Abstract

WHAT IS ECHOCARDIOGRAPHY?

Echocardiography evolved in the early 1950s, predominantly as a tool to help select patients for mitral valvotomy. Its pre-eminence in the 1990s arose from advances in microcomputing. These days the echocardiography machine is effectively a powerful computer, which uses ultrasound to image and map blood flow within the heart and great vessels.

Imaging

Most ultrasound entering the body is scattered or absorbed, but some is reflected back to the transducer at interfaces where the acoustic density of tissue changes. The two-dimensional echocardiographic image is therefore a map of the acoustic density of the heart, and it happens to resemble a pathological section. Two-dimensional imaging shows the anatomy and motion of the chambers and valves and can be used to measure wall thickness and cavity size (Fig. 1). The echocardiographer builds up a three dimensional image in his or her head, and formulae making geometric assumptions can be