What happens in heart failure, exactly?

What is it?

Heart failure, HF, occurs when the body isn’t able to pump sufficient amounts of blood to the body. Typical symptoms include shortness of breath, tiredness, and leg swelling.

In developed countries, 2% of adults and as much as 6-10% of those older than 65 suffer from HF.  About half of the people who develop HF die within 5 years of diagnosis.

What causes it?

Practically any condition which damages or overworks the heart muscle can cause HF. Under continuous stress the heart weakens over time.

Coronary artery disease causes plaques to build up inside and block the blood vessels that supply the heart, for example, and this reduced blood flow also reduces the heart’s capacity to work, as muscle cells need oxygen in order to efficiently release energy for contraction. High blood pressure (read about it here) makes the heart pump with more force than would be ideal, which over time weakens the muscle. Many abnormalities of heart structure and function can also compromise its function and lead to HF.

What happens during it? 

Our blood isn’t confined inside our veins. It is mostly water, and while the blood cells tend to stay inside the blood vessels, the fluids can go to and from other tissues, especially where the vessels are small and hence their walls are thin. If the heart doesn’t pump with sufficient force and frequency to build up pressure even in the lower limbs, the blood fluid will rather stay in the tissues than fight its way up back to the heart against gravity – it will go where the pressure is lowest, and during heart failure, this isn’t always in the circulation. The fluid accumulates inside the lungs, where it causes shortness of breath and cough, and in the low parts of our limbs like our feet, where it causes swelling.

Our cells need oxygen in order to efficiently release energy from glucose. We breathe in, oxygen moves from the air to our blood, and our heart pumps the blood to everywhere in our body. In HF the heart isn’t able to perform as well as it should. Our brain realizes that is has to prioritize, so it makes blood flow to less important organs like muscles reduce, so that the vital ones get enough oxygen to function properly. This causes the characteristic tiredness.

How can it be treated?

The management of HF focuses on preventing the progression of the condition as well as relieving the symptoms. Getting rid of the underlying problem is very important. If HF is caused by a high blood pressure, it can be useful to advice the patient to for example reduce their salt intake. Medication is also very commonly used – some work by relaxing and opening the blood vessels in order to make pumping easier for the heart, some by slowing down the heart rate, some by increasing urination so that excess fluids are removed. If HF is caused by abnormalities of heart rhythm or structure, interventions like inserting pacemakers, or surgery, may be necessary.

 

 

Sources: https://en.wikipedia.org/wiki/Heart_failure, http://www.nhs.uk/Conditions/Heart-failure/Pages/Treatment.aspx, https://www.nhlbi.nih.gov/health/health-topics/topics/hf/causes,  https://www.nhlbi.nih.gov/health/health-topics/topics/hf, http://www.heart.org/HEARTORG/Conditions/HeartFailure/WarningSignsforHeartFailure/Warning-Signs-of-Heart-Failure_UCM_002045_Article.jsp#.V7b1Z2B4K00

 

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