If you're having a heart attack or experiencing the painful grip of chest pain, chances are the doctor who treats you will be a cardiologist -- one of the more than 10,000 physicians nationwide who specialize in treating diseases of the heart and cardiovascular system.

About one in every 48 doctors in the United States is a cardiologist. To qualify, a physician spends five to six years training after medical school, and must pass at least one examination given by the National Board of Medical Examiners.

Cardiology is dominated by white males -- just three percent are women and less than two percent are black, reports the American Medical Association. The majority are 30 to 59 years of age. Exact income figures are not available, says the AMA, which offers instead the 1983 average annual income for internal medicine, of which cardiology is a sub-specialty: $93,300 after expenses and before taxes.

Cardiologists don't perform heart surgery -- that is the domain of thoracic surgeons and cardiac surgeons -- but they often do techniques which require entry into the body. Among the most dramatic: threading a catheter through blood vessels in the leg up to heart and injecting new drugs able to dissolve blood clots during a heart attack.