Class 6 Flashcards
Ventricular dilation will give an increase in what?
Increase in ventricular compliance or LVEDPVR slope
How can you examine how ventricular dilation can effect EDV?
Compliance filling curve
A normal heart has a steeper slope which means what for the compliance?
Lower compliance
Dilated ventricle enhances what?
Venous return
Hypertrophic heart has a steeper slope which means what on the LVEDPVR?
Lower complains
Increased heart thickness means web for compliance?
Decrease in ventricular compliance
Decrease compliance will increase or decrease end diastolic pressure?
Increases EDP
Increase in Venus return will (-)ventricular filling in therefore (-) preload
Increase, increase
Increase in end diastolic volume will cause an (-) in end diastolic pressure
Increase
In a heart lesser the compliance, slower or quicker venous return
Slower
A decrease in venous return will do what to EDV?
Decrease
Decrease in pre-load or EDV caused by a decrease in compliance will lead to what for the EDP?
An increase in EDP, lesser volume means higher pressure to eject blood
Increase in EDP Implies that the heart must do what to counteract the increase in EDP?
Contract more forcefully to eject the blood
Increases in venous return will
- increase preload
- stretch the myocardial contractile myocytes
- increase force of contraction
- increase stroke volume - increase cardiac output
What ensures the outputs of both the ventricles are matched overtime and prevents shifting of blood between pulmonary and systemic circulation?
Frank starling mechanism
Describe frank starling mechanism
To ensure the outputs of both the ventricles are matched and prevent the shifting of blood between pulmonary and systemic circulation
Increase in EDV will do what to force of contraction?
Increase ventricular developed force or force of contraction?
For any heart at any time an increase in LVDV will always lead to what?
Increase in LVEDP
If you increase the LVEDP what happens to stroke volume?
It increases
When keeping all cardiac factors constant except increasing the preload, what happens to SV?
Instantaneous increase in stroke volume, resulting in increase in cardiac output but no change in ESV
Increase in stroke volume from an increase in EDV by increasing the venous return alone but not changing the ESV implies that
Such an increase in stroke volume is a direct result from an increase in EDV
Is the frank starling mechanism the intrinsic property of a heart at a given physiological condition?
Yes
Illustrates relationship between changes of the initial length of a myocyte to the contractile force developed by the heart muscle describes what relationship?
Length tension relationship
What is the biophysical basis for the starlings law?
Length tension relationship of the ventricle
With an increase in preload what happens to active tension?
Increase
Increase in active tension will be accompanied by what happening to the velocity of tension development
Increase in the velocity of tension development, or velocity of muscle shortening
What can be defined as the ventricular wall tension developed during ventricular ejection?
Afterload
The magnitude of the ventricular wall tension developed is directly related to what?
Resistance, impedance, or pressure that the ventricle must be able to overcome before blood can be ejected
What is one of the major components of afterload for the left ventricle?
Aortic pressure
Defined as the load against which the heart must counteract before blood can be checked it out
Afterload
What can estimate ventricular wall stress?
Laplace’s law
How do you calculate wall stress?
O is proportional to (pxr)/2h
Wall stress calculations in words
Wall stress is proportional to the product of the intraventricular pressure P, and ventricular radius R, divided by wall thickness H
Wall stress increases in response to
A higher pressure loud, hypertension
Wall stress increases in response to (ventricle)
Increase in the chamber size, increase in preload
What will reduce wall stress and therefore reduce afterload?
Increase in ventricular wall thickness, ex. left ventricular hypertrophy
Ventricular hyper trophy is used as an adaptive mechanism for what?
- offset an increase in wall stress
- Induced by the increase in afterload
Increase in afterload does what to the frank starling curve?
Shifts it down and to the right
With an increase in after load, the heart has to do what?
The heart has to generate a higher pressure to eject the same volume of blood
An increase in afterload will do what to the velocity of fibre shortening?
Decrease the velocity during contraction
Decrease in velocity of muscle fibres shortening will result in what to stroke volume?
Decrease
Changes in afterload produce secondary changes in what?
Preload
When there is an increase in afterload/aortic pressure, the ventricle has to do what to the pressure in order to open the aortic valve?
Generate a higher pressure
Higher up the road will do what to ejection velocity?
Decrease ejection velocity, decreases SV and increases ESV
Increases in ESV due to the increase in afterload is greater than the increase in EDV such that the SV is increased or decreased?
Decreased
