Pulse Pressure

Definition:  Pulse pressure is the difference between systolic and 
diastolic pressure

Pulse pressure is mainly a function of stroke volume and arterial compliance.  
It corresponds to some arterial volume increment V2 - V1, where V2 is the maximal 
arterial volume (during systole) and V1 is minimal arterial volume (during diastole).  

Let us first analyze the effect of a change in stroke volume on pulse pressure, under
the conditions in which the arterial compliance remains constant.  When a heart beats
at a normal frequency, the volume increment during the rapid ejection phase is a 
large fraction of the stroke volume (80%).  It is this increment that will raise 
arterial volume rapidly from V1 to V2 and thus will cause the arterial pressure to rise
from the diastolic to the systolic level. (pg. 145)  

Doubling the stroke volume will cause the volume increment to be twice as large as the 
previous volume increment.  (This is assuming that each volume increment is solely caused 
by the stroke volume.)  Finally, twice the volume increment leads to twice the pulse 
pressure.  

Let us now examine how arterial compliance affects pulse pressure.  Given the same volume 
increment, pulse pressure will be greater if the arterial compliance is less, and pulse
pressure will be less if the arterial compliance is greater. 

Equation:  Pulse pressure = P(systole) - P(diastole)
           Pulse Pressure ~ 1/C
	     Pulse Pressure ~ Stroke Volume

Sample Problems:

1)  Given the same volume increment, cardiac output, and total peripheral 
    resistance, who will usually have the greater pulse pressure -- an 
    elderly individual or a young person?
2)  What effects do different combinations of total peripheral resistance 
    and arterial compliance have on pulse pressure?

Answers:

1)  The elderly individual will have the greater pulse pressure because he/she 
    will often have less distensible arteries than those of a young person's.  
2)  Study the Fig. 6-13 on pg. 147.  It has all the answer you need if you'd only
    concentrate a little harder.  

For more information on this topic, please refer to Berne & Levy , pp. 144-147.

Also, check out the following links that may be helpful:

• Cardiovascular Diseases: Testing for heart problems: Blood Pressure
• Lecture notes on Hemodynamics from Brown University
• And, as always, if you have questions, or if you can suggest a helpful link, please e-mail me.

No!
Please don't make me go to any of those pages!
I want to go somewhere completely different!

This page was written by Ethan Y. Chen, a student in this course. Email me!

BME 403 Pages maintained by the T.A., Douglas Miles.