Evoked response variability as an indicator of autonomic tone and surrogate for patient condition

An implantable cardiac stimulation device comprising:

• at least one pulse generator that is capable of generating stimulation energy to be delivered to cardiac tissue;
• at least one sensor that is capable of sensing an evoked response resulting from applied stimulation energy;
• and
• a controller coupled to the at least one pulse generator and to the at least one sensor, the controller being operative to derive at least one parameter from the sensed evoked response, determine variation of the at least one parameter over time, and derive an indicator of patient condition based on the parameter variation.

A method of operating an implantable cardiac stimulation device comprising:

• delivering stimulation energy to cardiac tissue;
• sensing an evoked response of the cardiac tissue;
• deriving at least one parameter from the evoked response;
• determining variation of the at least one parameter over time;
• and
• deriving an indicator of patient condition based on the parameter variation.

An implantable cardiac stimulation device comprising:

• a pulse generator capable of coupling to cardiac tissue for stimulating an evoked response in the cardiac tissue;
• a sensor capable of coupling to the cardiac tissue for sensing the evoked response;
• a processor coupled to the pulse generator and coupled to the sensor;
• a memory coupled to the processor and capable of storing data;
• and
• executable means capable of execution in the processor for executing a sequence of actions further comprising:
• means for deriving at least one parameter from the sensed evoked response;
• means for determining variation of the at least one evoked response parameter over time;
• and
• means for deriving an indicator of patient condition based on the parameter variation.

An implantable cardiac stimulation comprising:

• means for providing stimulation energy to cardiac tissue;
• means for deriving at least one parameter from an evoked response signal;
• means for determining a variation of the at least one parameter over time;
• and
• means for deriving an indicator of patient condition based on the parameter variation.