Cardiac amyloidosis causes


 * Associate Editor:

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 (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 (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.

Cardiac amyloidosis is the most typical restrictive cardiomyopathy, and it is also known as “stiff heart syndrome.” Much less frequently, cardiac amyloidosis leads to dilated cardiomyopathy.

Several lines of evidence indicate that the degree of myocardial dysfunction does not depend only on the extent of amyloid deposits but also on the biochemical characteristics of the amyloidogenic proteins which dictate the aggregation process.

Cardiac amyloidosis is more common in men than in women.