Abstract: Techniques for determining a patient's orientation using an accelerometer that is part of a medical device carried by or implanted in a patient. The medical device may use the accelerometer to determine the orientation of the medical device with respect to gravity. When the medical device is fixed in a known orientation on the patient, the medical device may perform a calculation to determine the orientation of a patient. To simplify calculations and reduce power consumption, the device may calculate an inner product (dot product) multiplication between the orientation vector of the medical device and one or more known reference templates. In some examples, the medical device may determine which reference template is closest to the orientation vector, based on the dot product. In other examples, the medical device may determine one or more body part angles for the patient, based on the dot product.

Abstract: A three-axis accelerometer signal is used in a medical device for detecting that a patient has fallen. The accelerometer signal is sampled at a low sampling rate for determining a patient position. The accelerometer signal is sampled at a high sampling rate for determining an acceleration magnitude in response to determining the patient position. The patient position and acceleration magnitude are used to detect that a patient has fallen.

Abstract: An implantable medical device and associated method predict syncope based on detecting a change in ejection time. A physiological signal is sensed that is responsive to mechanical changes associated with the cardiac ejection phase. A time interval corresponding to cardiac ejection time is detected from the physiological signal. A sudden change in the time interval is used as a predictor of syncope and causes a patient alert to be generated in response to the detected change.

Abstract: An implantable medical device having a prioritized multiplexor sensing circuit used for monitoring the condition or status of a patient. The device includes patient parameter sensors, such as electrodes, that are monitored for indications of significant events. Sensors indicating the presence of significant events may then be monitored more often than the other sensors.

Abstract: Waveform analysis is used to identify and distinguish components of a sensed input signal, such as P-wave and Far Field R-wave signal components present in a sensed cardiac signal, even when the components are so closely spaced in time that the overlap to create a distorted input signal. A set of composite waveforms are generated by superimposing waveform templates of the signal components with different time delays or degree of overlap. Form parameters for each composite waveform are derived and mapped in a multidimensional map, from which form parameter boundaries are derived. Waveform data is collected from an input signal during a sensed event time window, and form parameters for the input signal waveform are derived. An output identifying the signal component of interest (e.g., a P-wave) and its location within the sensed event time window is produced based upon the set of form parameters of the input signal waveform and the form parameter boundaries.

Abstract: A method and device for detecting the implanted orientation of an implantable medical device (IMD) in a patient. IMD includes an accelerometer for measuring acceleration signals in three orthogonal directional axes. A y-axis orientation of IMD is determined from the measured accelerometer signals using a gravitational force analysis. IMD includes a magnetic sensor that senses a varying magnetic field exerted on the magnetic sensor from an external magnet moved along a medial-lateral direction with respect to IMD. The z-axis orientation of IMD is determined from the location of the external magnet where the magnetic field exerted on the magnetic sensor is greatest. Based on a known relationship between the accelerometer and magnetic sensor, an orthogonal transformation calculation is performed on the y-axis and z-axis orientations to yield the x-axis orientation. The implanted orientation of IMD with respect to the patient is thus known and used to compensate accelerometer measurements.

Abstract: A three-axis accelerometer signal is used in a medical device for detecting that a patient has fallen. The accelerometer signal is sampled at a low sampling rate for determining a patient position. The accelerometer signal is sampled at a high sampling rate for determining an acceleration magnitude in response to determining the patient position. The patient position and acceleration magnitude are used to detect that a patient has fallen.

Abstract: An implantable medical device and associated method predict syncope based on detecting a change in ejection time. A physiological signal is sensed that is responsive to mechanical changes associated with the cardiac ejection phase. A time interval corresponding to cardiac ejection time is detected from the physiological signal. A sudden change in the time interval is used as a predictor of syncope and causes a patient alert to be generated in response to the detected change.

Abstract: An implantable loop recorder (ILR) is subcutaneously implantable to record cardiac data. The ILR includes a patient activation mechanism whereby the patient can input commands to the ILR without using an external device. The patient activation mechanism may be a subcutaneous switch disposed on an outer portion of the ILR or a motion sensor that senses tapping of the device as an input. The patient input will direct the device to store data, telemeter data, or send a message summoning an emergency response. The ILR has distance telemetry capabilities so that a telemetered message is wirelessly transmitted to an external device which then relays the message to a remote location.

Abstract: Waveform analysis is used to identify and distinguish components of a sensed input signal, such as P-wave and Far Field R-wave signal components present in a sensed cardiac signal, even when the components are so closely spaced in time that the overlap to create a distorted input signal. A set of composite waveforms are generated by superimposing waveform templates of the signal components with different time delays or degree of overlap. Form parameters for each composite waveform are derived and mapped in a multidimensional map, from which form parameter boundaries are derived. Waveform data is collected from an input signal during a sensed event time window, and form parameters for the input signal waveform are derived. An output identifying the signal component of interest (e.g., a P-wave) and its location within the sensed event time window is produced based upon the set of form parameters of the input signal waveform and the form parameter boundaries.

Abstract: An implantable medical device having a prioritized multiplexor sensing circuit used for monitoring the condition or status of a patient. The device includes patient parameter sensors, such as electrodes, that are monitored for indications of significant events. Sensors indicating the presence of significant events may then be monitored more often than the other sensors.

Abstract: Method and device for determining capture status of a heart chamber that receives a pulse from an implantable pulse generator (IPG). Signal processing can be used to improve the reliability of capture detection by transforming the sensed response signal into a set of morphological characteristics. Analysis of selected morphological characteristics serves to distinguish signals indicative of capture from signals indicative of loss of capture.

Abstract: In general, the invention is directed to techniques for determining capture status of a heart chamber that receives a pulse from an implantable pulse generator (IPG). Digital signal processing (DSP) can be used to improve the reliability of capture detection by transforming the sensed response signal into a set of morphological characteristics. Analysis of selected morphological characteristics serves to distinguish signals indicative of capture from signals indicative of loss of capture.