The invention is generally directed to an accessing system for a patient's coronary sinus which includes a tubular support member with a distal extremity extending into the right atrium of the patient's heart. A guide member is disposed within a first lumen of the tubular support member and advanced out an angled distal tip, through the patient's coronary sinus ostium and into the coronary sinus. A stabilizing member, similar to a conventional intravascular guidewire, is disposed within a second lumen of the tubular support member and extends into the right ventricle of the patient and is seated in the apex thereof. To advance the guide member into the CS ostium, the position of the distal extremity of the tubular support member is adjusted within the atrial chamber by moving longitudinally along or rotating about (or both) the stabilizing member and the guide member is advanced into the CS ostium. These steps may be repeated in a predetermined pattern in order to pass into the coronary sinus ostium.