CVPR Week 3: Pressure Volume Loops Flashcards
Objectives
What is a pressure volume loop?
The value of pressure-volume loops
Question 1
A.
Question 2
C.
Question 3
B.
Question 4
B
What is this?
How to create a pressure-volume loop?
- What happens between 1 and 2?
What happens between 2 and 3?
What happens between 3 and 4?
What happens between 4 and 1?
What is stroke volume =
end diastolic volume - end systolic volume = SV
What is the stroke volume?
What is the ejection fraction?
What does the whole shaded area represent?
ventricular stroke work
Work = Force x Distance
Work = Pressure x Volume
Describe Starling’s Law of the heart
What is preload?
Preload equation
P(r)/2w
r = radius of sphere
w = wall thickness
preload directly proportional to pressure
Preload directly proportional to volume
End-diastolic pressure volume relationship
End-diastolic pressure volume relationship on a pressure volume loop
What is afterload?
Afterload equation
P(r)/2w
Afterload is directly proportional to?
Pressure
or
to simplify further
Afterload is proportional to systemic systolic blood pressure
Preload proportionality
- preload is directly proportional to volume
- preload is directly proportional to pressure
What point on a pressure-volume loop represents maximal ventricular contraction
point 3
Identify
End-systolic pressure volume relationship
ESPVR and Contractility
Review of preload, afterload and contractility?
ESPVR AKA
End-systolic pressure volume relationship
EDPVR AKA
End-diastolic pressure-volume relationship
Changing parameters: Increase preload
Changing parameters: Decrease preload
Changing parameters: Increase afterload
Changing parameters: Decrease afterload
Changing parameters: Increase contractility
Changing parameters: Decrease contractility
Pressure-volume loop: Systolic heart failure
systolic heart failure
Pressure-volume loop: Diastolic heart failure
Inotropy definition and examples
- An inotrope is an agent that alters the force or energy of muscular contractions.
- Negatively inotropic agents weaken the force of muscular contractions.
- Positively inotropic agents increase the strength of muscular contraction.
Post spinal hypotension treatment
An increase in contractility does what to the ESPVR?
steepens it
An decrease in contractility does what to the ESPVR?
flattens it or decreases it
What is afterload represented by?
Afterload is represented by the pressure seen between 2 and 3
How is contractility represented?
by the steepness of the ESPVR
What is preload represented by?
how far out (to the right) on the EDPVR we go
What is the line of contractility referring to?
The slope of the ESPVR represent?
The slope of this line represents
(ΔP/ΔV) = End-systolic elastance
What is End-systolic elastance?
End-systolic elastance = (ΔP/ΔV)
it is represented by the slope of the ESPVR
Label the Diastolic pressure, systolic pressure, end-diastolic volume, end-systolic volume and stroke volume on a pressure-volume loop (define ejection fraction)
Elastance equation
ΔP / ΔV
