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Cardiac amyloidosis
Classification and external resources

Micrograph showing senile cardiac amyloidosis. The amyloid is the red-orange extracellular material. Congo red stain.
ICD-9 277.3
eMedicine med/3365

Cardiac amyloidosis is a medical disorder, a type of amyloidosis, caused by deposits of an amyloid protein in the heart tissue, resulting in decreased heart function. It is a cause of restrictive cardiomyopathy.[1]

Contents

Symptoms

  • Palpitations (sensation of feeling heart beat)
  • Swelling of legs, ankles, or other portion of the body (such as abdominal swelling or enlargement)
  • Excessive urination at night
  • Fatigue, reduced activity tolerance
  • Shortness of breath with activity
  • Breathing difficulty while lying down

Causes

Amyloidosis is the buildup of a fibril called amyloid in any tissue in the body. Fibrils are proteins produced in excess and slowly deposited where they replace normal tissue.

Different types of amyloidosis are caused by different types of proteins, such as "AL" and "AA". In cardiac amyloidosis there may be associated conduction disturbances (changes in the way the cardiac electrical impulse is transmitted through the heart).

Cardiac amyloidosis usually occurs during primary or AL amyloidosis. Primary amyloidosis usually accompanies multiple myeloma, a blood disorder in which too much of a certain type of protein is produced. This excess protein is deposited in the heart and in other organs such as the kidney. Deteriorating kidney function also occurs.

The heart is less often compromised by secondary or AA amyloidosis. A type of secondary amyloidosis that involves the heart is senile amyloidosis. It is caused by overproduction of a protein different from both the AA and AL types. This protein is deposited mainly in the heart, but can also infiltrate blood vessels. Senile cardiac amyloidosis is becoming more common as the average age of the population increases.

Diagnosis

Micrograph showing fluffy extracellular material proven to be amyloid with congo red staining. H&E stain.
Micrograph showing senile cardiac amyloidosis. The amyloid is the red-orange extracellular material. Congo red stain.

Cardiac amyloidosis can be difficult to diagnose without invasive tests. The findings from clinical examination are not specific and may only indicate enlargement of the heart and fluid in the lungs.

Listening with a stethoscope may reveal lung crackles, heart murmurs, or other abnormal sounds. The liver may be enlarged and neck veins may be distended. The blood pressure may be low or may drop when rising to a standing position (orthostatic hypotension).

Heart enlargement, congestion of the lungs or the veins in the lungs, decreased movement and/or functioning of the heart, heart failure, or signs of amyloidosis in the heart and other organs may show on the following tests:

An ECG may reveal conduction disturbances, arrhythmias such as atrial fibrillation, ventricular tachycardia, or premature and ectopic beats.

An echocardiogram may be used to assess the thickness of the heart wall, the size of the chambers in the heart, and the ability of the heart to fill and pump blood. Sometimes an unusual texture of the heart muscle or the endocardium (the lining of the heart) can be seen as well.

A cardiac biopsy that reveals amyloid is the definitive test. As cardiac biopsy carries significant risks, the biopsy of other tissues may be diagnostic and tried first; amyloidosis is frequently confirmed by biopsy of the abdominal fat, kidney, or bone marrow. Amyloid is characteristically red-orange with congo red staining and has apple-green birefringence in polarized light.

Treatment

Physical activity may continue as long as the patient can tolerate it. Diet restrictions vary with the extent of cardiomyopathy and heart failure. These may include salt and/or fluid restrictions.

Diuretics (water pills) may be given to remove excess fluid. Digoxin should not be used, as cardiac amyloid patients are especially sensitive to digitalis induced arrhythmias. Daily weight measurement may be recommended. A weight gain of 3 or 4 pounds or more over 1 or 2 days can indicate excessive fluid accumulation.

Some people benefit from chemotherapy or prednisone.

A pacemaker may be needed if the conduction system is involved. When heart function is very poor, a heart transplant may be considered for some patients, but not those with AL type amyloidosis since their disease compromises many organs. In one type of secondary amyloidosis, liver transplantation is also required.

Prognosis

Cardiac amyloidosis is a chronic and progressive condition. A cardiologist may estimate the prognosis according to the thickness of the left ventricle and to the degree of restriction in the heart (cardiac stiffness). For primary amyloidosis, the median survival after diagnosis is about 2.1 years.

Complications include:

Epidemiology

Cardiac amyloidosis is more common in men than in women.

Notable cases

Robert Jordan, author of the Wheel Of Time series as well as several Conan the Barbarian stories was diagnosed with cardiac amyloidosis on March 23, 2006, and died of it on September 16, 2007.

Additional images

References

  1. ^ Nihoyannopoulos, P.; Dawson, D. (Dec 2009). "Restrictive cardiomyopathies.". Eur J Echocardiogr 10 (8): iii23-33. doi:10.1093/ejechocard/jep156. PMID 19889655.  
  2. ^ vanden Driesen RI, Slaughter RE, Strugnell WE (June 2006). "MR findings in cardiac amyloidosis". AJR Am J Roentgenol 186 (6): 1682–5. doi:10.2214/AJR.04.0871. PMID 16714659. http://www.ajronline.org/cgi/pmidlookup?view=long&pmid=16714659.  







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