Abstract: In some examples, a medical system includes a medical device. The medical device may include a housing configured to be implanted in a target site of a patient, a light emitter configured to emit a signal configured to cause a fluorescent marker to emit a fluoresced signal into the target site, and a light detector that may be configured to detect the fluoresced signal. The medical system may include processing circuitry configured to determine a characteristic of the fluorescent marker based on the emitted signal and the fluoresced signal. The characteristic of the fluorescent marker may be indicative of a presence of a compound in the patient, and the processing circuitry may be configured to track the presence of the compound of the patient based on the characteristic of the fluorescent marker.

Abstract: A relatively compact implantable medical device includes a fixation member formed by a plurality of fingers mounted around a perimeter of a distal end of a housing of the device; each finger is elastically deformable from a relaxed condition to an extended condition, to accommodate delivery of the device to a target implant site, and from the relaxed condition to a compressed condition, to accommodate wedging of the fingers between opposing tissue surfaces at the target implant site, wherein the compressed fingers hold a cardiac pacing electrode of the device in intimate tissue contact for the delivery of pacing stimulation to the site. Each fixation finger is preferably configured to prevent penetration thereof within the tissue when the fingers are compressed and wedged between the opposing tissue surfaces. The pacing electrode may be mounted on a pacing extension, which extends distally from the distal end of the device housing.

Abstract: In some examples, a medical system includes a medical device. The medical device may include a housing configured to be implanted in a target site of a patient, a light emitter configured to emit a signal configured to cause a fluorescent marker to emit a fluoresced signal into the target site, and a light detector that may be configured to detect the fluoresced signal. The medical system may include processing circuitry configured to determine a characteristic of the fluorescent marker based on the emitted signal and the fluoresced signal. The characteristic of the fluorescent marker may be indicative of a presence of a compound in the patient, and the processing circuitry may be configured to track the presence of the compound of the patient based on the characteristic of the fluorescent marker.

Abstract: A biocompatible medical device may include an electrochemical sensor including a common reference electrode; at least one counter electrode; and a work electrode platform comprising a plurality of respective work electrodes, each respective work electrode electrically coupled to the common reference electrode and comprising a respective reagent substrate configured to react with a respective analyte to produce a respective signal indicative of a concentration of the respective analyte; and processing circuitry operatively coupled to the electrochemical sensor, and configured to receive from the electrochemical sensor a plurality of signals from the plurality of respective work electrodes; identify the respective signal corresponding to a respective selected work electrode; and process the identified signal to determine the concentration of the respective analyte associated with the respective selected work electrode.

Abstract: Techniques are disclosed for measuring an analyte in a biological system. A system may include a medical device with an electrochemical sensor configured to sense the concentration of a plurality of analytes present in a biological system. Processing circuitry of the system may retrieve, identify, and process a respective signal from a respective work electrode to determine the concentration of a respective analyte. The system may further include an implantable medical device configured to sense a cardiac electrogram (EGM). In some examples, the system may be configured to determine one or more patient-specific relationships between the respective signals of the electrochemical sensor and the cardiac EGM during a first period of time. Based on the patient-specific relationships, the system may estimate concentrations of the one or more analytes corresponding to the respective signals based on the cardiac EGM of the patient collected over a second period of time.

Abstract: A method for implanting a medical lead. The method includes advancing a tunneling tool posteriorly proximate the caudal end of the sternum toward a first location. The tunneling tool is advanced superiorly underneath the sternum through the anterior mediastinum from the first location to a second location cranial to the first location. A guidewire is advanced from the first location to the second location. A medical lead is slid along at least a portion of the guidewire, the medical lead at least substantially spanning the distance between the first location and the second location.

Abstract: Systems, devices, and techniques for establishing communication between two medical devices are described. In one example, an implantable medical device comprises communication circuitry, therapy delivery circuitry, and processing circuitry configured to initiate a communication window during which the implantable second medical device is capable of receiving the information related to a cardiac event detected by a first medical device, the communication window being one of a plurality of communication windows defined by a communication schedule that corresponds to a transmission schedule in which the first medical device is configured to transmit the information, control the communication circuitry to receive, from the first medical device, the information related to the cardiac event that is indicative of a timing of the cardiac event with respect to a timing of the communication window, schedule and control delivery of a therapy according to the information related to the cardiac event.

Abstract: In some examples, a medical system includes a medical device. The medical device may include a housing configured to be implanted in a target site of a patient, a light emitter configured to emit a signal configured to cause a fluorescent marker to emit a fluoresced signal into the target site, and a light detector that may be configured to detect the fluoresced signal. The medical system may include processing circuitry configured to determine a characteristic of the fluorescent marker based on the emitted signal and the fluoresced signal. The characteristic of the fluorescent marker may be indicative of a presence of a compound in the patient, and the processing circuitry may be configured to track the presence of the compound of the patient based on the characteristic of the fluorescent marker.

Abstract: A biocompatible medical device may include an electrochemical sensor including a common reference electrode; at least one counter electrode; and a work electrode platform comprising a plurality of respective work electrodes, each respective work electrode electrically coupled to the common reference electrode and comprising a respective reagent substrate configured to react with a respective analyte to produce a respective signal indicative of a concentration of the respective analyte; and processing circuitry operatively coupled to the electrochemical sensor, and configured to receive from the electrochemical sensor a plurality of signals from the plurality of respective work electrodes; identify the respective signal corresponding to a respective selected work electrode; and process the identified signal to determine the concentration of the respective analyte associated with the respective selected work electrode.

Abstract: In some examples, a medical system includes a medical device. The medical device may include a housing configured to be implanted in a target site of a patient, a light emitter configured to emit a signal configured to cause a fluorescent marker to emit a fluoresced signal into the target site, and a light detector that may be configured to detect the fluoresced signal. The medical system may include processing circuitry configured to determine a characteristic of the fluorescent marker based on the emitted signal and the fluoresced signal. The characteristic of the fluorescent marker may be indicative of a presence of a compound in the patient, and the processing circuitry may be configured to track the presence of the compound of the patient based on the characteristic of the fluorescent marker.

Abstract: A biocompatible medical device may include an electrochemical sensor including a common reference electrode; at least one counter electrode; and a work electrode platform comprising a plurality of respective work electrodes, each respective work electrode electrically coupled to the common reference electrode and comprising a respective reagent substrate configured to react with a respective analyte to produce a respective signal indicative of a concentration of the respective analyte; and processing circuitry operatively coupled to the electrochemical sensor, and configured to receive from the electrochemical sensor a plurality of signals from the plurality of respective work electrodes; identify the respective signal corresponding to a respective selected work electrode; and process the identified signal to determine the concentration of the respective analyte associated with the respective selected work electrode.

Abstract: A relatively compact implantable medical device includes a fixation member formed by a plurality of fingers mounted around a perimeter of a distal end of a housing of the device; each finger is elastically deformable from a relaxed condition to an extended condition, to accommodate delivery of the device to a target implant site, and from the relaxed condition to a compressed condition, to accommodate wedging of the fingers between opposing tissue surfaces at the target implant site, wherein the compressed fingers hold a cardiac pacing electrode of the device in intimate tissue contact for the delivery of pacing stimulation to the site. Each fixation finger is preferably configured to prevent penetration thereof within the tissue when the fingers are compressed and wedged between the opposing tissue surfaces. The pacing electrode may be mounted on a pacing extension, which extends distally from the distal end of the device housing.

Abstract: The disclosure describes systems and techniques for detection of pump thrombosis in mechanical circulatory support (MCS) devices. An example pump thrombosis detection system includes a transducer and processing circuitry. The transducer may be configured to generate a signal representative of a mechanical wave from a mechanical circulatory support device. The processing circuitry is communicatively coupled to the transducer. The processing circuitry may be configured to determine an indication of pump thrombosis based on the signal and, based on the indication of pump thrombosis, control the pump thrombosis detection system to at least one of generate an alert or initiate an intervention.

Abstract: A relatively compact implantable medical device includes a fixation member formed by a plurality of fingers mounted around a perimeter of a distal end of a housing of the device; each finger is elastically deformable from a relaxed condition to an extended condition, to accommodate delivery of the device to a target implant site, and from the relaxed condition to a compressed condition, to accommodate wedging of the fingers between opposing tissue surfaces at the target implant site, wherein the compressed fingers hold a cardiac pacing electrode of the device in intimate tissue contact for the delivery of pacing stimulation to the site. Each fixation finger is preferably configured to prevent penetration thereof within the tissue when the fingers are compressed and wedged between the opposing tissue surfaces. The pacing electrode may be mounted on a pacing extension, which extends distally from the distal end of the device housing.

Abstract: In some examples, determining a heart failure status includes using an implantable medical device configured for subcutaneous implantation and comprising a plurality of electrodes and an optical sensor. Processing circuitry of a system comprising the device may determine, for a patient, a current tissue oxygen saturation value based on a signal received from the at least one optical sensor, a current tissue impedance value based on a subcutaneous tissue impedance signal received from the electrodes, and a current pulse transit time value based on a cardiac electrogram signal received from the electrodes and at least one of the signal received from the optical sensor and the subcutaneous tissue impedance signal. The processing circuitry may further compare the current tissue oxygen saturation value, current tissue impedance value, and current pulse transit time value to corresponding baseline values, and determine the heart failure status of the patient based on the comparison.

Abstract: In some examples, determining a health status includes using an implantable medical device configured for subcutaneous implantation and comprising at least one optical sensor. Processing circuitry of a system comprising the device may determine, for a patient, a current tissue oxygen saturation value based on a first signal received from the at least one optical sensor and a current pulsatile oxygen saturation value based on a second signal received from the at least one optical sensor. The processing circuitry may further compare the current tissue oxygen saturation and current pulsatile oxygen saturation values to corresponding baseline values, determine corresponding heart failure and pulmonary statuses of the patient based on the comparisons, and determine the health status of the patient based on the statuses.

Abstract: In some examples, a medical system includes a medical device. The medical device may include a housing configured to be implanted in a target site of a patient, a light emitter configured to emit a signal configured to cause a fluorescent marker to emit a fluoresced signal into the target site, and a light detector that may be configured to detect the fluoresced signal. The medical system may include processing circuitry configured to determine a characteristic of the fluorescent marker based on the emitted signal and the fluoresced signal. The characteristic of the fluorescent marker may be indicative of a presence of a compound in the patient, and the processing circuitry may be configured to track the presence of the compound of the patient based on the characteristic of the fluorescent marker.

Abstract: In some examples, a medical system includes a medical device. The medical device may include a housing configured to be implanted in a target site of a patient, a light emitter configured to emit a signal configured to cause a fluorescent marker to emit a fluoresced signal into the target site, and a light detector that may be configured to detect the fluoresced signal. The medical system may include processing circuitry configured to determine a characteristic of the fluorescent marker based on the emitted signal and the fluoresced signal. The characteristic of the fluorescent marker may be indicative of a presence of a compound in the patient, and the processing circuitry may be configured to track the presence of the compound of the patient based on the characteristic of the fluorescent marker.

Abstract: A method for implanting a medical lead. The method includes advancing a tunneling tool posteriorly proximate the caudal end of the sternum toward a first location. The tunneling tool is advanced superiorly underneath the sternum through the anterior mediastinum from the first location to a second location cranial to the first location. A guidewire is advanced from the first location to the second location. A medical lead is slid along at least a portion of the guidewire, the medical lead at least substantially spanning the distance between the first location and the second location.

Abstract: Systems, devices, and techniques for establishing communication between two medical devices are described. In one example, an implantable medical device comprises communication circuitry, therapy delivery circuitry, and processing circuitry configured to initiate a communication window during which the implantable second medical device is capable of receiving the information related to a cardiac event detected by a first medical device, the communication window being one of a plurality of communication windows defined by a communication schedule that corresponds to a transmission schedule in which the first medical device is configured to transmit the information, control the communication circuitry to receive, from the first medical device, the information related to the cardiac event that is indicative of a timing of the cardiac event with respect to a timing of the communication window, schedule and control delivery of a therapy according to the information related to the cardiac event.