What is an angiogram for the heart?

Special Heart X-Ray: In this test, a tube (or catheter) is inserted through a small hole into an artery and passed to the heart where pressures can be measured and special dye can be injected. Blockages of dye flow are visible on x-rays and indicte artery blockages. The valves and contraction of the heart muscle are observed.

X-RayShadowsDyeBlood: Heart, blood & surrounding tissues all water densities & block x-ray photons ~same; thus no detail visible. However, if small amount x-ray absorbing dye is added to the blood, for a few seconds, while present, one can see shadows of the blood location & movement, depending where added. A thin long tube (catheter) is used so as to guide the dye to location doc chooses to visualize briefly with dye.

Contrast is: Injected into the heart arteries while x-ray movies are taken.