Coronary sinus conduction system pacing and delivery

A delivery system for an implantable medical device, the system comprising:

• an implantable catheter advanceable into a coronary sinus of a patient's heart, the catheter comprising a sheath body extending between a proximal portion and a distal portion, the catheter comprising a side lumen and an angled opening proximal to the distal portion in fluid communication with the side lumen, wherein the side lumen and the angled opening define a deflection angle;
• a guide element receivable in the side lumen, the guide element extending from a proximal portion to a distal portion, wherein the distal portion includes at least one testing electrode, wherein the guide element is advanceable through the angled opening to be deflected laterally away from the catheter at the deflection angle to position the at least one testing electrode in a myocardium of the patient's heart when the distal portion of the catheter is positioned in the coronary sinus;
• an implantable lead receivable in the side lumen, the lead comprising a lead body extending from a proximal portion to a distal portion, wherein the implantable lead comprises an anchoring element disposed along the lead body and at least one pacing electrode disposed along the distal portion, wherein the lead is advanceable through the angled opening to be deflected laterally away from the catheter at the deflection angle to implant the at least one pacing electrode in the myocardium to pace a conduction system of the patient's heart;
• and
• an electrical analyzer operably coupled to the at least one testing electrode, the electrical analyzer configured to provide pacing pulses to a potential implant location when the at least one testing electrode is positioned in the myocardium of the patient's heart and the distal portion of the catheter is positioned in the coronary sinus.

A method comprising:

• advancing a catheter into a coronary sinus of a patient's heart, the catheter comprising a sheath body extending between a proximal portion and a distal portion, the catheter comprising a side lumen and an angled opening proximal to the distal portion in fluid communication with the side lumen;
• orienting the angled opening toward a wall of the coronary sinus proximate to a conduction system of the patient's heart;
• advancing a guide element including at least one testing electrode through the side lumen and the angled opening, the guide element extending from a proximal portion to a distal portion, wherein the angled opening is configured to deflect the guide element laterally away from the catheter to position the at least one testing electrode in a myocardium of the patient's heart;
• pacing one or more potential implant locations using the at least one testing electrode positioned in the myocardium;
• monitoring QRS duration corresponding to each potential implant location in response to pacing the one or more potential implant locations;
• and
• implanting at least one pacing electrode of an implantable lead at a selected implant location of the potential implant locations based on a corresponding QRS duration below a duration threshold.