query: Do cardiologists have to do surgery?
passage: Cardiology
All cardiologists study the disorders of the heart, but the study of adult and child heart disorders are through different training pathways. Therefore, an adult cardiologist (often simply called "cardiologist") is inadequately trained to take care of children, and pediatric cardiologists are not trained to take care of adult heart disease. The surgical aspects are not included in cardiology and are in the domain of cardiothoracic surgery. For example, coronary artery bypass surgery (CABG), cardiopulmonary bypass and valve replacement are surgical procedures performed by surgeons, not cardiologists. However the insertion of stents and pacemakers are performed by cardiologists
passage: Angiography
After an angiogram, a sudden shock can cause a little pain at the surgery area, but heart attacks and strokes usually don't occur, as they may in bypass surgery. A heart attack occurs when blood flow to a part of the heart is blocked, usually by a blood clot. Without oxygenated blood, the heart muscle begins to die. A stroke is a brain attack, cutting off vital blood flow and oxygen to the brain. Stroke happens when a blood vessel feeding the brain gets clogged or bursts.