HRR: cardiodynamics IV Flashcards
How does reduced afterload impact preload and cardiac output?
Reduces it, but cardiac output will increase.
Describe the Treppe/Bowditch effect.
As heart rate increases, contractility increases. The increased rate ramps up calcium release from the SR and there is less time to remove calcium from the cytoskeleton, resulting in increased contractile force. The diastolic tension increases as well.
Describe the Bowditch effect in people with heart failure.
As heart rate increases, contractile force decreases. There will be a massive increase in diastolic tension.
What is the Anrep effect?
Over time, increased afterload increases inotropy. At first, the increase causes a reduction in stroke volume to account for the pressure change. Over time, the heart will adapt and increase its inotropy to increase the stroke volume.
High stroke volume with no change in preload reflects what change?
Increased inotropy.
How can we measure contractility?
By comparing preload with stroke work.
What are we changing when a heart remodels?
The ECM; fibroblasts and collagen largely.
Which part of the endocardium has the lowest blood supply?
Endocardium.
What does an increase in the slope of EDPVR represent?
Greater stiffness.
What is tamponade?
Excess fluid cumulative causes restriction.
How does abnormal relaxation impact EDPVR?
If myocytes relax too slowly, the AV valves open at higher LV pressures.
How does pericardial restraint impact the EDPVR?
Additional pressure from outside the ventricle restricts filling, reducing the volume.
How does increased chamber stiffness impact the EDPVR?
It takes more pressure to fill the same volume.
How does chamber dilation impact the EDPVR?
The whole curve shifts right; a larger ESV leads to more residual pressure.
What is the preferred fuel for the heart?
Fatty acids.
