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.