Rate Drop Response is nominally programmed Off and is available when the pacing mode is programmed to DDD, DDI, or AAI<=>DDD (MVP mode). For the MVP mode, the device operates in DDD mode during Rate Drop Response interventions. It does not operate during Mode Switch episodes or tachyarrhythmias in ICDs.

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

To program this feature in pacemakers, ICDs go to Pacing -> Additional Features -> Rate Drop Response.

Programming for pacemakers

Programming for ICDs (and Advisa DR MRI™)

Programming considerations and restrictions:

• During sleep, a patient’s sinus rate may fall below the programmed Lower Rate, thereby triggering intervention pacing at an inappropriate time. There are two ways to address this: turn off Low Rate Detection, or turn on the Sleep feature, if available. The Sleep Function replaces the programmed Lower Rate with a slower pacing rate during the time of day the patient normally sleeps. Features that adjust the pacing rate, such as Atrial Rate Stabilization, Atrial Preference Pacing, and Ventricular Rate Stabilizaton, are unavailable when Rate Drop Response is programmed on.
• When both Capture Management™ (Atrial Capture Management, Left Ventricular Capture Management, or Ventricular Capture Management) and RDR are operating, RDR will be suspended during the pacing threshold search. Programming Capture Management to search for pacing thresholds at night can mitigate the interaction.
• Rate Adaptive AV, sensor-varied PVARP, and Automatic PVARP are unavailable when RDR is programmed On.

As shown in the diagram below, Rate Drop Response operates in phases. During the detection phase, the device monitors the heart for rate drops that satisfy the programmed drop detection criteria. During the intervention phase, the device paces the heart at a programmed elevated rate for the programmed duration. During the step-down phase, the device gradually slows pacing to the sinus rate or the Lower Rate.

Rate Drop Response provides two methods for detecting significant rate drops: Drop Detection and Low Rate Detection. Both can be programmed On if necessary.

Drop Detection
As shown in the example below, with Drop Detection, the device intervenes when the ventricular rate drops by a specified number of beats per minute to below a specified heart rate within a specified period of time. These conditions are established by programming the Drop Size, Drop Rate, and Detection Window parameters, respectively.

Low Rate Detection
As shown in the example below, with Low Rate Detection, the device intervenes when the atrium is paced at the Lower Rate for the number of consecutive beats specified by the Detection Beats parameter.

Drop and Low Rate Detection On
When both detection methods are programmed, the device intervenes when either Drop Detection or Low Rate Detection criteria are met. For example, if the heart rate drops too slowly to meet programmed Drop Detection criteria and continues to drop, the heart is eventually paced at the Lower Rate. If this continues for the programmed number of detection beats, the device intervenes.

Intervention and Step Down
When a rate drop is detected, the device paces the heart at the programmed Intervention Rate for the programmed Intervention Duration. After the Intervention Duration is complete, the device reduces the pacing rate by 5 bpm steps every minute. This step-down process continues until the sinus rate or the Lower Rate is reached.

Intervention pacing and step-down pacing are immediately ended when the device senses 3 consecutive nonrefractory atrial events.

Below is an example of an interval plot stored during a rate drop episode. The Y axis shows rate in bpm. The rate initially is very constant at approximately 70 bpm and the A-V pattern indicates normal sinus rhythm. The rate increases slightly, followed by a sudden drop in rate. At this point, the patient would begin to feel unwell without intervention. Intervention is indicated on the plot followed by the programmed pacing rate of 100 bpm.