What is a dicrotic notch, and why do they call it dicrotic?

The notch indicates closure of the aortic valve, and comes at the end of diastole, as the pressure falls. Why is it called dicrotic?

2. 
   What is diastolic augmentation?
   

Remember that the balloon inflates at the end of diastole, just after the aortic valve closes – the rapid inflation is what augments the perfusion of the coronary arteries through the ostea. This rapid inflation can produce a pressure wave that’s actually higher than the patient’s systolic pressure, and that high pressure wave is referred to as diastolic augmentation. That’s the high waveform in the middle of the three peaks.

2. 
   How does inflation help?
   

Inflation helps by forcibly perfusing the coronary arteries, instead of letting them be perfused passively. Look at the “PDP” point in the diagram below – that’s the pressure perfusing the coronaries generated by the inflation of the balloon. A lot of pressure! This is often enough to control angina/ischemia along with ischemic symptoms, and can stabilize an ischemic patient until they can go to either the cath lab or the OR.

Everybody has their own system for labelling the important points on a balloon timing waveform, but they refer to the same events. Starting at the left:

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  PSP: meaning the “patient’s systolic pressure”.
  
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  Next is IP – here I think they mean “inflation point”, which of course is also what?- correct, the dicrotic notch.
  
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  Next? What do they mean by PDP? I have no idea. I would call this the “augmented diastolic peak”.
  
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  After that? BAEDP – that’s what I call it as well.
  
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  Then – APSP: this I think means “assisted patient systolic pressure”. Close enough – I call this “assisted systole”.
  
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  DN – okay, this one they call the dicrotic notch.
  
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  PAEDP: probably “patient’s aortic end-diastolic pressure”. Which is to say, the patient’s diastolic, unassisted.
  

2. 
   How do I make sure my inflation timing is right?
   

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The safe position for the control knobs is always inwards towards the center – the inflation knob is the left-hand one on the console, and turning it to the left, counterclockwise – outwards from the center – will move the inflation wave to the left (earlier) as you watch on the arterial line trace. The inflation wave should coincide with the dicrotic notch. See the arrow?