Cardiologists typically work as members of much larger patient teams that include general practitioners and other specialists. In most places, people who worry that they are having trouble with their hearts or who have symptoms of cardiac problems like shortness of breath or chest pressure must first be evaluated by a general physician who in turn makes a referral to a cardiologist. If the cardiologist discerns that something like an operation is required, he or she may again refer the patient to a cardiothoracic surgeon.
Referring a patient does not usually mean that a physician ends communication or care, though. Most cardiologists stay in very close communication with all people involved in treating a particular patient. On a practical level, this means that he or she must regularly brief these other professionals about what is going on, and must also take their recommendations and advice into account when drawing up treatment plans.