Over the last 30 years, echocardiography has arguably transformed cardiology more dramatically than any diagnostic test since the development of the electrocardiogram. With echocardiography, direct visualization of cardiac structures such as the atria, ventricles, valves, great vessels, and pericardium became possible. With the additional application of Doppler principles, besides structural information, echocardiography can now accurately estimate intracardiac blood flow and pressures.