في أي مرحلة من دورة القلب ينتفخ بالون الأبهر الداخلي (IABP)؟

During which phase of the cardiac cycle does the intra-aortic balloon inflate?

1. Continuously throughout the cycle
2. Diastole, after the aortic valve closes
3. Only when the heart stops
4. Systole, as the aortic valve opens

Answer: B) Diastole, after the aortic valve closes. The balloon inflates in diastole, raising aortic pressure and coronary perfusion, and deflates just before systole, lowering afterload. Timing is set from the ECG or arterial waveform.