A pediatric cardiologist diagnoses and treats heart disease in infants, children, and young adults. As a pediatric cardiologist, your responsibilities include reviewing patient medical history, ordering lab tests, and performing exams to assess the cardiac problem. Once you gather medical history and test results, you determine the best course of treatment to address the issues you detect. Depending on the condition of the heart, the treatment may range anywhere from a lifestyle or diet change to rehabilitation or cardiac surgery. You usually work with the patient through each step to prevent future disease or illness.