Cardiac amyloidosis

Definition

Cardiac amyloidosis is a disorder caused by deposits of an abnormal protein (amyloid) in the heart tissue, which make it hard for the heart to work properly.

Alternative Names

Amyloidosis - cardiac; Primary cardiac amyloidosis - AL type; Secondary cardiac amyloidosis - AA type; Stiff heart syndrome; Senile amyloidosis

Causes

Amyloidosis refers to a family of diseases in which there is a buildup of clumps of proteins called amyloids in body tissues and organs. These proteins slowly replace normal tissue, leading to failure of the involved organ. There are many forms of amyloidosis.

Cardiac amyloidosis usually occurs during primary amyloidosis (AL type amyloidosis). Primary amyloidosis is often seen in people with multiple myeloma cancer.

Cardiac amyloidosis ("stiff heart syndrome") occurs when amyloid deposits take the place of normal heart muscle. It is the most typical type of restrictive cardiomyopathy. Cardiac amyloidosis may affect the way electrical signals move through the heart (conduction system). This can lead to arrhythmias and conduction disturbances (heart block).

Secondary amyloidosis (AA type) rarely affects the heart. However, a form of secondary amyloidosis called senile amyloidosis involves the heart and blood vessels. Senile amyloidosis is caused by overproduction of a different protein. The condition is becoming more common as the average age of the population increases.

Cardiac amyloidosis is more common in men than in women. The disease is rare in people under age 40.

Symptoms

• Excessive urination at night
• Fatigue, reduced activity tolerance
• Palpitations (sensation of feeling heart beat)
• Shortness of breath with activity
• Swelling of legs, ankles, or other part of the body (See: abdominal swelling)
• Trouble breathing while lying down

Some patients may have no symptoms.

Exams and Tests

It can be difficult to diagnose cardiac amyloidosis, because the signs can be related to a number of different conditions.

Signs may include:

• Abnormal sounds in the lung (lung crackles) or a heart murmur
• Blood pressure that is low or drops when you stand up
• Enlarged neck veins
• Swollen liver

The following tests may be performed to help diagnose cardiac amyloidosis:

• Chest or abdomen CT scan (this is considered the "gold standard")
• Coronary angiography
• Echocardiogram
• Magnetic resonance imaging (MRI)
• Nuclear heart scans (MUGA, RNV)

An ECG may show problems with the heart beat or heart signals (conduction disturbance).

A cardiac biopsy is used to confirm the diagnosis. A biopsy of another area, such as the abdomen, kidney, or bone marrow, is often done to confirm the diagnosis.

Treatment

Your doctor may tell you to change your diet. This may include salt and fluid restrictions.

You may need to take water pills (diuretics) to help your body remove excess fluid. The doctor may tell you to weigh yourself every day. A weight gain of 3 or more pounds over 1 - 2 days can mean there is too much fluid in the body.

Digoxin, calcium channel blockers, and beta blockers may be used with caution in patients with atrial fibrillation. However, the dosage must be carefully monitored. Patients with cardiac amyloidosis may be unusually sensitive to any side effects.

Other treatments may include:

• Chemotherapy
• Implantable cardioverter-defibrillator (AICD)
• Pacemaker, if there are problems with heart signals
• Prednisone, an anti-inflammatory medicine

A heart transplant may be considered for some patients with very poor heart function. However, it is not done in those with AL type amyloidosis, because the disease weakens many other organs. People with hereditary amyloidosis will need a liver transplant.

Outlook (Prognosis)

Cardiac amyloidosis is a long-term (chronic) condition that slowly gets worse. On average, persons with cardiac amyloidosis live less than 1 year.

Possible Complications

• Atrial fibrillation or ventricular arrhythmias
• Congestive heart failure
• Fluid buildup in the abdomen (ascites)
• Increased sensitivity to digoxin
• Low blood pressure and dizziness from excessive urination (due to medication)
• Sick sinus syndrome
• Symptomatic cardiac conduction system disease (arrhythmias related to abnormal conduction of impulses through the heart muscle)

When to Contact a Medical Professional

Call your health care provider if you have this disorder and new symptoms develop, particularly:

• Dizziness when you change position
• Excessive weight (fluid) gain
• Excessive weight loss
• Fainting spells
• Severe breathing difficulty

References

Hare JM. The dilated, restrictive, and infiltrative cardiomyopathies. In: Bonow RO, Mann DL, Zipes DP, Libby P, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 9th ed. Philadelphia, Pa:Saunders Elsevier; 2011:chap 68.

McKenna W. Diseases of the myocardium and endocardium. In:Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, PA: Saunders Elsevier; 2011:chap 60.

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