Library · Physiology
Pulse pressure
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When your blood pressure is taken you get two numbers, and they are almost always read separately. Pulse pressure is one subtracted from the other: systolic minus diastolic.
With the figures everyone recognizes, 120 and 80, that subtraction comes out around 40, and that is the value considered typical.
What is interesting is what it depends on. It depends on two things that pull in opposite directions. One is the volume that the left ventricle, the chamber that pumps to the whole body, ejects with each beat: the more it sends out at once, the bigger the difference. The other is the distensibility of the arteries, meaning how much they give when that blood arrives: the more they give, the smaller the difference. A rigid tube transmits the blow; an elastic one cushions it.
That explains a detail that seems odd. The aorta is the most distensible artery you have, and precisely for that reason it is where pulse pressure is lowest along the whole route.
In population studies, pulse pressure has been analyzed as a risk factor for heart disease.
In brief
Pulse pressure is the difference between systolic and diastolic pressure.
At 120 over 80 millimeters of mercury, that difference is about 40.
It rises with the volume the left ventricle ejects with each beat and falls when arteries are more elastic.
A rigid tube transmits the blow; an elastic one cushions it.
That is why it is lowest in the aorta, the most distensible artery in the body.
It has been studied as a risk factor for heart disease in populations.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingPhysiology, Pulse Pressure, StatPearlsPublished
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