Leadless pacemakers are self-contained in a hermetically sealed capsule. The capsule houses battery and electronics to operate the system. Similar to most pacing leads, the tip of the capsule includes a fixation mechanism and a monolithic controlled-release device. The controlled-release device elutes glucocorticosteroid to reduce acute inflammation at the implantation site. Leadless pacemakers have rate-responsive functionality, and current device longevity estimates are based on bench data. Estimates have suggested that these devices may last over ten years, depending on the programmed parameters.
The Micra transcatheter pacing system may be considered medically necessary in individuals when both conditions below are met:
The Micra transcatheter pacing system is considered investigational in all other situations in which the above criteria are not met.
Per the FDA label, the Micra Model MC1VR01 pacemaker is contraindicated for individuals who have the following types of devices implanted:
As per the FDA label, the Micra Model MC1VR01 pacemaker is also contraindicated for individuals who have the following conditions:
As per the FDA label, the Micra Model MC1VR01 pacemaker should not be used in individuals for whom a single dose of 1.0 mg dexamethasone acetate cannot be tolerated because the device contains a molded and cured mixture of dexamethasone acetate with the target dosage of 272 μg dexamethasone acetate. It is intended to deliver the steroid to reduce inflammation and fibrosis.
For axillary transvenous pacemakers, there is a concern that leads, or the generator could be impacted by the recoil of using a firearm (e.g., rifles or shotguns). Thus, leadless cardiac pacemakers can provide an alternative for individuals who suffer lead fracture or malfunction from mechanical stress and may be considered when axillary venous access is present only on a side of the body that would not allow use of equipment producing such mechanical stress (e.g., a firearm).
American College of Cardiology Foundation et al
The American College of Cardiology Foundation, American Heart Association, and Heart Rhythm Society’s (2012) focused update on device-based therapy of cardiac rhythm abnormalities incorporated into their joint 2008 guidelines for device-based therapy of cardiac rhythm abnormalities does not include recommendations on leadless cardiac pacemakers.
The Heart Rhythm Society and American College of Cardiology Foundation (2012) expert consensus statement on pacemaker device and mode selection did not include recommendations on leadless cardiac pacemakers.