What are invasive and noninvasive procedures?

In noninvasive procedures, nothing penetrates your body except perhaps a needle to draw some blood from your arm. A good example is an electrocardiogram, in which electrodes are attached to the outside of your chest. Sometimes when your physcian suspects a major problem and you could be a candidate for surgery, an invasive procedure can give better and more reliable information than the noninvasive type. A good example of an invasive procedure is when a catheter a flexible, fine plastic tube is inserted through a blood vessel in the arm or leg. The physician pushes this flexible tube into the heart, most often to inject dye for an angiogram to find out where the blockages are in the heart’s arteries (the coronary arteries).