Acute Heart Failure Flashcards
Define heart failure.
Either:
And inadequate CO
or a maintained CO at the expense of a raised filling pressure
What are the 2 types of heart failure and how do they differ?
Acute vs chronic
Onset of time is the difference
Acute = carcinogenic shock = heart can not pump enough blood to meet bodies requirements
What is a normal CVP?
5mmHg
What is a normal aortic pressure?
100mmHg (around systolic BP)
What is a normal CO?
8L/min
Where are baroreceptors found?
In the carotid sinus of the aortic arch
What is the pressure in the pulmonary artery and why?
30mmHg
As the lungs/pulmonary vasculature are a low pressure low resistance structure
Why is aortic pressure kept constant at 100mmHg as the surroundings fail in heart failure?
To keep the brain perfused
What changes in RHF?
CVP rises as the right ventricle fails, meaning it backs up.
The cardiac output (of both sides of the heart, as they are in series meaning a change in one results in a change in the other) falls to 6L/min
Reflexes maintain the other pressures within the system at normal
What changes in LHF?
Left ventricular output drops (to 6L/min) which causes the right ventricular output to reduce to the same (this is the same as RHF so far!)
Pulmonary venous pressure rises from 10mmHg to 18mmHg as the left heart backs up
This transmits back through the lungs due to its low pressure low resistance vasculature to cause a slight increase in pulmonary artery pressure (from 30mmHg to 40mmHg)
Aortic pressure (for the purpose of perusing the brain) remains at 100mmHg
Due to the right side having to pump against a higher pressure (40mmHg) the right side follows suit of the left (with time) which is called CONGESTIVE HEART FAILURE
What are the 3 broad primary reasons for heart failure (with example conditions)?
1) pressure overload (hypertension, aortic stenosis)
2) volume overload (aortic or mitral valve regurgitation)
3) contractile dysfunction (cardiomyopathy)
What is the law of Laplace?
How does this relate to the heart?
A small radius holds back a larger pressure
The heart has to work harder to create the same pressures if it is bigger (such as it is with heart failure)
What is it called when the myocardium inner grows in and outer grows out to increase the wall thickness in heart failure?
Concentric hypertrophy
Why is concentric hypertrophy an issue in heart failure?
The heart tissue that grows is not normal, it is pathological
What is ANP?
When is it released?
What does it do?
Atrial Natiuretic Peptide
Released in response to trial stretch
It inhibits aldosterone release (blocking water reabsorption) and vasodilates, it also blocks noradrenaline release (therefore inhibiting vasoconstriction)
