Automatic Sensor Adjustment in a Rate Modulated Pacemaker

A new feature (AutoSlope) has been introduced that can automatically adjust the sensor slope based on the chronic activity level of the patient. The algorithm adjusts the slope once per week so that 99% of the sensor response is maintained between the base rate and 23% of the difference between the programmed Base Rate and the Max Sensor Rate. Offsets are available for fine titration of sensor response in individual patients. The AutoSlope feature was evaluated in 93 patients with DDDR pacemakers (Trilogy DR+, Pacesetter). Patients were seen at 1, 3, and 6 months for a total of 178 evaluations. At each evaluation, the AutoSlope value was recorded. Patients then performed a brisk walk at sensor values equivalent to the AutoSlope value. Desired sensor rate was compared to the rate achieved by AutoSlope for the exercise period. Long-term sensor performance was evaluated by analyzing the sensor histogram. AutoSlope provided the desired sensor rate in most patients. Use of AutoSlope offsets allows fine titration of rate modulation in individual patients. Ongoing changes in sensor performance provided by AutoSlope allow patients to achieve a desired sensor rate from one evaluation to another without changes in permanent programmed settings. Programming a low maximum sensor rate may limit sensor response in some patients.