One of the procedures that can be performed by the transradial approach is angiography. The term “angiography” refers to “pictures” of the heart, although the procedure is used for more than just images of the heart and its structures -- it can also be used to measure the pressures and flow capacities in the different heart structures. The images are obtained by injection of a contrast dye through the catheter into the heart. The contrast dye is called “radiopaque” because it can be seen on x-ray film. In angiographic procedures, the dye permits the doctor to see moving, real-time x-ray images of the heart on the fluoroscope screen while the test is being performed.

One of the tests cardiac catheterization provides is a study of blood flow and pressures in the heart chambers and blood vessels leading into and away from the heart. Called a hemodynamics study, it evaluates blood flow, pressure and cardiac output. During this evaluation, the catheter is positioned in a heart chamber or one of the “great” vessels of the chest. Specific measurements that can be obtained with this technique include:

• Pressure changes in the heart chambers during each cardiac cycle or heartbeat.
• The location and degree of any resistance to flow through the valves or blood vessels.
• The amount of blood that is pumped out of the left ventricle during each cardiac cycle.

Another part of the catheterization study is coronary arteriography, which is the most authoritative test for coronary artery disease. Coronary arteriography involves injection of the radiopaque dye into the aorta and the coronary circulation, the arteries that supply blood to the heart muscle. X-ray pictures, called coronary arteriograms, are taken as the dye travels into the coronary arteries and show how well the dye passes into and through each vessel. Any narrowing of a vessel or obstruction to the flow of dye can be documented for the doctor’s evaluation. This information may include:

• Number of vessels affected by narrowing or obstruction
• Location of narrowing or obstruction
• Severity of obstruction