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.
Pharmacokinetic: The majority of drugs that potentially prolong the QT interval are hepatically metabolized by the cytochrome isoenzymes CYP3A4, 1A2, and 2D6, with CYP3A4 responsible for the metabolism of approximately 50% of all drugs.13 Most drugs that prolong the QT interval work in a concentration-dependent manner.