- The term 'cardiomyopathy' simply means that there's something wrong with the muscle of the heart. In dilated cardiomyopathy (DCM), there is enlargement of one or both ventricles, and the thickness of the muscle wall can vary from excessively thick to very thin.
- The commonest causes of DCM are i schaemia due to coronary artery disease , h eart valve disease , v irus infections , g enetic cardiomyopathy and a lcoholism .
- DCM usually presents with symptoms of left-sided heart failure. These include inappropriate shortness of breath (dyspnoea) and decreased effort tolerance.
- Diagnosis can be made by means of physical examination; chest X-ray; e lectrocardiogram; echocardiogram; exercise testing; catheterisation; and other, more s pecific diagnostic tests.
- Different types of treatments are used to improve symptoms, slow or reverse the deterioration of heart function, and reduce mortality.
- The majority of patients with DCM (80%) will survive for five years after the initial diagnosis has been made, but will suffer progressively increasing symptoms and decreasing quality of life.
- Measures that may decrease the chances of developing a DCM include refraining from excessive alcohol intake, refraining from doing physical exercise if you have a viral infection, as well as early diagnosis and treatment of hypertension.
What is dilated cardiomyopathy?
In plain language, the term 'cardiomyopathy' simply means that there's something wrong with the muscle of the heart. In other words, the cardiomyopathies are disorders or diseases of the heart muscle.
In dilated cardiomyopathy (DCM), there is enlargement of one or both ventricles, and the thickness of the muscle wall can vary from excessively thick to very thin. In extreme cases, all four chambers of the heart may be enlarged.
The incidence of DCM seems to vary widely, but some studies suggest that more than 14% of the elderly population have some degree of DCM.
What causes it?
The commonest causes of D CM are :
- Ischaemia due to coronary artery disease ( i.e. an inadequate flow of blood to the heart, caused by blockage of the blood vessels)
- Heart valve disease
- Virus infections
- Genetic cardiomyopathy (a late manifestation of hypertrophic cardiomyopathy)
What are the symptoms?
DCM usually presents with symptoms of left-sided heart failure. These include inappropriate shortness of breath (dyspnoea) and decreased effort tolerance. However, so-called right-sided symptoms (a tender, swollen abdomen, legs that swell etc.) sometimes predominate.
Less common presentations are dysrhythmias (abnormal cardiac rhythm) leading to syncope (falls due to brief loss of consciousness) or, rarely, sudden death. Systemic emboli (blood clots that affect a part of the body distant from the heart), which can present as a stroke or other medical problems, are sometimes the first sign.
How is it diagnosed?
Your doctor will ask about your symptoms and perform a physical examination. Certain physical signs (such as heart murmurs and chamber enlargement) should alert an examining doctor to the possible presence of cardiomyopathy.
The following special investigations may also help to make the correct diagnosis:
- Chest X-ray. This will point to any enlargement of the heart and major blood vessels in the chest. Accumulation of fluid in the lungs (indicating heart failure) will also be shown.
- Electrocardiogram (ECG). There are no changes diagnostic of cardiomyopathy, but rhythm disorders, coronary artery disease and muscle thickness may be identified.
- Echocardiogram. This form of ultrasound provides information about the functioning of the heart and its valves, and the thickness of the muscle walls. It can also be used to measure the cardiac output (pumping ability) and the pressures within the heart.
- Exercise testing can record how the heart functions during physical activity. If a patient cannot exercise, other methods can be used to simulate exercise.
- Catheterisation. This angiogram shows the chambers of the heart, as well as the flow through the coronary arteries. During the angiogram, accurate pressure readings can be made to assess heart function.
- Specific diagnostic tests for suspected underlying causes may include blood tests (e.g. to test for virus infection).
How is it treated?
Different types of treatments are used to improve symptoms, slow or reverse the deterioration of heart function, and reduce mortality.
- Treatment of the underlying causes where identified, e.g. total abstinence from alcohol.
- Vasodilator therapy. Drugs that dilate (increase the diameter) of the arteries both improve the symptoms of cardiac failure and decrease the rate of further heart enlargement. Unless contraindicated, all patients with DCM should be on such drugs. The classes of drugs that are currently very popular are the so-called ACE-inhibitors and the AT2-receptor blockers.
- Beta-blockers. In recent years, there has been great interest in the potential benefits of these drugs, previously thought to be harmful. Used correctly, the beta-blockers have been shown to increase life expectancy in people with DCM.
- Drugs used to treat the symptoms of cardiac failure. Resistant cardiac failure usually requires diuretic therapy (water pills) and digoxin (which improves the way in which the heart contracts).
- Drugs used to treat the complications of DCM. These include anti-coagulation (to keep the blood from clotting where thrombi are found) and specific anti-arrhythmic therapy.
- Dual-chamberpacing (two pacemaker leads are inserted into the heart, one into the atrium or upper chamber and the other into the ventricle or lower chamber, to facilitate synchronised contraction of the heart) and implantable cardioverter-defibrillators (a lead is placed into the heart that may record an abnormal cardiac rhythm and initiate a local electric shock to restore the normal rhythm) are treatments only available in very specialised centres. An implantable cardioverter-defibrillator automatically puts the heart back into the correct rhythm if a potentially fatal arrhythmia occurs.
- Heart transplantation. Worldwide, DCM is currently the commonest reason for this potentially lifesaving procedure.
What is the prognosis?
The majority of patients with DCM (80%) will survive for five years after the initial diagnosis has been made, but will suffer progressively increasing symptoms and decreasing quality of life.
Predictors of mortality (factors that increase the risk of death) include:
- Severe heart failure
- Massive cardiac enlargement
- Poor contractility and wall motion abnormalities in the heart muscle
- Syncope attacks (fainting)
- Male sex
- Advanced age
Death may result from either progressive heart failure or from dysrhythmias, which cause so-called 'sudden death'. This may be the eventual cause of death in up to 50% of people who have this condition.
On the other hand, people may live for many years with only mild to moderate symptoms, adequately alleviated (but not cured) by medical means.
When to call your doctor
The following signs are definitely indications that you should consult your doctor:
- Unexplained shortness of breath.
- Chest pains.
- Unexplained fainting.
- Previous unexplained cardiac arrest.
- A family history of cardiomyopathy.
How can it be prevented?
Measures that may decrease the chances of developing a DCM are:
- Refraining from excessive alcohol intake.
- Refraining from physical exercise during viraemia (i.e. when viral particles are found in the blood, e.g. during the early phases of influenza).
- Early diagnosis and treatment of hypertension.