and scars. This can increase procedure times and time exposed to xray as pacemakers are inserted using x-rays to guide where the lead is implanted.
Read more
This study aims to allow conduction system pacemakers to be implanted without the use of normal xray (fluoroscopy).
The investigators will create an anatomical shell of the heart using special plastic (mapping) catheters that is inserted within the heart from the groin. The investigators will use a special heart scanning (echo) catheter to see how the pacemaker wire is inserted into the heart muscle. The investigators will use MRI to confirm that the information we collect is accurate. Using this information the investigators will create a protocol to implant a lead that does not require xray, using only the mapping catheter.
Read the detailed description
A total of 75 patients will be recruited for the study
50 patients with a ventricular pacing indication (high grade atrioventricular block and symptomatic trifasicular or bifasicular block) for pacing will be recruited prospectively. The patients will be divided into two groups; 25 patients in the derivation cohort and 25 patients in the validation cohort. The derivation cohort will undergo a detailed research protocol to determine the optimised work flow and this will be applied prospectively to the validation cohort.
The success rates, procedure times, complication rates and fluoroscopy times will be assessed. The 25 patients undergoing conventional methods of conduction system pacing will be recruited as a control arm to compare these outcomes.
In summary, the 75 patients will be grouped as following; 25 patients in the derivation cohort, 25 patients in the validation cohort and 25 patients in the control arm.
Methodology
Derivation The derivation cohort will comprise of 25 prospectively recruited patients. These patients will undergo the research protocol. In these patients, the investigators will attempt to implant a permanent conduction system pacing lead, in lieu of the RV or LV lead. The lead will be implanted by operators who have implanted more than 40 leads to overcome the learning curve.
Pre-implant Prior to the procedure, patients will undergo a clinically indicated Cardiac MRI. The investigators will use these scans to retrospectively assess for the presence of potential mechanisms which could prevent successful lead implantation, such as the presence of septal fibrosis and chamber dimensions, so that we can assess how these can contribute to challenges at the time of implant. We will also be able to review mechanisms for successful implants. This information will be corroborated with data collected from the electro-anatomical maps.
The MRI scans will also be used to merge the anatomical information using CartoMerge to reduce procedure times by building the anatomical geometry prior to the mapping-catheter collecting this information invasively.
During Implant
The participants will undergo the following procedural steps after written informed consent is gained:
- A left infraclavicular incision and axillary access for the lead will be gain as per standard clinical protocol.
- Access from the femoral vein will be sought where a sheath will be placed in the femoral vein to introduce the mapping catheter.
- Fast anatomical mapping (FAM) of the right atrial and right ventricular anatomy will be made where CartoMerge has not already created this anatomy. This will include the right ventricle, the tricuspid valve and the right ventricular outflow tract. Activation and voltage maps will be then be made of the His-bundle area (including the His cloud), right ventricle, right ventricular outflow tract and right ventricular septum.
This will help determine a few key aspects
- Level of conduction system block and therefore guide site of lead deployment
- Anatomy of the right heart and overcome challenges this may propose
- Evidence of septal fibrosis and/or scar that need to be overcome
- Activation pattern of the septum in conduction system block
- Anatomical FAM maps, voltage maps and activation patterns will be compared against the data collected from the cardiac MRI to assess;
- Accuracy of anatomy
- Fibrosis and scar patterns
The CartoMerge module will be used to expedite anatomical mapping using the MRI data collected.
- The mapping catheter will be removed and an intracardiac echo (ICE) catheter, will be inserted through the femoral vein.
- The conduction system pacing lead will be inserted through the axillary vein. A right atrial lead will be inserted into the right ventricular apex for back up pacing in the instance the conduction system is bumped. The basal-septum, mid-septum, high-septum and anterior walls will be paced to identify electrical markers for optimal implant sites.
- The lead will be visualised on the CARTO maps created.
- The lead will be deployed at the predetermined target site under direct visualisation using the ICE catheter. Through direct visualisation, three key determinants can be assessed:
- Lead trajectory through the septum with the goal of achieving perpendicularity
- Lead septum interaction and whether there is evidence of entanglement preventing lead progression.
- Relationship between the sheath and lead that can lead to or prevent failure of lead deployment.
- Once the conduction system lead is secured the right atrial lead will be pulled back and secured in the right atrium.
- The procedure will be completed as per standard clinical implant protocol with routine clinical follow-up thereafter:
The information from echocardiography will be corroborated with the lead-septum interaction visualised on electro-anatomical maps created on CARTO.
In this cohort of patients, the conduction system lead will initially pace the His-bundle then the left bundle in order to collect data for both methods of physiological pacing. The information collected from ICE and electro-anatomical mapping will be used to develop a streamlined workflow that will map targeted areas, where challenging implant sites will be rapidly identified (such as areas of scar), reducing the number of attempted lead deployments and visualise lead-septum interaction, apposition and progression, improving safety parameters.
At the end of the procedure, the lead position will be documented with a very short, single fluoroscopic acquisition. This remains integral for future comparison in the instances of lead complications and in particular lead displacement.
Validation
25 patients will be recruited to the validation cohort.
An optimised work flow will be derived using the information collected from the derivation cohort. Namely, the target areas for FAM and electro-anatomical maps will be determined, and the successful pattern of lead septum interaction on CARTO will be defined.
The streamlined workflow will then be applied to 25 prospective patients. The success rates, procedure time, fluoroscopy time, capture threshold, number of attempted lead deployments and complication rates will be assessed.
Control Arm The control arm will consist of 25 patients undergoing a conduction system pacemaker using conventional pacing methods, with the same pacing indications as the study arm.
Follow-up All 75 patients will have standard clinical follow-up at 6 weeks, 6 months and 1 year. The clinical information at these visits will be used to identify complications rates that will include lead displacement, rise in capture threshold and lead injury, device related infections.
- Conditions
- Pacemaker, Conduction System Pacing
- Keywords
- fluoroless, conduction system pacing, left bundle area pacing
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
| Study group | Role | What they receive |
|---|---|---|
| Derivation | These patients will undergo the research protocol. In these patients, we will attempt to implant a permanent conduction system pacing lead, in lieu of the RV or LV lead. The lead will be implanted by operators who have implanted more than 40 leads to overcome the learning curve. | |
| Validation | An optimised work flow will be derived using the information collected from the derivation cohort. Namely, the target areas for FAM and electro-anatomical maps will be determined, and the successful pattern of lead septum interaction on CARTO will be defined. The streamlined workflow will then be applied to 25 prospective patients. The success rates, procedure time, fluoroscopy time, capture threshold, number of attempted lead deployments and complication rates will be assessed. | |
| Control | The control arm will consist of 25 patients undergoing a conduction system pacemaker using conventional pacing methods, with the same pacing indications as the study arm |
What is being measured
The primary outcome is the main question the study is designed to answer.
Successful conduction system lead implantation with a fluoroless implant protocol
The primary objective of this study is to develop a fluoroless implant protocol of conduction system leads using 3D electroanatomical mapping. Electroanatomical mapping will be used to understand the cardiac anatomy, removing the reliance on fluoroscopy to position the pacemaker lead. Successful conduction system lead implant rates will be assessed against a control arm utilising conventional fluoroscopic methods.
Measured: From time of first patient recruited to the last patient recruited in the in the derivation cohort, upto 52 weeks
Secondary outcomes (2)
Change in fluoroscopy time
Is there a change in the overall procedure and fluoroscopy time with utilisation of targeted lead deployment.
Measured: From time of first patient recruited to the time of last patient recruited in the validation cohort upto 52 weeks
Change in complication rates
With better visualisation of the cardiac anatomy using the electroanatomical mapping, is there a change in complication rates
Measured: From time of first patient recruitment to the 1 year after last patient recruited
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted30 Jul 2025
- Study start30 Jul 2025 (estimated)
- Primary completion30 Jul 2026 (estimated)
- Study completion30 Jul 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for PacemakerStudies of the same condition, open and under way.
- More trials run by Imperial College LondonThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Prospective
- Enrolment
- 75 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Imperial College London
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- Zachary Whinnett, BM.BS, Principal investigator, Imperial College London, Imperial College Healthcare Trust
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07094217
- Sponsor's protocol ID
- 23HH8384
- Status last verified
- Jul 2025
- First submitted
- 17 Jul 2025
- Last updated
- 30 Jul 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Undecided
Study at a glance
From the registry record, last updated by the sponsor on 30 Jul 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Fluoroless Conduction System Implant
- ClinicalTrials.gov ID
- NCT07094217
- Acronym / sponsor ID
- 23HH8384
- Conditions
- Pacemaker, Conduction System Pacing
- Keywords
- fluoroless, conduction system pacing, left bundle area pacing
- Study type
- Observational
- Recruitment status
- Not yet recruiting
- Enrolment
- 75 participants (estimated)
- Lead sponsor
- Imperial College LondonUniversity, hospital or other
- Study start
- 30 Jul 2025 (estimated)
- Primary completion
- 30 Jul 2026 (estimated)
- Study completion
- 30 Jul 2026 (estimated)
- First posted
- 30 Jul 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Conduction system pacing is a new way of stimulating the heart using pacemaker wires. Traditional pacemakers stimulate the heart muscle which causes disordered heart beats: the walls of the heart move at different times. This wears down the heart over time.
Conduction system pacemakers stimulate the heart's electrical system directly producing natural heart beats that are much less disordered. These pacemakers can be challenging to insert with different heart shapes, sizes and scars. This can increase procedure times and time exposed to xray as pacemakers are inserted using x-rays to guide where the lead is implanted.
This study aims to allow conduction system pacemakers to be implanted without the use of normal xray (fluoroscopy).
The investigators will create an anatomical shell of the heart using special plastic (mapping) catheters that is inserted within the heart from the groin. The investigators will use a special heart scanning (echo) catheter to see how the pacemaker wire is inserted into the heart muscle. The investigators will use MRI to confirm that the information we collect is accurate. Using this information the investigators will create a protocol to implant a lead that does not require xray, using only the mapping catheter.
Detailed description
A total of 75 patients will be recruited for the study
50 patients with a ventricular pacing indication (high grade atrioventricular block and symptomatic trifasicular or bifasicular block) for pacing will be recruited prospectively. The patients will be divided into two groups; 25 patients in the derivation cohort and 25 patients in the validation cohort. The derivation cohort will undergo a detailed research protocol to determine the optimised work flow and this will be applied prospectively to the validation cohort.
The success rates, procedure times, complication rates and fluoroscopy times will be assessed. The 25 patients undergoing conventional methods of conduction system pacing will be recruited as a control arm to compare these outcomes.
In summary, the 75 patients will be grouped as following; 25 patients in the derivation cohort, 25 patients in the validation cohort and 25 patients in the control arm.
Methodology
Derivation The derivation cohort will comprise of 25 prospectively recruited patients. These patients will undergo the research protocol. In these patients, the investigators will attempt to implant a permanent conduction system pacing lead, in lieu of the RV or LV lead. The lead will be implanted by operators who have implanted more than 40 leads to overcome the learning curve.
Pre-implant Prior to the procedure, patients will undergo a clinically indicated Cardiac MRI. The investigators will use these scans to retrospectively assess for the presence of potential mechanisms which could prevent successful lead implantation, such as the presence of septal fibrosis and chamber dimensions, so that we can assess how these can contribute to challenges at the time of implant. We will also be able to review mechanisms for successful implants. This information will be corroborated with data collected from the electro-anatomical maps.
The MRI scans will also be used to merge the anatomical information using CartoMerge to reduce procedure times by building the anatomical geometry prior to the mapping-catheter collecting this information invasively.
During Implant
The participants will undergo the following procedural steps after written informed consent is gained:
- A left infraclavicular incision and axillary access for the lead will be gain as per standard clinical protocol.
- Access from the femoral vein will be sought where a sheath will be placed in the femoral vein to introduce the mapping catheter.
- Fast anatomical mapping (FAM) of the right atrial and right ventricular anatomy will be made where CartoMerge has not already created this anatomy. This will include the right ventricle, the tricuspid valve and the right ventricular outflow tract. Activation and voltage maps will be then be made of the His-bundle area (including the His cloud), right ventricle, right ventricular outflow tract and right ventricular septum.
This will help determine a few key aspects
- Level of conduction system block and therefore guide site of lead deployment
- Anatomy of the right heart and overcome challenges this may propose
- Evidence of septal fibrosis and/or scar that need to be overcome
- Activation pattern of the septum in conduction system block
- Anatomical FAM maps, voltage maps and activation patterns will be compared against the data collected from the cardiac MRI to assess;
- Accuracy of anatomy
- Fibrosis and scar patterns
The CartoMerge module will be used to expedite anatomical mapping using the MRI data collected.
- The mapping catheter will be removed and an intracardiac echo (ICE) catheter, will be inserted through the femoral vein.
- The conduction system pacing lead will be inserted through the axillary vein. A right atrial lead will be inserted into the right ventricular apex for back up pacing in the instance the conduction system is bumped. The basal-septum, mid-septum, high-septum and anterior walls will be paced to identify electrical markers for optimal implant sites.
- The lead will be visualised on the CARTO maps created.
- The lead will be deployed at the predetermined target site under direct visualisation using the ICE catheter. Through direct visualisation, three key determinants can be assessed:
- Lead trajectory through the septum with the goal of achieving perpendicularity
- Lead septum interaction and whether there is evidence of entanglement preventing lead progression.
- Relationship between the sheath and lead that can lead to or prevent failure of lead deployment.
- Once the conduction system lead is secured the right atrial lead will be pulled back and secured in the right atrium.
- The procedure will be completed as per standard clinical implant protocol with routine clinical follow-up thereafter:
The information from echocardiography will be corroborated with the lead-septum interaction visualised on electro-anatomical maps created on CARTO.
In this cohort of patients, the conduction system lead will initially pace the His-bundle then the left bundle in order to collect data for both methods of physiological pacing. The information collected from ICE and electro-anatomical mapping will be used to develop a streamlined workflow that will map targeted areas, where challenging implant sites will be rapidly identified (such as areas of scar), reducing the number of attempted lead deployments and visualise lead-septum interaction, apposition and progression, improving safety parameters.
At the end of the procedure, the lead position will be documented with a very short, single fluoroscopic acquisition. This remains integral for future comparison in the instances of lead complications and in particular lead displacement.
Validation
25 patients will be recruited to the validation cohort.
An optimised work flow will be derived using the information collected from the derivation cohort. Namely, the target areas for FAM and electro-anatomical maps will be determined, and the successful pattern of lead septum interaction on CARTO will be defined.
The streamlined workflow will then be applied to 25 prospective patients. The success rates, procedure time, fluoroscopy time, capture threshold, number of attempted lead deployments and complication rates will be assessed.
Control Arm The control arm will consist of 25 patients undergoing a conduction system pacemaker using conventional pacing methods, with the same pacing indications as the study arm.
Follow-up All 75 patients will have standard clinical follow-up at 6 weeks, 6 months and 1 year. The clinical information at these visits will be used to identify complications rates that will include lead displacement, rise in capture threshold and lead injury, device related infections.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
- Number of arms
- 3
| Arm | Type | Receives |
|---|---|---|
| Derivation | – | –These patients will undergo the research protocol. In these patients, we will attempt to implant a permanent conduction system pacing lead, in lieu of the RV or LV lead. The lead will be implanted by operators who have implanted more than 40 leads to overcome the learning curve. |
| Validation | – | –An optimised work flow will be derived using the information collected from the derivation cohort. Namely, the target areas for FAM and electro-anatomical maps will be determined, and the successful pattern of lead septum interaction on CARTO will be defined. The streamlined workflow will then be applied to 25 prospective patients. The success rates, procedure time, fluoroscopy time, capture threshold, number of attempted lead deployments and complication rates will be assessed. |
| Control | – | –The control arm will consist of 25 patients undergoing a conduction system pacemaker using conventional pacing methods, with the same pacing indications as the study arm |
Who may qualify
- Ages
- 18 to 100 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
- Study population
- The study population will consist of patients referred for a cardiac pacemaker at Imperial College Healthcare Trust.
Key inclusion criteria (3 listed)
- Patients with a ventricular pacing indication: high grade atrioventricular block and symptomatic trifasicular, bifasicular block or left bundle branch block LBBB for cardiac resynchronisation therapy
- Adults willing to take part (ages 18 - 100 years old)
- Able to give consent.
Key exclusion criteria (3 listed)
- Unable to give consent
- Children age < 18 years and adults > 100 years old
- Pregnant patients • As per standard of care, female patients of child-bearing age will have a urine pregnancy test prior to their procedure.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Primary outcome
Successful conduction system lead implantation with a fluoroless implant protocol
Time frame: From time of first patient recruited to the last patient recruited in the in the derivation cohort, upto 52 weeks
The primary objective of this study is to develop a fluoroless implant protocol of conduction system leads using 3D electroanatomical mapping. Electroanatomical mapping will be used to understand the cardiac anatomy, removing the reliance on fluoroscopy to position the pacemaker lead. Successful conduction system lead implant rates will be assessed against a control arm utilising conventional fluoroscopic methods.
2 secondary outcomes
Change in fluoroscopy time
Time frame: From time of first patient recruited to the time of last patient recruited in the validation cohort upto 52 weeks
Change in complication rates
Time frame: From time of first patient recruitment to the 1 year after last patient recruited
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 30 Jul 2025.
- Individual participant dataSharing planned: Undecided
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Zachary Whinnett, BM.BS principal investigator
Imperial College London, Imperial College Healthcare Trust
Questions about this trial
What is this clinical trial studying?
An observational study of Pacemaker and Conduction System Pacing, run by Imperial College London.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 3 inclusion and 3 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: opening soon, as of the sponsor's last update on 30 Jul 2025. Status can change between updates, so confirm with the study contact before making plans.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Akriti Naraen, MBChB (+91203-31-31000, a.naraen@imperial.ac.uk), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Successful conduction system lead implantation with a fluoroless implant protocol (time frame: From time of first patient recruited to the last patient recruited in the in the derivation cohort, upto 52 weeks). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 30 Jul 2025; AzTrials last refreshed its copy on 28 Oct 2026.