Haemodynamics COPY Flashcards
How are the right and left coronary arteries perfused?
Backflow of blood in aorta
to coronary ostium
enters right and left coronary arteries
What does the perfusion rate of the peripheries depend on?
Peripheral resistance
state of arterioles
What is the systolic uptake?
Increase in pressure in aorta
due to LV ejecting blood into it
in systole
What is another term for systolic uptake on a graph?
The anacrotic limb
What is the peak systolic pressure?
Maximum pressure in aorta
What is the average peak systolic pressure?
120mmHg
What is sytolic decline?
LV ejects less blood into aorta
pressure in aorta falls
What is the dicrotic notch?
Pressure in aorta is higher than LV pressure
aortic valve closes
aorta recoils
gives slight increase in pressure
What is the diastolic run-off?
Aorta recoils
pushes blood out of aorta into arteries
pressure in aorta decreases
What is the end-diastolic pressure?
Lowest pressure in aorta
at end of diastole
What is the average end-diastolic pressure?
80mmHg
What is the dicrotic limb?
The overall decline in pressure in the aorta
Wjhat is the pulse pressure?
Peak systolic pressure - end-diastolic pressure
What is the average pulse pressure?
120 - 80 = 40mmHg
How is mean arterial blood pressure calculated?
Diastolic pressure + 1/3pulse pressure
What is the average mean arterial pressure?
80 + (1/3 x 40)
80 + 13 = 93mmHg
What happens if mean arterial pressure falls below 70mmHg?
Organ perfusion is impaired
What is felt in a pulse?
Shock wave that arrives before the blood itself
What does the strength of a pulse depend on?
Force of contraction of LV
Pulse pressure
What can cause a decrease in the strength of a pulse?
LV failure
Aortic valve stenosis
Hypovolaemia
What can cause hypovolaemia?
Dehydration
Bleeding
What is a weak pulse described as?
Thready
What is a strong pulse described as?
A bounding pulse
What can cause a bounding pulse?
Bradycardia
Low peripheral resistance
How does bradycardia cause a bounding pulse?
Diastole has more time to occur
Increased diastolic run-off
Lower end-diastolic pressure
Widens pulse pressure
What can cause low peripheral resistance?
Exercise
Pregnancy
How does low peripheral resistance cause a bounding pulse?
Increased blood flow
Lower end diastolic volume, pressure
Widens pulse pressure