Tropical diseases Cardiac disease
Acquired valvular disease is still by far the commonest cause of cardiac pathology in the tropics
and essential hypertension is widespread. However, there are several cardiac diseases which are specific to the tropical countries: it is not possible to describe all of them in detail here, but they must be distinguished from many of the common, nontropical cardiac problems.
Cardiomegaly
An enlarged heart in South America may be due to Chaga's disease, but in Africa cardiomegaly may be due to idiopathic endomyocardial fibrosis, which can be predominantly right- or left sided. Alternatively,
idiopathic cardiomegaly can occur as an acute or chronic disorder of unknown aetiology. A different problem is the subvalvular aneurysms which can occur below the aortic and mitral valves. They can be single or multiple and are also of unknown aetiology. Such aneurysms are often a chance radiological or echocardiographic finding, or even first recognised at autopsy. On an erect frontal chest radiograph, the large heart may have a significant bulge, usually on the left
cardiac border, perhaps only clearly seen on an oblique or overpenetrated film: there may seem to be a double
cardiac contour (Fig. 34).
Calcification can occur in the aneurysms. The distorted
cardiac outline can be mistaken for a pericardial
cyst or for rupture of the
sinus of Valsalva. Careful
echocardiography will usually confirm the diagnosis, but if surgery is to follow, angiocardiography or
cardiac MRI may be required.
Philip E.S. Palmer, with Stanley P. Bohrer, Carlos Bruguera, Xing-Rong Chen, Mahmoud R. EImeligi, Hassen A. Gharbi, S.B. Lagundoye, M. W. Wachira