A medical device system , comprising: an implantable medical device comprising: a control circuit configured to: determine a numerical value of a monitored variable that is monitored by the implantable medical device based on a monitoring protocol; and convert the numerical value of the monitored variable to a data sequence comprising a plurality of modulated stimulation rate intervals; and a pulse generator configured to deliver a plurality of electrical stimulation pulses according to the plurality of modulated stimulation rate intervals of the data sequence to cause a modulated rate of activation of an excitable tissue of a patient that corresponds to the modulated stimulation rate intervals, the modulated rate of activation being detectable by a rate monitor for demodulation of the modulated rate of activation to the numerical value of the monitored variable, characterized in that the pulse generator is configured to deliver a modulated stimulation rate sequence including: a header comprising at least one modulated stimulation rate interval; and the data sequence following the header , wherein the control circuit is configured to set the at least one modulated stimulation rate interval of the header to indicate information about the data sequence . an implantable medical device comprising: a control circuit configured to: determine a numerical value of a monitored variable that is monitored by the implantable medical device based on a monitoring protocol; and convert the numerical value of the monitored variable to a data sequence comprising a plurality of modulated stimulation rate intervals; and a pulse generator configured to deliver a plurality of electrical stimulation pulses according to the plurality of modulated stimulation rate intervals of the data sequence to cause a modulated rate of activation of an excitable tissue of a patient that corresponds to the modulated stimulation rate intervals, the modulated rate of activation being detectable by a rate monitor for demodulation of the modulated rate of activation to the numerical value of the monitored variable, a control circuit configured to: determine a numerical value of a monitored variable that is monitored by the implantable medical device based on a monitoring protocol; and convert the numerical value of the monitored variable to a data sequence comprising a plurality of modulated stimulation rate intervals; and determine a numerical value of a monitored variable that is monitored by the implantable medical device based on a monitoring protocol; and convert the numerical value of the monitored variable to a data sequence comprising a plurality of modulated stimulation rate intervals; and a pulse generator configured to deliver a plurality of electrical stimulation pulses according to the plurality of modulated stimulation rate intervals of the data sequence to cause a modulated rate of activation of an excitable tissue of a patient that corresponds to the modulated stimulation rate intervals, the modulated rate of activation being detectable by a rate monitor for demodulation of the modulated rate of activation to the numerical value of the monitored variable, characterized in that the pulse generator is configured to deliver a modulated stimulation rate sequence including: a header comprising at least one modulated stimulation rate interval; and the data sequence following the header , a header comprising at least one modulated stimulation rate interval; and the data sequence following the header , wherein the control circuit is configured to set the at least one modulated stimulation rate interval of the header to indicate information about the data sequence . <EOS>