The 20th century witnessed a number of key breakthroughs that became cornerstones of the logic of the heart to this day – starting from Einthoven’s development of the electrocardiogram, which is the most widely used non-invasive diagnostic tool for detecting the electrical activity, structure, and function of the heart. Following Forssmann’s pioneering attempt of the catheterization into the heart, performed on himself in 1929, Cournand and Richards developed the catheterization technique on patients. Catheterization is a broadly used life-saving procedure that assesses pressure changes in the heart chambers, and other problems of the heart, especially those of coronary circulation, and is used for coronary intervention or angioplasty in cases of myocardial infarction. The next greatest innovation, by Edler and Hertz, is echocardiography, a non-invasive examination that made real-time “visualization” of the heart possible. Echocardiography is now an essential tool for medical diagnosis of the heart around the world. Results from these Nobel Prize-awarded innovations have significantly improved our understanding of heart diseases and their diagnosis, treatment, and prevention for over a century.