The non-specific
nature of the term "cardiomyopathy" allows a number of diseases
directly or indirectly affecting myocardial function to be included
under this heading. Many of these are rare, but the echocardiogram
may be very useful in identifying patients with certain forms of
cardiomyopathy. In general, echocardiography can detect any gross
alterations they may cause in the structure or functioning of the
heart, but such findings are likely to be non-specific.
 |
| Fig. 26 |
Many cardiomyopathies are the result of infiltrative disorders
that result in regional or global left ventricular thickening.
One such disorder is sarcoidosis (Fig.
26), where the echocardiogram may reveal regional abnormalities.
As a rule, however, most infiltrative cardiomyopathies affect
all the myocardium. Amyloid infiltration of the myocardium usually
presents a striking picture of marked left ventricular wall thickening
(usually with normal cavity size), pericardial effusion and a
very reflective myocardium (Fig.
27).
 |
| Fig. 27 |
While this appearance is non-specific, echocardiography provides
a readily available method for identifying patients with infiltrative
cardiomyopathy. Endomyocardial biopsy may be needed to provide
more specific diagnostic information.
 |
| Fig. 28 |
The fact that many infiltrative cardiomyopathies have similar
echocardiographic
manifestations is shown in (Fig. 28). Here, a severely thickened and
highly reflective myocardium is seen in an infant with Pompe's disease,
a rare autosomally recessive inherited disorder of glycogen storage.
As is obvious from the echocardiographic appearance of these disorders,
infiltrative cardiomyopathies are also referred to as "restrictive
cardiomyopathies". The markedly thickened myocardium impairs its
elasticity and results in significant difficulties of filling the
ventricle in diastole but with more or less normal systolic contraction.
As in the last figure that depicted a patient acutely dyspneic at
birth, the echocardiogram frequently identifies genetic difficulty.
 |
| Fig. 29 |
Some restrictive cardiomyopathies do not result from thickening
of the muscle. Endocardial fibroelastosis (EFE) is manifest by marked
endocardial thickening (Fig. 29) and normal (or thin) myocardium.
This echocardiographic appearance is virtually diagnostic of this
uncommon disorder.
Other, non-restrictive cardiomyopathies also occur. Entities such
as idiopathic dilated cardiomyopathy result in global dilatation,
wall thinning and hypocontractility that are echocardiographically
the same as shown previously in Fig. 19. Severe ischemic cardiomyopathy
may end in the same pattern. Inflammatory disease of the myocardium,
or myocarditis, may be caused by a wide variety of bacterial and
viral agents. Some forms are associated with specific cardiac abnormalities;
for example, complete heart block in Chagas' disease and hydatid
cysts in Echinococcus infection. The majority, however, do not cause
specific echocardiographic abnormalities. The findings may mimic
a dilated cardiomyopathy as a result of depressed myocardial function.
Serial echocardiographic studies can be useful in monitoring the
progress of the disease. Echocardiographic monitoring of left ventricular
function is also of value in patients who are being treated with
immunosuppressive or cytotoxic drugs.
2004