A lead-in-lead system may include a first implantable lead having a first electrode and a second implantable lead having a second electrode guided by the first implantable lead to an implantation site. The second electrode may be implanted in a patient's heart distal to the first electrode at the same implantation site or at a second implantation site. Various methods may be used to deliver the lead-in-lead system to one or more implantation sites including at the triangle of Koch for ventricle-from-atrium (VfA) therapy, at the right ventricular septal wall for dual bundle-branch pacing, or in the coronary vasculature for left side sensing and pacing.
