Dilated cardiomyopathy is a condition of the heart muscle. The heart dilates (becomes enlarged) and pumps blood less well. Symptoms vary according to the severity of the condition. Treatment depends on the type of symptoms and whether complications develop. Some forms of dilated cardiomyopathy run in families.
The heart has four chambers - two atria and two ventricles. The walls of these chambers are mainly made of specialised heart muscle called the myocardium. During each heartbeat both of the atria contract, first to pump blood into the ventricles. Then both ventricles contract to pump blood out of the heart into the arteries. There are one-way valves between the atria and ventricles and also between the ventricles and the large arteries coming from the heart. The valves make sure that when the atria or ventricles contract, the blood flows in the correct direction.
Cardiomyopathy is a disorder of the heart muscle. There are four main types:
The rest of this leaflet is only about DCM.
In this condition the heart muscle is weakened. The ventricles then dilate (enlarge) because their muscular walls are weaker and more floppy than normal. This means the heart does not pump blood as strongly as normal.
(Note: other common heart conditions can cause a dilated heart. For example, coronary heart disease, high blood pressure and heart valve disease. These conditions can put a strain on the heart, which may cause the heart to dilate. With DCM, the heart dilates because of a problem with the heart muscle itself.)
DCM is the most common type of cardiomyopathy. It can affect both children and adults. It is most common in middle-aged men. About 2 in 10,000 people in the UK develop dilated cardiomyopathy each year.
For most people the cause is not known. This is sometimes called idiopathic DCM. Another possibility is that an unknown viral infection may be responsible. About one in four people with idiopathic DCM have a familial (hereditary) form. This means that several members of their family also have DCM. It is still not clear exactly how hereditary factors may work in this condition.
Some cases are due to known causes. There are many conditions which can cause damage or disease to heart muscle. Most are rare. They include:
If you only have mild enlargement of the heart, you may not have any symptoms. However, if your heart becomes very dilated, symptoms will develop. Symptoms may develop gradually or quite quickly, depending on how quickly the disease progresses. Possible symptoms include the following:
DCM is one cause of heart failure. There are many other causes of heart failure. Heart failure means that your heart does not pump as well as it used to. (It does not mean that your heart is going to stop at any minute.) The amount of power that is lost from the heart varies from person to person.
For many people with DCM, heart failure is mild or moderate. Symptoms can often be treated. In some people with heart failure, the power of the heart becomes very low and then the symptoms become severe.
Symptoms of heart failure are mainly due to fluid building up in tissues of the lungs and body. This happens because your heart does not pump effectively. Symptoms include the following:
Palpitations sometimes occur. You may be aware that your heartbeat is fast and/or irregular. Some people develop chest pains. If the cardiomyopathy is a result of another cause (such as alcohol excess, myocarditis, etc) then you may also have various other symptoms.
A doctor may suspect this condition because of:
Various other tests may be done to find, or exclude, causes of an enlarged heart. If no underlying cause is found then the diagnosis of idiopathic DCM is confirmed. Further tests on the heart may be done to assess the severity of the condition.
More specialised tests may be performed depending on the severity of your cardiomyopathy. New tests to monitor the progression of DCM are currently being developed and studied in clinical trials.
This can be difficult to predict. In some cases, the condition remains stable or does not get much worse. Medication may keep the symptoms of heart failure away and your lifestyle may be little affected. In some people, the function of the heart gradually deteriorates. Symptoms of heart failure then get worse and need more intensive treatment.
Complications occur in some cases and include the following:
An arrhythmia is an abnormal rate or rhythm of the heartbeat. There are various types of arrhythmia and some are more serious than others. An arrhythmia can come and go and can cause bouts of palpitations, dizziness and other symptoms. Some arrhythmias become permanent. An arrhythmia called atrial fibrillation is the most common one that develops in people with DCM. See separate leaflets called 'Arrhythmias' and 'Atrial Fibrillation'.
The blood flow through the heart is slower than normal, especially when the heart is very dilated. This can lead to small blood clots developing within the chambers of the heart. These may travel in the bloodstream and get stuck in arteries of the body. This may lead to a stroke if a clot gets stuck in an artery in the brain, or to other problems. The risk of blood clots developing can be reduced greatly by taking an anticoagulant medicine such as warfarin (see below).
Sudden collapse and death without any warning occurs rarely in people with DCM. This is probably due to a severe arrhythmia which may develop suddenly. Medication and/or an implantable defibrillator may reduce this risk.
Treatment aims to ease symptoms if they occur and to prevent complications. If you do not have any symptoms, or only mild symptoms, you may not need any treatment. Treatment which may be required includes one or more of the following:
Various medicines are used to control the symptoms of heart failure. These include:
There are various anti-arrhythmic medicines (for example, amiodarone) which are used to treat and to prevent arrhythmias. They work by interfering with the electrical impulses in the heart.
An anticoagulant is a medicine which helps to prevent blood clotting so easily. An anticoagulant may be advised if you develop atrial fibrillation or have a very dilated heart. When the heart beats irregularly, there is an increased risk of blood clots developing. Warfarin is a commonly used anticoagulant.
Other treatments may be an option if you develop arrhythmias. For example:
This is a newer treatment developed to help the changes in your heart muscle. Cardiac resynchronisation tries to improve how the electrical impulses in your heart make it pump. This makes it pump more efficiently. This is done by using a pacing device. This is a small box that is placed just under the skin on your chest wall. It has been shown to improve survival for some. Unfortunately, up to 1 in 3 of people with DCM treated this way see no benefit.
Surgery has also been used to improve how efficiently the heart pumps. This is a rapidly developing area and there are various procedures used.
In some cases the condition progresses and severe heart failure develops. If this cannot be treated by the methods mentioned here, the only option for treatment is a heart transplant.
The outlook with DCM varies and depends on the severity of the condition. However, the the outlook for many people with DCM has improved a lot in the last ten years. This is due to new medical and surgical treatments. In some people with DCM their hearts start pumping more efficiently again. This is called reverse re-modelling. It is seen after some of the treatments mentioned above.
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