The heart in Chagas' disease
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|The heart in Chagas' disease|
|This is a higher-power photomicrograph of an H & E stained heart biopsy from this patient. Note the T. cruzi amastigotes (arrows) within this longitudinal section of a myocyte. |
Image courtesy of Professor Peter Anderson DVM PhD and published with permission © PEIR, University of Alabama at Birmingham, Department of Pathology
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Chronic Chagas' disease leads to congestive heart failure. These patients commonly have right bundle branch block and/or other arrhythmias. These hearts are dilated and hypertrophied, have areas of fibrosis especially in the apex, and often contain mural thrombi. The myocardium is infiltrated with lymphocytes and macrophages and there is interstitial edema and fibrosis. This inflammatory reaction is most severe around the area of the right bundle branch. Patients may also develop megaesophagus and/or megacolon.   
Acute form of Chagas Disease
In a patient with diagnosed Chagas disease, cardiac damage is suspected if one or more following ECG findings occurs:
- Right bundle-branch block (RBBB),
- Left anterior fascicular block (LAFB),
- Atrio-Ventricular blocks
- Multifocal PVCs
- Sinus bradycardia
- Abnormal ST segment and / or T wave changes
- Abnormal T and / or Q waves
Chronic form of Chagas Disease
The histologic diagnosis of Chronic Chagas cardiomyopathy (CCM) consists of a diffuse and patchy chronic myocarditis, interstitial mononuclear cell infiltrates, and myocardial fiber destruction with fibrotic replacement. Grossly enlarged hearts have been found in autopsy studies in subjects with end stage of Chagas disease. Left ventricular apical aneurysms are also frequently found on autopsy.
The degree of myocardial fibrosis increases progressively from the mildest to the most severe disease stages. Additionally, myocardial fibrosis correlates inversely with left ventricular ejection fraction and clinical status.
Cardiac MRI may demonstrate myocardial involvement (hyperenhancement) among seropositive patients without clinical symptoms or left ventricular wall motion abnormalities.
Across groups A-D, coronary angiography is usually normal or shows minimally obstructive disease.
Case Example: Heart Involvement in Chagas Disease
A 12-year-old boy, whose family had recently emigrated from Brazil, presented to the emergency room with a three-day history of malaise, fever, anorexia, and edema of the face and upper extremities.
On physical examination the patient had generalized lymphadenopathy and hepatosplenomegaly.
The patient was tachycardic and dysgenic with signs of congestive heart failure.
A cardiac biopsy was performed which revealed an active myocarditis with leishmanial forms of parasitic organisms within cardiac myocytes.
Close examination of peripheral blood smears revealed occasional circulating trypomastigotes. A complement fixation test for antibodies to Trypanosoma cruzi was strongly positive.
- Acquatella H, Echocardiography in Chagas Heart Disease, Circulation. 2007;115:1124-1131
- Mady C, Ianni BM, Arteaga E, et al. Relation between interstitial myocardial collagen and the degree of clinical impairment in Chagas’ disease. Am J Cardiol 1999;84:354–6.
- Rochitte C. E., Oliveira P. F., Andrade J. M. et. al. Myocardial Delayed Enhancement by Magnetic Resonance Imaging in Patients with Chagas Disease; a Marker of Disease Severity. J Am Coll Cardiol 2005; 46: 1553-58