(Figs 1a and 1b)
(Figs. 2a and 2b)
(Figs 1a and 1b)
(Figs. 2a and 2b)
Click on Images for Enlarged View
Findings: The PA and lateral chest x-ray shows marked enlargement of the cardiac silhouette. The course of the unipolar pacer suggest marked right atrial enlargement. There is a "double density" and splaying of the carina c/w left atrial enlargement (Fig. 1a and b). The CT shows massive enlargement of the right and left atria (Fig 2a.), with marked enlargement of both the coronary sinus and great cardiac vein (Fig 2b.) The ventricles are of normal size.
Diagnosis: Rheumatic heart disease.
Discussion: The differential diagnosis of right atrial enlargement includes tricuspid insufficiency secondary to bacterial endocarditis (often seen in IV drug abusers), carcinoid syndrome, hyperthyroidism and Ebstein's anomaly. When coupled with the presence of a giant left atrium, rheumatic heart disease should be a primary consideration. In the setting of right atrial enlargement and tricuspid valve disease, it is important to determine the state of the right ventricle. The most common cause of tricuspid valve disease is secondary to right ventricular failure/pulmonary artery hypertension. It is important to consider right ventricular disease in the evaluation of tricuspid valve disease.
This patient also showed CT evidence of a component of tricuspid insufficiency, with enlargement of the intrahepatic IVC and reflux of contrast into the IVC following the patients subclavian vein injection. Tricuspid insufficiency can cause a mottled appearance of the liver in early phase of the contrast bolus, and can occasionally mimic metastatic disease of the liver.
Rheumatic heart disease has a number of classic radiographic findings, including the "double density" of the enlarged left atrium, the splaying of the mainstem bronchus, and posterior displacement of the left lower lobe bronchus and left atrial enlargement on the lateral film. Left atrial appendage enlargement is felt to be highly suggestive of mitral stenosis secondary to rheumatic heart disease.
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