When I saw a cardiologist for the first time:
. An ultrasound
of my heart.
2. Holter Monitor
. A device with electrodes on your chest. You wear it for 24 hours and it provides an EKG (a reading of your heartbeats).
If your general physician referred you to a cardiologist, he/she may have already done bloodwork that might include a basic metabolic panel (http://www.webmd.com/a-to-z-guides/basic-metabolic-panel-topic-overview) and a simple short EKG (electrocardiogram) (http://www.webmd.com/heart-disease/electrocardiogram). This information will be sent to the cardiologist so he/she doesn't have to repeat those tests unless he/she chooses.
This website provides a good description of all the diagnostic testing a cardiologist might do: http://www.mercyunity.com/ahs/mercyunity.nsf/page/cardiac_testing