Cardiac catheterization (heart cath) is the insertion of a catheter into a chamber or vessel of the heart. This is done for both investigational and interventional purposes. Coronary catheterization is a subset of this technique, involving the catheterization of the coronary arteries.

A small puncture is made in a vessel in the groin, the inner bend of the elbow, or neck area (the femoral vessels or the carotid/jugular vessels), then a guidewire is inserted into the incision and threaded through the vessel into the area of the heart that requires treatment, visualized by fluoroscopy or echocardiogram, and a catheter is then threaded over the guidewire. If X-ray fluoroscopy is used, a radiocontrast agent will be administered to the patient during the procedure. When the necessary procedures are complete, the catheter is removed. Firm pressure is applied to the site to prevent bleeding. This may be done by hand or with a mechanical device. Other closure techniques include an internal suture. If the femoral artery was used, the patient will probably be asked to lie flat for several hours to prevent bleeding or the development of a hematoma. Cardiac interventions such as the insertion of a stent prolong both the procedure itself as well as the post-catheterization time spent in allowing the wound to clot.

A cardiac catheterization is a general term for a group of procedures that are performed using this method, such as coronary angiography. Once the catheter is in place, it can be used to perform a number of procedures including angioplasty, angiography, and balloon septostomy.