Current steering for cardiac pacing

A computer readable storage medium containing instructions that when executed by processing circuitry of an implantable medical device, cause the processing circuitry to:

• electrically connect a first current source to a first electrode of a plurality of electrodes to output an electrical current stimulation pulse to cardiac tissue;
• and
• electrically connect a second current source to a second electrode of the plurality of electrodes to sink the electrical current stimulation pulse,
• wherein a cardiac lead comprising the plurality of electrodes is coupled to the implantable medical device,
• wherein the implantable medical device is configured to deliver pacing therapy to the cardiac tissue of a heart via the plurality of electrodes of the cardiac lead,
• wherein the implantable medical device comprises the first current source configured to output an electrical current stimulation pulse and the second current source configured to sink the electrical current stimulation pulse to capture a portion of the cardiac tissue, and
• wherein a first channel of implantable medical device comprises the first current source, the first channel further comprising:
• a first switch configured to connect an output terminal of the first current source to the first electrode;
• a first recharge switch configured to connect the first electrode to a reference voltage;
• a second recharge switch configured to connect the first electrode to the reference voltage through a capacitor;
• and
• a second first channel current source, comprising an input terminal and an output terminal wherein:
• the output terminal of the second first channel current source connects to the reference voltage,
• the input terminal of the second first channel current source is configured to connect to the first electrode through the capacitor and a second switch, and
• the second first channel current source is configured to sink current from the first electrode when the second switch is closed and conducting current.

A medical system comprising:

• an implantable medical device coupled to a cardiac lead and configured to deliver pacing therapy to cardiac tissue of a heart via a plurality of electrodes of the cardiac lead, wherein the implantable medical device comprises a first current source configured to output an electrical current stimulation pulse and a second current source configured to sink the electrical current stimulation pulse to capture a portion of the cardiac tissue;
• and
• processing circuitry configured to:
• electrically connect the first current source to a first electrode of the plurality of electrodes to output the electrical current stimulation pulse to the cardiac tissue;
• and
• electrically connect the second current source to a second electrode of the plurality of electrodes to sink the electrical current stimulation pulse to the cardiac tissue,
• wherein a first channel of implantable medical device comprises the first current source,
• wherein a second channel of implantable medical device comprises the second current source,
• wherein the first channel further comprises:
• a first switch configured to connect an output terminal of the first current source to the first electrode;
• and
• a first recharge switch configured to connect the first electrode to a reference voltage (GND);
• wherein the second channel further comprises:
• a second recharge switch configured to connect the second electrode to the reference voltage through a capacitor;
• the second current source comprising an input terminal and an output terminal wherein:
• the output terminal of the second current source connects to the reference voltage,
• the input terminal of the second current source is configured to connect to the second electrode through the capacitor and a second switch, and
• the second current source is configured to sink current from the second electrode when the second switch is closed and conducting current.