Cardiologists are physicians who diagnose and treat heart diseases and cardiovascular ailments. It usually takes 10-13 years to become a cardiologist. They specialize in treating diseases like congenital heart defects, heart failure, coronary artery diseases, and valvular heart diseases. They only work with people who need special heart-related care or have had heart-related conditions earlier. A cardiologist will often focus on one type of patient. An adult cardiologist sees only adult patients. Likewise, a pediatric cardiologist sees only infant, child, or teen patients. Cardiology job is one of the most complex fields in medicine, therefore many cardiologists specialize in different areas. All cardiologists are clinical cardiologists who focus on the diagnosis, medical management, and prevention of cardiovascular diseases.