When the heart contracts, blood is pushed out of the left ventricle through the aortic valve into the aorta. From the aorta, blood moves to different parts of the body, supplying oxygen and vital nutrients to organs, tissues and cells.
The amount of blood that is pumped out of the left ventricle is called the ejection fraction. It is basically the fraction (or percentage) of blood in the left ventricle that is pumped out into the aorta to the rest of the body.
Ejection fraction is also called EF. You will see this in most echocardiography reports.
How is ejection fraction measured?
Ejection fraction can be measured through –
- Coronary angiography
- Nuclear scanning
- MRI scanning
- CT scanning of the heart
Echocardiography is the most common way of measuring ejection fraction.
Normal ejection fraction
Normally, the heart pumps around 50 to 60% of the blood that is present in the left ventricle. In other words, the normal EF is more than 50%.
In certain situations, the ejection fraction can reduce. A reduced ejection fraction is called heart failure. There can be different degrees of low EF.
Mild heart failure – The EF is between 40 – 50%
Moderate heart failure – The EF is between 30 – 40%
Severe heart failure – The EF is less than 30%
The symptoms of heart failure are often in line with how bad the function of the heart is. For example, patients with mild heart failure may have no symptoms, while those with severe heart failure can have breathing difficulty and extreme tiredness.
That being said, there are patients who have severe heart failure and do not have any symptoms at all. This is mostly due to them taking the right combination of treatments and tablets.
Why would a patient have a low ejection fraction?
A low ejection fraction is often due to some type of damage to the heart muscle. This can be due to –
- Heart attacks
- Valve diseases
- Viral illnesses (cardiomyopathy)
- High blood pressure that has not been controlled for a long time
Importance of ejection fraction
The ejection fraction is probably the most important parameter looked for when doing an echocardiogram. A low ejection fraction is indicative that the heart is weak and not working well. In patients with a low ejection fraction and coronary disease, the mortality risk is high. This is also the case with other types of heart disease associated with a low EF.
Certain non-cardiac surgeries may not be performed if the patient has a low ejection fraction. However, there are many patients who have a low ejection fraction who lead completely normal lives for many years.