Cardiac Function Curves + Pressure-Volume Loops - Quiz 6 Flashcards
What is the cardiac function curve?
Frank Starling Curve
How does Contractility affect Cardiac Function Curve?
↑Contractility = Up and Left
↓Contractility = Down and Right
How does afterload affect Cardiac Function Curve?
↑Afterload = Down and Right
↓Afterload = Up and Left
Why does the venous return curve plateau as RA pressure becomes negative?
At negative RAP, veins collapse as they enter thorax and restricts venous return
How do blood volume changes affect Venous Return Curve?
↑TBV =
↑Venous Return
↑RAP
↑MCFP
How do venous compliance changes affect Venous Return Curve?
↓Compliance =
↑Venous Return
↑RAP
↑MCFP
Mean Circulatory Filling Pressure
Circulatory Pressure when heart is stopped and there is no flow
Arterial Pressure falls & Venous Pressures rise until equal
MCFP = 8 mmHg
What factors affect MCFP?
TBV & Compliance
Venous Compliance will have most impact
Does CO = Venous Return?
It should according to Frank Starling
What is thought to be the mechanism behind Frank Starling Relationship?
Optimization of Myosin & Actin - more Ca+ to bind to cardiac muscles
Factors that Effect Cardiac Function Curve
Afterload & Contractility
Blood Reservoirs
Spleen
Liver
Large Abdominal Veins
Venous Plexus under Skin
Heart & Lungs
What is Unstressed Volume?
Amt of blood in the vein before pressure is generated
When are different Venous Curves parallel?
Changes in Blood Volume or Venous Compliance
How do resistance changes effect Venous Return Curve?
↑SVR = Down and Left
↓SVR = Up and Right
No MCFP Change
Curves Unparallel
What is the point of Intercept between the Starling Curve and Venous Return Curve?
Where Cardiac Output = Venous Return
What happens to the Starling Curve & Venous Return curve during exercise?
Sympathetic stimulation & Low ↑CO & Venous Return
then
Big ↑CO, Venous Return, MCFP
What is the Y-axis on Pressure-Volume Loop
Pressure
What is the X-axis on the Pressure Volume Loop
Volume
What is time’s role in Pressure Volume Loops?
Time plays no role
List 1-4
1: Filling
2: Isovolumic Contraction
3: Ejection
4: Isovolumic Relaxation
List 1-4
1: Mitral Valve Open
2: Mitral Valve Close
3: Aortic Valve Open
4: Aortic Valve Close
List 1-2
1: End-Diastole
2: End-Systole
What is the Red Line?
End-Systolic Pressure-Volume Relationship
(ESPVR)
End Systolic Pressure Volume Relationship Changes
Change of Intercept Point = ΔAfterload
Change in Slope = ΔContractility
What is this showing?
End-Diastolic Pressure-Volume Relationship
Ventricular Compliance
Red line indicates stiff ventricle & higher filling pressure
Whats happening here?
Increased Afterload
Whats happening Here?
Increased Contractility
Whats happening here?
Increased Preload
