|
|
Chronic
Chagas' Myocardiopathy (CCM)
Imaging
Diagnosis
In
20% of patients with severe chronic Chagas' myocardiopathy, the cardiac
size is normal or only slightly enlarged. Equally, some patients who
have severe heart disease clinically with cardiomegaly and advanced
atrioventricular block have few or no symptoms. There is good correlation
between the intensity of the microscopic changes and the degree of cardiac
enlargement. The size of the heart depends on the severity and location
of myocardial lesions and varies from normal to enormous dilatation
and hypertrophy.
In the early stages of heart failure, isolated dilatation of the left
ventricle may be present, since damage there is usually more severe
than in other chambers and it has a heavier work load. Loss of distensibility
of the left ventricular wall due to marked fibrosis may cause annular
dilatation and functional incompetence of the mitral valve, and restricted
diastolic filling of the left ventricle with resultant pulmonary venous
congestion. Dyspnea is then more marked and on chest x-rays the cardiac
contour, lung fields and hila resemble the radiographic appearance of
mitral and aortic valvular disease rather than a myocardiopathy (Fig.
4.29). At times, the left atrium may be quite prominent and an apical
systolic murmur may be present, imitating mitral insufficiency.
 ...
Fig. 4.29 Chronic Chagas' myocardiopathy in a 55-year-old
black Brazilian man. PA (A), right anterior oblique with barium
in the esophagus (B), and left anterior oblique views of the chest
(C) show marked generalized cardiac enlargement with prominence
especially of the left ventricle and left atrium. The latter causes a
prominent indentation upon the barium-filled esophagus in the RAO view,
and also elevation of the left main stem bronchus and straightening of
the left heart border on the PA view. There is minimal pulmonary vascular
congestion with some cephalization of venous blood flow. There is also
dilatation of the superior vena cava and a small right pleural effusion.
In such patients, loss of distensibility of the left ventricular wall
from fibrosis may cause functional mitral valve incompetence and restricted
diastolic filling of the left ventricle, with resultant pulmonary venous
congestion. The cardiac silhouette, pulmonary vasculature and hilar areas
may resemble the radiographic appearance of mitral and/or aortic valvular
disease rather than a myocardiopathy. Clinically, this patient had shortness
of breath, easy fatiguability, an enlarged liver, and weight gain for
the past year. The heart sounds were weak with a few premature beats.
No murmurs were heard. EKG showed slight sinus tachycardia, complete right
bundle branch block, left ventricular hypertrophy, a wide QT interval
and isolated premature ventricular contractions. Serologic reaction for
Chagas' disease (Machado-Guerreiro test) was positive. Necropsy showed
Chagas' cardiopathy with a heart weight of 650 gm, generalized cardiac
enlargement, right ventricular infarction, chronic passive congestion
of the viscera, hydrothorax and ascites, and partial denervation of the
esophagus and Auerbach plexi of the sigmoid colon. (Courtesy of Dr. Clovis
Simao, Sao Paulo).
|
|
