Method of reducing left atrial pressure

A method of forming an opening between a coronary sinus and a left atrium, the method comprising:

• providing a first delivery catheter and a second delivery catheter pre-loaded within the first delivery catheter, and a medical device carried by a distal portion of the second delivery catheter;
• advancing the first delivery catheter, the second delivery catheter, and the medical device together from a right atrium of a heart and into the coronary sinus;
• positioning a side outlet opening of a distal portion of the first delivery catheter within the coronary sinus and orienting the side outlet opening toward the left atrium;
• expanding an expandable anchor coupled to the first delivery catheter to contact an inner surface of the coronary sinus for stabilizing the first delivery catheter within the coronary sinus;
• advancing the distal portion of the second delivery catheter outwardly through the side outlet opening toward a target wall portion of the coronary sinus;
• puncturing the target wall portion with a puncture component associated with a distal end of the second delivery catheter to form the opening between the coronary sinus and left atrium while the medical device carried by the second delivery catheter is positioned in the coronary sinus;
• and
• positioning the medical device within the opening between the coronary sinus and the left atrium.