Rate responsive pacemaker adapted to adjust lower rate limit according to monitored patient blood temperature

A rate responsive pacemaker system, having a controllable pulse generator for producing and delivering pace pulses, rate means for sensing at least one parameter containing information indicative of desired pacing rate and control means for controlling the rate of delivery of pace pulses as a function of said at least one parameter, said control means further comprising limit means for limiting rate pacing adjustment to rates above a low rate limit (LRL), and having LRL means for adjusting said LRL, said LRL means further comprising:

• a temperature sensor for determining patient blood temperature,
• threshold means for setting a low blood temperature threshold, said threshold means comprises low temperature means for determining patient daily average low blood temperature;
• temperature rate means for determining a measure of the rate of drop of patient blood temperature,
• determining means for determining the occurrence when patient blood temperature has fallen below said temperature threshold and said rate of drop has exceeded a predetermined rate, and
• initiating means for initiating a drop of LRL to a lower LRL when a said occurrence is determined.