This document provides a summary of imaging and interpretation of biventricular pacemakers and leadless pacemakers. It describes the anatomy and placement of leads for biventricular pacemakers and ICDs. It also summarizes the indications for biventricular pacemakers in patients with heart failure and conduction abnormalities. The document further describes leadless pacemakers, including the Micra and Nanostim devices, and their benefits over traditional pacemakers in eliminating device-related complications. Potential candidates for leadless pacemakers include those with high-degree AV block or tachy-brady syndrome.

1. Imaging Of Medical Devices
Biventricular & Leadless Pacemakers
Matthew Cravens, MD, Project Lead Author
Department of Emergency Medicine
Brian Powell, MD, Lora Raines PA, Kristin Stemmler PA
Guest Authors: Sanger Heart & Vascular Institute
Michael Gibbs, MD, Faculty Editor

2. Disclosures
 This ongoing imaging interpretation series is proudly sponsored by the
Emergency Medicine Residency Program at Carolinas Medical Center.
 Sanger Heart & Vascular clinicians provide expert Cardiology input.
 The goal is to promote widespread mastery of imaging interpretation.
 There is no personal health information [PHI] within, and all ages have
been changed to protect patient confidentiality.

3. Visit Our Website
www.EMGuidewire.com
For A Complete Archive Of Imaging Presentations And Much More!

4. Airway
Bones
Cardiac
Diaphragm
Effusion
Foreign body
Gastric
Hilum

5. It’s All About The Anatomy!

6. Biventricular Devices and Leadless Pacemakers
Cases From Carolinas Medical Center

8. Biventricular ICD: The right atrial lead (arrow) assumes a “J-shape” that curves upwards towards
the right atrial appendage. The right ventricular ICD lead (arrowhead) crosses the spine on the
anterior projection, and on the lateral projection it courses towards the RV septum or apex. The
left ventricular lead (star) enters the coronary sinus in the RA and terminates at the LV.

10. Biventricular ICD

12. Biventricular ICD

14. Biventricular Pacemaker

15. Biventricular Devices: The LV lead courses through the coronary sinus
and overlies the left ventricle.

17. Leadless Pacemaker: The device is attached to the myocardium of the right ventricle (arrowhead).

19. Leadless Pacemaker

21. Leadless Pacemaker

22. Webb SR. The Leadless Pacemaker. Journal of the American College of Cardiology.
June 10, 2019.
• Two leadless pacemaker have been approved by the US Food and Drug
Administration for use in the United States: (Micra™ [Medtronic PLC; Minneapolis,
MN]) and (Nanostim™ [Abbott Laboratories; Abbott Park, IL]).
• Micra™ attaches to the right ventricle myocardium via four linear self-expanding
nitinol tines. Nanostim™ attaches via an active screw-in helix and secondarily via
three nitinol tines angled perpendicularly to the helix.

23. Leadless Pacemaker: The Nanostim™ is shown on the left, and the Micra™ on the right.

24. Test yourself!
Cases From Carolinas Medical Center

26. Dual Chamber Pacemaker - ICD

28. Leadless Pacemaker

30. Dual Chamber Pacemaker: RA lead (arrow), RV lead (arrowhead). This patient also has a mechanical
valve replacement (star). Sternal wires and an additional metallic circular object are also seen.

32. Leadless Pacemaker (arrowhead): The patient also has an implantable loop recorder (arrow).

34. Single Chamber Pacemaker

36. Biventricular Pacemaker

38. Subcutaneous ICD

40. Single-Chamber ICD

41. More On Biventricular Devices

42. More On Biventricular Pacemakers
• Biventricular pacing is also called Cardiac Resynchronization Therapy
(CRT). A CRT device may be either a CRT-Pacemaker (CRT-P) or CRT-
Defibrillator (CRT-D).
• CRT is an established therapy for medically refractory, mild-to-severe
systolic heart failure with impaired LV function and wide QRS complex.
• Indications vary by society, with highest recommendations for advanced heart
failure with QRS> 150ms and left bundle branch block morphology (see next
slides).

43. Indications For Biventricular Pacemakers

44. Indications For Biventricular Pacemakers

45. Indications For Biventricular Pacemakers

46. More On Biventricular Pacemakers
Summary Of Indications:
Cardiac resynchronization therapy is recommended with patients with
• NYHA Grade III-IV heart failure
• QRS >130 msec
• On optimal medical therapy for ≥3 months
AHA/ACC 2018 Guidelines

47. Nanostim™
Micra™
More On Leadless Pacemakers

48. Editorial Comparing Both Trials Describes Similar Outcomes And Efficacy.

49. More On Leadless Pacemakers
• The leadless pacemaker, which is 90% smaller than a transvenous
pacemaker, is a self-contained generator and electrode system implanted
directly into the right ventricle. The device is implanted via a femoral vein
transcatheter approach; it requires no chest incision or subcutaneous
generator pocket.
• The primary advantage of a leadless pacemaker is the elimination of
several complications: pocket infections, hematoma, lead dislodgment, and
lead fracture. The leadless pacemaker also has cosmetic appeal because
there is no chest incision or visible pacemaker pocket.
• Current leadless pacemakers are designed to be compatible with magnetic
resonance imaging.

50. More On Leadless Pacemakers
• Leadless pacemakers provide only single-chamber ventricular pacing and
lack defibrillation capacity.
• Leadless pacemakers may be suitable for patients with permanent atrial fibrillation
with bradycardia or bradycardia-tachycardia syndrome or those who infrequently
require pacing.
• Leadless pacemakers are inappropriate for patients who require dual-chamber
pacing, such as patients with certain forms of heart block or sinus node dysfunction.
• Battery life is approximately 5-15 years, comparable to that of a
transvenous pacemaker.
• At end of battery life, a leadless pacemaker can be turned off and a new leadless or
traditional pacemaker implanted.
• A leadless pacemaker is theoretically retrievable, but there is only limited experience
with retrieval.

51. More On Leadless Pacemakers
Summary Of Indications:
• Paroxysmal or permanent high degree AV block – in the presence or
absence of atrial fibrillation
• Symptomatic tachy-brady syndrome
• Symptomatic sinus node dysfunction

52. More On Leadless Pacemakers
Benefits:
• Eliminates complications:
• Infection
• Lead malfunction
• Thromboembolic complications
• Tricuspid valve dysfunction
• Aesthetically more appealing

53. Micra™ Leadless Pacemaker

54. Selected Embedded References:
• Percutaneous Implantation of an Entirely Intracardiac Leadless Pacemakers. New
England Journal of Medicine. 2015. 373;12.
• A Leadless Intracardial Transcatheter Pacing System. New England Journal of
Medicine. 2016. 374(6).
• Webb SR. The Leadless Pacemaker. Journal of the American College of Cardiology.
June 10, 2019.
• Link M. Achilles’: Lead Will Pacemakers Break Free? New Journal of Medicine.
2016. 374(6).

55. If You Have Interesting Cases Demonstrating Cardiac Devices We Invite You To
Send A Set Of Digital PDF Images And A Brief Clinical History To:
michael.gibbs@atriumhealth.org
Your De-Identified Case(s) Will Be Posted On Our Education Website And You
And Your Institution Will Be Recognized!

56. See You Next Month!