1 Most episodes of acute lower back pain are caused by muscle strain, such as from lifting a heavy object, a sudden movement or a fall. 2  The low back pain can be very severe and last for several hours, several days or even a few weeks.
3. Characteristics of the Normal ECG. It is important to remember that there is a wide range of normal variability in the 12 lead ECG. The following normal ECG characteristics, therefore, are not absolute. It takes considerable ECG reading experience to discover all the normal variants.
These diagnoses are considered to be the minimum knowledge necessary for competence in interpreting 12-lead ECGs. Items in the list are linked to topics in the ECG Outline of the Alan E. Lindsay ECG Learning Center or to ECG examples in the Image Index. Normal ECG.