An implantable medical device, comprising: processing circuitry configured to receive input signals from one or more sensors, the input signals comprising signals generated in response to measured physiological parameters associated with a patient, and to determine a status for each of a set of input parameters based on the input signals, the status for each of the set of input parameters indicative of whether or not current value for the input parameter satisfies a threshold value for that input parameter; trigger circuitry configured to automatically generate a trigger output signal based at least in part on a determination that the statuses of the input parameters are indicative of the patient engaging in a patient initiated physical activity; and communication circuitry configured to receive the trigger output signal generated by the trigger circuitry, and to wirelessly transmit the trigger output signal to a pressure sensing device that is implanted in a vessel of the cardiovascular system of the patient, the pressure sensing device configured to sense a cardiovascular pressure upon receipt of the trigger output signal; and characterized by further comprising a timer, the timer configured to provide a status indication that is indicative of whether a minimum time period has elapsed since the last occurrence of the trigger circuitry issuing a trigger output signal; the trigger circuitry configured to receive that status indication provided by the timer, and to only issue a trigger output signal if the status indication indicates that the minimum time period has elapsed since the last issuance of a trigger output signal. processing circuitry configured to receive input signals from one or more sensors, the input signals comprising signals generated in response to measured physiological parameters associated with a patient, and to determine a status for each of a set of input parameters based on the input signals, the status for each of the set of input parameters indicative of whether or not current value for the input parameter satisfies a threshold value for that input parameter; trigger circuitry configured to automatically generate a trigger output signal based at least in part on a determination that the statuses of the input parameters are indicative of the patient engaging in a patient initiated physical activity; and communication circuitry configured to receive the trigger output signal generated by the trigger circuitry, and to wirelessly transmit the trigger output signal to a pressure sensing device that is implanted in a vessel of the cardiovascular system of the patient, the pressure sensing device configured to sense a cardiovascular pressure upon receipt of the trigger output signal; and characterized by further comprising a timer, the timer configured to provide a status indication that is indicative of whether a minimum time period has elapsed since the last occurrence of the trigger circuitry issuing a trigger output signal; the trigger circuitry configured to receive that status indication provided by the timer, and to only issue a trigger output signal if the status indication indicates that the minimum time period has elapsed since the last issuance of a trigger output signal.