American Board of Surgery Qualifying Exam (ABS QE) Practice Test

During diastole, the function of an intra-aortic balloon pump (IABP) is to inflate. When the balloon inflates during diastole, it creates a significant increase in pressure within the aorta, which enhances coronary perfusion. This is crucial in patients with compromised cardiac function, as it allows for improved oxygen delivery to the myocardium during the heart's relaxation phase. The timing of the inflation corresponds with the closure of the aortic valve, providing support to the heart by increasing blood flow to the coronary arteries when they are most perfused. This action helps to reduce the workload of the heart as well.

In contrast, during systole, the balloon deflates, which decreases the afterload the heart has to overcome when ejecting blood, thereby facilitating better cardiac output. The IABP's dual actions—inflating during diastole and deflating during systole—work synergistically to optimize cardiac function in patients experiencing myocardial ischemia or heart failure.