Question:
What are the characteristics of Medtronic Micra™ leadless pacemakers (VR, AV, and second‑generation VR2/AV2)?
Quick overview
- Family: Micra™ VR (first‑gen VVI), Micra™ AV (first‑gen VDD‑like AV synchrony), and the second‑generation Micra™ VR2 & AV2.
- Form factor: Capsule that sits entirely in the right ventricle with nitinol tines fixation; delivered via a 23‑Fr femoral venous introducer.
- MRI: MRI SureScan™ (1.5T & 3T labeling when programmed appropriately).
- Remote monitoring: BlueSync™/Bluetooth® connectivity with the MyCareLink Heart™ app (CareLink™ network).
Micra™ VR (first‑generation, single‑chamber VVIR)
- Intended use: Single‑chamber ventricular pacing (e.g., AF with slow ventricular response, SND where atrial lead not desirable).
- Pacing modes: VVI, VVIR, VOO, OVO, OFF.
- Rate response: 3‑axis accelerometer with dual‑slope RR; programmable (Lower/ADL/Upper Sensor rates; Activity Accel/Decel; Rate Profile Optimization).
- Capture Management: Automatic RV capture threshold testing and output adjustment.
- Size & weight: ~26 mm × 6.7 mm; mass ≈ 1.75 g; volume ≈ 1.0 cm³.
- Projected longevity: ~12.5 years (usage‑dependent).
- Complications: Low major complication, dislodgement, and infection rates vs. transvenous systems (in trials).
Micra™ AV (first‑generation, AV‑synchronous VDD‑like)
- What’s new vs VR: Uses an internal accelerometer to sense atrial mechanical activity (A1–A4 signals) to deliver AV‑synchronous ventricular pacing (VDD‑like) when sinus rhythm is present; switches to VVIR with higher activity (Activity Mode Switch).
- Pacing modes: VVI, VVIR, VOO, OVO, VDD, VDI, ODO, OFF.
- Programming & algorithms: Automated Atrial Sensing Setup; AV Conduction Mode Switch; Rate Smoothing; Activity Mode Switch.
- Typical longevity: ~8–13 years (depends on degree of AV block and pacing burden).
- MRI/size: MRI SureScan; capsule form factor similar to VR.
- Limits: AV synchrony can be limited at higher sinus rates; device provides VVIR support during intermittent AVS.
Second‑generation Micra™ VR2 & AV2
- Regulatory status: FDA‑cleared in 2023 as next‑gen Micra devices.
- Battery life: ~40% longer vs prior gen; projected median ≈ 16.7 years (VR2) and 15.6 years (AV2) (model‑dependent).
- Form factor: Mass ≈ 1.75 g; volume ≈ 0.8 cc; electrode spacing 18 mm; MRI SureScan ≤3T.
- AV2 algorithm upgrades: “Auto+ A3 Threshold” and improved Atrial Sensing Setup reduce manual programming and improve automatic AV synchrony, especially at 80–100 bpm; upper tracking now 135 bpm.
- Connectivity: MyCareLink Heart™ app (Bluetooth/BlueSync) for remote monitoring and alerts.
Notes
- Dimensions & mass: First‑gen Micra VR manual lists volume ≈ 1.0 cm³; newer portfolio/spec pages list 0.8 cc for AV/VR and second‑gen devices. Actual model‑specific specs should be confirmed against current manuals.
- Implant hardware: Delivery catheter OD ≈ 23 Fr; fixation via nitinol tines.
- Indications: Devices are intended only for the right ventricle. Micra AV/AV2 provide VDD‑like AV synchrony for appropriate patients; AV synchrony varies by physiology and activity.
This page is informational and not a substitute for device manuals or medical advice. Always consult the latest Medtronic manuals and your electrophysiologist for patient‑specific programming.