An<unk>  The<unk>  <unk>  is a mechanical device that increases myocardial oxygen perfusion and indirectly increases cardiac output through afterload reduction. It consists of a cylindrical polyurethane balloon that sits in the aorta, approximately from the left subclavian artery. The balloon inflates and deflates via counter pulsation, meaning it actively deflates in systole and inflates in diastole. Systolic deflation decreases afterload through a vacuum effect and indirectly increases forward flow from the heart. Diastolic inflation increases blood flow to the coronary arteries via retrograde flow. These actions combine to decrease myocardial oxygen demand and increase myocardial oxygen supply. A computer-controlled mechanism inflates the balloon with helium from a cylinder during diastole, usually linked to either an electrocardiogram (ECG) or a pressure transducer at the distal tip of the catheter; some<unk> s, such as the Datascope System 98XT, allow asynchronous counterpulsation at a set rate, though this setting is rarely used. Helium is used to inflate the balloon as it is low density means there is little turbulent flow, so the balloon can inflate fast and deflate slowly. It is also relatively benign and eliminated quickly if there is a leak or rupture in the balloon.
Intra-aortic balloon pump
Corticotomy
Aortic cross-clamp
Balloon tamponade
Pericardial window
Mechanical filter 
Cardiopulmonary bypass
Pericardiocentesis