A system for accessing a patient's cardiac anatomy which includes an occlusion catheter with a first expandable member or balloon in a distal extremity of the catheter which when expanded within the patient's ascending aorta separates the heart and coronary blood vessels from the rest of the patient's arterial system, and a second expandable member, distal to the first, which when expanded will be seated within the left ventricle. A cardiopulmonary bypass system is connected to a major vein, e.g. femoral, to withdraw blood, remove carbon dioxide, oxygenate the withdrawn blood and then return the oxygenated blood to the patient's arterial system through a major artery. Preferably, the heart muscle or myocardium is paralyzed by the antegrade and/or retrograde delivery of a liquid containing cardioplegic material to the myocardium through patient's coronary arteries or coronary sinus. The cardiac accessing system is suitable for a wide variety of cardiac procedures including opened and closed chest procedures.