Dislodged Leadless Pacemaker in the Left Pulmonary Artery

Dizziness and syncope. Diagnosis? • Xray of the Week

Figure 1. What is this foreign body in the chest?

Figure 2. Figure 1. Dislodged leadless pacemaker within the left pulmonary arterial circulation. (A) Frontal chest radiograph demonstrates the radiopaque leadless pacemaker projecting over the left hilar region (arrow), rather than its expected position within the right ventricle. (B) Axial CT image confirms the leadless pacemaker within the left pulmonary arterial circulation (arrow).

Figure 3. Frontal and lateral CXR. Normal position of leadless pacemaker in a different patient (A) in the right ventricle. Incidental cardiac loop recorder (B).

Epidemiology

Leadless pacemaker dislodgement is a rare complication of implantation. In the Micra Post-Approval Registry, device dislodgement occurred in 0.13% of patients within 30 days. More recent post-market data reported dislodgement and/or embolization in 0.29% of 72,237 Micra VR implants and 0.88% of 5,990 AVEIR VR implants. Migration into the pulmonary arterial circulation is particularly uncommon and has predominantly been described in case reports.

Clinical Findings

Leadless pacemaker dislodgement may be clinically silent or associated with pacemaker malfunction. Device displacement may result in abnormal pacing parameters or loss of capture. In this case, the patient presented with dizziness and syncope. Pulmonary artery embolization itself may remain asymptomatic, although serious vascular complications can rarely occur.

Pathology

Leadless pacemakers are implanted directly into the right ventricular endocardium and use dedicated fixation mechanisms to maintain device stability. Inadequate fixation or device-release problems may result in dislodgement and subsequent embolization into the pulmonary arterial circulation. Once dislodged from the right ventricle, the device may pass through the right ventricular outflow tract and pulmonary valve and lodge within a pulmonary arterial branch.

Radiographic Features

On chest radiography, a normally positioned leadless pacemaker appears as a radiopaque device implanted within the right ventricular wall. Device dislodgement should be suspected when the pacemaker is no longer seen in its expected intracardiac position and instead projects over the pulmonary arterial circulation (Figure 1A). Serial radiographs, when available, may demonstrate interval migration. CT provides cross-sectional anatomic localization of an embolized device within the pulmonary vasculature and can delineate its relationship to adjacent pulmonary arterial branches (Figure 1B). Published cases demonstrate embolization into both central and more peripheral pulmonary arterial branches.

Treatment and Prognosis

Management of an embolized leadless pacemaker depends on device location, clinical status, duration since implantation, and feasibility of retrieval. Percutaneous retrieval may be performed using snare-based techniques introduced through a large-bore delivery catheter or steerable sheath. When complete endovascular removal is not technically feasible, a surgical component may occasionally be required. Following successful retrieval, further pacing therapy can be provided when clinically indicated.

Conclusion

Leadless pacemaker dislodgement with pulmonary arterial embolization is a rare complication that may be clinically silent or result in pacemaker dysfunction and potentially serious vascular complications. Chest radiography can identify abnormal device position, while CT provides more precise anatomic localization within the pulmonary arterial circulation. Prompt recognition of device migration is important for guiding subsequent management.

References

1. Roberts PR, Clementy N, Al Samadi F, et al. A leadless pacemaker in the real-world setting: the Micra Transcatheter Pacing System Post-Approval Registry. Heart Rhythm. 2017;14(9):1375-1379. https://doi.org/10.1016/j.hrthm.2017.05.017

2. Bahbah A, Sengupta J, Witt D, et al. Device dislodgement and embolization associated with a new leadless pacemaker. J Cardiovasc Electrophysiol. 2024;35(12):2483 2486. https://doi.org/10.1111/jce.16485

3. Terricabras M, Khaykin Y. Successful leadless pacemaker retrieval from the left pulmonary artery: a case report. HeartRhythm Case Rep. 2020;6(10):798-799. https://doi.org/10.1016/j.hrcr.2020.08.004

4. Barbieri F, Kranewitter C, Frech A, Hintringer F, Stühlinger M. Lost but not lost—embolization of a leadless pacemaker to the pulmonary artery with consecutive endovascular recovery. J Cardiovasc Dev Dis. 2021;8(4):37. https://doi.org/10.3390/jcdd8040037

5. Sugiura K, Baba Y, Hirota T, Kubo T, Kitaoka H. A drifting dislodged leadless pacemaker in the bilateral pulmonary arteries. JACC Case Rep. 2022;4(14):844-846. https://doi.org/10.1016/j.jaccas.2022.03.034

6. Amin MI, Saif S, Shivappa S, Noor H. Leadless pacemaker dislodgment: difficulty in release as a predictor for dislodgment and tools for successful retrieval. Heart Rhythm O2. 2024;5(10):739-740. https://doi.org/10.1016/j.hroo.2024.08.010

7. Abraham H, Assar MD, Chugh Y. A novel technique for percutaneous retrieval of an embolized atrial leadless pacemaker from the pulmonary artery. JACC Cardiovasc Interv. 2026;19(10):1333-1335. https://doi.org/10.1016/j.jcin.2026.02.025

8. El-Chami MF, Roberts PR, Kypta A, Omdahl P, Bonner MD, Kowal RC, Duray GZ. How to implant a leadless pacemaker with a tine-based fixation. J Cardiovasc Electrophysiol. 2016;27(12):1495-1501. https://doi.org/10.1111/jce.13092

9. Mathew RP, Alexander T, Patel V, Low G. Chest radiographs of cardiac devices (Part 1): cardiovascular implantable electronic devices, cardiac valve prostheses and Amplatzer occluder devices. S Afr J Radiol. 2019;23(1):1730. https://doi.org/10.4102/sajr.v23i1.1730

10. Conyers JM, Rajiah P, Ahn R, Abbara S, Saboo SS. Imaging features of leadless cardiovascular devices. Diagn Interv Radiol. 2018;24(4):203-208. https://doi.org/10.5152/dir.2018.17462

11. Afzal MR, Daoud EG, Cunnane R, et al. Techniques for successful early retrieval of the Micra transcatheter pacing system: a worldwide experience. Heart Rhythm. 2018;15(6):841-846. https://doi.org/10.1016/j.hrthm.2018.02.008

Umaiza Ihsan, MD, is a medical graduate of King Edward Medical University,

Pakistan. She completed her internship at Mayo Hospital, Lahore, including a three-

month rotation in Radiology, which further strengthened her interest in diagnostic

imaging. She has gained additional clinical exposure in Radiology through observerships at Mon Health Morgantown and the University of Maryland, Baltimore. She has a strong interest in Radiology, particularly diagnostic imaging and its role in clinical decision-making, and is actively interested in clinical research, with experience in systematic reviews and medical research.

Kevin M. Rice, MD is the president of Global Radiology CME and is a radiologist with Cape Radiology Group. He has held several leadership positions including Board Member and Chief of Staff at Valley Presbyterian Hospital in Los Angeles, California. Dr. Rice has made several media appearances as part of his ongoing commitment to public education. Dr. Rice's passion for state of the art radiology and teaching includes acting as a guest lecturer at UCLA. In 2015, Dr. Rice and Natalie Rice founded Global Radiology CME to provide innovative radiology education at exciting international destinations, with the world's foremost authorities in their field. In 2016, Dr. Rice was nominated and became a semifinalist for a "Minnie" Award for the Most Effective Radiology Educator. He was once again a semifinalist for a "Minnie" for 2021's Most Effective Radiology Educator by AuntMinnie.com. He has continued to teach by mentoring medical students interested in radiology. Everyone who he has mentored has been accepted into top programs across the country including Harvard, UC San Diego, Northwestern, Vanderbilt, and Thomas Jefferson.

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