Cardiologists are doctors who specialize in the diagnosis, prevention and treatment of conditions related to the heart and blood vessels. A patient may be referred to a cardiologist if he experiences symptoms like chest pains, shortness of breath, dizziness, or high blood pressure. The physician will then evaluate your symptoms, take your health and family history and your weight. The cardiologist may order additional diagnostic tests, such as an echocardiogram, X-ray or blood tests. If necessary, the cardiologist may also call for a cardiac catheterization - a procedure in which a small tube is inserted into or near the heart that can take pictures of the heart's activity, or relieve blockage. Once determining whether there is a heart condition, a cardiologist will treat a patient through cholesterol management, cardiac rehabilitation, and fitness. If surgical intervention is required, like open-heart surgery, a cardiologist will make that determination, but a cardiothoracic surgeon will perform the procedure.

A family practitioner is a doctor who specializes in caring for people of all ages, at all stages of life. Rather than focusing on the treatment of one disease or patient population, family practitioners are often the doctors that people see for their everyday ailments, like cold and flu or respiratory infections, and health screenings. When necessary, family practitioners will provide referrals for conditions that require the expertise of another specialist.The doctors may also provide physicals, inoculations, prenatal care, treat chronic diseases, like diabetes and asthma, and provide advice on disease prevention.

An infectious disease specialist has specialized training in the diagnosis and treatment of contagious diseases.Infectious diseases, also known as contagious or transmissible diseases, are those that stem from pathogen from a host organism. These infections may spread to other carriers through physical touch, airborne inhalation, bodily fluids or contaminated foods.Infectious disease specialists identify whether the disease is caused by bacteria, a virus, a fungus or a parasite often through blood tests and then determine what course of treatment, if any, is necessary.

An internist is a physician who focuses on the diagnosis and treatment of conditions that affect the adult population—both acute and chronic.These doctors are often who adults see as their primary physicians because they treat a broad range of illnesses that do not require surgical or specialist interventions. They also work to help a patient maintain optimal health in order to prevent the onset of disease.In addition to treating the common cold and flu, internists also treat chronic diseases like diabetes and heart disease.