What is Heart Failure?
Heart or cardiac failure occurs when the pumping action of the heart is inadequate and fails to maintain proper circulation and therefore adequate oxygenation of the tissues.
There is reduced forward blood flow to the body tissues (reduced cardiac output), back-up congestion in the lungs (causing breathlessness) and/or the body (causing swelling or oedema) and other associated physiological changes in many organs of the body, causing biochemical, metabolic and functional impairments. Symptoms experienced include breathlessness, reduced exercise tolerance, oedema and malaise.
Heart failure is a very complex medical condition. It is useful to classify it into right and left heart failure though there are other ways of classifying it.
These are
- Classification according to whether it is due to systolic dysfunction, (where the heart’s pumping is weaker and less blood is pumped to the body and lungs) and diastolic dysfunction (where the heart is stiff, and cannot fill with enough blood, causing back pressure and congestion).
- High output failure (the heart cannot meet greatly increased requirements), low output failure (an adequate output is not possible) and fluid overload (where the heart cannot efficiently deal with an excessive amount of blood).
The heart is a pump and moves blood out of the veins into the right side of the heart where it then is pumped to the lungs for oxygenation. Oxygen - rich blood is then pumped to the left side of the heart, and subsequently to the tissues of the body. The pumping action of the two sides of the heart occurs simultaneously.
Right and left sided heart failure frequently exist together - this is known as congestive cardiac failure because of congestion in the veins and congestion in the lungs.
In left heart failure there is an accumulation or backlog of blood coming to the left side of the heart from the lungs. It accumulates in the lungs causing congestion with symptoms of breathlessness and fatigue.
In right heart failure there is sluggish circulation of blood coming into the right side of the heart from the body. This causes distension in the veins, fluid accumulation in the legs (called oedema) and enlargement of organs, such as the liver.
The clinical course is often one of chronic heart failure, which can develop slowly and be easily missed. Acute episodes of heart failure can dramatically occur e.g. acute left heart failure causing sudden severe breathlessness, fast heartbeat (tachycardia), oedema of the peripheral parts of the body or the lungs; and it can occur on a background of chronic heart failure.
Acute and chronic heart failure are part of the same disease process.
