[Crowbob]

For those not in the know, an EKG simply measures the electrical conductivity of cardiac muscle. High conductivity equals healthy tissue. Low, of course, equals unhealthy tissue. Unhealthy tissue results from inadequate vascularity and diminished blood-flow which itself results from clogged cardiac arteries (i.e, coronary atherosclerosis).

A myocardial infarction (MI) means some heart muscle tissue did not get enough blood and died. A transmural MI means the heart muscle died all the way through the muscle wall from inside the heart to the outside of the heart. When that happens the muscle cannot contract with sufficient force so that the heart does not pump blood efficiently.

An exercise EKG (stress test) measures electrical conductivity while stressing the heart muscle.