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

Which statement correctly describes the function of the intra-aortic balloon pump (IABP)?

1. Deflates on diastole, during the T wave

2. Inflates on systole, during the P wave

3. Indicated for septic shock and anaphylaxis

4. Deflates on systole, during the P wave

The correct answer is: Deflates on systole, during the P wave

The intra-aortic balloon pump (IABP) is a mechanical device used to support the heart's function and improve coronary perfusion. Its primary actions involve inflation and deflation in synchronization with the cardiac cycle. When considering the functioning of the IABP, during the cardiac cycle, the balloon inflates during diastole (the heart's relaxation phase) and deflates just before the heart's systole (the contraction phase). Specifically, the balloon inflates during diastole, which helps to increase coronary artery perfusion pressure and assist with blood flow to the heart muscle. Conversely, the balloon deflates just prior to systole, which reduces afterload on the heart and enhances cardiac output. The correct description indicates that the IABP deflates during systole, allowing for the heart to eject blood more efficiently. In this context, the balloon's deflation timing is crucial as it facilitates the heart's contraction by reducing the workload. In contrast, the other options present inaccurate depictions of the balloon's inflation and deflation timings or indicate inappropriate clinical indications for the IABP, such as in cases of septic shock and anaphylaxis, where the device is not indicated. Understanding the timing of the balloon pump’s operation is