When does the intra-aortic balloon pump inflate?

The intra-aortic balloon pump (IABP) operates by inflating at the onset of diastole, which corresponds with aortic valve closure. This timing is critical because the IABP is designed to increase myocardial oxygen supply during diastole by augmenting diastolic pressure, thus improving coronary perfusion.

When the aortic valve closes, blood flow into the aorta ceases, allowing the balloon to inflate with helium. This inflation occurs just as the heart is preparing for the next contraction, efficiently displacing blood and enhancing circulation. By understanding the specific timing of the balloon inflation, it becomes clear that this mechanism is crucial for optimizing the support provided to patients with compromised cardiac function.

The other choices refer to either phases of the cardiac cycle that do not coincide with the effective timing of IABP inflation. The IABP mechanics are intricately linked to the timing of the cardiac cycle to maximize its benefits in assisting with cardiac output and perfusion.