Cardiomyopathy
What is cardiomyopathy?
Cardiomyopathy is simply the term doctors use to describe a range of diseases of the heart muscle. It is not the same as a heart attack, where the primary cause is disease of the coronary arteries. Cardiomyopathy is a term used to describe the effects of many possible conditions that damage the structure or function of the muscular wall of the lower chambers of the heart (the ventricles), leading to a weakening of the heart. This weakness can eventually lead to heart failure.
What causes it?
Doctors classify cardiomyopathy as either primary or secondary. In primary cardiomyopathy, tests can’t usually show what the cause is, whereas in secondary cardiomyopathy they can. Secondary cardiomyopathy has several causes: here are some of them.
- Heavy alcohol consumption. Alcohol in large doses can damage the heart and some people are especially sensitive to alcohol even at normal levels of consumption. Fortunately, some people whose hearts have been damaged by alcohol can recover completely if they stop drinking.
- Viral infections. These are a common cause of cardiomyopathy but damage may take months to show up. Most viral infections don’t cause any heart problems at all.
- Hereditary factors. If one member of a family has primary cardiomyopathy (of unknown cause) then others in the family might also be affected and should be checked by a cardiologist.
- Coronary heart disease. As well as causing heart attacks, narrowing of the coronary arteries can cause weakness of the heart muscles.
- Chronic conditions. These include diabetes and thyroid disease.
- Pregnancy and connective tissue diseases such as rheumatoid arthritis. These have also been associated with cardiomyopathy but this is rare.
What types of cardiomyopathy are there?
There are several types, the main ones being:
- dilated, or ‘enlarged heart’;
- hypertrophic, or ‘thickened muscle’; and
- restrictive or ‘stiff heart’.
Dilated (congestive) cardiomyopathy
This is the most common form of cardiomyopathy. Although the cause is not apparent in many cases, there are numerous conditions that may result in this form of cardiomyopathy. About 20 per cent of people with dilated cardiomyopathy inherit it. Or it may be the end result of damage from a variety of agents, such as alcohol, viruses and some diseases.
In this form of cardiomyopathy, the heart muscles stretch to compensate for the reduced pumping action and become dilated and damaged in the process. The heart is then unable to pump enough blood for the body’s needs. Irregular rhythms and disturbances of the heart’s electrical activity can also occur.
Because blood flows more slowly through the enlarged heart, blood clots can form easily. Sometimes these clots break free and circulate in the bloodstream. This is called an embolus, which can be life-threatening if it travels to the brain or a coronary artery and lodges there.
Hypertrophic cardiomyopathy
This is sometimes termed ‘thickened muscle’ and is often present as a birth defect. More than half of all cases are hereditary, and sometimes close relatives of people with the condition have enlarged septums (the wall between the two ventricles) yet no symptoms. The walls of the ventricles thicken, making it more difficult for the heart to fill with blood from the lungs. This can result in fluid build-up in the lungs so that the person is chronically short of breath. As the condition progresses, further thickening of the ventricles can result in obstruction of the blood flow out of the heart, further impairing the heart’s ability to pump properly.
Restrictive cardiomyopathy
This is the least common form of the condition and the cause is often unknown. The muscles of the ventricles become stiff, but not necessarily thickened, making it harder for them to fill with blood between heartbeats.
What are the main symptoms?
The symptoms of cardiomyopathy can include:
- shortness of breath;
- fatigue;
- lethargy;
- fainting attacks;
- palpitations;
- swelling due to fluid retention in the legs and abdomen (oedema); and
- sometimes, chest pain.
When cardiomyopathy results from an infection, the first symptoms noticed may be similar to those of the 'flu.
Diagnosis and treatment
Your doctor may suspect cardiomyopathy if you have any of these symptoms, and he or she may often be able to identify the disease by physically examining you and listening to your heart sounds through a stethoscope.
Your doctor may recommend tests such as an electrocardiogram (ECG), chest X-ray or an echocardiogram (an ultrasound scan of your heart) to confirm the diagnosis and determine what type of cardiomyopathy you have. In some cases, your doctor may recommend magnetic resonance imaging (MRI) to gain even more information about your condition.
Other more advanced tests include cardiac catheterisation, in which a small tube is inserted into your heart to measure its pressure, or biopsy, in which a sample of tissue is removed for examination under a microscope.
Cardiomyopathies cannot usually be completely cured and the condition varies in severity. However, depending on the type of cardiomyopathy, treatments can help many people lead relatively normal lives for some time.
The exact treatment will depend on what sort of cardiomyopathy you have. One commonly used mediation is a beta-blocker, such as metoprolol (e.g. Betaloc). Treating the underlying cause, such as alcohol abuse or an infection, can help. You may also be given medicines (anticoagulants) that can help reduce blood clots.
Pacemakers and implantable defibrillators are sometimes used and surgery can help some people with the condition. If your cardiomyopathy becomes very advanced and leads to heart failure then doctors may ask you to consider a heart transplant. This operation has good long-term results.
What can I do to help myself?
Modifying your lifestyle can do much to help improve your quality of life if you have cardiomyopathy. If you smoke, you should definitely stop as smoking can contribute to blocked arteries.
As alcohol has been implicated in cardiomyopathy, you should stay away from this altogether if you can.
You should also talk to your doctor about a gentle exercise programme that incorporates aerobic exercise such as swimming or walking. Avoiding salty, fatty or highly processed food is also a must.
For the best advice about your particular form of cardiomyopathy, you should talk to your doctor.
Last Reviewed: 18 April 2009
