Automatic PVARP Feature
Automatic PVARP is an adaptive setting for the post ventricular atrial refractory period (PVARP) that varies its value based on the mean atrial rate. Automatic PVARP enhances protection against pacemaker-mediated tachycardia (PMT) by lengthening PVARP at lower tracking rates and provides a higher 2:1 block rate by shortening PVARP and SAV (if necessary) at higher rates.
This feature can be found in some Medtronic Pacemaker, ICD, 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.
PVARP is nominally programmed to Auto with a programmable Minimum PVARP value, nominally 250 ms. Auto PVARP is available when the device is operating in AAI <=> DDD, AAIR <=> DDDR, DDD, DDDR, DDI and DDIR modes.
To program this feature in pacemakers and CRT-P devices, go to Params -> PVARP.
To program this feature in ICDs and CRT-D devices go to Params -> Pacing -> PVARP.
Automatic PVARP is not available in Adapta™,Versa™,Sensia™ pacemakers when:
- the pacemaker is programmed in a non-tracking mode, such as DDI or DDIR.
- Rate Drop Response is programmed On.
*MAR – mean atrial rate is a running average of the atrial rate based on all A-A intervals except AS-AP or AR-AP.
In Advisa™ pacemakers, ICDs, and CRT devices programmed in a non-tracking mode (DDIR or DDI), PVARP varies with the current pacing rate to be long enough to promote AV synchrony at a low pacing rate and short enough to prevent atrial competitive pacing at a high pacing rate. The device calculates PVARP to attempt to maintain a 300 ms window of time between the end of PVARP and the next scheduled atrial pace. PVARP is limited to be no shorter than the programmed interval for the Post-Ventricular Atrial Blanking (PVAB) parameter.
Operation of Auto PVARP in a non-Tracking Mode
- When automatic PVARP is active and Search AV+ is set to On, the pacemaker will ignore conduction times that are the result of automatic PVARP shortening of the SAV interval.
- If the pacemaker is in ModeSwitch, PVARP is calculated based on the sensor varied rate.
Sources: Medtronic Adapta™/Versa™/Sensia™ Reference Guide; Medtronic Consulta™ CRT-P Clinician Manual;Medtronic Protecta™ XT DR Clinician Manual; Medtronic Protecta™ XT CRT-D Clinician Manual, Evera™ DR Reference Manual.