Orientation determination for an implantable medical device

A system, comprising:

• an implantable medical device (IMD), comprising:
• at least three subcutaneous electrodes having fixed relative spacing, for detecting electrical signals;
• a hermetically sealed, biocompatible housing;
• a power supply installed within the housing;
• electronic components installed within the housing and energized by the power supply, including:
• signal conditioning components, wherein each signal conditioning component is connected between a pair of electrodes for sensing amplitudes of electrical activity so as to form a set of at least three sensing vectors;
• a digital memory;
• a processor connected to the digital memory and the signal conditioning components, the processor being implemented to receive data from the signal conditioning components, compute amplitude ratios corresponding to each of the sensing vectors, and store in the digital memory the amplitude ratios corresponding to at least one orientation of the IMD, and determine an orientation of the IMD, by comparing the computed amplitude ratios to the stored amplitude ratios;
• and
• a telemetry unit, connected to the processor, for transmitting the orientation;
• and
• a remote device, for receiving the transmitted orientation, storing the orientation in the digital memory, and comparing different stored orientations to determine a change in orientation of the IMD.

A method of determining an orientation for an implanted medical device (IMD), comprising:

• detecting at least three electrical signals;
• conditioning the electrical signals so as to form a set of at least three sensing vectors;
• computing amplitude ratios corresponding to each of the sensing vectors;
• storing the amplitude ratios corresponding to at least one orientation of the IMD;
• and
• determining the orientation of the IMD by comparing the computed amplitude ratios to the stored amplitude ratios.

A computer-implemented method of determining an orientation change of an implantable medical device (IMD), comprising:

• detecting at least three electrical signals;
• conditioning the electrical signals so as to form a set of at least three sensing vectors;
• computing amplitude ratios corresponding to each of the sensing vectors;
• storing the amplitude ratios corresponding to at least one orientation of the IMD in a digital memory;
• determining an orientation of the IMD by comparing the computed amplitude ratios to the stored amplitude ratios;
• transmitting the determined orientation to a remote device;
• receiving the determined orientation at the remote device;
• storing the orientation in the digital memory;
• and
• comparing orientations stored at different times to determine an orientation change of the IMD.