What is Cardiomyopathy?

By Dr Ananya Mandal, MD

Cardiomyopathy is a disease of the heart muscles which may cause them to become enlarged and inflamed. Inflamed muscles become stretched, weak, less efficient at pumping blood and less able to maintain a normal electrical pattern. This can eventually lead to heart failure. While patients with mild cardiomyopathy may lead a near-normal life, those with severe heart failure may require a heart transplant to survive.

Causes

There are four major factors that predispose to cardiomyopathy. These include:

  • Family history of cardiomyopathy – People with a family member (usually a first degree relative) who has had cardiomyopathy are at a higher risk of developing the condition.
  • Viral infection – Viral infections are thought to be a common cause of cardiomyopathy. A viral infection can damage the heart muscle, although the damage may not be obvious for months or years
  • Previous heart attack – A previous episode of a heart attack can leave the heart muscles damaged and weak. Scar tissue forms at the site of damage, which does not contract in the same way as healthy cardiac muscle, meaning the heart has to work harder to compensate.
  • Alcohol abuse is also known to cause cardiomyopathy. The recommended amount is two standard drinks a day. Damage to the heart can sometimes be reversed by stopping drinking.

Types of cardiomyopathy

Two examples of the main types of cardiomyopathy are:

  • Dilated (congestive) cardiomyopathy

This is the most common form of cardiomyopathy and usually develops before the age of 60. In dilated cardiomyopathy, the ventricles and atria become dilated, stretched and thin, which creates enlarged heart chambers that do not contract properly. The heart cannot pump blood efficiently and it becomes weaker. Eventually, the heart may fail which causes symptoms such as tiredness, shortness of breath and fluid retention in the lower limbs and abdomen.

  • Hypertrophic Cardiomyopathy

This is the most common cause of sudden cardiac arrest. The condition describes a thickening of the ventricular walls that may prevent blood flow out of the ventricle. The heart compensates for this blockage by pumping harder.

Symptoms

Mild cardiomyopathy often does not give rise to symptoms. In more severe cases, however, heart failure may develop and cause the following:

  • Fatigue
  • Breathlessness
  • Swelling across the abdomen, face and legs

Diagnosis

A diagnosis of cardiomopathy is based on various tests including:

  • A detailed physical examination
  • An X-ray to check whether the heart is enlarged
  • An echocardiogram to examine the size, shape and movement of the heart using ultrasound
  • Cardiac magnetic resonance imaging to look at the structure and function of the heart
  • Electrocardiogram to look at the electrical activity of the heart
  • Routine blood tests

Treatment

There are several treatments available to treat cardiomyopathy which include:

  • ACE inhibitors such as enalapril and captopril. These agents reduce blood levels of the vasoconstrictor angiotensin II and therefore reduce blood pressure and the heart’s workload.
  • Diuretics such as hydrochlorthiazide which act on the kidneys to increase the amount of fluid excreted from the body. This reduces the blood volume and therefore the blood pressure. Diuretics also reduce swelling in the legs, face and abdomen caused by heart failure.
  • Beta-blockers such as atenolol and metoprolol, which block the heart’s beta receptors and lower the force and rate the heart pumps at.
  • Digitalis (digoxin) helps the heart to beat more strongly, increasing the cardiac output and reducing symptoms of heart failure. Digoxin can also slow and regulate the heartbeat in cases of abnormal heart rhythm.
  • Anticoagulants such as warfarin prevent blood clots and lower the risk of stroke and heart attacks.
  • Surgery may be required in some types of cardiomyopathy where there is excessive thickening of the heart muscles.
  • A heart transplant may be needed in very severe cases where the heart fails to pump any blood.
  • Apart from medications, some lifestyle changes can improve the heart’s condition. Examples of measures that can be taken include stopping smoking, reducing salt intake, maintaining a healthy diet and engaging in regular light-to-moderate physical exercise such as walking, cycling and swimming.

Reviewed by Sally Robertson, BSc

Sources

  1. http://www.heartfoundation.org.au/SiteCollectionDocuments/Cardiomyopathy.pdf
  2. http://www.towson.edu/wellness/documents/Cardiomyopathy.pdf
  3. http://www.strokeassociation.org/idc/groups/heart-public/@wcm/@hcm/documents/downloadable/ucm_312224.pdf
  4. http://heart.bmj.com/content/83/4/469.full.pdf
  5. http://www.mcrfmd.com/links/Antle-Cardiomyopathy1.pdf

Further Reading

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