Dilated cardiomyopathy is a condition in which the structure and function of the heart muscle is altered. As the heart muscle weakens, the heart finds it more difficult to contract and relax and less blood is pumped to the lungs and the rest of the body. This can affect bot he left ventricle and the right ventricle. Eventually, if left untreated, the heart dilates and enlarges and heart failure ensues.
The are many causes of dilated cardiomyopathy. In a proportion, dilated cardiomyopathy can run in families (‘familial dilated cardiomyopathy’). The cause of familial cardiomyopathy is a genetic defect that cannot be corrected. In such cases, the condition develops between the ages of 20 and 60. In around 50% of cases of DCM, no cause can be found and the condition is then termed ‘idiopathic’ dilated cardiomyopathy.
Symptoms occur when heart failure ensues. They include:
• Breathlessness: This can be due to accumulation of fluid in the lungs (pulmonary oedema), but can also occur in its absence. When there is fluid in the lungs, a cough or wheezing can occur.
• Fluid retention (oedema): In heart failure, the kidneys respond by promoting the retention of fluid. This collects in the most dependent parts of the body, ie. the legs. Passing urine at night, breathlessness on lying down (orthopnoea) and waking up at night gasping for air (paroxysmal nocturnal dyspnoea) can also occur.
• Fatigue: this results from a reduction in the blood suppy to all parts of the body.
• Palpitations: As the heart tries to compensate for the reduction in blood supply, it speeds up and this is felt as rapid or irregular heartbeats.
Doctors can diagnose heart failure by taking a history and examining the patient. Often, investigations are needed to explore what has caused heart failure and how best to treat it.
• ECG (heart trace): Although the ECG does not confirm the diagnosis of heart failure, it is more than likely abnormal in patients with the condition. It can reveal previous heart attacks and disorders of heart rhythm.
• NT pro-natriuretic peptide (NT pro-BNP) blood test. This hormone is secreted from the heart when it stretches in an abnormal fashion. High levels make heart failure more likely, but it does not confirm the diagnosis. A low BNP test makes heart failure unlikely.
• Chest X-ray: A chest X-ray can give an approximation of the size of the heart and can show whether there is fluid in the lungs (pulmonary oedema and pleural effusions). It does not, however, provide information of heart function.
• Echocardiogram: provides a very comprehensive assessment of the heart structures and function. It should be performed for the diagnosis and monitoring of heart failure.
• Cardiac MRI scan: This specialised scan provides very accurate information on heart function and the causes of heart failure.
• Cardiac catheterisation: This may required to assess the cause of heart failure.
Between 30 and 50%percent of people with idiopathic dilated cardiomyopathy have inherited a genetic mutation for the disease. Some of these mutations can be identified with blood testing. In the majority of cases, however, genetic testing is unfruitful. This is because there many genes to consider and even if you carry the gene, that does not mean you are going to develop the disease. Conversely, absence of a genetic defect does not necessarily mean you are not going to develop the disease.
Screening tests are geared towards monitoring of cardiac function and structure with an echocardiogram and/or a cardiac MRI scan.
This is geared towards treatment of the underlying cause and its effects on cardiac function. If the cause of the cardiomyopathy is identified, this may involve avoiding exposure to toxins, such as alcohol and cocaine. The treatment of the function of the heart is as for heart failure.
Traditionally, heart failure has been treated only with drugs. Over the past decade, however, the treatment of patients with heart failure has been revolutionised by cardiac device therapy – cardiac resynchronisation therapy (CRT) and implantable cardioverter defibrillators.
These are designed to relieve swelling and to improve the function of the heart. Here are some examples:
• Diuretics (water tablets), such as furosemide and bumetanide relieve breathlessness and ankle swelling by getting rid of fluid.
• ACE inhibitors, such as ramipril and perindopril, reduce blood pressure in the arteries and improve the pumping action of the heart.
• Beta-blockers, such as bisoprolol and carvedilol, slow down the heart rate and neutralise the undesirable effects of substances released by the body when the heart fails.
• Aldosterone receptor blockers, such as spironolactone and eplerenone, counteract the effects of a harmful secretion of a body hormone (aldosterone). They are unlikely to improve symptoms, but will make you live longer.
• Ivabradine, which can help reduce the heart rate if it is not reduced by beta-blockers.
• Digoxin regulates the heart rhythm in patients with atrial fibrillation. It is sometimes used in patients with heart failure who do not have atrial fibrillation.
Cardiac device therapy
These treatments have revolutionised the treatment of patients with heart failure. The suitability for CRT depends on symptoms (breathlessness), the ECG and the echocardiogram.
• Cardiac resynchronisation therapy (CRT): Cardiac resynchronisation therapy (CRT) is aimed to correct delays in electrical impulses across the heart in patients with heart failure It does so by delivering electrical impulses to various areas of the heart, usually three – the right atrium, the right ventricle and the left ventricle. CRT has been shown to improve quality of life and to make patients live longer. Importantly, it does so even in patients who take all the required medications for heart failure.
• CRT with defibrillator therapy: CRT can be combined with a cardiac defibrillator (ICD). This device detects abnormal heart rhythms (ventricular tachycardia and fibrillation) and shocks the patient out of the rhythm with an electrical discharge. Currently, around 80% of patients who are treated with CRT receive this combination (CRT-D).
• Implantable left ventricular assist device (LVAD): The LVAD is known as a ‘bridge to transplantation’ for patients who haven't responded to other treatments and are hospitalised with severe systolic heart failure. This device helps your heart pump blood and allows you to be mobile, sometimes returning home to await a heart transplant. In the UK NHS, only patients who are accepted to the heart transplant waiting list can be treated with LVADs.
• Heart transplantation: Most patients with heart failure are well controlled on drug treatment. A minority of patients, however, may need surgery to improve the pumping action of the heart. Heart transplantation is the last resort. In the UK, it is only available to the few, due to the shortage of donors.
Stem cell therapy has not been proven to be effective in dilated cardiomyopathy or in heart failure.
What can I do ?
• Take your medications as prescribed. These are not only prescribed to improve your symptoms (breathelessness, fatigue) but also, to make you live longer. Some medications will not make you feel better. Other medications are designed to treat the causes of heart failure, such as a heart attack and high blood pressure.
• Keep your blood pressure in target. Your specialist will guide you as to the best blood pressure for you to keep.
• Monitor fluid retention. You should know from your doctor what your ‘dry weight’ is. Check for fluid retention by weighing yourself daily. Weigh yourself daily, preferably in the morning without clothes, after passing urine but before eating. You should suspect a worsening of heart failure if if you gain weight (1.5 kg in one day or 2.5 kg in one week). You should also check for ‘pitting oedema’ by pressing on the skin of the lower legs for 5 seconds. If the finger leaves a mark, then you have ‘pitting oedema’.
• Keep a record of fluid intake. This is useful if you have or are likely to develop accumulation of fluid. If so, you should keep your fluid intake to less than 2 litres per day.
• Keep an eye on salt intake: Sodium is found in most foods, but the highest concentrations are in processed foods. A low sodium diet reduces fluid accumulation.
• Be alert for new symptoms. You should seek specialist medical advice if new symptoms occur or if your symptoms worsen.
• Keep regular appointments. Once heart failure is stable, you should be assessed by a specialist at least every 6 months. More frequent appointments will be needed if symptoms change or if you need changes in medication.
• Exercise regularly. Exercise rehabilitation may be suitable for some patients with heart failure.
• Stop smoking.
• Keep up to date with immunisations: Your GP will inform you on influenza and pneumonia immunisations.
• Keep up to date with device follow-up: If you have had a CRT or an ICD implanted, ensure that you keep up your appointments in the device clinic.
The Cardiomyopathy Association: http://www.cardiomyopathy.org/
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