Abstract: Apparatus and associated methods relate to an open-loop control circuit (OLCC) configured to determine a photodiode element (PDE) drive voltage as a function of a commanded photodiode gain level and a measured temperature signal. In an illustrative example the OLCC may receive a current temperature of an APD element. The OLCC may, for example, receive a commanded gain for the APD relative to a predetermined reference gain. The OLCC may, for example, retrieve a predetermined efficiency characteristic (PEC) of the APD based on the current temperature. If the temperature corresponds to a substantially non-linear portion of the PEC, the OLCC may, for example, determine the drive voltage as a function of the temperature and the commanded gain based on the PEC. Various embodiments may advantageously provide direct control of output gain of photodiodes over a wide dynamic range of temperature associated with the photodiode.

Abstract: Apparatus and associated methods relate to an open-loop control circuit (OLCC) configured to determine a photodiode element (PDE) drive voltage as a function of a commanded photodiode gain level and a measured temperature signal. In an illustrative example the OLCC may receive a current temperature of an APD element. The OLCC may, for example, receive a commanded gain for the APD relative to a predetermined reference gain. The OLCC may, for example, retrieve a predetermined efficiency characteristic (PEC) of the APD based on the current temperature. If the temperature corresponds to a substantially non-linear portion of the PEC, the OLCC may, for example, determine the drive voltage as a function of the temperature and the commanded gain based on the PEC. Various embodiments may advantageously provide direct control of output gain of photodiodes over a wide dynamic range of temperature associated with the photodiode.

Abstract: A method and apparatus for detecting a cardiac event in a medical device that includes sensing a cardiac signal, detecting a cardiac event in response to the sensed signal, determining whether an interval associated with the cardiac signal is less than an interval threshold, determining a noise metric in response to an interval associated with the cardiac signal being less than the interval threshold, determining whether the noise metric is greater than a noise metric threshold, and determining whether to inhibit detecting in response to determining whether an interval associated with the cardiac signal is less than the interval threshold and determining whether the noise metric is greater than the noise metric threshold.

Abstract: In general, this disclosure is directed to signal processing based methods to reject undersensing in a signal indicative of cardiac activity, e.g., ECG. The undersensing may be due to very small signal amplitudes or due to a sudden increase in single peak amplitude resulting in an increased sensing threshold. The undersensing may result in falsely detecting a cardiac event, e.g., asystole or bradycardia. The techniques of this disclosure monitor the behavior of the signal to determine when a detected asystole is false.

Abstract: A lead including one or more electrodes having circuitry associated therewith. Each such electrode includes a circuit extending along and conforming to at least a portion of an inner surface of the electrode. The circuit includes an isolation substrate contacting at least a portion of the inner surface of the cylindrical electrode portion, a first contact electrically isolated from the electrode portion by the isolation substrate and an integrated circuit electrically coupled to the first contact and the electrode.

Abstract: A method and apparatus for detecting a cardiac event in a medical device that includes sensing a cardiac signal, detecting a cardiac event in response to the sensed signal, determining whether an interval associated with the cardiac signal is less than an interval threshold, determining a noise metric in response to an interval associated with the cardiac signal being less than the interval threshold, determining whether the noise metric is greater than a noise metric threshold, and determining whether to inhibit detecting in response to determining whether an interval associated with the cardiac signal is less than the interval threshold and determining whether the noise metric is greater than the noise metric threshold.

Abstract: In general, this disclosure is directed to signal processing based methods to reject undersensing in a signal indicative of cardiac activity, e.g., ECG. The undersensing may be due to very small signal amplitudes or due to a sudden increase in single peak amplitude resulting in an increased sensing threshold. The undersensing may result in falsely detecting a cardiac event, e.g., asystole or bradycardia. The techniques of this disclosure monitor the behavior of the signal to determine when a detected asystole is false.

Abstract: A lead including one or more electrodes (e.g., electrodes, such as those having circuitry associated therewith).