Portable device for monitoring electrocardiographic signals and indices of blood flow

An implantable monitoring device comprising:

• a device body configured to be implanted subcutaneously into a patient;
• a plurality of impedance electrodes configured on or near the device body and for implantation into the patient with the device body, the plurality of impedance electrodes being configured to be positioned less than about 5 centimeters from an extra-cardiac artery or extra-cardiac tissue that pulsates in response to pulses in the extra-cardiac artery, the plurality of impedance electrodes adapted to inject a current across the extra-cardiac artery or extra-cardiac tissue and measure a resulting voltage across the extra-cardiac artery or extra-cardiac tissue to determine an extra-cardiac arterial electrical impedance measure across a path that traverses the extra-cardiac artery or extra-cardiac tissue, the extra-cardiac arterial electrical impedance measure being indicative of pressure in the extra-cardiac artery;
• a plurality of electrocardiographic, ECG, electrodes configured on or near the device body and for implantation into the patient with the device body, the plurality of ECG electrodes adapted to detect an ECG signal of the patient;
• a memory in operable communication with a processor programmed to store in the memory information from which a hypotension episode of the patient is identifiable and from which it is determinable whether an ECG signal accompanying an identified hypotension episode was normal during the identified hypotension episode, the information comprising both the extra-cardiac arterial electrical impedance measures and the accompanying ECG signal obtained over a period of time by, respectively, the plurality of impedance electrodes and the plurality of ECG electrodes, the processor being programmed to store the extra-cardiac arterial electrical impedance measures and the accompanying ECG signal for the period of time in a manner such that the extra-cardiac arterial electrical impedance measures and the accompanying ECG signal are correlated with one another in time, wherein the memory and the processor are each disposed within the device body;
• and
• a telemetry component disposed inside the body of the device, wherein the processor is programmed to control the telemetry component to transmit the stored and time correlated extra-cardiac arterial electrical impedance measures and the accompanying ECG signal for the period of time to a device external of the patient.