What is cardiomyopathy?
Cardiomyopathy is a disorder of the heart muscle. There are four main types of cardiomyopathy:
- Dilated cardiomyopathy - where the heart dilates (enlarges).
- Hypertrophic cardiomyopathy - where the heart muscle becomes thickened ('hypertrophied').
- Restrictive cardiomyopathy - where the heart muscle cannot relax properly between heartbeats. This is rare.
- Arrhythmogenic right ventricular cardiomyopathy - a rare type which mainly affects the right side of the heart.
The rest of this page is only about hypertrophic cardiomyopathy.
What happens in hypertrophic cardiomyopathy
In this condition the heart muscle becomes thickened (it 'hypertrophies') in parts of the heart. The muscle surrounding the left ventricle is the area commonly affected. Sometimes the muscle around the right ventricle is affected. The degree of thickening may vary in different places. For example, the septum (the wall dividing the right and left ventricle) is often the area with the greatest thickening. In about 1 in 4 cases the muscle thickening is evenly distributed throughout the walls of the left ventricle.
The thickened heart muscle usually contracts well to pump blood out of the heart. However, it may lead to problems which include the following.
- The affected heart muscle (usually around the left ventricle) may become 'stiff'. So, the ventricle may not fill as easily as normal. This means that less blood than normal may be pumped out from the heart each heartbeat.
- The thickening is often most marked in the upper part of the septum next to the aortic valve. This may partly obstruct the outflow of blood from the left ventricle into the aorta. So, less blood may be pumped out from the heart. The partial obstruction may also create turbulent flow of blood in this area of the heart.
- The thickened heart muscle may affect the function of the heart valves. In particular, the mitral valve may become 'leaky' if it does not close properly.
- In some cases the abnormal heart muscle affects the electrical conducting system of the heart. This may cause abnormal heart rates and / or rhythms to develop (arrhythmias).
What causes hypertrophic cardiomyopathy?
The muscle cells of the heart are 'disorganised' and not arranged in the normal way. It is not known why this occurs.
In most cases the condition is inherited. Men and women are affected equally. Children born to a couple where one parent has hypertrophic cardiomyopathy have a 50:50 chance of inheriting the condition. This pattern of inheritance is called autosomal dominant. It seems that affected people inherit defective genes which are involved in making parts of the heart muscle cells.
Who develops hypertrophic cardiomyopathy?
About l in 500 people in the UK develop hypertrophic cardiomyopathy. It most commonly first develops in the teenage years or early adulthood. However, it can first develop in young children, and is sometimes present at birth.
What are the symptoms of hypertrophic cardiomyopathy?
Symptoms largely depend on how severe the thickening is, and where it occurs in the heart. Symptoms can range from mild to severe, and some people have no symptoms. Symptoms may develop at any stage in life, even though you may have had the condition for a number of years. Possible symptoms include:
- Breathlessness (shortness of breath). This may develop only when you exercise if the condition is mild. In more severe cases you can be breathless at rest.
- Chest pain (angina). This may develop only when you exercise, but can also occur at rest in severe cases. The pain occurs because the supply of blood and oxygen to the heart muscle is not sufficient to meet the demands of the thickened muscle.
- Palpitations. You may have an increased awareness of your heartbeat. Arrhythmias develop in some cases which can cause palpitations.
- Dizziness and fainting attacks. This more commonly occurs when you exercise, but may occur when you are resting. This may be due to a reduced output of blood from the heart, or to bouts of arrhythmias.
How is hypertrophic cardiomyopathy diagnosed?
A doctor may suspect this condition from your symptoms, family history, or changes on a heart tracing (ECG). To confirm the diagnosis, an ultrasound scan of the heart called an echocardiogram is used. This is a painless test where sound waves 'bounce' back off heart tissue. It can measure the thickness of the heart muscle. Another type of ultrasound test called a Doppler ultrasound can detect blood flow through the heart chambers. This shows how well the heart ventricles are filling and contracting. A Doppler ultrasound can also show if there is any turbulent blood flow within the ventricles.
Once the diagnosis is confirmed, other tests may be advised to assess the severity of the condition.
How does the condition progress?
The thickening of the heart muscle does not tend to progress once you stop growing. So, in many cases, the symptoms that develop remain stable over many years in adulthood. In some cases, the symptoms gradually become worse as the heart muscle becomes more 'stiff'. In some cases the function of the heart gradually deteriorates and heart failure may develop (see separate page called 'Heart Failure'). Complications occur in some cases and include the following.
Arrhythmias
An arrhythmia is an abnormal rate or rhythm of the heartbeat. There are various types of arrhythmia, some more serious than others. Sometimes an arrhythmia develops intermittently and can cause bouts of palpitations, dizziness and other symptoms. Some arrhythmias become permanent. Arrhythmias can usually be treated. See separate page called 'Arrythmias'.
Endocarditis
This is a rare complication. It is an infection of the inside lining of the heart chambers and heart valves. Unless promptly treated, endocarditis can cause serious illness. See separate page called 'Infective Endocarditis'.
Sudden Death
Sudden collapse and death without any warning occurs in a small number of cases. This is probably due to a severe arrhythmia which may develop suddenly. People most at risk are those more severe disease, especially those who have had previous serious arrhythmias. Some people at high risk may be advised on treatments which aim to prevent or treat arrhythmias.
What is the treatment for hypertrophic cardiomyopathy?
There is no treatment which can reverse the changes of the heart muscle. 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.
Medication
The medicines advised depend on what symptoms or complications develop. For example:
- Beta-blocker medicines (such as propranolol), and calcium antagonist medicines (especially verapamil) are the mainstay of treatment. These can slow the heart rate, make the heart contract less forcefully, and can allow more time for the ventricle to fill each heartbeat. These medicines may be used to treat chest pain, breathlessness and palpitations.
- Various other medicines called 'anti-arrhythmic' medicines (for example, amiodarone) are used to treat and to prevent arrhythmias. They work by interfering with and helping to correct the electrical impulses in your heart.
- Warfarin may be advised if you develop atrial fibrillation (a common arrhythmia). With this arrhythmia a blood clot is a possible complication. Warfarin is an anticoagulant which means it helps to prevent blood clotting.
- Antibiotics may be advised before you have dental treatment or certain other procedures such as cystoscopy or colonoscopy. During these procedures, some bacteria may be 'pushed' into the bloodstream. The antibiotics kill any bacteria which may get into the bloodstream and help to prevent endocarditis (described above).
Other types of treatment for arrhythmias
Other treatments may be an option if you develop arrhythmias. For example:
- Cardioversion is an option for some types of arrhythmia. Whilst under anaesthetic, you are given an electrical shock over the heart. This may revert the rhythm back to normal.
- Artificial pacemakers are used in certain types of arrhythmia where the heart beats abnormally slowly (complete heart block), and in certain other situations. An artificial pacemaker is a small device which is inserted just under the skin on the upper chest. Wires from the pacemaker are passed through veins into the heart chambers. The pacemaker can then stimulate the heart to maintain a regular normal heartbeat.
- Implantable cardioverter defibrillators (ICD's) are sometimes used in certain situations - especially if you are at risk of developing serious and life threatening arrhythmias. They are small devices which are similar to pacemakers and are inserted under the skin in the upper chest. Wires are passed through a vein to the heart. The device monitors the heartbeat. If it detects a change to an severe life threatening abnormal rhythm, the device can send a short electrical shock to the heart to stop the abnormal rhythm.
Surgery
An operation is option in severe cases.
- Myectomy. This is an operation done via open heart surgery to remove a segment of thickened muscle from the septum. It is not a cure, but can help if the thick septum is causing obstruction to the flow of blood through the aortic valve.
- Valve replacement may be needed if the mitral valve is affected and does not work properly.
- A heart transplant may be needed in a small number of cases.
A recent development is a technique which destroys part of the heart muscle without the need for open heart surgery. It is done by injecting alcohol into small arteries supplying blood to the septum. This has been used in some cases to destroy parts of a thickened septum which is causing obstruction to the flow of blood through the aortic valve.
Some other general points
- Family testing (screening). Your first degree relatives (mother, father, brother, sister, child) should have tests such as a heart tracing and an echocardiogram. Some people with hypertrophic cardiomyopathy do not have any symptoms which is why close relatives should be screened. People with hypertrophic cardiomyopathy, with or without symptoms, have a 50:50 chance of passing the condition on to their children who may develop symptoms. Genetic counselling may be appropriate.
- Exercise. Depending on the severity of the condition, some people are advised not to take part in strenuous sports or jobs. Your doctor will advise.
- Weight. Try not to become overweight which can put an extra strain on your heart.
- Alcohol. Normal social drinking in moderation should not affect your heart. But, too much alcohol can affect the heart muscle and should be avoided.
Further help and information
Cardiomyopathy Association, 40 The Metro Centre, Tolpits Lane, Watford, Herts, WD1 8SB
Tel: 01923 249 977 or Freephone 0800 018 1024 Web:
www.cardiomyopathy.org
©EMIS and PIP 2004 Updated: July 2004 Review Date: August 2005 CHIQ Accredited
