Cardiomyopathies

Original Editor - Lucinda hampton

Top Contributors - Lucinda hampton, Kim Jackson and Rucha Gadgil  

Introduction

Cardiomyopathies are abnormalities of the myocardium (heart muscle) with associated cardiac dysfunction, often occurring in families, and can lead to abnormal heart muscle thickening or weakness. Although the majority of these conditions affect adults, changes in the heart can begin in childhood. Some conditions can lead to sudden death, with medical and psychological interventions key to providing the best possible protection and preservation of quality of life. In rare cases, a heart transplant in childhood will be needed.

• Cardiomyopathies are a diverse group of cardiac disorders that frequently cause heart failure and death and are now recognized with increasing frequency.
• There has been substantial progress in the clinical recognition and understanding of the natural history of these conditions. Well-established and new techniques of cardiac imaging are helping in this regard.
• Nearly, 50% of patients dying suddenly in childhood or adolescence or undergoing cardiac transplantation are affected by cardiomyopathies.

Cardiomyopathy can be acquired or inherited. Many times, the cause of cardiomyopathy isn’t known. This often is the case when the disease occurs in children.

Classification

Cardiomyopathy classification separates the various cardiomyopathies into several subtypes. It was classified according to the 1995 World Health Organisation / International Society and Federation of Cardiology (WHO/ISFC) system as follows:

1. Dilated cardiomyopathy
2. Hypertrophic cardiomyopathy
3. Restrictive cardiomyopathy  
4. Arrhythmogenic right ventricular cardiomyopathy
5. Unclassified Cardiomyopathy: Other types of cardiomyopathy are grouped into this category and can include: eg Takotsubo cardiomyopathy, or broken heart syndrome, happens when extreme stress leads to heart muscle failure. Though rare, this condition is more common in post-menopausal women.

Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy is very common and can affect people of any age. Hypertrophic cardiomyopathy affects men and women equally, and about 1 out of every 500 people has the disease.

Hypertrophic cardiomyopathy usually is inherited. It’s caused by a mutation or change in some of the genes in heart muscle proteins. Hypertrophic cardiomyopathy also can develop over time because of high blood pressure, aging, or other diseases, such as diabetes or thyroid disease. Sometimes the cause of the disease isn’t known.

Pathophysiology

• Heart muscle enlarges and thickens without an obvious cause.
• Usually the ventricles (the lower chambers of the heart), and septum (wall that separates the left and right side of the heart) thicken.
• The thickened areas create narrowing or blockages in the ventricles, making it harder for the heart to pump blood.
• Hypertrophic cardiomyopathy also can cause stiffness of the ventricles, changes in the mitral valve, and cellular changes in the heart tissue.

Dilated Cardiomyopathy

Pathophysiology: Dilated cardiomyopathy develops when the ventricles enlarge and weaken.

• Usually starts in the left ventricle and over time can affect the right ventricle.
• Weakened ventricles of the heart don’t pump effectively, causing the heart muscle to work harder.
• Over time, the heart loses the ability to pump blood effectively.
• Dilated cardiomyopathy can lead to heart failure, heart valve disease, irregular heart rate, and blood clots in the heart.

The cause of dilated cardiomyopathy often isn’t known. About one-third of the people who have dilated cardiomyopathy inherit it from their parents. Certain diseases, conditions, and substances also can cause the disease, such as:

• Alcohol, especially combined with a poor diet
• Certain toxins, eg poisons and heavy metals
• Complications during the last months of pregnancy
• Ischemic heart disease, heart attack, high blood pressure, diabetes, thyroid disease, viral hepatitis, and HIV
• Illegal drugs, eg cocaine and amphetamines, and some medicines used to treat cancer
• Infections, especially viral infections that inflame the heart muscle

Restrictive Cardiomyopathy

Pathophysiology: Restrictive cardiomyopathy develops when the ventricles become stiff and rigid but the walls of the heart do not thicken.

• As a result, the ventricles do not relax and don’t fill with the normal blood volume.
• As the disease progresses, the ventricles do not pump as well and the heart muscle weakens.
• Over time, restrictive cardiomyopathy can lead to heart failure and problems with the heart valves.

Certain diseases, conditions, and factors can cause restrictive cardiomyopathy, including:

• Amyloidosis: A disease in which abnormal proteins build up in the body’s organs, including the heart
• Connective tissue disorders
• Hemochromatosis: too much iron builds up in the body. The extra iron is toxic to the body and can damage the organs, including the heart.
• Sarcoidosis: causes inflammation and can affect various organs in the body. Researchers believe that an abnormal immune response may cause sarcoidosis. This abnormal response causes tiny lumps of cells to form in the body’s organs, including the heart.
• Some cancer treatments, eg radiation and chemotherapy

Arrhythmogenic Right Ventricular Dysplasia

Arrhythmogenic right ventricular dysplasia is a rare type of cardiomyopathy. Researchers think that arrhythmogenic right ventricular dysplasia is an inherited disease.

Pathophysiology:

• Occurs when the muscle tissue in the right ventricle is replaced with fatty or fibrous tissue.
• Can lead to disruptions in the heart’s electrical signals and causes arrhythmias.
• Arrhythmogenic right ventricular dysplasia usually affects teens or young adults and can cause sudden cardiac arrest in young athletes.

Resources

• bulleted list
• x

or

1. numbered list
2. x