April 6, 2016
The U.S. Food and Drug Administration approved the first pacemaker that does not require the use of wired leads to provide an electrical connection between the pulse-generating device and the heart.
While the Micra Transcatheter Pacing System works like other pacemakers to regulate heart rate, the self-contained, inch-long device is implanted directly in the right ventricle chamber of the heart.
Pacemakers are surgically implanted medical devices that generate electrical impulses to treat irregular or stalled heart beats, and nearly 1 million people worldwide are implanted with pacemakers each year. The leads in a traditional single chamber pacemaker run from the pacemaker, implanted under the skin near the collarbone, through a vein directly into the heart’s right ventricle; the leads deliver electric pulses from the generator to the right ventricle and help coordinate timing of the chamber’s contractions. Micra eliminates these leads, which cansometimes malfunction or cause problems when infections develop in the surrounding tissue, requiring a surgical procedure to replace the device.
Image: Reynolds D, Duray GZ, Omar R, Soejima K, Neuzil P, Zhang S, Narasimhan C, Steinwender C, Brugada J, Lloyd M, Roberts PR. A leadless intracardiac transcatheter pacing system. New England Journal of Medicine. 2015 Nov 9.
The Micra transcatheter pacemaker, a singlechamber ventricular pacemaker, is self-contained in a hermetically enclosed capsule with a volume of 0.8 cm3 , a length of 25.9 mm, an outer diameter of 6.7 mm, and a weight of 2.0 g. Its functionality and features are similar to those of existing ventricular pacemakers, with features that include accelerometer-based rate-adaptive pacing and automated pacing capture threshold management to maximize battery longevity.
ADVANTAGES OF MICRA
Redefines the patient experience
- Potential to increase pacemaker patient satisfaction
- No chest scar, bump, and no visible or physical reminder
- Minimally-invasive procedure
- Potential for fewer post-implant activity restrictions
Eliminates pocket-related complications 3
Pocket-related complications with traditional systems: 8% at 5 years.
Eliminates lead-related complications 3
- Insulation breaches
- Venous thrombosis and obstruction
- Tricuspid regurgitation
Long-term, lead-related complications: 11% at 5 years.
Zero dislodgements with FlexFix nitinol tines 4
- Provides atraumatic and secure device placement
- Two tines have 15 times the holding force necessary to hold the device in place6
- Designed to minimize tissue trauma during deployment, repositioning, and retrieval5
- Optimal electrode tissue interface allows for low and stable chronic thresholds 2
- MRI SureScan allowing safe MRI scans using either 1.5T or 3T full-body MRI
The FDA evaluated data from a clinical trial of 719 patients implanted with the Micra device, which found that 98 percent of patients in the trial had adequate heart pacing (known as pacing capture threshold) six months after the device was implanted. Complications occurred in fewer than 7 percent of participants in the clinical trials and included prolonged hospitalizations, blood clots in the legs (deep vein thrombosis) and lungs (pulmonary embolism), heart injury, device dislocation and heart attacks.
Micra is contraindicated for patients who have implanted devices that would interfere with the pacemaker, who are severely obese, or who have an intolerance to materials in the device or the blood thinner heparin.
It is also contraindicated for patients with veins that are unable to accommodate the 7.8 millimeter introducer sheath or pacemaker implant.
The Micra device is manufactured by Medtronic, located in Mounds View, Minnesota.
Image Source: Reynolds D, Duray GZ, Omar R, Soejima K, Neuzil P, Zhang S, Narasimhan C, Steinwender C, Brugada J, Lloyd M, Roberts PR. A leadless intracardiac transcatheter pacing system. New England Journal of Medicine. 2015 Nov 9.
1.Nippoldt, Doug; Whiting, Jon. Micra Transcatheter Pacing System: Device Volume Characterization Comparison. November 2014. Medtronic Data on File.
2.Williams, Eric, Whiting Jon; Micra Transcatheter Pacing System Size Comparison, November 2014, Medtronic Data on File.
3.Udo EO, Zuithoff NP, van Hemel NM, et al. Incidence and predictors of short- and long-term complications in pacemaker therapy: the FOLLOWPACE study. Heart Rhythm. May 2012;9(5):728-735.
4.Reynolds DW, Duray GZ, Omar R, et al. A Leadless Intracardiac Transcatheter Pacing System. N Engl J Med. Published online November 9, 2015.
5.Eggen, Mike. FlexFix Tine Design. April 2015. Medtronic Data on File.