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The most
common causes of dilation are conditions that directly damage the heart muscle.
The heart’s healing response is a thinning and stretching-out of the muscle.
Types of damage include prior heart attack, long-term alcohol abuse, and heart
muscle inflammation. Heart muscle inflammation, or myocarditis, is sometimes of
unknown cause and is often associated with a viral infection or interaction
between the immune system and the heart muscle. This immune reaction can be seen
with inflammatory diseases like lupus or toward the end of pregnancy
(approximately 1 in 4000 chance). Other sources of damage to the heart muscle,
which can lead to dilatation, include:
- Some types of cancer
chemotherapy
- Excess iron
accumulation in the body from the disease hemochromatosis
- Cocaine use
- Several of the
anti-viral medications used to treat HIV
- Some of the older
medications to treat schizophrenia
- Exposure to metals
like cobalt, lead, and mercury (an important consideration for those who work in
manufacturing processes that includes exposure to these metals)
Cardiac
dilation may also be associated with thyroid disease. There is a genetic form of
dilated cardiomyopathy, related to many of the several forms of muscular
dystrophy; in these, the disease process which affects and weakens body muscle
does the same to the heart muscle. Finally, problems with the heart valves can
cause abnormal cardiac dilation. In situations where the heart valves cannot
fully close, a condition called valvular regurgitation, a backflow of blood with
each heartbeat stretches out a chamber of the heart (typically the left atrium
or left ventricle), causing it to dilate over time. |
