How Can You Tell if You Have White Mold or Efflorescence? First, look at the type of material on which you see the white substance. If you see it on anything other than concrete or masonry, itâs mold. Second, spray the substance with a little water in a spray bottle and simply wipe it with a rag.
Thus, as shown in electrophysiologic studies, PR interval prolongation (ie, first-degree AV block) may be due to conduction delay within the right atrium, the AVN, the His-Purkinje system, or a combination of these. Overall, dysfunction at the AVN is much more common than dysfunction at the His-Purkinje system.
The PR interval represents the time it takes for the impulse sent. from the SA node to travel to the ventricles. A segment refers to a period of time from the end of one wave to the. beginning of the next wave. For example, the PR segment represents the time of AV nodal delay and transmission to. the ventricles.