The role of echocardiography in the differential diagnosis of the large heart (cardiomegaly)

The differential diagnosis of a large heart is a common clinical problem. Clinicians rely primarily on routine chest X-Rays for the estimation of cardiac size. The accuracy of this technique is however very limited mainly because only the external borders of the heart are visualized. Determination of chamber size is not possible with ordinary chest X-Rays. Reliance is entirely placed on the changes of one or two border forming walls of the chambers. For example, the estimation of the Left Ventricle is at best a very gross measurement. A radiologically large heart may be due to dilatation or hypertrophy secondary to valvular, congenital, myocardial ischemia or hypertensive heart disease. A heart may appear large because of pericardial effusion or pericardial mass or aneurysm of the left ventricle. Clinical examination with the help of a chest X-Ray complemented by a 12 lead ECG usually helps to narrow the diagnostic list, but one still remains very uncertain about the nature of the disease and which lumen or chamber is responsible for cardiomegaly.Investigative facilities such as angiography and cardiac catheterization and pericardiocentisis are very invasive. Skills and facilities for angiography and catheter studies are not common in the third world though they are essential to establish the diagnosis in cardiac haemodynamics. Echocardiography obviates the need for invasive investigations. It is possible to evaluate the size of chambers and functional anatomy of the heart without a single needle prick to the patient.