Atrial Tracking Recovery (ATR) Feature
Atrial Tracking Recovery (ATR) is designed to help the device recover atrial tracking when it is lost because of PVCs or a fast conducted atrial rhythm that inhibits pacing in the ventricles. This restoration of atrial tracking helps maintain AV synchrony and ensures continuous biventricular (BiV) pacing in cardiac resynchronization therapy (CRT).
This feature can be found in some Medtronic CRT-P and CRT-D devices. Please go to manuals.medtronic.com or consult with your local Medtronic representative regarding device models available in your geography.
Atrial Tracking Recovery (ATR) is an On/Off feature. There are no additional programmed parameters.
To program this feature, go to Params -> Pacing... -> Additional Features... -> Atrial Tracking Recovery…
Atrial Tracking Recovery is available in atrial tracking modes DDD and DDDR, while Mode Switch is not in effect.
Atrial Tracking Recovery monitors for sustained ventricular sensing that may be due to loss of tracking of sensed atrial events falling in the post ventricular atrial refractory period (PVARP). To recover atrial tracking and CRT therapy, ATR temporarily shortens PVARP so that sensed atrial events can be tracked and BiV pacing can resume.
Atrial Tracking Recovery looks for 8 consecutive pacing cycles where all the following occur:
- Ventricular sensing followed by an atrial refractory event (VS-AR pattern).
- Regular atrial rate less than the Upper Tracking Rate.
- VS-AR intervals greater than Post Ventricular Atrial Blanking (PVAB).
If these conditions are satisfied, the device temporarily shortens PVARP. On subsequent pacing cycles during ATR intervention, the device recalculates the temporary PVARP. ATR intervention ends when the ventricular pace occurs at the scheduled SAV interval or when the computed temporary PVARP is no longer shorter than the otherwise indicated PVARP.
Atrial Tracking Recovery interventions occur only when the sinus rate is below the programmed Upper Tracking Rate. Therefore, the selection of Upper Tracking Rate relative to the patient’s range of sinus rates may affect the frequency and necessity of Atrial Tracking Recovery interventions.
Considerations: The Atrial Tracking Recovery operation is suspended during tachyarrhythmia therapies, system tests, EP study inductions, manual therapies, and emergency fixed burst, cardioversion, and defibrillation therapies.
The following example shows ATR in action in a CRT-D device programmed to DDD. In the beginning of the strip, there is no BiV pacing because the atrial rate has increased to the point where the atrial sensed events are falling in the refractory period of the prior ventricular event (PVARP). The patient’s intrinsic conduction from the atrial impulse results in ventricular activation that is sensed by the device. ATR recognizes this VS-AR pattern and begins to shorten PVARP to allow the device to sense the atrial event, start the SAV delay, and BiV pace the ventricles to restore CRT.
Sources: Medtronic Protecta™ XT CRT-D Clinician Manual; Medtronic Consulta™ CRT-P Clinician Manual.