Cardiac Lecture 4 Flashcards
Which medications are considered mixed vasodilators?
Sodium nitroprusside and nitroglycerine (NO donors)
Dilation of the veins decreases ______
Psf and RVR
Nitroglycerine relaxes _____ more than ______
the veins more than the arteries
What medications are arterial-specific vasodilators?
Hydrazaline and ACEi
Which medication is a mixed pressor?
Phenylephrine
Describe the body’s compensatory mechanisms for a failing heart
- Short term:
Decreased CO → increased sympathetic activity → increased venous tone and HR → increased RAP and CO - Long term:
Prolonged sympathetic activity → increased fluid retention → increased Psf and RAP → back to normal sympathetic activity
_______ includes the pressures available to fill the heart
preload
______ the force that the heart has to overcome to open the aortic valve and eject blood
afterload
________ the change in SV when preload and afterload remain constant
contractility
______the volume in the ventricle after filling is complete
EDV
EDV is a function of _______
preload
a normal ESV is _____
50 mL
increased preload results in?
increased EDV and SV
a normal afterload is ______
80 mmHg
How is contractility represented on a pressure-volume loop?
the slope at the top left-hand corner of the pressure-volume loop
as contractility increases, the line shifts to the ______ and shifts to the _____ when it decreases
left (steeper slope); right
increased afterload results in?
- increased ESV and duration of phase II
- decreased duration of phase III and SV
increased contractility results in?
- decreased ESV
- increased SV, CO, and BP
“Everybody has ______ by the time they’re 50”
aortic valve stenosis - most common valve problem
Describe the effects of aortic valve stenosis on a pressure-volume curve
high afterload → increased ESV → decreased SV and CO
- elevated HR to compensate for low CO
increased preload
Why would someone with aortic valve stenosis have a normal MAP?
the pressure choke point is before the aorta, so the aortic pressure would be lower and could result in a normal MAP
You would expect the pulse pressure on someone with aortic valve stenosis to be _______
Narrow
Describe the effects of mitral valve stenosis on a pressure-volume curve
- issues with filling → increased Psf, atrial pressure, and blood volume
- decreased EDV → decreased SV → increased HR
Eventually, mitral valve stenosis will result in ______
pulmonary edema
Describe the effects of aortic regurgitation on a pressure-volume curve
retrograde blood movement when the valve is closed and pressure in the aorta > ventricle → phase IV not isovolumetric
- increased EDV → increased SV
- decreased afterload
At which point during phase IV does blood flow backward into the ventricle at the greatest speed?
end of phase IV - reflects low pressure in the ventricle bc it’s supposed to be empty; slows down as the ventricle fills up
What would you expect in the BP of someone with aortic regurgitation?
Wide pulse pressure
Describe the effects of mitral regurgitation on a pressure-volume curve
- both phase II and IV not isovolumetric
- increased ESV and EDV → increased SV
