A heart murmur involves an abnormal sound which is heard when a doctor listens to your heartbeat. Murmurs can be faint or loud and at times they may sound like a swishing noise. The ‘lub-dub’ sound heard when you listen to your heartbeat is caused by the heart valves closing and is completely normal.
A heart murmur is not a medical condition or disease, but is instead a noise that can be heard by a doctor when they listen to your heart beating through a stethoscope. In most cases heart murmurs are completely harmless. However, they can be a symptom or sign of something wrong with the heart and should be investigated, especially if the patient has additional symptoms.
Heart murmurs are usually classified into two categories: innocent and abnormal.
Innocent heart murmurs
This type of murmur is also known as a harmless heart murmur. Individuals with this type of heart murmur usually have no other symptoms or signs of heart problems. Innocent heart murmurs are most common among healthy children.
Abnormal heart murmurs
People who have abnormal heart murmurs usually have other symptoms or signs of heart problems. In children they are usually caused by congenital defects (they are there at birth). In adults, however, unusual heart murmurs are usually caused by problems relating to the heart valves, which may be caused by infection, ageing or disease.
Your heart is a large muscle and is roughly the same size as your fist. Its primary role is to pump blood around the body to provide tissues and organs with oxygen. The heart pumps around 100,000 times each day.
The heart is made up of two sides and they are separated by the septum, which acts like a wall between the two sides. The right section of the heart drives blood towards the lungs to collect oxygen, while the left hand section pumps blood around the remainder of the body. The blood rich in oxygen then flows to the left hand part of the heart and is taken to the remainder of the body in the bloodstream.
The heart is comprised of four valves and four chambers and is connected to veins and arteries (types of blood vessel). Arteries take blood from the heart and distribute it around the remainder of the body, while veins transport blood from the body towards the heart.
The heart is made up of four chambers, which are known as:
The heart contains four valves which are responsible for allowing the passage of blood and preventing backflow. The valves open and shut like doors and it is this action which causes the ‘lub-dub’ sound you hear when listening to the heart beating. The initial sound is caused by the closing of mitral valves and tricuspid, when the heart constricts and forces blood out and into the body (this is known as systole), and the next sound is caused by the closing of the pulmonary and aortic valves, when the heart settles slightly to fill with blood (this is known as diastole).
The valves include:
The arteries are major blood vessels which are joined to the heart and are responsible for carrying blood towards the remainder of the body. Major arteries include:
The veins are major blood vessels which are connected to the heart and are responsible for carrying blood to the heart. Major veins include:
Innocent heart murmur:
Abnormal heart murmur:
Innocent heart murmurs
Innocent heart murmurs occur when the blood travels in the course of the heart loudly. This may be caused by the blood travelling through the blood vessels and heart quicker than average or by a larger amount of blood running in the course of the heart. Certain conditions can cause the blood to travel in the course of the heart quicker than average, including:
Heart murmurs are very common in children. Pregnancy is also a common source of fast flowing blood. Many females acquire an innocent heart murmur at times of pregnancy, because the body is producing additional blood for the developing foetus. In some cases innocent heart murmurs can develop following heart surgery or as a consequence of getting older.
Abnormal heart murmurs
The most common reason for abnormal heart murmurs are congenital heart defects. These are defects which affect the development of the heart or vessels around the heart and are present at birth. A number of babies have one defect or more. Examples of defects that may lead to abnormal heart murmurs include:
Other health conditions and infections can cause heart murmurs, including:
The majority of people with heart murmurs do not display any symptoms or signs of heart difficulties and the only symptom they have is the loud noise the heart makes when it beats. Heart murmurs are often innocent, meaning that they are harmless, but this is not always the case and some people do develop symptoms. Possible symptoms associated with a heart murmur include:
The severity and type of symptoms will depend on the source of the murmur.
Doctors assess the beating heart using an instrument known as a stethoscope. When they monitor the heart beating they can identify the murmurs. Innocent heart murmurs are often identified during routine physical examinations or health checks. It is also possible for doctors to pick up signs of an abnormal heart murmur during a routine examination, but most abnormal murmurs are caused by congenital conditions and diagnosed at birth.
If a doctor suspects an abnormal heart murmur it is likely that they will refer the patient to a heart specialist (known as a cardiologist) for further tests.
During a physical examination a doctor will listen to the patient’s heart using a stethoscope. They will listen to the heartbeat carefully to detect any murmurs and try to decide whether a murmur is abnormal or innocent. They do this by listening to the sound and evaluating how loud it is, how long it lasts and where it is coming from.
The doctor will also take a medical history, family history (to see if there is a history of heart problems) and ask the patient whether they are experiencing any symptoms. They will also look for signs of heart problems, such as rapid breathing, blue discolouration of the hands and mouth, dizziness and chest pain during an examination.
When listening to the heart and assessing a murmur, doctors will consider the following things:
Murmurs are classified as follows:
If a doctor suspects that a patient has an irregular heart murmur they will order further tests, which may include:
Once a patient has been referred to a specialist cardiologist further tests will be carried out, including:
Innocent heart murmurs
Innocent heart murmurs do not usually require any treatment. Children with innocent heart murmurs have healthy hearts and do not require treatment, and the same is true for pregnant women. However, it is worth mentioning the heart murmur when you have health checks to ensure the doctor is aware of the murmur and can monitor the situation. If the murmur is caused by a condition or infection, such as anaemia or fever, treating the cause will often cure the murmur.
Abnormal heart murmurs
Treatment is based on the severity and reason for the murmur, with treatments likely to include medication and surgery. Children with congenital heart defects will be treated by paediatric cardiologists.