What is a procainamide challenge testing for?

Reveals Arrhythmia . Procainamide is a local anesthetic that acts on sodium channels. In the heart muscle sodium channels play a central role in the excitability of myocardial cells. So if you are given a bolus of this drug, it has the ability to increase the detection rate of an arrhythmia without losing predictive value. Meaning if it can produce an arrhythmia you may have a condition that needs to be treated.