Cardiomyopathy

Definition

Cardiomyopathy is a weakening of the heart muscle or a change in heart muscle structure. It is often associated with inadequate heart pumping or other heart function abnormalities.

Causes, incidence, and risk factors

Cardiomyopathy can be caused by viral infections; heart attacks; alcoholism; long-term, severe high blood pressure; or for other reasons not yet known.

Specific types of cardiomyopathy include:

• Ischemic cardiomyopathy: This is caused by heart attacks, which leave scars in the heart muscle (myocardium). The affected myocardium is then unable to contribute to the heart pumping function. The larger the scars (or the more numerous the heart attacks), the higher the chance there is of developing ischemic cardiomyopathy.
• Idiopathic cardiomyopathy: The term "idiopathic" means that the cause is unknown. Usually, this term refers to dilated cardiomyopathy.
• Dilated cardiomyopathy: This is a global, usually idiopathic myocardial disorder characterized by a marked enlargement and inadequate function of the left ventricle. It may affect young people.
• Hypertrophic cardiomyopathy: This is a disproportionate growth of the left ventricle muscle. Sometimes, the right ventricle is also affected. In up to 70% of cases, there is a family history of this condition.
• Alcoholic cardiomyopathy: This is a type of dilated cardiomyopathy that usually begins about 10 years after sustained, heavy alcohol consumption. It can occur with both typical signs of heart failure, as well as with atrial fibrillation or other heart rhythm problems.
• Peripartum cardiomyopathy: This is a dilated cardiomyopathy appearing in women during the last trimester of pregnancy, or after childbirth.
• Restrictive cardiomyopathy: This is a disorder affecting the diastolic (when the heart muscle is relaxing between contractions) function of the heart. The heart cannot relax adequately after each contraction (systole), and thus it cannot be adequately filled with blood. Examples of restrictive cardiomyopathy are amyloidosis and sarcoidosis.

Cardiomyopathy is not common, but can be severely disabling or fatal. Extreme cardiomyopathy with heart failure may require a heart transplant.

Symptoms

• Shortness of breath
• Decreasing ability to tolerate physical exertion
• Chest pain - also known as "angina," consists of a feeling of sharp, unrelenting pressure the middle of the chest (more common in ischemic cardiomyopathy)
• Fainting - especially after activity; temporary and brief loss of consciousness
• Light-headedness - especially after activity
• Dizziness
• Palpitations - the sensation of feeling the heart beat
• High blood pressure

Additional symptoms that may occur:

• Swelling of legs, ankles, or other portion of the body
• Abdominal swelling or enlargement (liquid in the abdomen is called "ascites")
• Low amount of urine during daytime
• Need to urinate at night
• Fatigue
• Change in mental status
• Decreased alertness
• Difficulty concentrating
• Cough - may be caused by extra liquid accumulating in the lungs, secondary to heart failure
• Loss of appetite
• Deconditioning may occur as a consequence of the other symptoms, leading to a reduction in the heart's muscle mass

Signs and tests

Examination may reveal an irregular heartbeat. Heart sounds and breath sounds may be abnormal. Additionally, there may be other signs of heart failure.

Decreased heart function and heart enlargement may appear in these tests:

• Coronary angiography
• Echocardiogram and ultrasound examination of the heart.
• Chest x-ray
• Chest CT scan
• MRI of chest
• ECG

Rarely, a heart biopsy may be needed to rule out other disorders. The following lab tests may be used to rule out other disorders and to assess the condition of the heart:

• CBC
• Coronary risk profile
• Blood chemistries
• Cardiac enzymes: (CPK isoenzymes, CK-MB, LDH isoenzymes)

Treatment

While all types of cardiomyopathy can cause heart failure, each case requires specific strategies for recovery. Heart failure is treated with a vigorous blend of patient education, dietary changes, and medications.

Possible medications include:

• Positive inotropic agents: These chemicals help the heart contract. The main agent of this category is digoxin. In-hospital options include dopamine, dobutamine, and milrinone.
• Diuretics: Often called "water pills," diuretics help relieve the fluid overloads in heart failure.
• Vasodilators: These drugs dilate blood vessels at several levels in the body, reducing the workload for the heart.
• ACE-inhibitors and Beta blockers: These treatments act as vasodilators while helping to preserve the normal architecture of the heart muscle
• Other drugs: Angiotensin II receptor blockers, antiarrhythmic drugs, and blood thinners.

In some individuals with severely weak pumping function of the heart and severe heart failure, a special pacemaker, called a biventricular pacemaker, may be needed. It makes the contraction of the left and right bottom chambers (ventricles) more efficient. In very specific cases, biventricular pacemakers with defibrillation functions are used.

In severe cases, surgical procedures, which can be implemented to sustain life until a transplant donor becomes available, can help but do not cure the disease. They include:

• Left Ventricular Assist Device (LVAD): Treatment provides mechanical circulatory support.
• Dynamic Cardiomyoplasty: A procedure in which a skeletal-muscle flap, created from a patient's thoracic (chest) muscle, is trained to contract often and "wrapped around" the heart to help it contract.

Advanced, severe heart failure requires heart transplant.

Expectations (prognosis)

The outcome varies. The disorder is chronic and the condition may deteriorate rapidly.

Complications

• Heart failure

Calling your health care provider

Go to the emergency room or call the local emergency number (such as 911) if symptoms indicating heart failure develop, or if chest pain is present and not relieved by rest or medication.

Illustrations

Heart, section through the middle

Heart, front view

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