Rate Response (RR) Feature

Rate-responsive pacing adapts the pacing rate to changes in the patient's physical activity. An activity sensor is used to measure the patient's movement and to determine the appropriate pacing rate.

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.

Programming parameters include:

  • Rate Profile Optimization* – Automatically adjusts the rate response slope as a patient’s conditions change. Changes are based on comparing the pacemaker’s historical sensor-indicated rate profiles against a clinician prescribed target rate profile of the patient. Nominally On.
  • Lower Rate – The programmed rate at which a pacemaker will pace the heart in the absence of intrinsic cardiac activity. Nominally 60 bpm.
  • ADL (Activities of Daily Living) Rate* – The average target rate that the patient achieves for moderate activities. Nominally 95 bpm.
  • ADL Response* – Determines the incremental increase or decrease in the sensor-driven rate for a given level of activity in the ADL rate range.
    • The nominal setting for the ADL Response parameter is 3.
    • Programming a higher number increases the sensor indicated pacing rate for a given amount of activity, increasing rate responsiveness in the ADL rate range.
    • Programming a lower number decreases the sensor indicated pacing rate for a given amount of activity, thereby decreasing rate responsiveness.
  • Upper Sensor Rate – The fastest rate at which the heart will be paced in response to signals from the rate-response sensor. Nominally 130 bpm.
  • Exertion Response* – Determines the incremental increase or decrease in the sensor-driven rate for a given level of activity in the exertion rate range.
    • The nominal setting for the Exertion Response parameter is 3.
    • Programming a higher number increases the sensor indicated pacing rate for a given amount of activity, increasing rate responsiveness in the exertion rate range.
    • Programming a lower number decreases the sensor indicated pacing rate for a given amount of activity, thereby decreasing rate responsiveness.
  • Activity Threshold – The activity sensor converts detected motion into electrical signals and is used in computing the sensor-indicated rate.
    • Programmable settings:
      • Low – Responds to most body activity, including minimal exertion.
      • Medium/Low – Limited response to minimal exertion, responds to moderate/greater exertion.
      • Medium/High – Limited response to moderate body movements and exertion.
      • High – Responds to only vigorous body movements and exertion.
  • Activity Acceleration – Determines how quickly the pacing rate increases to the target sensor rate when the patient exercises.
  • Activity Deceleration – Determines how quickly the pacing rate declines to the target sensor rate when the patient’s activity stops.
  • Rate Response – Determines the level of rate response for devices with single zone rate response programming options. Higher numbers indicate a more aggressive increase in rate for a given level of sensed physical activity.
* These programming options are only available in devices that have dual zone rate response.

To program this feature in pacemakers, go to Params -> Rate Response.

To program this feature in ICDs, go to Params -> Pacing -> Rate Response.

Programming for devices with dual zone rate response

 

Programming for devices with single zone rate response

Rate responsive (also called rate modulated) devices provide patients with the ability to vary heart rate (between the programmed lower and upper sensor rate) when the sinus node cannot provide the appropriate rate.

Operation of Rate Response in devices with dual zone Rate Response
The device may provide appropriate rate response for patients who require cardiac pacing support at both submaximal and maximal rates. Submaximal rates are moderate pacing rates near the Activities of Daily Living Rate (ADL Rate) obtained during typical daily activities, such as walking or daily chores. Maximal rates are rates (at or near the Upper Sensor Rate) obtained during vigorous activities. To achieve appropriate rate response, the pacemaker provides activity sensor-driven pacing with rate response control in both the ADL rate range and the exertion rate range.

The device provides appropriate rate response by employing the following operations:

  • Three programmable rates control the submaximal and maximal rate ranges: Lower Rate, ADL Rate (Activities of Daily Living Rate), and Upper Sensor Rate. The ADL Rate is equivalent to the average target rate that the patient achieves for moderate activities.
  • Independent control of rate response is provided in the Activity Threshold setting and the ADL/Exertion rate ranges.
    • Activity Threshold is used in computing the sensor-indicated rate. The activity sensor converts detected motion into electrical signals.
    • Programmable settings:
      • Low – Responds to most body activity, including minimal exertion.
      • Medium/Low – Limited response to minimal exertion, responds to moderate/greater exertion.
      • Medium/High – Limited response to moderate body movements and exertion.
      • High – Responds to only vigorous body movements and exertion.

For models in a rate responsive mode, the device automatically enables rate response after implant and automatically adjusts rate response using Rate Profile Optimization, if necessary, once each day.

  • For pacemakers during the first 30 minutes after implant, pacing occurs at the implanted mode but without rate response. 30 minutes after implant, rate response operation is enabled.
    • The Micra™ transcatheter pacing system (TPS) does not have automatic Implant Detect, so once you enable VVIR, the Rate Response starts immediately.  
  • For ICDs Rate Response and Rate Profile Optimization begin operating after implant, when VF Detection is programmed to On.
  • Once each day, rate response is assessed and adjusted, if necessary, in the ADL and exertion rate ranges. The assessment is based on comparing the pacemaker’s historical sensor-indicated rate profiles against a clinician prescribed target rate profile of the patient. If the rate profiles differ, rate response is adjusted slightly in the appropriate rate range, and the assessment is repeated again the next day.
  • As the ADL Response and Exertion Response parameter settings are changed, the device will make it easier or harder to achieve these rate regions. Increasing the ADL or Exertion response settings results in the device defining a new Target Profile, or ideal rate distribution. This may eventually cause the device to automatically adjust the corresponding setpoints for the ADL Rate and USR to a different value. For example, as the setpoint value decreases, the slope is made more aggressive, thus the patient is able to achieve higher rates with less effort, and ultimately, spend a larger percentage of time in that particular rate range.
  • If Rate Profile Optimization is set to Off, the setpoints will not change and a new Target Profile will not be created.
  • Micra TPS is implanted inside the heart where heart motion resides. This heart motion is filtered out via a Lower Rate (LR) Setpoint. The LR Setpoint determines the activity counts required to pace at a rate higher than the lower rate. 

Micra TPS Rate Response Curve

Operation of Rate Response in devices with single zone Rate Response
The sensor-indicated rate is determined by the sensed activity and the Rate Response parameter setting, and it can range between the programmed Lower Rate and the Upper Sensor Rate. The sensed activity is measured using the activity threshold that operates as described in the dual zone operation description above. The Rate Response parameter is set to a number between 1 and 10 (see Figure below). If this parameter is set to a larger number, the indicated pacing rate is higher for a specified level of detected activity.

  • If the sensor-indicated rate is greater than the current pacing rate, the pacing rate accelerates toward the sensor-indicated rate. The speed of this increase is determined by the Activity Acceleration parameter setting.
  • If the sensor-indicated rate decreases, the pacing rate decelerates to the sensor-indicated rate. The rate of deceleration is determined by the programmed Activity Deceleration setting.

References

Sources: Micra™ Clinician Manual, 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.

Last updated: 
18 Aug 2016