Single-pass left-sided ddd pacing lead

A system comprising:

• a single-pass cardiac pacing lead configured to deliver cardiac pacing stimulation to a right atrium and a left ventricle of a heart, the lead comprising:
• a lead body component comprising a proximal end and a distal end,
• a first electrode and a second electrode wherein the first and second electrodes are configured with a relative spacing such that, when a distal portion of the lead body component is implanted within the coronary sinus, the first electrode is positioned within a cardiac vein of the heart, the second electrode is positioned within the right atrium of the heart, and the second electrode is positioned proximate an atrium of the heart, and
• a fixation member attached to the lead body and spaced along the lead body to be located within the coronary sinus when the distal portion of the lead body component is implanted within the coronary sinus;
• and
• a processor configured to receive sensed cardiac signals from at least the first second electrode to control electrical stimulation provided first electrode;
• wherein the processor is further configured to detect an AV block based on signals sensed by the second electrode and, in response to detecting the AV block, provide a ventricular pace electrical stimulation pulse via the first electrode.