In the mid-seventies, echocardiographic devices for clinical use have been developed to generate real-time cross-sectional images of the heart with a rate of about 30 frames per second. This technique improved the diagnostic power of M-mode echocardiography by visualizing the chambers, valves and walls of the heart in a variety of planes. Cross-sectional echocardiography provides important information for example in the evaluation of left ventricular function, diagnosis of congenital heart diseases, endocarditis, hypertrophic cardiomyopathies, cardiac tumors and others, that cannot be determined adequately by M-mode echocardiography alone.
