Intra-Aortic Balloon Pump

An intra-aortic balloon pump (IABP) is a temporary mechanical circulatory support device, not a replacement heart. A helium-filled balloon sits in the descending thoracic aorta and changes aortic pressure in synchrony with the cardiac cycle. At aortic valve closure, the balloon inflates during early diastole. This raises diastolic pressure in the aortic root and improves the pressure gradient driving coronary perfusion. Immediately before ventricular systolic ejection, the balloon deflates. The resulting reduction in aortic end-diastolic pressure lowers left ventricular afterload and creates a relative vacuum effect that makes ejection easier. The desired balance is increased myocardial oxygen supply with reduced myocardial oxygen demand. The haemodynamic effect is modest: cardiac output commonly rises by approximately 0.5–1 L/min, cardiac index may improve, and pulmonary capillary wedge pressure may fall. An IABP therefore supports native cardiac function; it cannot provide adequate flow when the ventricle has little or no effective ejection. The device only helps when inflation and deflation are correctly timed. A poorly timed balloon can increase ventricular workload rather than reduce it.