Cardiac Catheterization: This is a procedure to examine blood flow to the heart, measure blood pressure within the heart and test how well the heart is pumping. A cardiologist inserts a catheter (thin plastic tube) into an artery or vein in the arm or leg. From there it can be advanced into the chambers of the heart or into the coronary arteries. Coronary angiography is when a catheter is used to inject dye into the coronary arteries.