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The downward slope - Heart failure

6 important questions on The downward slope - Heart failure

What happens during acute heart failure?

Cardiac output and venous return temporarily decrease.
Sympathetic activity counteracts this by activating beta1-adrenergic receptors.
Sympathetic activity will also increase arterial resistance= increasing mean systemic filling pressure=increases venous return= increases cardiac output.
Therefore, the hypoeffectiveness of the heart during acute heart failure is short lived.

What happens after the first few minutes of an acute heart attack?

Prolonged semichronic state:
- retention of fluid in the kidneys:
- a low cardiac output will affect the ability of the kidneys to produce urine- fluid retention can lead to a low urine output/

How can fluid retention of the kidneys increase cardiac output?

Fluid retention can increase cardiac output by:
- increasing the mean systemic filling pressure, so that venous return increases and more blood flows into the right atrium.
- distends the veins so that venous resistance can decrease.

What are the consequences of severe fluid retention?

- severe fluid retention without appropriate intervention can have an effect on the excretion of salt and water by the kidneys. the excess fluid volume can:
1. cause excessive muscle hypertrophy of the heart- enlarged heart can affect the conductance of signals therefore affecting heart beat.
2. increased workload can get too much for the heart
3. increased right atrial pressure can lead to pulmonary oedemas, which can affect gas exchange and can reduce the amount of oxygen in the blood.
4. excessive oedemas can form systemically.

What happens to the cardiac reserve after an acute heart failure?

The cardiac reserve decreases- this means that as long as the person remains in a rested state, their cardiac output has returned to normal. If they exercise, their heart may not have recovered enough to increase the cardiac output to cope with the extra demands, and so they may suffer from another attack.

What is the difference between compensated heart failure and decompensated heart failure?

compensated heart failure: when the cardiac output increases to the point where the kidneys output returns to normal= fluid retention decreases.
decompensated heart failure: when the cardiac output is not enough for the kidneys excrete fluid= oedema and enlargement of the heart- complete heart failure.