Why does the balloon inflate at the dicrotic notch?

The balloon is supposed to inflate towards the end of diastole. So - the walls of the heart open up, the chambers fill, and the aortic valve flips shut. It turns out that the anatomical openings - the ostea - leading to the coronary arteries are in the wall of the aorta, just above the valve, and at the end of diastole the aorta rebounds a little bit, and the coronaries perfuse – passively. Now, if your ischemic patient needed more than just passive perfusion – what could you do? Inflate the balloon. How do you know when to inflate? It turns out that the dicrotic notch, coming at the end of diastole, indicates exactly the event we want – the closure of the aortic valve. Once the valve is closed, the balloon inflates, and blood is forcibly pushed backwards along the aortic arch, and into the coronary arteries under pressure, improving perfusion.

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   Why do we use the arterial wave for timing?
   

Simple: we use the arterial wave to look for the dicrotic notch, to use as the marker for inflating the balloon. Use the inflation knob to move the inflation wave leftwards, until it meets the dicrotic notch.

Arrows again. This time, the arrows from above are pointing to the dicrotic notches. The arrows from below are pointing to the inflation waves of the balloon. (The inflation wave is a lot smaller in this picture than it usually is. Bad diastolic augmentation…) Is it anywhere near where it ought to be? At the notch? No – it needs to be moved leftwards. Move it to the left with the inflation knob, turning away from the center of the console. If you do it slowly, you’ll see the inflation wave actually move over until it intersects with the dicrotic notch. Don’t go too far! Bingo! Can you see how the arrows coming later in the strip point to the same things? The augmentation should improve as you fix the inflation timing.

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