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.
QT Prolongation. Recognition of a prolonged QT interval is complicated by the problems inherent in identification of T wave end and the inaccuracy of Bazlet's formula for correcting for heart rate. It may be preferable to judge the QT interval by changes in length or when it exceeds 50% of the R-R interval.T prolongation can be due to rare hereditary abnormalities, to type Ia anti-arrhythmics such as quinidine, and to hypocalcemia or hypomagnesia. The importance of recognizing prolonged QT interval is that it is associated with PVC's, ventricular tachycardia and fibrillation (ie., vulnerability to lethal arrhythmia).