When it's necessary to evaluate the heart for complex blood pressure problems, blood oxygen supply, or blood vessel disease, cardiac catheterization (cath-eh-ter-ih-ZAY-shun) may be used.

Sometimes the heart is suspected of having abnormal pumping action, or its surrounding membrane is thought to be atypically thickened, diseased, or filled with fluid.

The heart muscle beats in response to electronic impulses that originate in specific sections of heart tissue. These signals can be measured, recorded, and evaluated to detect the presence of abnormalities associated with heart disease.

Certain heart conditions are not easily identified when the heart is at rest, but quickly become evident during exercise. For example, a heart with obstructed arteries may receive sufficient blood supply while relaxing, but suddenly reveal ischemia (iss-KEE-mee-uh) or insufficient blood supply as the level of pumping activity increases.

Sometimes, heart disease and abnormalities don't occur continuously, but only for brief intervals, making them difficult to identify and correct. For example, the heart may beat in an irregular pattern for a few minutes, then return to normal.

If a person experiences significant but unexplained chest pain, or if narrowing of blood vessels is suspected, it may be helpful to observe the heart's blood flow in cross section or as a three dimensional image.