Early, Recent And Future Applications Of Echocardiography

In Cardiology the first use on ultrasound was described in 1953 by Inge Edler and Helmuth Herz in Lund, Sweden. They used the M-mode technique which is, in brief, the registration of moving echoes as recorded in a single ultrasound beam. Two dimensional (2D) real time echography appeared in the late sixties with mechanically and electronically swept spoundbeams. The linear- and phased array approaches are examples of electronic real time systems which today represent the majority of apparatus. Use of frequency analyses of the echoes allowed indication of blood velocity over the 2D image. This is called Colour Doppler where a colour coding separates velocity towards the transducer from blood velocity away from the transducer. This is very powerful since now 2D geometry becomes available together with the blood flow information. Echo contrast is an old technique to enhance the echo image at the location of the contrast fluid. This fluid contains small gas containing bubbles. Present use aims at better identification of cardiac chambers contours as well as myocardial perfusion. Semi invasive is the Trans Oesophageal Isographic (TEE) approach. Here a transducer is mounted at the tip of a long tube. It allows contact with the heart with improved image quality. The IntraVascular Ultrasound System (IVUS) uses echography at the tip of a catheter. Following this, techniques for real time 3D will be presented and a brief description of portable echo equipment is given.