Dual sensors to control pacing rate

A method comprising:

• generating cardiac pacing pulses at a pacing rate;
• generating an acceleration signal;
• generating a temperature signal;
• storing a transfer function that relates an activity metric to a target cardiac pacing rate, the transfer function being defined by at least one slope and at least one set point;
• determining a first activity metric representative of patient physical activity from the acceleration signal;
• determining from the acceleration signal a second activity metric representative of patient physical activity at a time later than the first activity metric;
• determining the target cardiac pacing rate based on the second activity metric according to the transfer function;
• determining that the second activity metric is equal to or greater than the first activity metric;
• determining a temperature change from the temperature signal;
• in response to the second activity metric being equal to or greater than the first activity metric, determining an adjusted target cardiac pacing rate by:
• adjusting the transfer function by adjusting at least one of the at least one slope or the least one set point based on the temperature change;
• and
• determining the adjusted target cardiac pacing rate based on the second activity metric according to the adjusted transfer;
• and
• adjusting the pacing rate according to the adjusted target cardiac pacing rate.

A non-transitory, computer-readable storage medium storing a transfer function that relates an activity metric to a target cardiac pacing rate, the transfer function being defined by at least one slope and at least one set point, and storing a set of instructions which, when executed by a control circuit of a medical device, cause the medical device to:

• deliver cardiac pacing pulses at a pacing rate;
• generate an acceleration signal;
• generate a temperature signal;
• determine a first activity metric representative of patient physical activity from the acceleration signal;
• determine from the acceleration signal a second activity metric representative of patient physical activity at a time later than the first activity metric;
• determine the target cardiac pacing rate based on the second activity metric according to the transfer function;
• determine that the second activity metric is equal to or greater than the first activity metric and the first activity metric is greater than a first set point of the at least one set point of the transfer function;
• determine a temperature change from the temperature signal;
• and
• in response to the second activity metric being greater than or equal to the first activity metric, determine an adjusted target cardiac pacing rate based at least on the temperature change by:
• adjusting the transfer function by adjusting at least one of the at least one slope or the least one set point based on the temperature change;
• and
• determining the adjusted target cardiac pacing rate based on the second activity metric according to the adjusted transfer function;
• and
• adjust the pacing rate according to the adjusted target cardiac pacing rate.