Implantable medical device with distal electrode arrangement

A method comprising:

• sensing, by sensing circuitry of an implantable medical device (IMD) and via a plurality of combinations of a distal electrode extending distally from a distal end of an elongated housing of the IMD, a reference electrode extending from the distal end of the elongated housing, and one or more proximal electrodes extending from the distal end of the elongated housing, a plurality of electrical signals from a heart;
• determining, by processing circuitry of the IMD and based on the sensed electrical signals and a sensing vector, a combined electrical signal;
• and
• delivering, by one or more of the distal electrode and the one or more proximal electrodes, cardiac pacing therapy to one or more chambers of the heart based on the combined signal,
• wherein the distal electrode is configured to penetrate into the wall tissue of the second chamber, and wherein the one or more proximal electrodes and the reference electrode are configured to maintain contact with the wall tissue of the first chamber without penetration of the wall tissue of the first chamber by the one or more proximal electrodes.

A device comprising:

• an elongated housing extending from a proximal end to a distal end, the elongated housing being configured to be implanted wholly within a first chamber of a heart;
• a distal electrode extending distally from the distal end of the elongated housing, the distal electrode being configured to penetrate into wall tissue of a second chamber of the heart, the second chamber of the heart being separated from the first chamber of the heart;
• two proximal electrodes extending from the distal end of the elongated housing, wherein the two proximal electrodes are separate from the distal electrode, and wherein each proximal electrode of the two proximal electrodes is configured to maintain contact with wall tissue of the first chamber without penetration of the wall tissue of the first chamber;
• a reference electrode extending from the distal end of the elongated housing and separate from the distal electrode and the two or more proximal electrodes, the reference electrode being configured to:
• define a first axis with the distal electrode;
• define a second axis with a first proximal electrode of the two proximal electrodes;
• and
• define a third axis with a second proximal electrode of the two proximal electrodes;
• sensing circuitry disposed within the elongated housing;
• signal generation circuitry disposed within the elongated housing;
• and
• processing circuitry within the elongated housing, the processing circuitry being configured to:
• cause the sensing circuitry to sense electrical signals from the heart along at least two of the first axis, the second axis, and the third axis via the distal electrode, the first proximal electrode, and the second proximal electrode, respectively;
• determine, based on the sensed electrical signals and a three-dimensional (3D) sensing vector, a combined signal;
• and
• cause the signal generation circuitry to deliver cardiac pacing therapy to the heart via one or more of the distal electrode, the first proximal electrode, or the second proximal electrode based on the combined electrical signal.