What is the primary hemodynamic effect of an intra-aortic balloon pump (IABP) when it inflates during diastole?

• A. Increases afterload.
• B. Increases coronary perfusion during diastole.
• C. Decreases cardiac output.
• D. Provides oxygenation.

Answer: (B)

The balloon inflates at end-diastole to boost coronary perfusion. By filling during diastole, it raises aortic diastolic pressure, increasing the pressure gradient into the coronary arteries and improving blood flow to the myocardium. This enhances oxygen delivery to the heart muscle, especially during diastole when the coronary vessels are perfused. The afterload reduction that helps cardiac output comes from balloon deflation just before systole, not from diastolic inflation. It doesn’t provide oxygenation, which is a lung function, not the IABP’s role. So the primary diastolic effect is increased coronary perfusion during diastole.